Being a long time fan of rotary cars, but knowing only a little about them, having not owned one or worked on one I'm curious to know about modified rotaries and boosting them to hell.

I reccently took my six pistoned GT-R out to a meeting of street racers. I had probably one of the fastest cars there ( 2.1kgm boost good 580 at all fours, 11.5 secs or under all day long) got pissed allover by a Series 6 bat, the guy claimed he was running 35psi boost with extended ports, titanium seals, lightened rotors and a redline of 9000rpm. don't remember what housings used and a also holinger dog 6 similar to mine.

How the hell can a near stock internal combustion engine make 3 times the power of standard?? It seems rare to hear talk of having to replace rotors with aftermarket ones, are the mazda ones really that tough??

Now everybody knows a good nissan RB26 will take numbers like 25psi boost and 8500rpm on all stock bits. But you'll need a chunky head gasket and some machine work to get that comp ratio down.

What I don't understand is rotorheads don't ever talk about compression ratios (how the hell do you change that in a wankel anyway?), or octane for these mad boost levels. Those I have talked to only talk about avgas or octane booster in conversations talking about 2.2kgm or more.

Are wankels not as vunerable to detonation as a ottoman?



So someone enlighten me on the engineering reasons why rotories can stand such and increase over the manurfacturers intentions

 

Sorry most of us dont understand you ..We have some Ausies here...somewhere..



So you have concluded that, rotarys owns you.....

 

on the compression ratio the turbo versions have a slightly bigger pocket in the faces of the rotors. some people run the non turbo rotors as turbo, which requires really good tuning. porting is like changing cam lift, duration and timing. Im sure you will get some more info on this post later too. oh yea i`ve been in a 12a when it was over 10,000 rpms. stock eshafts arent supposed to do that either. the more fuel you can get into a rotor the more power it produces.

 

I know a guy at a pretty well know Rotary shop that runs 30psi on stock 2mm apex seals and it is doing just fine.



He has a few of the right goodies in the right places but it is a stock motor other than a standard steet port.



I couldn't tell you his a/f ratio.

I haven't seen the compression readings either .

 

is it true our rotary engines have no limit as to what the rpms can go up too? say i remove the rev limiter on a 13b n/a and floor it, considering its a stock motor,what could it go up to before it blew? i read in an old scc or some import magazine about 12a motors in 1st gen RX-7's racing on a race track and they were cranking out 12,000 rpm's! ive downloaded a 3rd gen rx7 that was on a dyno and had 710 hp, the car had to have people sit on the rear of the car just to keep it on the dyno! the U.S.A. can now import GTR or GTS skylines, go to www.skylinegtr.com if anyone is interested?

 

all of the stock internal parts can handle something like 1200hp, UNDER NORMAL COMBUSTION. all you really need to do is make sure it doesn't detonate, and you are fine. the only way to change compression in a rotary is to change the rotors, or raise the port overlap (same as the valve overlap in a piston engine), its easier to up the octane than to change the compression.



mike

 

i have a friend that is selling an r32, its a motorex car. your 88 should not have a rev limiter, you should be able to bury the tach needle. the limit to excessive rpms is twofold.

1. the clutch explodes, at 9500/10,000? not good

2. the eccentric shaft flexes in the center where its not suported, and the rotors will hit the housings, not good either. this happens about 8500+



mike

 

Rotary engines do NOT survive detonation well, just ask some of the guys here They don't last long if you run them lean, apex seals shatter.



Yes, the rotary does have RPM limits, after about 9k rpm on stock parts you start to run the risk of apex seals taking up residence in the nearest rotor housing.



I've never heard of anyone breaking a rotor, ever. 13BAce?



Compression wise, guys run the turbo rotors to help with that, otherwise Racing Beat is a good resource. Get their catalog!



Rotary engines produce three strokes of power for every "revolution"



There is someone *cough* who runs a VERY large turbo on here....

 

i don't know about breaking, but this one is definately damaged from too much boost





Mazdatrix overboost

 

thanks guys, answers a few q's ok now i understand about why the only major mods for the extreme hp rotarys are a beefy eccentric shaft and some good seals.



on a interesting note just today i saw a triple rotor rx7 race car in a workshop with 480hp / 300lbft naturally aspirated.... guy said comp was 9.44 to 1 and would run on any pump gas. he showed me a dyno chart which had flat torque from 4000-8000rpm and could be street driven if they wanted.