So i have a bit of a love for the rotary engine... actually a 'bit' is an understatement!
I wont bore you with fanboy stuff here, i simply want to build a FF1600 car powered by a Rotary.
I have done a lot of work on rotary engines, cars, etc but the thing that keeps getting me stuck is the gearbox!
Is it normal to run a H-box in a FF chassis? more so, is it even practical!?
Noise regulations for track days are also worrying me, a rotary is incredibly hot and incredibly loud *drools*
Is an end-can type muffler sufficient in lowering DB's? are resonators feasible?
Cooling should be ok, the cooling set up on the RX8 lends itself to a side-pod radiator design, which is quite nice!
Finally, if this post is in the wrong area, my apologies!
A planetary gearbox (automatic without the torque converter) would be a better gearbox for the high revving rotary engine.
Turbo charging would reduce noise and benefit engine efficiency by improving the less than perfect chamber scavenging of the rotary.
Using silencers on a bi-rotor turbocharged Mazda engine has proved to be very good at keeping noise down so it is definitely possible. The car in question has now no silencer and it is one of the most noisiest thing I have ever heard. 500+ bhp tho for a 1.3L engine.
MadMatt wrote:Using silencers on a bi-rotor turbocharged Mazda engine has proved to be very good at keeping noise down so it is definitely possible. The car in question has now no silencer and it is one of the most noisiest thing I have ever heard. 500+ bhp tho for a 1.3L engine.
How is that 13B getting 500+ hp? Is it turbocharged?
Keep in mind the RX-8 Renesis is side-port exhaust and intake, not the usual racing pp or bridge-port. This will lead to less overlap, so actually a smaller turbo setup or a supercharger might be the best way to go on the Renesis without reporting it.
tuj wrote:Keep in mind the RX-8 Renesis is side-port exhaust and intake, not the usual racing pp or bridge-port. This will lead to less overlap, so actually a smaller turbo setup or a supercharger might be the best way to go on the Renesis without reporting it.
Got points there, for the FF build i will keep it fully NA, i think having forced induction will spike the costs and just make the car too nuts, im aiming for 400-450bhp per tonne with a NA engine, anything more and i will probably die
but the thing that keeps getting me stuck is the gearbox!
Is it normal to run a H-box in a FF chassis? more so, is it even practical!?
Thanks guys!
When you say H-Box I assume you mean H-Pattern gearbox? So are you asking if its practical to run the standard RWD gearbox from an RX7/8 in a FF?
FF1600's do/did use H-Pattern boxes but thats the only real resemblence, they are racing transaxles (Hewland et al). I really think you would struggle (even with the tiny rotary engine) to get an Engine-Gearbox-Diff inline in the back of a FF chassis.
Lots of rolling chassis FF's for sale come with the gearbox though (as they mount the rear running gear) so you could get an adaptor plate made for the 13b but then you have the issue of power....
"A pretentious quote taken out of context to make me look deep" - Some old racing driver
Every FF1600 I've seen had a Hewand gearbox in them - basically a modified and highly upgraded VW Beetle gearbox. The shift pattern isn't so much what matters, as much as how the gearbox is packaged. A stock RX7/8 gearbox takes power in the front, and sends it out the back of the gearbox. However, a FF1600 gearbox takes power in the front and then sends it out each side to each rear wheel.
Your best bet might be to take the FF1600 gearbox and just modify it to work with the 13B. You'll need to get an adapter made for the flywheel/bellhousing side, as well as propbably uprated gears from Hewland to handle the power levels you're looking at. Hewland should be able to help with getting you what you need for this, but if you can keep the same gearbox case, it will make your rear suspension setup MUCH easier to manage.
Another option would be to get a Formula Mazda or Formula Pro Mazda gearbox - those are both designed to work off a 13B or 13B-MSP (Renesis) motors in small formula cars, comparable to a FF1600. The trick is both of them are designed for non-turbo power levels - and with the FPM gearbox being a sequential paddle-shift setup, it's not going to be cheap to source.
How much muffler you need will depend on where you plan on driving it. Does the track have no limits? If so, then just throw a simple muffler on it to keep your eardrums from bleeding. Is it a 100db limit? 98db? 95db? 92db? 86db? All of those will have different solutions.
Cooling will certainly be a big concern, simply because a turbo 13B will make a lot more heat than the Pinto engine the chassis was designed for. Plan on fitting larger radiators and reworking the cooling ducts to pass more air through them. If you're looking at doubling the FF1600's power, then you could easily need 2-3x the cooling air.
Scootin159 wrote:Every FF1600 I've seen had a Hewand gearbox in them - basically a modified and highly upgraded VW Beetle gearbox. The shift pattern isn't so much what matters, as much as how the gearbox is packaged. A stock RX7/8 gearbox takes power in the front, and sends it out the back of the gearbox. However, a FF1600 gearbox takes power in the front and then sends it out each side to each rear wheel.
Your best bet might be to take the FF1600 gearbox and just modify it to work with the 13B. You'll need to get an adapter made for the flywheel/bellhousing side, as well as propbably uprated gears from Hewland to handle the power levels you're looking at. Hewland should be able to help with getting you what you need for this, but if you can keep the same gearbox case, it will make your rear suspension setup MUCH easier to manage.
Another option would be to get a Formula Mazda or Formula Pro Mazda gearbox - those are both designed to work off a 13B or 13B-MSP (Renesis) motors in small formula cars, comparable to a FF1600. The trick is both of them are designed for non-turbo power levels - and with the FPM gearbox being a sequential paddle-shift setup, it's not going to be cheap to source.
How much muffler you need will depend on where you plan on driving it. Does the track have no limits? If so, then just throw a simple muffler on it to keep your eardrums from bleeding. Is it a 100db limit? 98db? 95db? 92db? 86db? All of those will have different solutions.
Cooling will certainly be a big concern, simply because a turbo 13B will make a lot more heat than the Pinto engine the chassis was designed for. Plan on fitting larger radiators and reworking the cooling ducts to pass more air through them. If you're looking at doubling the FF1600's power, then you could easily need 2-3x the cooling air.
Thats brilliant info, thanks for that! i had no idea that mazda did a gearbox that output directly in the fashion required! I won't be turbo-ing the 13b, just running NA so things should be ok so long as the exhaust is heat wrapped
)
