BHP of Full race 1700 X-flow
Discussion
We had a lively debate the other month about B series and Pinto bhp and whether power had improved over the last 25 years..... today I ran an Anderson Race X-flow 1700 on 36 mm chokes and 45 webers. Anderson had dynoed this at 198bhp (correction factor unknown)at the engine. We ran it up and achieved 175.3 at the wheels giving 201 Bhp SAE J1349, the DIN figure was calculated at 193 at the engine, both quite close to Andersons 198. It obviously does what it says on the can! The engine sounded wonderful and was clean to 9200 rpm! I attach a graph of the wheel horsepower SAE J1349.(edit) I forgot to explain, Andersonsbhp figure was from his engine dyno not a rolling road.
Peter
Peter
Edited by PeterBurgess on Tuesday 1st April 15:47
Not sure why the complaints, I was saying the figures are close to Andersons engine dyno, you can say what you like as it is a free world. remember parasitic losses are not constant at lower rpms the losses are so low that I think you ,may well find the torque/bhp is damn nigh flywheel. But hey ho, you are all experts. I presume you are saying Andersons engine dyno and mine are both wrong the same amount then?
Dave I am not sure where you work out SAE J1349 should give lower number, I attach a link to a website. We find the difference between SAE and DIN varies day to day but the on the day bhp is always nearer the SAE J1349 power figure than the DIN which can vary a lot from on the day, we feel the SAE J1349 is more representative of real world figures.
http://stmtune.wordpress.com/2012/06/13/how-to-gai...
Peter
I found this from DV on a thread Dave B and MaxTorque wrote on.....If DV can do it, why not Anderson whose stuff seems to be winning, so maybe up at the front for power and torque? Note DV quoting 103 lbs/ft per litre from posh engine.....that would be 175 from the x/flow would it not. Max torque was 143 plus parasitic transmission losses which must be less than the 25 bhp at max power, so still below the 103 lbsft per litre? In fact it hovers around 95 lbsft per litreish does it not? My guess is 160lbs ft max torque at engine, by the way, we are talking very expensive engine gentlemen! If the engine was built to what Vizard states has been achieved with a two valver you would be looking for 10% more than measured would you not?
David Vizard Friday 10th February 2012
Dave's Baker and Andrews,
Just want to back up what you are saying about exaggerated torque numbers. My push rod 10.5/1 motors consistently make 85 -86 lbs-ft per litre and getting them over that while still having a pump fueled street driver is a ton of hard work.
It is not until we start pushing the CR up that it is a practical issue to break the 90 lbs-ft per litre.
To get much past 90 per litre with a two valve engine you have to resort to such things as crank case vacuum (and plenty at that) low tension rings, hi - compression, optimal valve events in conjunction with matching tuned intake and exhaust etc.
The 712 inch BB Chevy I am currently working on with my friend Terry Walters is hovering around the 1110 lbs-ft mark at present giving some 95 lbs-ft per litre. We are expecting when all adjustments are done that this will very closely approach the 100 lbs-ft per litre.
But this is a motor that sports a 16/1 CR and all the trick stuff within the class rules allowed for its application. The big advantage here to making that near 100 per litre is the 16/1 CR. Take that out of the equation and everything gets really difficult to achieve.
That said I do know that in the days of the N/A BTCC super tourers that a top engine builder friend of mine was making 103 lbs-ft per liter from a 12.8/1 CR. Needless to say this was not a cheap engine!!!!
It is interesting that few, if any, magazine articles (other than the 2 -3 of mine) have ever directly addressed the means of maximizing torque output. If any of you guys are really keen to find out my Swansea seminar will cover it in micro-detail (www.davidvizardseminars.com)
David Vizard
Dave I am not sure where you work out SAE J1349 should give lower number, I attach a link to a website. We find the difference between SAE and DIN varies day to day but the on the day bhp is always nearer the SAE J1349 power figure than the DIN which can vary a lot from on the day, we feel the SAE J1349 is more representative of real world figures.
http://stmtune.wordpress.com/2012/06/13/how-to-gai...
Peter
I found this from DV on a thread Dave B and MaxTorque wrote on.....If DV can do it, why not Anderson whose stuff seems to be winning, so maybe up at the front for power and torque? Note DV quoting 103 lbs/ft per litre from posh engine.....that would be 175 from the x/flow would it not. Max torque was 143 plus parasitic transmission losses which must be less than the 25 bhp at max power, so still below the 103 lbsft per litre? In fact it hovers around 95 lbsft per litreish does it not? My guess is 160lbs ft max torque at engine, by the way, we are talking very expensive engine gentlemen! If the engine was built to what Vizard states has been achieved with a two valver you would be looking for 10% more than measured would you not?
David Vizard Friday 10th February 2012
Dave's Baker and Andrews,
Just want to back up what you are saying about exaggerated torque numbers. My push rod 10.5/1 motors consistently make 85 -86 lbs-ft per litre and getting them over that while still having a pump fueled street driver is a ton of hard work.
It is not until we start pushing the CR up that it is a practical issue to break the 90 lbs-ft per litre.
To get much past 90 per litre with a two valve engine you have to resort to such things as crank case vacuum (and plenty at that) low tension rings, hi - compression, optimal valve events in conjunction with matching tuned intake and exhaust etc.
The 712 inch BB Chevy I am currently working on with my friend Terry Walters is hovering around the 1110 lbs-ft mark at present giving some 95 lbs-ft per litre. We are expecting when all adjustments are done that this will very closely approach the 100 lbs-ft per litre.
But this is a motor that sports a 16/1 CR and all the trick stuff within the class rules allowed for its application. The big advantage here to making that near 100 per litre is the 16/1 CR. Take that out of the equation and everything gets really difficult to achieve.
That said I do know that in the days of the N/A BTCC super tourers that a top engine builder friend of mine was making 103 lbs-ft per liter from a 12.8/1 CR. Needless to say this was not a cheap engine!!!!
It is interesting that few, if any, magazine articles (other than the 2 -3 of mine) have ever directly addressed the means of maximizing torque output. If any of you guys are really keen to find out my Swansea seminar will cover it in micro-detail (www.davidvizardseminars.com)
David Vizard
Edited by PeterBurgess on Wednesday 2nd April 06:57
Edited by PeterBurgess on Wednesday 2nd April 07:05
Edited by PeterBurgess on Wednesday 2nd April 07:07
Dave, what is your guesstimated max engine torque and bhp from a 1700 X-flow engine?
What is the most you have achieved? I ask as I do not play with xflows beyond the occasional road head.
Are you saying Andersons engine dyno is crap as well as mine? I think the engine was in excess of 15 thousand.
The max torque per litre is not a hard and fast number which cannot ever be beaten is it?
I think you mention around 78lbsft per litre max for two valve motors in one of your articles?
Bear in mind 1700 size as quoted not as measured.
Peter
What is the most you have achieved? I ask as I do not play with xflows beyond the occasional road head.
Are you saying Andersons engine dyno is crap as well as mine? I think the engine was in excess of 15 thousand.
The max torque per litre is not a hard and fast number which cannot ever be beaten is it?
I think you mention around 78lbsft per litre max for two valve motors in one of your articles?
Bear in mind 1700 size as quoted not as measured.
Peter
Only restriction is 1700 cc, this one is, as far as we are aware, chambered head and flat top style pistons, dry sumped,no cr limit no fuelling restrictions etc etc. It is in 2nd position in class, all others are Full Race Pintos at +60.
I thought 100 lbsft/litre was the theoretical max target whether 2 or 4 valve, just easier with 4 valve.
Peter
I thought 100 lbsft/litre was the theoretical max target whether 2 or 4 valve, just easier with 4 valve.
Peter
A few more musings. Folk saying 2 valvers cannot make more than x per litre is based on what people have found so far, not what can be possibly achieved so the figures quoted are retroactive are they not? The 2/4 valve debate, it is easier to get more power from 4 valve than 2 valve but not impossible for the 2 valve, just very much harder, but what a target for hands on tuners not the armchair ones.
If you stick with numbers guesstimated from dodgy maths or plucked from thin air or cos it has always been that you will never reach beyond and achieve more. I fear that Dave B is stuck 20 plus years ago with regard to hands on state of the art racing and I do not know about MaxTorque pedigree, I feel Dave Andrews is a little more canny though. Power levels creep forward little by little as folk seek more from hands on work which is tested on the track, people learn and move forwards. Did I see that theorists said the bumble bee cannot fly? Sometimes the theorists have to alter to encompass reality.
I have figures from USA Nascars and NHRA prostock 2 valvers.
NHRA Pro stock is 500 cu in or 8.195 litres. 1400 + horsepower and over 800 lbft torque, so 170 hp and 97 lbft per litre.
Nascar 5868 cc and 835 hp, 540+ torque. So 142 hp and 92 lbft per litre.
This was a few years ago too.I am willing to bet if we go back 20 years the figures were lower and if we go back 20 years before that the figures were even lower! Mind you, the best way to attack this info is to say USA dynos over read so are not accurate
Peter
If you stick with numbers guesstimated from dodgy maths or plucked from thin air or cos it has always been that you will never reach beyond and achieve more. I fear that Dave B is stuck 20 plus years ago with regard to hands on state of the art racing and I do not know about MaxTorque pedigree, I feel Dave Andrews is a little more canny though. Power levels creep forward little by little as folk seek more from hands on work which is tested on the track, people learn and move forwards. Did I see that theorists said the bumble bee cannot fly? Sometimes the theorists have to alter to encompass reality.
I have figures from USA Nascars and NHRA prostock 2 valvers.
NHRA Pro stock is 500 cu in or 8.195 litres. 1400 + horsepower and over 800 lbft torque, so 170 hp and 97 lbft per litre.
Nascar 5868 cc and 835 hp, 540+ torque. So 142 hp and 92 lbft per litre.
This was a few years ago too.I am willing to bet if we go back 20 years the figures were lower and if we go back 20 years before that the figures were even lower! Mind you, the best way to attack this info is to say USA dynos over read so are not accurate
Peter
Now who is using second hand non scientific info? Those cars in thgat article were not state of the art race engines were they? Or fresh off the shelf engines.
You choose to use your lbsft per litre numbers as constants for some reason, why is this as it means you restrict power ouputs achievable in one fell, illogical swoop? Do you pluck the numbers from thin air or to suit what you personally think the maxima for two, four, five valve etc etc? It may prevent you moving forwards with power development,but it is a most excellent tool for you to use to pooh pooh what other people seem to achieve isnt it?
The knockers seem to see F1 as the ultimate for power comparison, very shortsighted approach in my humble opinion.F1 bhp, now then, is this no holds barred state of the art bhp? No it isnt, it is the result of seriously restricted/strangled regs which artificially hold the power down, so you cannot pontificate about F1 power comparing to no holds barred tuning. Interestingly it seems to have been restricted since the 1989 post turbo years.....that magic twenty plus years ago eh? Time warp stuff.
Do you state the USA Nascar and NHRA 2 valve figures are lying? I am still trying to find the twenty plus years ago nascar and nhra comparitive figures for your delight and possible edification.
I also asked how much bhp you could get from a 1700 x-flow as you have previously intimated you are a Ford four pot specialist tuner?
MGB racing the class you reckon you hammered us in...we won in 1992,1993 and 1994 Comparing old Clayton with new Dynocom Racing rolling road is very poor logic but if it keeps you in your comfort zone who am I to argue?
Seems to me you think Anderson dyno wrong, Agra Engineering dyno wrong, my dyno wrong, ignored USA figures so they must be wrong, it seems you are the only person right on the planet, and that without engine or rolling road dyno of your own?
Peter
You choose to use your lbsft per litre numbers as constants for some reason, why is this as it means you restrict power ouputs achievable in one fell, illogical swoop? Do you pluck the numbers from thin air or to suit what you personally think the maxima for two, four, five valve etc etc? It may prevent you moving forwards with power development,but it is a most excellent tool for you to use to pooh pooh what other people seem to achieve isnt it?
The knockers seem to see F1 as the ultimate for power comparison, very shortsighted approach in my humble opinion.F1 bhp, now then, is this no holds barred state of the art bhp? No it isnt, it is the result of seriously restricted/strangled regs which artificially hold the power down, so you cannot pontificate about F1 power comparing to no holds barred tuning. Interestingly it seems to have been restricted since the 1989 post turbo years.....that magic twenty plus years ago eh? Time warp stuff.
Do you state the USA Nascar and NHRA 2 valve figures are lying? I am still trying to find the twenty plus years ago nascar and nhra comparitive figures for your delight and possible edification.
I also asked how much bhp you could get from a 1700 x-flow as you have previously intimated you are a Ford four pot specialist tuner?
MGB racing the class you reckon you hammered us in...we won in 1992,1993 and 1994
Comparing old Clayton with new Dynocom Racing rolling road is very poor logic but if it keeps you in your comfort zone who am I to argue?Seems to me you think Anderson dyno wrong, Agra Engineering dyno wrong, my dyno wrong, ignored USA figures so they must be wrong, it seems you are the only person right on the planet, and that without engine or rolling road dyno of your own?
Peter
Edited by PeterBurgess on Thursday 3rd April 06:21
Edited by PeterBurgess on Thursday 3rd April 06:54
So are you saying the Americans are lying for 2 valve engines? The numbers you quote for lbsft per litre are as if they are constants and they are not.
NHRA Pro stock is 500 cu in or 8.195 litres. 1400 + horsepower and over 800 lbft torque, so 170 hp and 97 lbft per litre.
Nascar 5868 cc and 835 hp, 540+ torque. So 142 hp and 92 lbft per litre.
Peter
NHRA Pro stock is 500 cu in or 8.195 litres. 1400 + horsepower and over 800 lbft torque, so 170 hp and 97 lbft per litre.
Nascar 5868 cc and 835 hp, 540+ torque. So 142 hp and 92 lbft per litre.
Peter
Gentlemen, thank you for explaining the figures are what you both feel may be maxima not hard and fast rules.
Perhaps of interest re F1 engines, I understand the single ring pack leads to horrendous blow by so the Holy Grail is high rpm bhp not good cylinder filling as the blow by would be even worse, what say you gentlemen?
Dave the rolling road calibration was done in Texas when it was built for us. The mainstay is inertia testing so unless the rollers gain or lose a lot of weight the calibration will not change. The bearings are molly coddled and we would hopefully see on coastdown tests if frictional losses all seemed higher than usual implying dying bearings (mind you one usually hears and feels poorly bearings) The pau is calibrated against the inertia rollers. The figures may or not be correct but three dynocom dynos all give the same curves for same cars when run on them all. Doesnt mean the figures are correct but does imply consistency of manufacture and calibrating does it not?
I have a few folk digging out some power and torque figures for some special engines, if I ever get them I will post them for folk to peruse.
I am not trying to be aggressive but an answer or explanation re the Nascar and NHRA figures would be nice.
Peter
Perhaps of interest re F1 engines, I understand the single ring pack leads to horrendous blow by so the Holy Grail is high rpm bhp not good cylinder filling as the blow by would be even worse, what say you gentlemen?
Dave the rolling road calibration was done in Texas when it was built for us. The mainstay is inertia testing so unless the rollers gain or lose a lot of weight the calibration will not change. The bearings are molly coddled and we would hopefully see on coastdown tests if frictional losses all seemed higher than usual implying dying bearings (mind you one usually hears and feels poorly bearings) The pau is calibrated against the inertia rollers. The figures may or not be correct but three dynocom dynos all give the same curves for same cars when run on them all. Doesnt mean the figures are correct but does imply consistency of manufacture and calibrating does it not?
I have a few folk digging out some power and torque figures for some special engines, if I ever get them I will post them for folk to peruse.
I am not trying to be aggressive but an answer or explanation re the Nascar and NHRA figures would be nice.
Peter
Interesting that more recent V8 USA stuff is 100+lbsft/litre.
This seems to make a mockery of, and blow into the weeds, the 80lbsft/litre max torque/litre rule imposed by DA DB and MaxToruqe does it not? You cant have an 80 limit except for Nascar/NHRA engines as they are different from the rules governing all other 2 valve engines can you?
It doesnt matter if it is by virtue of special cylinder heads, after all, is that not what we try and do when we modify heads? Paul Ivey has told me a lot about the CNC machines producing the Nascar heads.
Moss remanufacture the TR4 Cast Iron head, it has been improved as there has been input from a few head modifiers and is a better base casting than the original. I started work on TR4 engines in 1986, first championship 1987,88,89 etc etc We pushed the engine bhp up by 35 to 162 at the wheels over those three years. It helped development as folk beat a path to use our rolling road and head modding abilities. We continue to improve the TR4 engine, with some £100000 invested by a TR4 race driver (not that we have seen anything like...just lots of dyno time and about 10 heads developed. With independant engine dyno work and rolling road work we are all agreeing on 177 at the wheels and just over 200 at the engine. Engine dyno suggests lbsft/litre is 87 on the best we have all done together ( five businesses working on this as a project...engine dyno not Agra or Anderson). What I am trying to say is the power creeps forwards under development. We have pushed, with limited monetary input, the TR4 Race Engine from 162 in 1989 to 177 at the wheels in 2014, not lots but steady progress. Imagine what the TR4 engine would produce if it was the Nascar engine of choice, I am willing to bet it would make our efforts look crap
DB says maybe USA V8 is special case re firing order or some such magic stuff. Maybe it is because the 2v American V8 just happens to be the most developed engine in the World? Extending this thought, if the Nascar/NHRA engine of choice was the Pinto, Essex, Kent, A series, B series etc etc would that not be doing 100+lbsft/litre instead of the clunky old USA V8?
Peter
This seems to make a mockery of, and blow into the weeds, the 80lbsft/litre max torque/litre rule imposed by DA DB and MaxToruqe does it not? You cant have an 80 limit except for Nascar/NHRA engines as they are different from the rules governing all other 2 valve engines can you?
It doesnt matter if it is by virtue of special cylinder heads, after all, is that not what we try and do when we modify heads? Paul Ivey has told me a lot about the CNC machines producing the Nascar heads.
Moss remanufacture the TR4 Cast Iron head, it has been improved as there has been input from a few head modifiers and is a better base casting than the original. I started work on TR4 engines in 1986, first championship 1987,88,89 etc etc We pushed the engine bhp up by 35 to 162 at the wheels over those three years. It helped development as folk beat a path to use our rolling road and head modding abilities. We continue to improve the TR4 engine, with some £100000 invested by a TR4 race driver (not that we have seen anything like...just lots of dyno time and about 10 heads developed. With independant engine dyno work and rolling road work we are all agreeing on 177 at the wheels and just over 200 at the engine. Engine dyno suggests lbsft/litre is 87 on the best we have all done together ( five businesses working on this as a project...engine dyno not Agra or Anderson). What I am trying to say is the power creeps forwards under development. We have pushed, with limited monetary input, the TR4 Race Engine from 162 in 1989 to 177 at the wheels in 2014, not lots but steady progress. Imagine what the TR4 engine would produce if it was the Nascar engine of choice, I am willing to bet it would make our efforts look crap
DB says maybe USA V8 is special case re firing order or some such magic stuff. Maybe it is because the 2v American V8 just happens to be the most developed engine in the World? Extending this thought, if the Nascar/NHRA engine of choice was the Pinto, Essex, Kent, A series, B series etc etc would that not be doing 100+lbsft/litre instead of the clunky old USA V8?
Peter
Edited by PeterBurgess on Friday 4th April 06:36
Poppop......Thanks for the first hand knowledge input re the F1 engines. Have the new fuel efficiency rules had much imapact on bhp/litre lbsft/litre? Too much info on PH is second and even third hand. I am happy to post power graphs for folk to see. Gives something to get teeth into
Dave B, I remember DV stating he had achieved 86 lbsft litre ( not sure which year) with a low 10.9:1 CR pinto (seemingly mild cammed), would this not have been better with higher CR and better fuel? It didnt say what year this was tested. See Stan Weiss interview Piston Heads.
What is interesting is DV saying about packages working. We have found massive differences in lbs/ft litre in fast road MGB engines with experimenting with off the shelf ex systems , 69 lbsft/litre with ubiquitous LCB to 75 lbs ft litre with 3 into 1 narrower primary manifold! Lost top end above 5000 rpm though! Lots and lots of hands on testing eventually evolves a package/combo that works well.
So it looks as if, if we accept DV is not being economical with the truth, we have moved on from a max achievable lbs/ft per litre at the onset of this thread to 85/86 rather than an inflexible 70/80 ? And we ignore the 2v 100+ from V8 engines as they have been developed so much? Which means the 87lbsft litre we reckon for the extra £100,000 spent developing the TR4 engine does not look pie in the sky?
Now those involved in racing whether humble track, sprint/hillclimb I work on to F1/nhra/nascar are all trying to find the edge for their engines and drivers and I still put it to all the poohpoohers, lbs/ft litre moves upwards with year on year development of that engine under race use.
Peter
Dave B, I remember DV stating he had achieved 86 lbsft litre ( not sure which year) with a low 10.9:1 CR pinto (seemingly mild cammed), would this not have been better with higher CR and better fuel? It didnt say what year this was tested. See Stan Weiss interview Piston Heads.
What is interesting is DV saying about packages working. We have found massive differences in lbs/ft litre in fast road MGB engines with experimenting with off the shelf ex systems , 69 lbsft/litre with ubiquitous LCB to 75 lbs ft litre with 3 into 1 narrower primary manifold! Lost top end above 5000 rpm though! Lots and lots of hands on testing eventually evolves a package/combo that works well.
So it looks as if, if we accept DV is not being economical with the truth, we have moved on from a max achievable lbs/ft per litre at the onset of this thread to 85/86 rather than an inflexible 70/80 ? And we ignore the 2v 100+ from V8 engines as they have been developed so much? Which means the 87lbsft litre we reckon for the extra £100,000 spent developing the TR4 engine does not look pie in the sky?
Now those involved in racing whether humble track, sprint/hillclimb I work on to F1/nhra/nascar are all trying to find the edge for their engines and drivers and I still put it to all the poohpoohers, lbs/ft litre moves upwards with year on year development of that engine under race use.
Peter
Edited by PeterBurgess on Tuesday 8th April 07:17
Edited by PeterBurgess on Tuesday 8th April 07:27
Thanks for that post Stevesingo, interesting read. I note the bronze valve seat inserts, we have been retrofitting these for folks with the very high revving single cylinder four stroke bike engines. We were lead to believe the bronze absorbs shock and prevents damage to the valve seats at the high revs. We find the inlet valves die(mushrooming of seat) before the ex valves purely down to weight difference and effects of 14000rpm +.
We did a lot of work on some 70s DFV heads and manifolds for a customer. The inlet manifolds were not OE to his heads as the oe ones were machined to the heads and to themselves with a forerunner of cnc type milling mahines, we had to match em up again, the original finish looked identical to those in the post you linked
Peter
We did a lot of work on some 70s DFV heads and manifolds for a customer. The inlet manifolds were not OE to his heads as the oe ones were machined to the heads and to themselves with a forerunner of cnc type milling mahines, we had to match em up again, the original finish looked identical to those in the post you linked
Peter
Much lively debate later........So to get up to date, no one seems to be happy with 90+lbsft litre, so instead of trying to prove my dyno faulty which gives folk great amusement, what if the dynos are somewhere close? That would mean the engine would have to be a lot bigger wouldn't it? So if we take 86lbs ft as a hard to reach (but not impossible) target, the engine would have to be around 1900 cc, not unheard of in racing circles making engines a little larger than the rules suggest?
Gentlemen, if I had built the engine I would say what size it was and what CR and what fuel, but I didnt, I am only the messenger
Dave, be honest, if this thread hadn't been posted none of us would have seen that most excellent link to the post on F1 stuff would we?
Peter
Gentlemen, if I had built the engine I would say what size it was and what CR and what fuel, but I didnt, I am only the messenger
Dave, be honest, if this thread hadn't been posted none of us would have seen that most excellent link to the post on F1 stuff would we?
Peter
I think the top US A and B engines are running 14:1 + CR and are very high revving. We are typically running 1000rpm lower for peak torque and bhp which we feel significantly extends the engine life for our specific uses.
We mainly build to FIA specs and we are not allowed alternative from standard rockers or rocker ratios which restricts the cam choice. This is so with the TR4 head work we do. These engines do endurance racing in terms of 3/4hr plus races and the really high CR ones do not seem to last long away from 10 lap shorter circuit stuff. We are also running pump fuel plus a small amount of additive so cannot run the 118 Octane(UK) race fuels. Consequently we are 11.8:1 CR for the 1840cc Bs and 12.5:1 for the A series. When you say stock valves for the A series I feel they will be running the Cooper S MG Metro 1.401" or even larger inlet valves not the OE 1275 Midget 1.33" as we get an easy 10 bhp more from fitting the 1.401 over the 1.33 and adding 10 to the figures you have given would be rather a lot.
Peter
We mainly build to FIA specs and we are not allowed alternative from standard rockers or rocker ratios which restricts the cam choice. This is so with the TR4 head work we do. These engines do endurance racing in terms of 3/4hr plus races and the really high CR ones do not seem to last long away from 10 lap shorter circuit stuff. We are also running pump fuel plus a small amount of additive so cannot run the 118 Octane(UK) race fuels. Consequently we are 11.8:1 CR for the 1840cc Bs and 12.5:1 for the A series. When you say stock valves for the A series I feel they will be running the Cooper S MG Metro 1.401" or even larger inlet valves not the OE 1275 Midget 1.33" as we get an easy 10 bhp more from fitting the 1.401 over the 1.33 and adding 10 to the figures you have given would be rather a lot.
Peter
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