To recap, a couple of months back we built a PP 13B with Renesis rotors for a Gen 1 S1 race car. Motor was specced & ported the same as the old one, with the rotors being the only real internal difference

All were interested in what difference the hi-comp rotors would make.

Well this motor has done 3 meets now with no issues other than a leaking oil cooler line. Car has dynoed (on the same dyno) at 24 hp more @ 8500 than the old engine when it was fresh. Mid-range torque is better, & driver reports much better punch out of corners.

So yes, using Renesis rotors gives an improvement. Not enough IMHO to pull apart a good motor to fit them (unless every last bit counts & the cost doesn't) The renesis rotors are the same price as the older types here, so 24rwhp for the cost of milling ther seal grooves makes it a must have at rebuild time for an NA! https://www.nopistons.com/forums/pub...IR#>/bigok.gif

Maybe even a turbo.......... https://www.nopistons.com/forums/pub...#>/biggrin.png

cool, the renisis rotors are cheap here, almost half the cost of the 9.7 rotors

Are they really that cheap? What can you get a set for? What is the compression?

CR is 10.0 and they cost $305 USD each.

what needs to be machined?

hmmm... high compression and turbocharge means....... faster spool up and better low end...... right?

theres a downside do high compression turbocharged cars too. like blowing **** up

lol...that's the cost of horsepower too https://www.nopistons.com/forums/pub...#>/BURNOUT.gif

It always gives you a good story to tell your friends. https://www.nopistons.com/forums/pub...DIR#>/wink.png

ok i have a question, when using lower compression rotors for a high hp application, it is easy to use healthy amounts of boost to up your power. now with the higher compression rotors you can still boost the engine but it will be at a limit and tuning must be very precise correct? now what i want to know is which method is better in the sense of flat out making high power? low comp/high boost or high comp/low boost?

I seconded to that inquiry.



plus how much did it cost for machining?

I'm guessing they machined the apex seal grooves to run the larger (older) apex seals?



It should be possible to run the renesis seals without machining anything, but the seals for the renesis are quite pricy, for the whole kit.



Theres also some concern with the renesis seals not being able to tolerate the peripheral ports on the previous series' rotor housings. Some people have claimed there is a risk of them bending and binding up in the ports, hence why someone would want to use the previous seals which are larger, requiring machining.



Hopefully Robbomaz can clear it up for us https://www.nopistons.com/forums/pub...IR#>/smile.png

I've ran 9.7 compression rotors on turbo applications without any problems. I've made close to 600rwhp and ran over 30psi with no drawbacks but only gains over the lower compression ones. Precise tuning is the key no matter what the compression is.

hmmm 600 hp..... ill take his word

I heard from somebody a few years ago that crispeed was doing that, but I never said anything because I was told that it was a secret. I guess I'm not special after all. https://www.nopistons.com/forums/pub...#>/biggrin.png

can u tell us the setup you were using??? is it the engine that you ran a 9.2 in??? unless it's a secret https://www.nopistons.com/forums/pub...R#>/unsure.png

http://www.fullboost.com.au/cars/featureca...hris_intro.html

I think he's now running an FD motor with a Cosmo intake manifold.

How to put it simply (& avoid typing heaps! https://www.nopistons.com/forums/pub...IR )

There is a mechanical limit to chamber pressure, which is the boost + CR.

Now heres some broad generalisations:

High CR/lower boost will show more midrange and equal power to a low CR/high boost setup. Off boost performance and the spool-up will be significantly better.

So what? Most turbo cars (even ours!) spend over 70% of their time off boost is why!



For flat out (drag, circuit etc) the flat response from a low CR is not an issue as the car spends 90% of it's time at WOT.



The difficulty (if it can be called that) is the tune must be far more precise on the high CR unit. But like crispeed said, the tune should be right no matter what.

My 20B Cosmo for example is richer and more retarded than our Fd racer. I want the 20B to go a few years between rebuilds, the FD gets a fresh engine every season.

We probably could have used the renesis seals, but this was not something I could be definate about, given that we knew the seals did not cross a port as designed.



The renesis seals may well be fine but that was not a risk I wanted to take with this guys motor. He is an unsponsored racer (apart from our discount price https://www.nopistons.com/forums/pub...IR ) and needed a season + package so it was decided to machine the grooves to take proven seals. I'm sure someone will use the new seal in an old motor soon. I believe the gas edge is better sealing on renesis seals.

Yes but the renesis seals are about half the height of the older seals, so will likely flex more when encountering the exhaust port in a pre-renesis motor.



Flex = bang!

Mazdatrix allready tried the Renn seals in a PP exhaust motor with no problems last i heard,.. think about it, the third piece on old apex seals was far thinner then the renn's are,..

Actually Dave did have a problem. Read about it here. Dave's reply is at the bottom.



http://www.coloradoscca.org/prodcar/...pic.php?t=2096



These guys know a thing or two about running rotary's at high rpm for extended periods.

That's a good link you found. https://www.nopistons.com/forums/pub...IR#>/bigok.gif

So the general answer from the masters on here is that it would be a relatively safe bet to run Renesis rotors in an FD that was boosting 20psi plus?? I would like to know seeing as I would love to have every advantage that I can while I'm building my new project FD. Please, all you motor gurus chime in. I'm wanting to hear any and all input!! Thanks in advance.



Zach

I would like to see install/mounting custom kits to drop in a Renesis in to a FD. Maybe it won't happen untill a turbo version comes out but I think the race shops should be fabricating it allready. If a new Renesis engine is $6k and a pieced together new FD engine is like $9k (guessing prices), then doesn't it make more sense to go with a more effecient, less polluting, higher power, less expensive engine?

https://www.nopistons.com/forums/pub...1047683473.gif

the fd engine is like 5-6k if you buy everythign brand new.

i think some people here are missing the point. I am pretty sure crispeed runs methanol injection AT LEAST, so having a high cr doesnt really limit him psi wise. For those of use SANE people https://www.nopistons.com/forums/pub...DIR#>/wink.png, running high comp rotors would really limit how much boost you could run on pump gas. IMO lower compression rotors (T2 8.5:1) is a better trade off. Slightly less spool, worse gas mileage, less low end, but MORE BOOST. Sounds good to me https://www.nopistons.com/forums/pub...IR#>/boink.gif

even mazda put 9.0:1 CR in the FD, I would hope you wouldnt go lower than that. check out maximum boost by corky bell, he has some interesting views on CR with regard to boost.

he has interesting views on a lot of other stuff too

No answers yet?? Judge, BDC where are you guys at when I need help? Crispeed, your opinion is MORE than welcome too!



Zach

what octane fuel did u use?

the link on teh top of the secodn page contradicts this statement? no?

it seems that their motor has failed with the renesis seals on the PP housing?

Robbomaz, what were your specific torque gains from the dyno?



Can you talk about what generation seals and springs you used? FD corner seals and springs? FC apex seals and springs?



Did you use the FE's extra blow-by/gas side seal?



Sorry for all the questions but 10:1 CR and lighter rotors! This is exciting stuff https://www.nopistons.com/forums/pub...IR#>/smile.png



thanx

And, the rotors are cheaper! Go fig..

i was calculating yesturday that if you are not able to use any other seals other then the apex seals on the new rotors and u have to buy rx8 seals it iwll run you 800 for everythign but the apexes. if everything fits then its great and all u have to do is mill the rotor.



what counterweights and flywheel did u use?

which old seals did u use?

what rpm are u revvign this motor to?

do u have a dyno graph u can post here?

is everyhting that u but the rotors from the old motor?



if its easier can u just tell us what exctly it is that u did ? https://www.nopistons.com/forums/pub...DIR#>/wink.png



sorry for allteh quastions https://www.nopistons.com/forums/pub...closedeyes.gif

Exactly the ?'s I wanted to know and also why the hell it matters if the CR is higher with boost.. I mean yes I realize high CR + boost = BANG but don't rotaries blow up on one ping or knock? So why would it matter?

Its just easier to blow up higher CR boosted motors. Very precise tuning and cold intake charger are required.

Usually the people who run high C/R + boost run alchohol. Or water injection with a 50/50 mix of alchohol. I wouldnt say the rotary will blow on first ping, but the high C/R would deffinately deminish the "safety net". Sometimes a ping is inevitable while tuning, and i would rather not risk my invesment.

No, they don't. I've had mine ping HARD like a dozen times without blowing up.

It sounded like a chisel getting thrown at a brick wall. Again, it did NOT blow up.

it will blow if u really ping it hard under load