New GTR Build - Engine and Gearbox questions
Discussion
Hi All
First of all, please allow me to introduce myself as a newbie to this forum.
Second, I have started the process of building a GTR, and am nearly always wondering about what engine and gearbox to run.
ENGINE: I would like to use an LS9, but I understand that it will not fit, so an LS7 seems to be the kiddy. I also believe that this is 600BHP as stock, but is the really 600BHP, as I have been told that American quoted BHP is not quite the same?
Coming from the bike industry, these engines seem quite low tech with push rod 2 valve heads and long stroke lazy engines. Are there any common upgrades available to spice things up a bit, or is it best to keep the stock character?
GEARBOX: Now this is a difficult one. I run a little company making racing shifting system for motoGP bikes and the like, and so would like a sequencial 6 speed gearbox that I can develop some electronic trickery for, such as quickshifter or paddle shift. At the same time I don't want to spend absolute fortunes on a gearbox.
If I can't find the right sequencial box, then is there a viable 6 speed box that I can use?
Thank you in advance?
Gareth
First of all, please allow me to introduce myself as a newbie to this forum.
Second, I have started the process of building a GTR, and am nearly always wondering about what engine and gearbox to run.
ENGINE: I would like to use an LS9, but I understand that it will not fit, so an LS7 seems to be the kiddy. I also believe that this is 600BHP as stock, but is the really 600BHP, as I have been told that American quoted BHP is not quite the same?
Coming from the bike industry, these engines seem quite low tech with push rod 2 valve heads and long stroke lazy engines. Are there any common upgrades available to spice things up a bit, or is it best to keep the stock character?
GEARBOX: Now this is a difficult one. I run a little company making racing shifting system for motoGP bikes and the like, and so would like a sequencial 6 speed gearbox that I can develop some electronic trickery for, such as quickshifter or paddle shift. At the same time I don't want to spend absolute fortunes on a gearbox.
If I can't find the right sequencial box, then is there a viable 6 speed box that I can use?
Thank you in advance?
Gareth
Different world really .... bikes sound like blue bottles with a stick up their arse,(no offence!) where as a full V8 rumble from an SBC or LS7 is another world.....You wont want to lose that..
Also, You could go for a 6 speed 911 box, but most find 5 gears too many. Lowish rev ranges and a lot more torque grunt than with a bike engine means you don't need a load of gears. IMO
Also, You could go for a 6 speed 911 box, but most find 5 gears too many. Lowish rev ranges and a lot more torque grunt than with a bike engine means you don't need a load of gears. IMO
http://www.eliteracingtransmissions.com/product.ph...
Cheapest seq I know of.... might even get one myself for the next car...
Cheapest seq I know of.... might even get one myself for the next car...
Hi
Well, I raced bikes for the most of my life so far.....now I'm too fat, unfit and don't mend like I used to....so I really fancy a complete change and build a ROAD GTR. I will be doing a few tracks days and may even enter into the odd race or two (would love to race, but bike racing a very, very expensive, and I imagine that racing these cars must be for the professional driver or millionaire enthusiast).
So, back to the engine choice. It is very interesting to read that I can fit an LS9. That would be great, but I guess that I then need to buy and fit the intercooler etc. which is not a problem, it just sounds very expensive. Also, the gearbox metioned earlier looks like it is exaclty what I am after (thanks for that!), and I rang them up today, it will not take more than 500ft/pound of torque, so either I change the box again, or back to a crate LS7?
Further research has shown that the crate LS7 is 505BHP and 470ft.lb of torque - a seemingly perfect match for the GTR. But is this enough? The last thing I want to do is build this and then think that I wish I had more power, that would then require tuning and a gearbox change!
Your hard earnt words of wisdom would be very much appreciated.
Gareth
Well, I raced bikes for the most of my life so far.....now I'm too fat, unfit and don't mend like I used to....so I really fancy a complete change and build a ROAD GTR. I will be doing a few tracks days and may even enter into the odd race or two (would love to race, but bike racing a very, very expensive, and I imagine that racing these cars must be for the professional driver or millionaire enthusiast).
So, back to the engine choice. It is very interesting to read that I can fit an LS9. That would be great, but I guess that I then need to buy and fit the intercooler etc. which is not a problem, it just sounds very expensive. Also, the gearbox metioned earlier looks like it is exaclty what I am after (thanks for that!), and I rang them up today, it will not take more than 500ft/pound of torque, so either I change the box again, or back to a crate LS7?
Further research has shown that the crate LS7 is 505BHP and 470ft.lb of torque - a seemingly perfect match for the GTR. But is this enough? The last thing I want to do is build this and then think that I wish I had more power, that would then require tuning and a gearbox change!
Your hard earnt words of wisdom would be very much appreciated.
Gareth
The NTL gearbox that's for sale in the Classifieds can handle a high hp and is sequential.
It's in the Ultima ad for 95% complete kit.
Mark at RapidGB has also fitted a Hewland gearbox to a 700hp motor, that was sequential too and air driven (I noticed that motor is also for sale at the moment as well).
I'm an older, fatter ex bike racer too and can testify that Ultima GTR's fill the void nicely...
It's in the Ultima ad for 95% complete kit.
Mark at RapidGB has also fitted a Hewland gearbox to a 700hp motor, that was sequential too and air driven (I noticed that motor is also for sale at the moment as well).
I'm an older, fatter ex bike racer too and can testify that Ultima GTR's fill the void nicely...
A stock LS7 can be modified to make 650bhp quite cheaply so its just a case of making sure the rest of car (specifically the box and clutch) is up to the task then you can modify later.
The GT3 and GT2 porsche boxs have sometimes been converted to sequential shift... they can handle a modified LS7 as well, if you do develope a sequential shift of your own for this box, please do 2
Id say stick with a Porsche box (specd and sourced carefuly) and a tweaked LS7 is the route youd best be going... my understanding is the LS9 is more of a tweaked LS3 with a supercharger?
The GT3 and GT2 porsche boxs have sometimes been converted to sequential shift... they can handle a modified LS7 as well, if you do develope a sequential shift of your own for this box, please do 2
Id say stick with a Porsche box (specd and sourced carefuly) and a tweaked LS7 is the route youd best be going... my understanding is the LS9 is more of a tweaked LS3 with a supercharger?
Gareth
There has been a lot of talk about what is the best transmission on this forum and I have paid particular attention to this also. It is pretty clear to me that the Porsche G50 series transmissions are the preferred choice due to there proven track record, 'rebuildabilty', ease of fitment to SBC's and LS's and the fact that the GT2,GT3 and Turbo boxes are a further enhancement over the standard 911/964 and 993 versions due to their larger crown wheel and pinion. However availability is somewhat of a problem and the price of these boxes is only going in one direction,Up!
As Andygtt says, there are companies out there who offer sequential systems for the cable operated Porsche transmissions. However the standard 996 C2 Porsche (G96/00) unit is not the best, so again the only option is either the GT2,GT3 or Turbo units from the 996 models. The 996 Turbos were AWD so you need to have it converted to 2WD, I have found a company who can do this. The GT2 and GT3 units are basically the same as the turbo transmissions albeit 2WD as standard. However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
There are other transmissions fitted in Ultimas but I do not know how these perform in normal road use or track use. Others on this forum maybe able to provide more info?
I have looked into this in alot of detail, to the point of reaching insanity, but I do think it is a real area that needs consideration from day one. More than happy to discuss further and let you know my choice!
There has been a lot of talk about what is the best transmission on this forum and I have paid particular attention to this also. It is pretty clear to me that the Porsche G50 series transmissions are the preferred choice due to there proven track record, 'rebuildabilty', ease of fitment to SBC's and LS's and the fact that the GT2,GT3 and Turbo boxes are a further enhancement over the standard 911/964 and 993 versions due to their larger crown wheel and pinion. However availability is somewhat of a problem and the price of these boxes is only going in one direction,Up!
As Andygtt says, there are companies out there who offer sequential systems for the cable operated Porsche transmissions. However the standard 996 C2 Porsche (G96/00) unit is not the best, so again the only option is either the GT2,GT3 or Turbo units from the 996 models. The 996 Turbos were AWD so you need to have it converted to 2WD, I have found a company who can do this. The GT2 and GT3 units are basically the same as the turbo transmissions albeit 2WD as standard. However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
There are other transmissions fitted in Ultimas but I do not know how these perform in normal road use or track use. Others on this forum maybe able to provide more info?
I have looked into this in alot of detail, to the point of reaching insanity, but I do think it is a real area that needs consideration from day one. More than happy to discuss further and let you know my choice!
stringvest1971 said:
Gareth
There has been a lot of talk about what is the best transmission on this forum and I have paid particular attention to this also. It is pretty clear to me that the Porsche G50 series transmissions are the preferred choice due to there proven track record, 'rebuildabilty', ease of fitment to SBC's and LS's and the fact that the GT2,GT3 and Turbo boxes are a further enhancement over the standard 911/964 and 993 versions due to their larger crown wheel and pinion. However availability is somewhat of a problem and the price of these boxes is only going in one direction,Up!
As Andygtt says, there are companies out there who offer sequential systems for the cable operated Porsche transmissions. However the standard 996 C2 Porsche (G96/00) unit is not the best, so again the only option is either the GT2,GT3 or Turbo units from the 996 models. The 996 Turbos were AWD so you need to have it converted to 2WD, I have found a company who can do this. The GT2 and GT3 units are basically the same as the turbo transmissions albeit 2WD as standard. However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
There are other transmissions fitted in Ultimas but I do not know how these perform in normal road use or track use. Others on this forum maybe able to provide more info?
I have looked into this in alot of detail, to the point of reaching insanity, but I do think it is a real area that needs consideration from day one. More than happy to discuss further and let you know my choice!
It's good to see someone else come to a similar conclusion. I wonder if we are trying to solve a problem that doesn't exist. The Ultima demonstrators including the record car all have the older G50 52 box and seem to work fine. The R/H shift is not really a problem and you can raise the 5th gear ratio for better/quieter cruising for very little money. There has been a lot of talk about what is the best transmission on this forum and I have paid particular attention to this also. It is pretty clear to me that the Porsche G50 series transmissions are the preferred choice due to there proven track record, 'rebuildabilty', ease of fitment to SBC's and LS's and the fact that the GT2,GT3 and Turbo boxes are a further enhancement over the standard 911/964 and 993 versions due to their larger crown wheel and pinion. However availability is somewhat of a problem and the price of these boxes is only going in one direction,Up!
As Andygtt says, there are companies out there who offer sequential systems for the cable operated Porsche transmissions. However the standard 996 C2 Porsche (G96/00) unit is not the best, so again the only option is either the GT2,GT3 or Turbo units from the 996 models. The 996 Turbos were AWD so you need to have it converted to 2WD, I have found a company who can do this. The GT2 and GT3 units are basically the same as the turbo transmissions albeit 2WD as standard. However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
There are other transmissions fitted in Ultimas but I do not know how these perform in normal road use or track use. Others on this forum maybe able to provide more info?
I have looked into this in alot of detail, to the point of reaching insanity, but I do think it is a real area that needs consideration from day one. More than happy to discuss further and let you know my choice!
I am not an engineer and this is my first kit build. The thought of trying to get everything to fit together and function correctly without the guidance of the factory, may spoil my build experience and enjoyment. I have now decided to keep mine simple and pretty much factory standard. If I find there are areas I don't like I will find a solution (preferably one that someone else has tried) and build again with all my mods. However, I suspect I will be quite happy with a well sorted (with factory help) factory spec car.
Paul
The factory have proved the durability of the G50 series transmission, and a version of it would be no doubt be their recommendation, especially for the high output engines that seem to be the direction most people are going in. The G50/52 came from the 911 turbo and is the 5 speed rod shift unit (not cable), so like Paul says is pefectly suited to the RH shift advocates, but not an option to convert to sequential shift. This transmission is quite rare, like 'hens teeth' in fact! Finding them is one thing paying for them is another, but I am a strong beliver in 'seak and you will find'. The UK is great place to source stuff you just need to look and ask lots of questions. Its amazing what you can find!
Ian
Ian
stringvest1971 said:
However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
I run a G96/50 turbo box in my Can-Am and there is to issue with running the standard plate type LSD. I run an upgraded version from California Motorsports (CMS). It works very well in practice. I am more than happy with it.Regards Dave
Welcome Gareth 
One other thing worth bearing in mind with the sequential, is that you simply won't be changing gear as much with a big V8. With masses of torque and fairly long gears you can use sheer grunt to get you around a track (although you are building primarily for the road).
Would be a great talking point and you obviously have right experience - but how much benefit will it bring vs the cost?
As for the engine, LS definitely the way to go now I'd say (if you have the budget). Depending on how quickly/slowly you want to build (and you want it to go!) and what you're prepared to do in terms of modifying from the 'factory' spec. will ultimately dictate what to go for.
One other thing worth bearing in mind with the sequential, is that you simply won't be changing gear as much with a big V8. With masses of torque and fairly long gears you can use sheer grunt to get you around a track (although you are building primarily for the road).
Would be a great talking point and you obviously have right experience - but how much benefit will it bring vs the cost?
As for the engine, LS definitely the way to go now I'd say (if you have the budget). Depending on how quickly/slowly you want to build (and you want it to go!) and what you're prepared to do in terms of modifying from the 'factory' spec. will ultimately dictate what to go for.
I run a G96/50 turbo box in my Can-Am and there is to issue with running the standard plate type LSD. I run an upgraded version from California Motorsports (CMS). It works very well in practice. I am more than happy with it.
Regards Dave
[/quote]
Dave...thanks, this is good information. Do you know the lock up ratio of your diff and did CMS change this? I understand the standard plate diff is 40/65%?
Ian
Regards Dave
[/quote]
Dave...thanks, this is good information. Do you know the lock up ratio of your diff and did CMS change this? I understand the standard plate diff is 40/65%?
Ian
Hi All
WOW! Thank you for all the advise and info.
Unless something changes, I will probalby now go for the G50 and a stock crated LS7. Once I have the engine, I will look into a bit of basic tuning myself (flowing, blue printing, cam/valves/valve train). What I know about US V8's is scary, but I do know my way around a bike engine... Can't be that different? LOL :-)
Knowing me, I will also have a look at making a system to bolt onto the G50 to change to paddle shift. I can probably use most of the stuff at work.
Thanks again.
Gareth
WOW! Thank you for all the advise and info.
Unless something changes, I will probalby now go for the G50 and a stock crated LS7. Once I have the engine, I will look into a bit of basic tuning myself (flowing, blue printing, cam/valves/valve train). What I know about US V8's is scary, but I do know my way around a bike engine... Can't be that different? LOL :-)
Knowing me, I will also have a look at making a system to bolt onto the G50 to change to paddle shift. I can probably use most of the stuff at work.
Thanks again.
Gareth
The installation and set-up can lose/reap as much as blueprinting Gareth, particularly with larger capacity/higher output motors.
The LS3 480 is an excellent starting point both in terms of out the crate performance/economy and low initial cost (55%ish of the LS7). You will not really notice the 25hp difference. When combined with appropriate ancilliaries and a post install re-map you'll most likely have more on tap than many LS7 combos' claim!
Maybe after your first season, a centrifugal blower kit can be added to the otherwise stock motor giving 30-45% increase with the added benefit of retaining its original manners when off boost....best of both worlds really.......relative economy and performance....almost unheard of in V8 world!
G50 for sure too (as already said well worth waiting for a large crown wheel if you can)
Good luck.
The LS3 480 is an excellent starting point both in terms of out the crate performance/economy and low initial cost (55%ish of the LS7). You will not really notice the 25hp difference. When combined with appropriate ancilliaries and a post install re-map you'll most likely have more on tap than many LS7 combos' claim!
Maybe after your first season, a centrifugal blower kit can be added to the otherwise stock motor giving 30-45% increase with the added benefit of retaining its original manners when off boost....best of both worlds really.......relative economy and performance....almost unheard of in V8 world!
G50 for sure too (as already said well worth waiting for a large crown wheel if you can)
Good luck.
Storer said:
stringvest1971 said:
Gareth
There has been a lot of talk about what is the best transmission on this forum and I have paid particular attention to this also. It is pretty clear to me that the Porsche G50 series transmissions are the preferred choice due to there proven track record, 'rebuildabilty', ease of fitment to SBC's and LS's and the fact that the GT2,GT3 and Turbo boxes are a further enhancement over the standard 911/964 and 993 versions due to their larger crown wheel and pinion. However availability is somewhat of a problem and the price of these boxes is only going in one direction,Up!
As Andygtt says, there are companies out there who offer sequential systems for the cable operated Porsche transmissions. However the standard 996 C2 Porsche (G96/00) unit is not the best, so again the only option is either the GT2,GT3 or Turbo units from the 996 models. The 996 Turbos were AWD so you need to have it converted to 2WD, I have found a company who can do this. The GT2 and GT3 units are basically the same as the turbo transmissions albeit 2WD as standard. However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
There are other transmissions fitted in Ultimas but I do not know how these perform in normal road use or track use. Others on this forum maybe able to provide more info?
I have looked into this in alot of detail, to the point of reaching insanity, but I do think it is a real area that needs consideration from day one. More than happy to discuss further and let you know my choice!
It's good to see someone else come to a similar conclusion. I wonder if we are trying to solve a problem that doesn't exist. The Ultima demonstrators including the record car all have the older G50 52 box and seem to work fine. The R/H shift is not really a problem and you can raise the 5th gear ratio for better/quieter cruising for very little money. There has been a lot of talk about what is the best transmission on this forum and I have paid particular attention to this also. It is pretty clear to me that the Porsche G50 series transmissions are the preferred choice due to there proven track record, 'rebuildabilty', ease of fitment to SBC's and LS's and the fact that the GT2,GT3 and Turbo boxes are a further enhancement over the standard 911/964 and 993 versions due to their larger crown wheel and pinion. However availability is somewhat of a problem and the price of these boxes is only going in one direction,Up!
As Andygtt says, there are companies out there who offer sequential systems for the cable operated Porsche transmissions. However the standard 996 C2 Porsche (G96/00) unit is not the best, so again the only option is either the GT2,GT3 or Turbo units from the 996 models. The 996 Turbos were AWD so you need to have it converted to 2WD, I have found a company who can do this. The GT2 and GT3 units are basically the same as the turbo transmissions albeit 2WD as standard. However I am assured the LSD fitted to the GT boxes would make the Ultima undrivable, and either an open diff or a ATB or similar would have to be used.
There are other transmissions fitted in Ultimas but I do not know how these perform in normal road use or track use. Others on this forum maybe able to provide more info?
I have looked into this in alot of detail, to the point of reaching insanity, but I do think it is a real area that needs consideration from day one. More than happy to discuss further and let you know my choice!
I am not an engineer and this is my first kit build. The thought of trying to get everything to fit together and function correctly without the guidance of the factory, may spoil my build experience and enjoyment. I have now decided to keep mine simple and pretty much factory standard. If I find there are areas I don't like I will find a solution (preferably one that someone else has tried) and build again with all my mods. However, I suspect I will be quite happy with a well sorted (with factory help) factory spec car.
Paul
Richard has asked me to correct my mistake with the gearbox the factory cars use. It is NOT the G50.52 but the G50-03's and G50-01's standard boxes. This includes the 720hp record car.
Sorry for the confusion.
Paul
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