300bhp, 350lbs feet torque 944 3 litre turbo
Discussion
It's very interesting seeing the detailed explanations Barry, keep it up, don't feel too attacked!
I am interested in the driving experience. From your description of the gearchange rev points, it looks to me when you change up, the revs drop to about 4k. That is roughly peak torque, but then all the acceleration is done on falling torque. Is that the outcome you wanted? what driving characteristic does it give? If your drive ratios were such that the gear change dropped the revs to somewhere the other side of the torque peak, would the car feel more exciting as the acceleration would build before falling? Obviously going too far would mean driving through a torque hole.
Second question is that earlier on, I think you said that at higher revs where you got more power even with lower torque, your acceleration would still increase. I may have mis-understood, but I don't think that is correct. Not trying to nit-pick, just getting my understanding correct!
Ta
Bert
I am interested in the driving experience. From your description of the gearchange rev points, it looks to me when you change up, the revs drop to about 4k. That is roughly peak torque, but then all the acceleration is done on falling torque. Is that the outcome you wanted? what driving characteristic does it give? If your drive ratios were such that the gear change dropped the revs to somewhere the other side of the torque peak, would the car feel more exciting as the acceleration would build before falling? Obviously going too far would mean driving through a torque hole.
Second question is that earlier on, I think you said that at higher revs where you got more power even with lower torque, your acceleration would still increase. I may have mis-understood, but I don't think that is correct. Not trying to nit-pick, just getting my understanding correct!
Ta
Bert
Baz,
If you are making a statement car, is there any reason not to run the 968 6 speed box? We ran a s2 944t on one, and other than fitting (splined shaft's splines a different fit, but with enough "persuasiuon" it went on), it was a really good addition to the car.
We also moddded the rear end's anti roll setup, and used coilovers that made the torsion bar essentially redundant - the end result car handled like a dream.
Man, I miss that 944
Graham
If you are making a statement car, is there any reason not to run the 968 6 speed box? We ran a s2 944t on one, and other than fitting (splined shaft's splines a different fit, but with enough "persuasiuon" it went on), it was a really good addition to the car.
We also moddded the rear end's anti roll setup, and used coilovers that made the torsion bar essentially redundant - the end result car handled like a dream.
Man, I miss that 944
Graham
I'm loving the Engineering principles in practice and lapping up as much information as possible as I'm hoping to start a course in Mechanical Engineering in September. Great to see something I've experienced with the 3.2's acceleration put into numbers and justified too. My back side dyno wasn't too far out;)
333pg333: Having met Barry I can assure you he's one of the good guys not nearly as sharp as could be read in some posts. Text on forums can easily be miss read.
Sorry to talk about you in the third person Barry but really I think its his desire to explain why something has been done to your car rather than leave you in the dark assuming things that's coming across. I always appreciate someone taking the time 'if they have it' to tell me / show me why.
Jon is the same and I've learn't a lot from him over the years.
333pg333: Having met Barry I can assure you he's one of the good guys not nearly as sharp as could be read in some posts. Text on forums can easily be miss read.
Sorry to talk about you in the third person Barry but really I think its his desire to explain why something has been done to your car rather than leave you in the dark assuming things that's coming across. I always appreciate someone taking the time 'if they have it' to tell me / show me why.
Jon is the same and I've learn't a lot from him over the years.
333pg333 said:
Baz, thanks for the reply. You have me intrigued on the wet/dry combo but I completely understand the need to keep that confidential. So are you coating the pistons with a Nikasil finish too? My understanding is that while Nikasil and Alusil are similar, they're not identical...but I stand to be corrected. Do you retain the original cylinders or have you come up with an interlocking system to decrease propensity for flex? We have used a deckplate arrangement on my 3l motor (pic) but I like Jon's system too.
I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Patrick, was the block in the picture originally a 2.5 block ?.I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Edited by 333pg333 on Monday 9th November 11:17
Edited by 333pg333 on Monday 9th November 11:18
Paul.
Yes a 6 speed box and coil overs at the rear would be great, (although if I was using one I would alter the power band characteristics to suit and lift the maximum torque through more boost, or a bigger turbo, and a larger exhaust and accept a reduction in bottom end torque as a result. But as someone else needs to take over the project I am just leaving it for now so they can do whatever they want. There is loads more potential because the boost is modest and much more to come from the engine.
We don’t really need a 6 speed box to prove our point because the wide spread of power/torque makes up for it – but if the inlet and exhaust was opened up – the cam changed (mainly to reduce overlap), and the boost pressure raised I feel sure it would reach the levels others have also achieved.
Regarding the torque – my emphasis has slightly exaggerated the advantages to compensate for the much held and misunderstood belief that all you need is to raise the revs and top end breathing to produce a higher bhp figure than anyone else and your car is perfect!
I am trying to encourage people see another issue to take into account as well such as track speeds, gear ratios, rear wheel torque etc.
Although torque and the right spread of power is absolutely right – there is an issue with power pulses and strain energy that is too complex to explain fully but basically means that more frequent power pulses (i.e. higher revs) with slightly less actual force on the pistons, can result in less power lost in the mass of the system and in strain energy and for the engine itself to accelerate itself just as quickly with slightly less torque at higher revs than at lower revs with slightly more torque. So the ideal power band is actually one with a slightly falling torque at the top end and the best place for maximum torque is probably nearer the bottom end of the power band (the range within the gear change points). You will find anyway that all engines have a falling torque graph but usually an increasing power graph at the top end of the rev range – which is about right. The mass of the system anyway has a damping effect on the power delivery making these changes feel less noticeable.
We have just made more torque than that at the bottom end to save costs and to improve driveability and it seems to have worked.
Driving experiences can be recalled by those driving the car in the next few days but the engine just feels to deliver equal acceleration whatever the revs above about 3000 rpm.
Anyway I don’t think I said that a falling torque curve would accelerate faster than before – what I said was “For those that quite rightly immediately recognised the achievement and the benefits of such a pair of graphs – can I add that although acceleration is proportional to torque (if resistance is constant or the same between compared cars) there is a phenomenon inside an engine and its transmission that relates to the stored energy between individual power pulses and strain energy lost as a result. It means that in actual fact there is a slight benefit from slightly reduced torque if the number of revs is increased and the strain energy lost is reduced. Put into more simple terms it means that a small increase in bhp at high revs can offer a small improvement in acceleration even if the torque is slightly lower and putting it simply it means that the best torque or power curve for the fastest acceleration, is one in which the torque is dropping off while the power is still increasing between the gear change revs”. Perhaps I expressed it wrongly because what I meant was that even when the torque is falling slightly and the revs are still increasing the actual acceleration still feels the same.
There are also usually benefits from slightly over revving an engine on reducing torque or power so that the revs you pick up on when you change up are higher – if for that particular engine the torque or power you pick up on at those higher revs is significantly higher (which it usually is) – but our engine has possibly too much torque at the lower end to make this relevant and the overall result should certainly be able to be improved upon – but probably with more expense and devotion.
Baz
We don’t really need a 6 speed box to prove our point because the wide spread of power/torque makes up for it – but if the inlet and exhaust was opened up – the cam changed (mainly to reduce overlap), and the boost pressure raised I feel sure it would reach the levels others have also achieved.
Regarding the torque – my emphasis has slightly exaggerated the advantages to compensate for the much held and misunderstood belief that all you need is to raise the revs and top end breathing to produce a higher bhp figure than anyone else and your car is perfect!
I am trying to encourage people see another issue to take into account as well such as track speeds, gear ratios, rear wheel torque etc.
Although torque and the right spread of power is absolutely right – there is an issue with power pulses and strain energy that is too complex to explain fully but basically means that more frequent power pulses (i.e. higher revs) with slightly less actual force on the pistons, can result in less power lost in the mass of the system and in strain energy and for the engine itself to accelerate itself just as quickly with slightly less torque at higher revs than at lower revs with slightly more torque. So the ideal power band is actually one with a slightly falling torque at the top end and the best place for maximum torque is probably nearer the bottom end of the power band (the range within the gear change points). You will find anyway that all engines have a falling torque graph but usually an increasing power graph at the top end of the rev range – which is about right. The mass of the system anyway has a damping effect on the power delivery making these changes feel less noticeable.
We have just made more torque than that at the bottom end to save costs and to improve driveability and it seems to have worked.
Driving experiences can be recalled by those driving the car in the next few days but the engine just feels to deliver equal acceleration whatever the revs above about 3000 rpm.
Anyway I don’t think I said that a falling torque curve would accelerate faster than before – what I said was “For those that quite rightly immediately recognised the achievement and the benefits of such a pair of graphs – can I add that although acceleration is proportional to torque (if resistance is constant or the same between compared cars) there is a phenomenon inside an engine and its transmission that relates to the stored energy between individual power pulses and strain energy lost as a result. It means that in actual fact there is a slight benefit from slightly reduced torque if the number of revs is increased and the strain energy lost is reduced. Put into more simple terms it means that a small increase in bhp at high revs can offer a small improvement in acceleration even if the torque is slightly lower and putting it simply it means that the best torque or power curve for the fastest acceleration, is one in which the torque is dropping off while the power is still increasing between the gear change revs”. Perhaps I expressed it wrongly because what I meant was that even when the torque is falling slightly and the revs are still increasing the actual acceleration still feels the same.
There are also usually benefits from slightly over revving an engine on reducing torque or power so that the revs you pick up on when you change up are higher – if for that particular engine the torque or power you pick up on at those higher revs is significantly higher (which it usually is) – but our engine has possibly too much torque at the lower end to make this relevant and the overall result should certainly be able to be improved upon – but probably with more expense and devotion.
Baz
blade7 said:
333pg333 said:
Baz, thanks for the reply. You have me intrigued on the wet/dry combo but I completely understand the need to keep that confidential. So are you coating the pistons with a Nikasil finish too? My understanding is that while Nikasil and Alusil are similar, they're not identical...but I stand to be corrected. Do you retain the original cylinders or have you come up with an interlocking system to decrease propensity for flex? We have used a deckplate arrangement on my 3l motor (pic) but I like Jon's system too.
I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Patrick, was the block in the picture originally a 2.5 block ?.I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Edited by 333pg333 on Monday 9th November 11:17
Edited by 333pg333 on Monday 9th November 11:18
Paul.
Oil squirters installed as well. The deckplate is a work of art and looks better in person than pics.
Edited by 333pg333 on Tuesday 10th November 19:33
Keep up the good work Baz, I don't agree your stance though that ppl misunderstand things because they only know theory and don't have the experience to know the practise, apart from one post about mathematics perhaps which I recognised whilst correct in terms of analysing a graph was an odd description of torque (to me at least anyways). In life there are good engineers/scientists and bad engineers/scientists, the underlying science doesn't change but its easy to misapply it and make some duff decisions. I spent 7 years studying for a degree and PhD in Physics and tbh your description of what torque and power is isn't really any different to my understanding. The explanation you give for an idealised way to measure torque is AFAIK exactly how the other broad category of dynamometer, the braked dynamometer works. In its simplest form one could attach a spring balance that reacts to the twisting output of the motor, its torque in a nutshell in its purest form. You are 100% correct though IMHO in emphasising torque (twisting force) as of course the dictionary definition of power is the rate at which work is done (or energy converted). In a rotational system this rate is angular velocity hence the relationship between torque and power that most ppl can apply to their engine, its not a lucky fiction but a statement of basic physics
http://en.wikipedia.org/wiki/Power_%28physics%29
The definition of force though is basically F=m.a or Newtons 2nd law to me and perhaps most scientists. To my mind the simple sprung balance to measure torque directly is a neat example of Newtons 3rd law as the sprung balance is reacting to balance the force generated by the motor.
http://en.wikipedia.org/wiki/Newton%27s_laws_of_mo...
http://en.wikipedia.org/wiki/Power_%28physics%29
The definition of force though is basically F=m.a or Newtons 2nd law to me and perhaps most scientists. To my mind the simple sprung balance to measure torque directly is a neat example of Newtons 3rd law as the sprung balance is reacting to balance the force generated by the motor.
http://en.wikipedia.org/wiki/Newton%27s_laws_of_mo...
Couple of observations about gearing and transmissions. Seems like many of the high performance 951 racecars in the US switch to the 968 gearbox. I believe that some the gearsets are interchangeable with those from the G50 box as well which would be of great benefit to a race team. My feeling is that the
standard gear ratios of the 968 box are not ideal for a high tq/hp motor though. Prior to the Economic crisis that crushed many a budget (mine included) I bought a 996 GT2 tranny that I had modified to fit in a 'flipped' position (to avoid 6 reverse gears lol) and for a high performance motor the gearing would have been wonderful. Like the GT2, you could drive it on the torque. This was for a racecar project with a 3.5L motor but that is all but extinguished now. However I think that the wider spaced gearing would suit more applications than the shorter ratios of the 968 stock tranny.
Just to argue my own point, hey I'm allowed, my belief was that while the crown wheel and pinion from the 'S' gearbox was weaker I understood that the S2 was as strong as the Turbo cwp. Having used the S2 cwp in my stock 951 box allowed me to run a turbo kit from Vitesse that was designed for a 3L motor. Sort of a hybrid GT35 size. This would have been too big for a stock 951 2.5L motor, but the shorter final drive ratio made it quite useable. It was probably quite opposite the characteristics of Baz's build, however I ran this at 1.3 to 1.5 bar all the time on the track (on E85) and so far the S2 cwp held up. So for stock to medium modified 2.5L builds I think that having the shorter final drive ratio is great. Superb on the track as you don't have to wait to be in the 'meat' of the powerband. I enjoyed it on the street as well although on longer trips I certainly could have used an extra cog. If/when I finally get the 3L into a car I will probably go back to a stock ratio 951 box though to utilise the extra tq.
standard gear ratios of the 968 box are not ideal for a high tq/hp motor though. Prior to the Economic crisis that crushed many a budget (mine included) I bought a 996 GT2 tranny that I had modified to fit in a 'flipped' position (to avoid 6 reverse gears lol) and for a high performance motor the gearing would have been wonderful. Like the GT2, you could drive it on the torque. This was for a racecar project with a 3.5L motor but that is all but extinguished now. However I think that the wider spaced gearing would suit more applications than the shorter ratios of the 968 stock tranny.
Just to argue my own point, hey I'm allowed, my belief was that while the crown wheel and pinion from the 'S' gearbox was weaker I understood that the S2 was as strong as the Turbo cwp. Having used the S2 cwp in my stock 951 box allowed me to run a turbo kit from Vitesse that was designed for a 3L motor. Sort of a hybrid GT35 size. This would have been too big for a stock 951 2.5L motor, but the shorter final drive ratio made it quite useable. It was probably quite opposite the characteristics of Baz's build, however I ran this at 1.3 to 1.5 bar all the time on the track (on E85) and so far the S2 cwp held up. So for stock to medium modified 2.5L builds I think that having the shorter final drive ratio is great. Superb on the track as you don't have to wait to be in the 'meat' of the powerband. I enjoyed it on the street as well although on longer trips I certainly could have used an extra cog. If/when I finally get the 3L into a car I will probably go back to a stock ratio 951 box though to utilise the extra tq.
Wikipedia seems to be getting pretty good these days;
http://en.wikipedia.org/wiki/Torque
Something Baz said earlier that is very important because it is easily missed. He made the point about a motor in the steady state e.g. cruising along at 70mph. As he correctly pointed out this engine still has torque, the reader should carefully note the section "Relationship between torque, power and energy" in the above article.
http://en.wikipedia.org/wiki/Torque
Something Baz said earlier that is very important because it is easily missed. He made the point about a motor in the steady state e.g. cruising along at 70mph. As he correctly pointed out this engine still has torque, the reader should carefully note the section "Relationship between torque, power and energy" in the above article.
hartech said:
Although torque and the right spread of power is absolutely right – there is an issue with power pulses and strain energy that is too complex to explain fully but basically means that more frequent power pulses (i.e. higher revs) with slightly less actual force on the pistons, can result in less power lost in the mass of the system and in strain energy and for the engine itself to accelerate itself just as quickly with slightly less torque at higher revs than at lower revs with slightly more torque.
Hi Baz, as someone with a motorbike engine background are you basically describing in effect what the Japanese did with very high revving but reliable motors. You obviously know the details better then anyone on here but ISTR they keep peak cylinder pressures relatively low and generate a lot of power through very high rpms. The approach with turbocharged engines of having a relatively low maximum rpm's and high torque was of course exploited for many years by the Swedes. I had a book written by a Saab chief engineer that explained all their thinking and logic but I stupidly gave it away.333pg333 said:
I bought a 996 GT2 tranny that I had modified to fit in a 'flipped' position (to avoid 6 reverse gears lol) and for a high performance motor the gearing would have been wonderful.
Sorry to jump in out of nowhere, but that's very interesting, did you test fit the GT2 tranny? I.e would it all just bolt up, or did you have to fabricate an adaptor plate, and sort out the thrust bearing, spline alignment, etc etcTo add to the general theme of this thread, as a current 944 Turbo owner, and a previous Ultima GTR owner, I can definately attest to the benefits of the wider torque band from a larger displacement engine on one's driving style, on track or road. The ability to drive longer in a gear before changing is something I definately miss about the GTR. I had a G50/21 6 speed in the GTR and was pretty much able to use 2nd as a first gear, and go from 2nd-4th-6th, skipping 3rd and 5th, due to the wide torque band of the V8, any VMax runs I made were done in this fashion. Plus the extra shove from the low down torque was a great way to make up lost ground coming out of a corner or gave you a gap before you need to make a gear shift and loose ground to the car behind.
just my 0.02 worth...
333pg333 said:
blade7 said:
333pg333 said:
Baz, thanks for the reply. You have me intrigued on the wet/dry combo but I completely understand the need to keep that confidential. So are you coating the pistons with a Nikasil finish too? My understanding is that while Nikasil and Alusil are similar, they're not identical...but I stand to be corrected. Do you retain the original cylinders or have you come up with an interlocking system to decrease propensity for flex? We have used a deckplate arrangement on my 3l motor (pic) but I like Jon's system too.
I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Patrick, was the block in the picture originally a 2.5 block ?.I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Edited by 333pg333 on Monday 9th November 11:17
Edited by 333pg333 on Monday 9th November 11:18
Paul.
Oil squirters installed as well. The deckplate is a work of art and looks better in person than pics.
Edited by 333pg333 on Tuesday 10th November 19:33
Edited by blade7 on Wednesday 11th November 00:28
Peter, no we didn't get as far as trial fitting it but we knew already that it would take some fabrication to make it work. One of the people I deal with was going to CNC an adapter plate up and actually try and build a frame that would hold the tranny and essentially weld it up, but as I said, we never got that far. It is still in the crate in the US fully factory rebuilt looking brand new. I could still contemplate using it, but my fear was that as I'd lost so much money with the G.E.C. that if something went wrong with the gearbox it would cost significantly more to repair than a 951 tranny. On the other side of the same coin you might contend that it is going to be so much stronger than a 951/968 tranny that nothing would go amiss. My inclination is still to sell it for a good price and put that into other parts of the upcoming project. Shame, as I believe that this incoming 3L motor will easily be within reach of 600bhp and this tranny would have suited it in many ways.
The Ultima was one of the cars that inspired me to go down this path.
To add to the general theme of this thread, as a current 944 Turbo owner, and a previous Ultima GTR owner, I can definately attest to the benefits of the wider torque band from a larger displacement engine on one's driving style, on track or road. The ability to drive longer in a gear before changing is something I definately miss about the GTR. I had a G50/21 6 speed in the GTR and was pretty much able to use 2nd as a first gear, and go from 2nd-4th-6th, skipping 3rd and 5th, due to the wide torque band of the V8, any VMax runs I made were done in this fashion. Plus the extra shove from the low down torque was a great way to make up lost ground coming out of a corner or gave you a gap before you need to make a gear shift and loose ground to the car behind.
just my 0.02 worth...
The Ultima was one of the cars that inspired me to go down this path.
peterpsg said:
333pg333 said:
I bought a 996 GT2 tranny that I had modified to fit in a 'flipped' position (to avoid 6 reverse gears lol) and for a high performance motor the gearing would have been wonderful.
Sorry to jump in out of nowhere, but that's very interesting, did you test fit the GT2 tranny? I.e would it all just bolt up, or did you have to fabricate an adaptor plate, and sort out the thrust bearing, spline alignment, etc etcTo add to the general theme of this thread, as a current 944 Turbo owner, and a previous Ultima GTR owner, I can definately attest to the benefits of the wider torque band from a larger displacement engine on one's driving style, on track or road. The ability to drive longer in a gear before changing is something I definately miss about the GTR. I had a G50/21 6 speed in the GTR and was pretty much able to use 2nd as a first gear, and go from 2nd-4th-6th, skipping 3rd and 5th, due to the wide torque band of the V8, any VMax runs I made were done in this fashion. Plus the extra shove from the low down torque was a great way to make up lost ground coming out of a corner or gave you a gap before you need to make a gear shift and loose ground to the car behind.
just my 0.02 worth...
blade7 said:
333pg333 said:
blade7 said:
333pg333 said:
Baz, thanks for the reply. You have me intrigued on the wet/dry combo but I completely understand the need to keep that confidential. So are you coating the pistons with a Nikasil finish too? My understanding is that while Nikasil and Alusil are similar, they're not identical...but I stand to be corrected. Do you retain the original cylinders or have you come up with an interlocking system to decrease propensity for flex? We have used a deckplate arrangement on my 3l motor (pic) but I like Jon's system too.
I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Patrick, was the block in the picture originally a 2.5 block ?.I like how you've integrated the gear ratios with the torque curve and appreciate the need or desire to do so. I have owned one of those more peaky type motors and they do require a certain driving style, not to mention a lot of suspension mods.
Patrick
Edited by 333pg333 on Monday 9th November 11:17
Edited by 333pg333 on Monday 9th November 11:18
Paul.
Oil squirters installed as well. The deckplate is a work of art and looks better in person than pics.
Edited by 333pg333 on Tuesday 10th November 19:33
Edited by blade7 on Wednesday 11th November 00:28
Maybe if I win one of those lotteries similar to that one that just went off in the UK
I was trying to find another 3L dyno sheet but all I could come up with was this. It was a first tune of a new motor and LINK standalone. Stock extractors and lesser turbo. Only running 9psi @ 5000 rpm too so turbo, cam etc had barely woken up. 
Edited by 333pg333 on Wednesday 11th November 08:35
Just recently got in from an excellent day out at Oulton Park with Barrys 3 litre creation and a number of Front engined fans. The morning started out very damp, misty and cold and there were several red flag stoppages early on due to people not minding the conditions. Paul F (who drives a 968 in the Porsche Club Champoinship) took to the wheel first thing and the rest of us waited whilst he warmed up the tyres and started to clear a dry line for us 
When my turn came round, I could instantly feel just how smooth this engine is. A standard 2.5 Turbo can often get bogged down if you take off too leisurely, but the low down grunt from an extra 500cc removes that entirely and yields a more accomplished drive. Once used to the slippy track and able to push on a little more you can really feel the low down 'shove' that this engine gives you. Slow corners that would normally be taken in 2nd gear can easily be taken in third, giving you much more control, much less gear changing and I believe a much faster drive onto the next straight. Yes the huge power does not increase further in the higher reaches of the rev range but that could be addressed if the owner wanted to exploit this setup further.
Boost was a totally standard 0.8 bar and in 3rd and 4th gear it was hitting that well below the 3500rpm of a standard 2.5 but the most remarkable thing is the smooth way in which the boost arrives. No bang, crash, on/off wallop like the car that Porsche built back in the 80's. If you like your turbo cars to behave like that then Barrys 3 litre creation is not for you
. This car is more like the effortless way that an S2 performs, but has 50% more power everywhere with no obvious lag.
Well done Baz, and thanks for a great day out. Others may now be very interested to hear that he has already tentatively started thinking about machining liners to turn any 2.5 car into a 3 litre like this. I appplaud any effort to keep these wonderfully balanced cars going as long as possible, and if it brings more power at the same time then who can complain. I've taken a few photo's of the day and also have some in car footage which I'll hopefully post at the weekend when I've had a chance to edit it down and upload to the web.
When my turn came round, I could instantly feel just how smooth this engine is. A standard 2.5 Turbo can often get bogged down if you take off too leisurely, but the low down grunt from an extra 500cc removes that entirely and yields a more accomplished drive. Once used to the slippy track and able to push on a little more you can really feel the low down 'shove' that this engine gives you. Slow corners that would normally be taken in 2nd gear can easily be taken in third, giving you much more control, much less gear changing and I believe a much faster drive onto the next straight. Yes the huge power does not increase further in the higher reaches of the rev range but that could be addressed if the owner wanted to exploit this setup further.
Boost was a totally standard 0.8 bar and in 3rd and 4th gear it was hitting that well below the 3500rpm of a standard 2.5 but the most remarkable thing is the smooth way in which the boost arrives. No bang, crash, on/off wallop like the car that Porsche built back in the 80's. If you like your turbo cars to behave like that then Barrys 3 litre creation is not for you
. This car is more like the effortless way that an S2 performs, but has 50% more power everywhere with no obvious lag.Well done Baz, and thanks for a great day out. Others may now be very interested to hear that he has already tentatively started thinking about machining liners to turn any 2.5 car into a 3 litre like this. I appplaud any effort to keep these wonderfully balanced cars going as long as possible, and if it brings more power at the same time then who can complain. I've taken a few photo's of the day and also have some in car footage which I'll hopefully post at the weekend when I've had a chance to edit it down and upload to the web.
Paul, thanks for a 'real world' account of Baz's car. Sounds a very convincing argument for those that don't want the real on-off feeling. Perhaps Oli might consider the switch
I hope to read of others who utilise Baz's expertise and move up to a larger capacity motor. You just have to drive one of these 3L to see what the fuss is about and it would seem that Baz might have come up with the most affordable version.
Good stuff.
I hope to read of others who utilise Baz's expertise and move up to a larger capacity motor. You just have to drive one of these 3L to see what the fuss is about and it would seem that Baz might have come up with the most affordable version.
Good stuff.
My Report on the track test day.
A success, an experience and I learned a lot from it too.
Firstly a very strange coincidence – we rushed to grab a pit garage and there – sharing it with us – was the very person who I posted about recently - who originally owned the first 944 turbo we sold, tried to track it and found it too difficult to get out of the corners – that stimulated this project and there I was some 10 years later with the same model of car – having solved the problem – and he still has the 944 – spooky or what!
I was quite apprehensive about the engine working Ok and the conditions being too bad - when the track was damp, slippery (tree lined circuit in Autumn) and several red flags incidents, and here we were testing a bog standard car with huge torque on standard tyres! The whole idea was to invite others to test the car so the feedback was objective and impartial and so I decided not to drive myself. Although I would have been ok as long as nothing untoward happened – I was not confident that I would have had the right reactions if the torque spun the rear or a car in front spun in front of us in those conditions – and wanted the car to get through the test day in one piece.
Paul Follett was brilliant (thanks again Paul) he kind of took over the organisation of the day and calmly got things ready and set a professional stamp on the day which helped towards its success.
I did passenger and from that seat it was very clear that the engine did do what I wanted. From the hairpin at 2,700 rpm in third (around 40mph) the car would accelerate as quickly as the tyres would stand, under control, all the way to 6K. As I suspected we only used 3rd and 4th (except a brief snatch at second for the chicane). I was surprised how “short” the circuit had become with the chicane – virtually 6 short straights and tight bends and almost only using 2 speeds. With the box ratios allowing 4th to peak out just before most of the corners (so I think a lower pinion ratio may have not suited that particular circuit) although if it had 6 speeds and all that power band – you could always be in the perfect gear and the gear change is quicker in the newer boxes.
We had set the geometry as Paul wanted and it was spot on (tyres running even temperatures across the faces) and the lowering of the front he wanted - kept the tendency for the rear to squat under power - more under control.
Paul Smith drove and confirmed the power band was much as he expected from his own more powerful 3.2 version and I look forward to seeing the footage he took.
Later in the day the track dried enough for Paul Follett’s stickier club tyres and the car continued to take everything we could throw at it in a completely fuss free and relaxed way.
It helped me solve a problem that I didn’t fully appreciate before. Knowing that the std version with a bleed of valve fitted would spin up the rear wheels so easily, despite believing that a smoother torque delivery may be better or not spin at all (and reading the postings that others said the 50/50 weight distribution didn’t prevent the rear wheels gripping) I was still pondering on why all this extra torque didn’t spin up the wheels. If we wanted to spin them in a standard car we would snatch at the clutch because shock loading doubles the effective load - but we had double the torque so I kind of expected that to still be a small problem - but it wasn't at all. Then I realised that – just like a motorcycle doing a wheely – if the torque delivery is smooth enough to maintain traction (despite it being high torque) the torque reaction of the car is to transfer the weight to the rear wheels and lift the front – as given enough grip and torque – it too would eventually wheely like a motorcycle). Following one of the main Laws of physics (to every action there is an equal and opposite reaction) and providing the torque is not quite enough to spin the rear wheels, once the weight is being transferred - it becomes almost a self sustaining system where the extra weight then enables even more torque to be transferred with rear wheel spin – and so on.
I now totally believe those that told me so and have learned something valuable in the process – and am sure now that the front engine configuration could indeed handle more power and torque than we have available – providing the delivery is smooth.
Despite the huge torque dropping off as the revs rise – the engine didn’t feel like that and felt powerful right through to peak revs – although I now think that the engine would be faster if we could shift that curve up the revs by say 750 revs say pushing it more towards 340 bhp.
However that was never the initial intention which was to prove that the characteristics of putting together some standard parts, despite being high torque at lower revs, would produce good and controllable performance and still be ideal for a track car – at reasonable cost and within the capabilities of most home mechanics – which was proven.
The benefit has been that after giving up my previous involvement in racing and engine performance development 25 years ago (and like an alcoholic- having to maintain abstinence to keep off the drug since) – I found the day extremely lifting, exciting and it has left me feeling menatlly years younger. Although tired out last night I awoke early today early with a buz, an enthusiasm for the future and my head spinning with ideas – just like I had years ago. It feels like a great antidote to the big “R” and although we have forced ourselves to concentrate on providing excellent services for standard road cars and although I enjoyed the engineering side of solutions to improve and rebuild Boxster and 996 engines – I think the time has come for Hartech to embrace some involvement in some form of competitive Porsche motor sport activity in the future (more than the Boxster racing series that we are supporting with engine rebuilds next season).
I think the other shareholders and I will want to do this with a modern model more relevant to our daily income generating cars, and pass this Turbo on to someone else to enjoy - although I am intrigued by the fact that it seems that everyone who has built something similar has ended up with a similar power curve – whatever they have altered. It would be nice to solve that problem – what is the restricting issue – is it the turbo, the exhaust, the ports and valve sizes, the camshaft?
The fall in bmep with increasing revs is exactly in line with the torque graph (as they are proportional) so implies it is a mass airflow breathing problem rather than turbo delivery capacity – the same maximum air flow rates in and/or out of the engine being in use from 4000 rpm onwards if you reduce the volume by the reduction in valve open timing. I wonder if retaining the 16 valve head might have provided more scope?. I suspect from this 8 valve set up that it may be camshaft timing, and then possibly exhaust capacity – but any ideas or experiences from elsewhere will be gratefully received.
At the end of the day when we were reviewing the engine characteristics – I realised that apart from Paul Smith, no one else had driven a std 944 turbo – and although impressed with our car didn't know what all the fuss was about - but by luck another std one was being driven around – so a few words and the owner (who turned out to be a 944 specialist breaker and worth us knowing anyway - James Eaton of “only 9”) agreed to allow Stuart to drive his car and in return he had a couple of laps in ours. It is fair to say that Stuart was shocked at just how “laggy” the std car was (even with a waste gate bleed off Valve) and James really appreciated the big engined version and this brought home to Stuart just what a transformation we had managed to bring about (reported more on Porsche 968.uk).
Finally A big thank you to Rob (our technician), Paul Smith, Stuart Cookson, James Eaton and especially Paul Follett – not only for helping the day and the exercise becoming such a success but also for re-igniting my enthusiasm at a time when I am thinking of what I can do to stop getting bored in the future.
Baz
A success, an experience and I learned a lot from it too.
Firstly a very strange coincidence – we rushed to grab a pit garage and there – sharing it with us – was the very person who I posted about recently - who originally owned the first 944 turbo we sold, tried to track it and found it too difficult to get out of the corners – that stimulated this project and there I was some 10 years later with the same model of car – having solved the problem – and he still has the 944 – spooky or what!
I was quite apprehensive about the engine working Ok and the conditions being too bad - when the track was damp, slippery (tree lined circuit in Autumn) and several red flags incidents, and here we were testing a bog standard car with huge torque on standard tyres! The whole idea was to invite others to test the car so the feedback was objective and impartial and so I decided not to drive myself. Although I would have been ok as long as nothing untoward happened – I was not confident that I would have had the right reactions if the torque spun the rear or a car in front spun in front of us in those conditions – and wanted the car to get through the test day in one piece.
Paul Follett was brilliant (thanks again Paul) he kind of took over the organisation of the day and calmly got things ready and set a professional stamp on the day which helped towards its success.
I did passenger and from that seat it was very clear that the engine did do what I wanted. From the hairpin at 2,700 rpm in third (around 40mph) the car would accelerate as quickly as the tyres would stand, under control, all the way to 6K. As I suspected we only used 3rd and 4th (except a brief snatch at second for the chicane). I was surprised how “short” the circuit had become with the chicane – virtually 6 short straights and tight bends and almost only using 2 speeds. With the box ratios allowing 4th to peak out just before most of the corners (so I think a lower pinion ratio may have not suited that particular circuit) although if it had 6 speeds and all that power band – you could always be in the perfect gear and the gear change is quicker in the newer boxes.
We had set the geometry as Paul wanted and it was spot on (tyres running even temperatures across the faces) and the lowering of the front he wanted - kept the tendency for the rear to squat under power - more under control.
Paul Smith drove and confirmed the power band was much as he expected from his own more powerful 3.2 version and I look forward to seeing the footage he took.
Later in the day the track dried enough for Paul Follett’s stickier club tyres and the car continued to take everything we could throw at it in a completely fuss free and relaxed way.
It helped me solve a problem that I didn’t fully appreciate before. Knowing that the std version with a bleed of valve fitted would spin up the rear wheels so easily, despite believing that a smoother torque delivery may be better or not spin at all (and reading the postings that others said the 50/50 weight distribution didn’t prevent the rear wheels gripping) I was still pondering on why all this extra torque didn’t spin up the wheels. If we wanted to spin them in a standard car we would snatch at the clutch because shock loading doubles the effective load - but we had double the torque so I kind of expected that to still be a small problem - but it wasn't at all. Then I realised that – just like a motorcycle doing a wheely – if the torque delivery is smooth enough to maintain traction (despite it being high torque) the torque reaction of the car is to transfer the weight to the rear wheels and lift the front – as given enough grip and torque – it too would eventually wheely like a motorcycle). Following one of the main Laws of physics (to every action there is an equal and opposite reaction) and providing the torque is not quite enough to spin the rear wheels, once the weight is being transferred - it becomes almost a self sustaining system where the extra weight then enables even more torque to be transferred with rear wheel spin – and so on.
I now totally believe those that told me so and have learned something valuable in the process – and am sure now that the front engine configuration could indeed handle more power and torque than we have available – providing the delivery is smooth.
Despite the huge torque dropping off as the revs rise – the engine didn’t feel like that and felt powerful right through to peak revs – although I now think that the engine would be faster if we could shift that curve up the revs by say 750 revs say pushing it more towards 340 bhp.
However that was never the initial intention which was to prove that the characteristics of putting together some standard parts, despite being high torque at lower revs, would produce good and controllable performance and still be ideal for a track car – at reasonable cost and within the capabilities of most home mechanics – which was proven.
The benefit has been that after giving up my previous involvement in racing and engine performance development 25 years ago (and like an alcoholic- having to maintain abstinence to keep off the drug since) – I found the day extremely lifting, exciting and it has left me feeling menatlly years younger. Although tired out last night I awoke early today early with a buz, an enthusiasm for the future and my head spinning with ideas – just like I had years ago. It feels like a great antidote to the big “R” and although we have forced ourselves to concentrate on providing excellent services for standard road cars and although I enjoyed the engineering side of solutions to improve and rebuild Boxster and 996 engines – I think the time has come for Hartech to embrace some involvement in some form of competitive Porsche motor sport activity in the future (more than the Boxster racing series that we are supporting with engine rebuilds next season).
I think the other shareholders and I will want to do this with a modern model more relevant to our daily income generating cars, and pass this Turbo on to someone else to enjoy - although I am intrigued by the fact that it seems that everyone who has built something similar has ended up with a similar power curve – whatever they have altered. It would be nice to solve that problem – what is the restricting issue – is it the turbo, the exhaust, the ports and valve sizes, the camshaft?
The fall in bmep with increasing revs is exactly in line with the torque graph (as they are proportional) so implies it is a mass airflow breathing problem rather than turbo delivery capacity – the same maximum air flow rates in and/or out of the engine being in use from 4000 rpm onwards if you reduce the volume by the reduction in valve open timing. I wonder if retaining the 16 valve head might have provided more scope?. I suspect from this 8 valve set up that it may be camshaft timing, and then possibly exhaust capacity – but any ideas or experiences from elsewhere will be gratefully received.
At the end of the day when we were reviewing the engine characteristics – I realised that apart from Paul Smith, no one else had driven a std 944 turbo – and although impressed with our car didn't know what all the fuss was about - but by luck another std one was being driven around – so a few words and the owner (who turned out to be a 944 specialist breaker and worth us knowing anyway - James Eaton of “only 9”) agreed to allow Stuart to drive his car and in return he had a couple of laps in ours. It is fair to say that Stuart was shocked at just how “laggy” the std car was (even with a waste gate bleed off Valve) and James really appreciated the big engined version and this brought home to Stuart just what a transformation we had managed to bring about (reported more on Porsche 968.uk).
Finally A big thank you to Rob (our technician), Paul Smith, Stuart Cookson, James Eaton and especially Paul Follett – not only for helping the day and the exercise becoming such a success but also for re-igniting my enthusiasm at a time when I am thinking of what I can do to stop getting bored in the future.
Baz
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