What transmission to use?
Discussion
I've had a potential project simmering on the back burner for quite a while now. The car is small, intended only for driving on the road (not a track day screamer). My current idea is to use the Mazda RX8 Renesis engine mid-mounted.
The simple question is what transmission can I attach the Renesis engine to? I'm looking for something relatively small with atleast 5 speed and reverse.
The simple question is what transmission can I attach the Renesis engine to? I'm looking for something relatively small with atleast 5 speed and reverse.
scooby (with the rear driveshaft remove and the diff sotred) could workand i think a Kit car company is doing that. the renault is would be ok and proberble strong enough. an Audi turbo or deiselbox will do it.
if you wanted the strongest though go the the 911 box. avaliable in 5 or 6 speed (6 is from the 996 onwars i think).
thanks Chris.
if you wanted the strongest though go the the 911 box. avaliable in 5 or 6 speed (6 is from the 996 onwars i think).
thanks Chris.
well if you use the 911 box or any other transaxle then you will need to use a torquetube, which will of course need shortening, thats a more in depth job than shortening a prop shaft.
As for the car being too long with engine gearbox on to back axle, how short does the car have to be, gearboxes aren't that long, and as mentioned you need a torque tube on the transaxle anyway, if you just mounted the engine straight to the transaxle as in a porsche you would end up with an incredibly short drivetrain package, which would have to go behind driver, now if your trying to keep length of car down that would mean moving the driving position forward, meaning you would be very close to the front of the car, making crash safety debatable.
I would go for renesis engine in front of driver, rx8 box down centre of car, to a short prop shaft (to provide some room for movement in the drive train) on to a rear axle, if you are only using a short or no propshaft though don't use a live rear axle, use a diff eg. sierra 4x4 with independant suspension, and mount the diff to the car body.
As for the car being too long with engine gearbox on to back axle, how short does the car have to be, gearboxes aren't that long, and as mentioned you need a torque tube on the transaxle anyway, if you just mounted the engine straight to the transaxle as in a porsche you would end up with an incredibly short drivetrain package, which would have to go behind driver, now if your trying to keep length of car down that would mean moving the driving position forward, meaning you would be very close to the front of the car, making crash safety debatable.
I would go for renesis engine in front of driver, rx8 box down centre of car, to a short prop shaft (to provide some room for movement in the drive train) on to a rear axle, if you are only using a short or no propshaft though don't use a live rear axle, use a diff eg. sierra 4x4 with independant suspension, and mount the diff to the car body.
wildoliver said:
well if you use the 911 box or any other transaxle then you will need to use a torquetube, which will of course need shortening, thats a more in depth job than shortening a prop shaft.
As for the car being too long with engine gearbox on to back axle, how short does the car have to be, gearboxes aren't that long, and as mentioned you need a torque tube on the transaxle anyway, if you just mounted the engine straight to the transaxle as in a porsche you would end up with an incredibly short drivetrain package, which would have to go behind driver, now if your trying to keep length of car down that would mean moving the driving position forward, meaning you would be very close to the front of the car, making crash safety debatable.
I would go for renesis engine in front of driver, rx8 box down centre of car, to a short prop shaft (to provide some room for movement in the drive train) on to a rear axle, if you are only using a short or no propshaft though don't use a live rear axle, use a diff eg. sierra 4x4 with independant suspension, and mount the diff to the car body.
As for the car being too long with engine gearbox on to back axle, how short does the car have to be, gearboxes aren't that long, and as mentioned you need a torque tube on the transaxle anyway, if you just mounted the engine straight to the transaxle as in a porsche you would end up with an incredibly short drivetrain package, which would have to go behind driver, now if your trying to keep length of car down that would mean moving the driving position forward, meaning you would be very close to the front of the car, making crash safety debatable.
I would go for renesis engine in front of driver, rx8 box down centre of car, to a short prop shaft (to provide some room for movement in the drive train) on to a rear axle, if you are only using a short or no propshaft though don't use a live rear axle, use a diff eg. sierra 4x4 with independant suspension, and mount the diff to the car body.
he wants to use the RX8 unit in a mid mounted setup, so no need for turque tube, and why everyone was talking about transaxle gearboxes!!
Chris.
but my point is depending how small the car is the engine will be shoved a long way in to the passenger compartment, at a guess the rx8 engine is say 24" long, a 911 box (don't know about audi/renault) are about 36" long leaving a package of circa 5ft, then when you account for space to be left around the engine from metal work etc you have an engine coming 6ft in to the car from the back, although unless the wheels are right at the back it actually comes 6ft from the back wheels, meaning the driver/passenger have to sit a long way forward to keep overall car length down.
Have you considered a bike engine? still has the very revvy characteristics you must like, and possibly easier to install too.
Have you considered a bike engine? still has the very revvy characteristics you must like, and possibly easier to install too.
Thank you for the suggestions.
A little bit more detail. The project is based on a Mkll Midas (Bronze) bodyshell. In the early eighties Gordon Murray converted on with a mid mounted Alfasud engine and gearbox. I just thought I would like to do something similar but with current components.
Phots of the mid-engined midas are on the Midas Yahoo group
A little bit more detail. The project is based on a Mkll Midas (Bronze) bodyshell. In the early eighties Gordon Murray converted on with a mid mounted Alfasud engine and gearbox. I just thought I would like to do something similar but with current components.
Phots of the mid-engined midas are on the Midas Yahoo group
wildoliver said:
Have you considered a bike engine? still has the very revvy characteristics you must like, and possibly easier to install too.
Yes, but rejected as not suitable very early on. Capacity too small (unless it was a 2.3 Triumph). It's not the 'revy' characteristic but the smoothness I want.
wildoliver said:
The sud engine would be a good conversion, its quite a compact engine, am i right in thinking it is a rear engine mini unit as standard?
No - front engined Mini based.
flossythepig said:
wildoliver said:
Have you considered a bike engine? still has the very revvy characteristics you must like, and possibly easier to install too.
Yes, but rejected as not suitable very early on. Capacity too small (unless it was a 2.3 Triumph). It's not the 'revy' characteristic but the smoothness I want.
wildoliver said:
The sud engine would be a good conversion, its quite a compact engine, am i right in thinking it is a rear engine mini unit as standard?
No - front engined Mini based.
Ok sounds like you have your work cut out lol!
I would seriously consider front engine rear wheel driving it, would be a lot easier given what you have to work with.
wildoliver said:
you have an engine coming 6ft in to the car from the back
A transaxle will in general have the driveshafts emerging from very close to the bell housing, therefore, this is negligible to the length of the package as the majority of the 'boxes length will be in the rear overhang. Also, the RX8 engine being a rotary, is pretty compact and hence wouldn't protrude that far from the bell housing. The alternative if space is really tight would be a FWD transverse engine and transaxle shifted back to drive the rear. I should think the use of the Renesis might be quite helpful with choice as you're not going to need to find a box capable of huge torque so something like a UN1 would be useable, rather than having to go to the expense of a G50 or similar like the Ultima boys.
steve_d said:
I don't know why some are talking about 6ft engine/box combos.
The back of the seat in my Ultima is 38" from the wheel axis and there's 6.7 litres of Chevy V8 in that distance.
Steve
The back of the seat in my Ultima is 38" from the wheel axis and there's 6.7 litres of Chevy V8 in that distance.
Steve
some one suggested a standard RWD gearbox, behind the engine, then the diff, Your Ultima should have a transaxle hence the suggestions of Renault, Audi or Porsche transaxles.
Me thinks some peeps have got thier layouts mixed up
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