anyone know of a transmission that would fit in a car similar to a gt40 in build that could take up to 800hp? a car that i'm finishing the design and engineering of is set to have an twin turbo ls7 engine that i've seen put out 725hp, but i expect more due to my intercooler design. originally, i was referred to the porsche g50 series, but the highest power handling number i've seen is 600, and that's in a custom 993 turbo. the carrera 4 transmission is too long for the chassis i designed, and i had a list of transmissions in my bookmarks until the page was taken offline. suggestions would be appreciated.
looking for good trans
- Thread starter 700west
- Start date
Ricardo from a Ford GT. Not sure about the dimensions though.
my only issue is i designed the chassis for the g5052 trans if i remember my notes correctly, and that model has an 8 inch difference from the bell housing to the axle mount. that is the longest model too, so i'm sure that most other transmissions for the same or similar design as the porsche will be fine.
The G50 porsche trans for the non-turbo carrera is not the same as the trans for the 911 turbo. So, in short, I'd be surprised if a basic G50 would take anywhere near 700hp without imploding pretty quickly. The old 4sp for the early 911 turbos ('77-83) would work fine as would the 5sp for the later turbos ('86-'88). Again, these are not the basic G50 trans for the later non-turbos ('84-'88).
The ZF box from the Pantera should be OK up to about 500hp but 700hp is really pushing it. Perhaps check out what's being put into the V8 Lotus Esprit as that's also a possible contender. Finally, for a really exotic transaxle, the Ferrari transaxle from a 355 (non-tiptronic/auto) should be able to handle 500hp and perhaps more. Good luck!
The ZF box from the Pantera should be OK up to about 500hp but 700hp is really pushing it. Perhaps check out what's being put into the V8 Lotus Esprit as that's also a possible contender. Finally, for a really exotic transaxle, the Ferrari transaxle from a 355 (non-tiptronic/auto) should be able to handle 500hp and perhaps more. Good luck!
I imagine the Ricardo found in the Ford GT could handle it. There are a couple of video of 800 plus RWHP Ford GTs running around the internet. Does anyone know how much hp the Ricardo is suppose to handle? Are those modified GTs going to eat the Ricardo or could they handle it? Does anyone know the price?
Theon Karabatsos
Theon Karabatsos
Ron Earp
Admin
That transmission is listed in the 2006 FMS catalog for $14,500. I was just talking to someone the other day who has one in their shop for a project and indicated it is a really nice shifting unit.
FMS indicates it handles 600+ ft/lbs but that is all they say. Weight is 200 lbs dry and will bolt to any mod motor with, what looks like, a integrated cast in bellhousing that would need adapting to a Windsor motor. Note mentions unique flywheel required, but that is no suprise.
For the price, $14,500, I'd say it'd have to be a serious consideration for anyone doing a car. $14,500 isn't cheap. But, it gets you a modern transaxle, a brand new one, that is extremely strong and has a 6th gear.
FMS indicates it handles 600+ ft/lbs but that is all they say. Weight is 200 lbs dry and will bolt to any mod motor with, what looks like, a integrated cast in bellhousing that would need adapting to a Windsor motor. Note mentions unique flywheel required, but that is no suprise.
For the price, $14,500, I'd say it'd have to be a serious consideration for anyone doing a car. $14,500 isn't cheap. But, it gets you a modern transaxle, a brand new one, that is extremely strong and has a 6th gear.
Lynn Larsen
Lynn Larsen
Take a look at the GrandAm Rolex series spec for the Daytona Prototype cars. I believe there are 3 transaxles spec'ed with the Enco being used in the lions share of the cars. As Ron pointed out, once you get into this range of transaxles, be prepared to spend big bucks.
These transaxles would handle the power you talk about, but dimensions may be a problem as the ones I have seen are fairly long.
Regards,
Lynn
These transaxles would handle the power you talk about, but dimensions may be a problem as the ones I have seen are fairly long.
Regards,
Lynn
i found information last night showing an audi 80 quattro that made an estimated 800hp at the flywheel, and the only transmission mod was a a stronger clutch with 3000lbs grabbing force. it sounds like that gearbox would be fine, but since all the load is going to the transaxle instead of being 50/50 between that and the rear output, im afraid the transaxle would fail long before any of the gears or synchros could see any damage. i'll check up on the cars that all your ideas showed up in, but i'm pretty sure any porsche trans won't be able to take the power that i expect to make.
yea well, just checking the specs on everything, the pantera has 333ft/lbs of torque while the gt box can handle around 600ft/lbs.
one problem: the twin turbo ls7 that i know of makes 730ft/lbs or torque. with my estimation of more horsepower comes more torque. god only knows what kind of trans is in that car to handle it, but what can handle it if the $14500 box is short of it?
one problem: the twin turbo ls7 that i know of makes 730ft/lbs or torque. with my estimation of more horsepower comes more torque. god only knows what kind of trans is in that car to handle it, but what can handle it if the $14500 box is short of it?
Lynn Larsen
Lynn Larsen
Westie,
Be careful about intermixing HP ratings and Torque ratings. Remember that HP=Torque X RPM, so if your motor will turn enough RPM, you can get high horsepower numbers with more modest torque numbers. And, it is torque which will kill a gear box. If you will do some research here on the board, you will find that, with high torque, an unmodified Audi box will have its pinion gear pushed back through its bearing and the bulkhead wall that holds it. There is a Lambo builder in Canada who was reinforcing the wall with a steel plate which did require modification of the pinion shaft.
The mode of failure with applications of high torque usually happens in one of two places: either the input shaft snaps or the torque will cause flexing that changes the lash between the ring and pinion. The flexing is, at best, made worse by and, at worst, caused by excess heat build up/lubrication break down in meshing of the teeth of the ring and pinion gears. As one might imagine this won't go on long before things start disintegrating.
Thus, a forced oiling system and oil cooler can increase the serviceable life of a transaxle pushed beyond its stated design limits. You can also find a lot of discussion here on transaxle oiling system that range from just coolers to sprays directed at only the R&P to spray bar systems that lubricate the R&P as well as each of the gear sets. Also, keep in mind that published numbers include a healthy margin of safety for the manufacturer/warranter of a component.
Lastly, the brain/foot connections of the driver will have a lot do with how well a car will stand up--this is obviously true for all of the machine. Case in point, the guys in the UK have been running some pretty healthy power plants through Renault boxes for years. Yes, some have broken, but a goodly number of them have provided their owners with years of enjoyment. So what you plan to do with the car will have everything to do with how you design it. If you are going to compete with it or just want to be able to hammer it to your hearts content then you'll have to design for that and pony up the bucks it will take to provide that kind of strength. If your desires don't go that far, then you can back off a little and save a little. If you have a finite budget, like most of us, you will do all you can to make your car as stout as you can afford and then modify your behavior to suit the machine you have. I'll guarantee you that you can soil yourself with considerably less horsepower than you plan; remember it ALL comes down to power-to-weight ratio!
Regards,
Lynn
Be careful about intermixing HP ratings and Torque ratings. Remember that HP=Torque X RPM, so if your motor will turn enough RPM, you can get high horsepower numbers with more modest torque numbers. And, it is torque which will kill a gear box. If you will do some research here on the board, you will find that, with high torque, an unmodified Audi box will have its pinion gear pushed back through its bearing and the bulkhead wall that holds it. There is a Lambo builder in Canada who was reinforcing the wall with a steel plate which did require modification of the pinion shaft.
The mode of failure with applications of high torque usually happens in one of two places: either the input shaft snaps or the torque will cause flexing that changes the lash between the ring and pinion. The flexing is, at best, made worse by and, at worst, caused by excess heat build up/lubrication break down in meshing of the teeth of the ring and pinion gears. As one might imagine this won't go on long before things start disintegrating.
Thus, a forced oiling system and oil cooler can increase the serviceable life of a transaxle pushed beyond its stated design limits. You can also find a lot of discussion here on transaxle oiling system that range from just coolers to sprays directed at only the R&P to spray bar systems that lubricate the R&P as well as each of the gear sets. Also, keep in mind that published numbers include a healthy margin of safety for the manufacturer/warranter of a component.
Lastly, the brain/foot connections of the driver will have a lot do with how well a car will stand up--this is obviously true for all of the machine. Case in point, the guys in the UK have been running some pretty healthy power plants through Renault boxes for years. Yes, some have broken, but a goodly number of them have provided their owners with years of enjoyment. So what you plan to do with the car will have everything to do with how you design it. If you are going to compete with it or just want to be able to hammer it to your hearts content then you'll have to design for that and pony up the bucks it will take to provide that kind of strength. If your desires don't go that far, then you can back off a little and save a little. If you have a finite budget, like most of us, you will do all you can to make your car as stout as you can afford and then modify your behavior to suit the machine you have. I'll guarantee you that you can soil yourself with considerably less horsepower than you plan; remember it ALL comes down to power-to-weight ratio!
Regards,
Lynn
well if i can ever afford the rbt 6 box (supposed to be in the saleen s7 which has 750 horses and 700ft/lbs of torque) then that might be a good idea. of course, it costs as much as the engine. i figure that would be about right with an oil cooler and pressurized lubrication keeping it in shape. if it were to fail, i'd bet on first gear when the turbos kick in, and that would either be at a stoplight or on the track. boomsmile
Chris Kouba
Supporter
700west said:
I'd bet differently- see Lynn's discussion of torque vs HP. I'd bet it'd shred a higher gear at lower rpm. The torque is what will pry the box apart. At low speed, trying to put large forces through the box will flex it and gnash something.
I probably can't type my way through explaining it though. Maybe someone else will correct me if I'm wrong or be able to quantify it.
Chris
When you have a good look at most transmissions you find that 2nd/3rd gears are furthest from any bearings or bulkheads & it stands to reason when under load the shafts will deflect & allow the gears to climb slightly higher against each other therefore creating more leverage on the teeth & invite failure.
In a standing start situation when your twin turbo boost kicks in it wont create the same shock load that slipping your foot sideways of the clutch @ 7000 rpm will!
I've had Ford Toploaders that last for seasons in circuit cars with 355 cu in fail within a couple of races behind 400 cu in. Why?, they both had the same HP but the 400 developed its peak torque about 1500 rpm below the 355. The input shaft starts to twist in the spline area and its all over. Thats why you will find most aftermarket trans use the slightly larger dia/higher spline count input shaft.
Jac Mac
In a standing start situation when your twin turbo boost kicks in it wont create the same shock load that slipping your foot sideways of the clutch @ 7000 rpm will!
I've had Ford Toploaders that last for seasons in circuit cars with 355 cu in fail within a couple of races behind 400 cu in. Why?, they both had the same HP but the 400 developed its peak torque about 1500 rpm below the 355. The input shaft starts to twist in the spline area and its all over. Thats why you will find most aftermarket trans use the slightly larger dia/higher spline count input shaft.
Jac Mac
"Scott, for your clarification, the 911 turbos before '89 had five speed boxes. Specifically, from '86 to '88 a five speed was standard on the 911 turbo. Ask me how I know."
Sorry, but this is not accurate. Many, many 911's prior to '89 had 915 5-speeds and some ('86 on) had getrag G50s...but not the pre-'89 turbos. A little research would show that THE reason '89 911 turbos are desirable is the first fittment of a 5-speed (G50/50)...as stated in the Porsche factory literature here in my hands. I will allow that some pre-'89 turbos have been converted to G50 fitment but this occurred after delivery from the dealer. The exceptions to this statement are RUF cars which are a different animal w/ a price tag to prove it.
I can't speak for cars you may have owned or encountered. I can speak for the established facts. If you still cannot believe me, search sloancars.com, rennlist.com or pelican.com. '88 or earlier turbo ads will show a 4 speed or point out a G50 conversion has been done. As stated earlier, '89 and later turbos were factory fitted w/ 2WD G50 variant 5 speeds...until 1996 when they went twin turbo, awd and 6-speed.
For the purposes of this message board and as you pointed out, this is an academic discussion as sourcing one of these boxes straight from a car should entail some home work on the specific box in question as there have been more than a few variations of transaxles (915, 930, Getrag, RUF, 5-speed, 6-speed, 2wd, AWD, open diff, LSD...) installed in various 911's at the factory and by owners over the years.
Best,
Scott
Sorry, but this is not accurate. Many, many 911's prior to '89 had 915 5-speeds and some ('86 on) had getrag G50s...but not the pre-'89 turbos. A little research would show that THE reason '89 911 turbos are desirable is the first fittment of a 5-speed (G50/50)...as stated in the Porsche factory literature here in my hands. I will allow that some pre-'89 turbos have been converted to G50 fitment but this occurred after delivery from the dealer. The exceptions to this statement are RUF cars which are a different animal w/ a price tag to prove it.
I can't speak for cars you may have owned or encountered. I can speak for the established facts. If you still cannot believe me, search sloancars.com, rennlist.com or pelican.com. '88 or earlier turbo ads will show a 4 speed or point out a G50 conversion has been done. As stated earlier, '89 and later turbos were factory fitted w/ 2WD G50 variant 5 speeds...until 1996 when they went twin turbo, awd and 6-speed.
For the purposes of this message board and as you pointed out, this is an academic discussion as sourcing one of these boxes straight from a car should entail some home work on the specific box in question as there have been more than a few variations of transaxles (915, 930, Getrag, RUF, 5-speed, 6-speed, 2wd, AWD, open diff, LSD...) installed in various 911's at the factory and by owners over the years.
Best,
Scott
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The first attachment is a list of 911 Porsches and their transaxles which I recently found in a rebuilder's catalog. I think it's one of the clearer references for determining which transaxle went with which car.
I have another table which enables one to decipher the code on a G50 or G64 tranny's tag from '89 onward. It helped me recently when a dismantler claimed the tranny I bought was from a '93, when the tag indicated it was from a '91. Unfortunately this table is too big for uploading here, and when I reduce its resolution, it becomes unreadable. Perhaps Ron or Al would have a suggestion for uploading?
John
I have another table which enables one to decipher the code on a G50 or G64 tranny's tag from '89 onward. It helped me recently when a dismantler claimed the tranny I bought was from a '93, when the tag indicated it was from a '91. Unfortunately this table is too big for uploading here, and when I reduce its resolution, it becomes unreadable. Perhaps Ron or Al would have a suggestion for uploading?
John
