3rd gen vs S5 rotors that are 9 to 1 compression
 

Ok so as some have noticed I've started making post and pm'ing people and asking all types of questions lol. The reason why is I have a RX8 Renesis that I'm going to put rx7 rotor's in...or should I say trying to do. This is my latest new thing I came across.

Cam at pettit racing told me I wanted the fd rotors cause they was 9.0 compression but when I look at a chart it shows that the s5 tII are 9.0 compression as well...and then he told me the S5 had a hardened stationary gear and he wasn't sure that'd be a good thing since mine isn't.

So I guess my question is can I run the S5 or no. Do you guys put the S5 TII in your FD with no problem or is that considered a no no?

Then if you say it's ok to do so..next question lol I noticed back in 86 n/a they had a 8.3 compression rotor. wouldn't that be better??? cause if so I have a 86 na sitting right here that needs rebuilt. That I could care less about right now.

It seems the difference is with the bearings:

https://www.rx7club.com/showpost.php...5&postcount=12

It seems that if you use later bearings, you should be good with using older rotors. I don't think I would go with the 8.5 rotors as they are heavier.

86-88 non turbo--9.4:1
86-88 turbo--8.5:1
89-91 non turbo--9.7:1 , lightened compared to 86-88
89-91 turbo--9.0:1 , lightened compared to 86-88

https://www.rx7club.com/attachment.p...1&d=1259072939

as for the rotor weight issue... I take my 86-88 rotors to 7500-8000rpm, right where the power starts flattening out. I don't feel comfortable taking the rpms much higher; rev limiter is about 8200. A nice advantage of the 8.5:1 is the increased safety factor though.

The s5 TII rotors work perfectly fine. Make sure to weigh the two rotors you are using and make sure the weight difference is within spec.

what does a stock 3rd gen rotor weight?

Thanks everyone for your input...so since I have a set of the 86 and I've already talked to someone else that was offering them cheap. I think I'm going with the low compression.

So far this is what I got for the car..lol I have a set of almost new rotor housing...I'll then have 8.5 compression with the ALS side seals and apex seals. I got the 6 port renesis...with a GT-35 turbo. I'm in the process of building my turbo manifold outta 321. So far I have water temp, oil temp, greddy boost controller and manual both, wideband and a EGT temp gauge...anything else you guys recommend?

From my understandings....from
0-15 psi I can run on pump gas with 11.1-11.5 afr
15-25 psi would run 10.8 - 11.3 ruff with water meth inj.
My EGT's should be around 1600 but can have peaks that hit like 1800 but not continuous...correct?

oh and I know everyone says you can't just give maps cause all cars are different..but could someone give me a timing curve for the lower compression rotor's that's safe. not to retarted but not advanced either. One that's just good enough I can get my break in miles onto the car and then I'm going to take it to banaza and have them to the car. As far as boost would I do the 1 degree per 2 pounds of boost or is it the other way around or kinda what's the rule of thumb on that.

For tuning assistance, post questions in the Engine Management forum:

https://www.rx7club.com/engine-management-forum-37/

The the 86 rotors are not a direct swap. You need a different counterweight and flywheel.

Im interested in how your putting the Rx8 Msp parts in this build?

it's 6 in the morning and I haven't been to bed yet...MSP help me out will ya

https://www.rx7club.com/attachment.p...1&d=1259153907

https://www.rx7club.com/attachment.p...1&d=1259153907

my 8.5:1 rotors timing map that I've been running for a few months now. AFR is about 11.4:1 rock solid, leaning out to 11.7:1 around 7500rpm as the power drops off. This tune is for straight 93 octane. It's safe but IMO not overly conservative for a 400+rwhp car (T67/T04R turbo). It's pretty much designed so I can just get in the car, put any 93 octane pump gas in it (I go to the discount gas stations sometimes), and beat the shit out of it without worrying. I am running 16psi which puts me right in the middle of the 20000 and 22000 rows.

units: 10000 is atmospheric pressure
20000 is 1.0 kg/cm^2 boost (about 14.22) psi , 22000 is 17psi,
30000 is 2.0 kg c/m^2 near where the MAP sensor maxes out

note that I use 4 stock Rx-7 trailing plugs (BUR9EQ)

MSP=Multi Side Port.The question really is if you plan to use the side port housings of an RX-8 motor,and if you use any 13B rotor(other than an RX8 rotor),how are you going to solve the issue of gas leakage when the rotor is at Top Dead Centre?

The RX8 rotor has a cut off seal between the side seal and the oil seal to prevent exhaust gas leakage into the intake.

Oh... ok I got ya...that grove has been machined into a couple junk rotor's already to test them. Everything went well and perfect.

That was the least of my concern...it's the side seals.

sounds interesting, could you spec out your motor a little more? whats been done/planned etc.

No you haven't got me!I was merely trying to explain MSP for you.

The side seals should not be a problem,your machinist should be able to cut a keystone grove to fit an rx8 side seal.

I see little point in using earlier rotors.Having turboed my RX8(which I sold 2 years ago and replaced with an FD3S),my real issue was engine management;but this appears to have been solved in the past 2-3 years(see Mazdamaniac et al).Power levels being achieved are coming up and reliability is getting better.With the 2009 model year changes to the lubrication system I would think that a turboed RX8 motor can be built with the same level of reliability as anything built with old rotors.

I was running 14psi with my gt-35 turbo. It had no problem suppling the boost..and I have heat shield after heat shield making sure the intake didn't see any heat from my front mount turbo. My car was good putting down in the upper 400's if not low 500's I hadn't dyno'd again after the boost went up. I was running just pump gas..car ran great for about 3 month and slowly it started giving out. Apex seals again for the second time. I had my own tune the first time and had it tuned the second time. This second more only lasted 3 months.. The first lasted about 6 months. I keep blowing seals so for me it's either my fuel isn't high enough grade or the rx8 seals just aren't that great. I don't know one person on the rx8club site that has a turbo or even supercharger that hasn't went threw a engine before they hit 10k miles with it. I use the microtech..just like a lot of these guys on here. Oh and the first go around...yeah it lasted 3 more months..boost was at 10psi.

First motor I ran low on gas...it's what did my motor in....I was going down the highway on my way to the gas station knowing I was low. Cruise set at 60 miles and hour couple of sputters and I pushed the clutch in and started coasting. I put gas in it and it ran like ass afterwards.

Second motor....well everything was good came home from work..with no problems...start my car the next day and it died...started it back up and ran fine..didn't think anything of it. Drove to work and it died a couple of times at the stop signs. By the time I went to work and got home it wouldn't idle period...thought maybe I have a charge piping leak. Tightened everything and checked over stuff. Found one small issue and fixed it. Went for a drive to the local gas station...still dieing..but pulled in and actually got it to idle...not smooth but it idled.. I used the rest room and got a pop. Hopped back into the car.. I had I'd say about 140 degree's of temp so I got on it a little in first...then hit second and all of a sudden at like 6000 it started to pull and fell on it's face. I let off and of course it died. I dropped the clutch to fire her back up and it's missing bigger then shit. Front apex gone and front corner seals swelled cutting groves in my irons.

So the corner seals is my guess why my idle was crap...loosing compression. But why did they do what they did and why did my apex go? corner seals and everything else still in tact just worn to hell

well it's the 6 port renesis. It has a little intake and exhaust porting done...there isn't a whole lot you can do. On my intake all my ports are opened up 24/7 I'm always a 6 port. Makes it where my idle has to be rich cause other wise it falls on it's face when you first touch light throttle. WOT is fine.

Car has the FD 5 speed transmission
3.9 gears in the rear
Gt-35 turbo
soon to have a water/meth inj.
it's a daily driver...previously pushing high 400's
It's a fast and furious look a like
spends more time in the garage then it does on the road lol.
IDK what do you want to know?

Any dyno graphs for videos of your last setup running.

Let me get this straight your last setup was a Gt35 on the Rx8 motor with all ports opened up and the rest stock internals.

Now your planning Rx8 side irons with all ports open, Fd housings, and S5 rotors machined to work with the Rx8 side irons?

And how hard was the Microtech wiring on the Rx8?

yeah that was my last setup...and yes the plan is to continue all the same stuff. The huge porting of the rx8 makes it easy to get plenty of air and fuel to it and so far the exhaust side is holding up. I didn't have a EGT before and I got one now.

And yes internals besides like bearing for racing are all stock. For the RX8 there isn't a whole lot of choices when it comes to seals. That's why I'm going with the rx7 seals. I was just going to machine my 8 rotors for the 7 groove...but then cam said something about doing lower compression and he said he's done it and it worked. So I thought the lower compression with better seals..and the added water/meth inj. should build me a very reliable and powerful engine.

Although it got mentioned to me and offered a set of unbreakable seals for my rx8 which really interest me.

oh and as far as the port I had the two set-ups the first and then the second. The first was with 4 ports on the low and mid end and open up to 6 at 6000. But why wait so long to let it have the air and for the power? I'll upload a video of what it was like with it that way.

ok here you go...the first take off shows the kinda torque I have with the ports open...and the last take off shows the big change in power when the ports open.

http://www.youtube.com/watch?v=WuJEWL7WfEE

Are you saying you think you were making close to 500rwhp on 14 psi on a 35R?:scratch: Hopefully I didnt understand fully and you realize it was maybe 400rwhp on 14psi with that turbo.

I'm not a 100% sure what my turbo is. I've heard it was a gt35. I have a mazsport kit..and they hid what turbo they used. There's no numbers or marking of any kind on it to figure it out.

As far as the power....I did low 300's with a extreme rich dyno at a bouncing 6 to 8 psi of boost. Everytime I hit 8 psi it was getting so much fuel that it was bogging and dieing out....dropping into the solid 9's. I was boosting 14 psi on the 10:1 rotors and I was comparing my car to others. There is a few 400 or so called 400 here and I pull them as well. I really have no clue what turbo or what power I had. I just guessed there is a guy named chris hitting over 500 or so said hitting over at 20 psi but then again you haven't heard him talk to much either. I assume he blew his up as well. They was making there own seals suppose to be top of the line.

The guy that claims this over 500 posted a video and I compared his acceleration in 3rd gear compared to mine and they was almost the same. So that's why I assume I'm...or was high 400 and low 500's

Oh and I just noticed you asked about FD housings. NO water ports and oil ports are different I believe. I was told there is a difference. This will be a 100 percent renesis besides the FD rotor's, apex, and side seals.

Ok here's my turbo... I don't even know where to begin to figure out what I have...or what to do to make mine better. you tell me what ya think and what I should do..my goal is 500 or so...maybe a little more

pull the compressor and turbine housings off. Measure the wheels, both the inner and outer diameter of both. What size compressor inlet is it? What size exhaust/downpipe outlet? That is a T4 turbine flange correct

Yes it's a T4 flange.... I'll go grab my turbo and take it apart and messure it all with pictures.

The cold side

Air in is 3 inch
exit is 2 inch
Wheel from bottom side is 3 3/8
Wheel from Top side is 3/4
Cold side housing is 6 3/4 inchs


The hot side

T4 inlet
Exit is 3 inch
Wheel from bottom is 3
Wheel from top is 5/8
Hot side housing is 6 inches

ok so I didn't know where I was suppose to measure..after I posted I started looking around and I can't figure it out. I think it may be a gt40 or blend of a gt35 and gt40. So that said here is the right measurements

compressor

85.7mm
69.85mm

Exhaust

76.2mm
63.5mm

I remember there was a guy on 8club who found out it the mazsport compared to to a T60 or T62. Dont quote me on that but its on 8club somewhere.

Yea, i was confused wondering how you got the car to go with exhaust ports in the FD housings and Renesis irons. lol.

That kick at 6k in the last section of the video is pretty sick. You have the microtech controlling the switch between 4 and 6 ports im assuming?

One of my friends is currently having a build done with all Renesis internals with stock rotors, machined to fit the RA super seals. You should look into this rather than going with lower compression rotors.

To my knowledge the lower compression rotors in the renesis will only require more Turbo than any true benefit over the stock rotors. Once again look into that option i have not actually compared results with lower compression and high compression rotors in the renesis.

If you haven't already look into porting on the irons as the triangular shape of the ports makes them prone to cracking under boost.

Ill try to look up pictures of it but if anything contact Dave at KD Rotary in PA hes the one who showed me several cases of it on the renesis.

yeah 4 vs 6 is a big difference I'd prefer power threw out vs a hard kick in.

I looked into the full seal on the rx8's but I've done bought the rx7 rotors so mind as well use them. There won't be any issues I'm pretty sure. So sure I'm throwing my money into it. Going to push her above 500.

Yes more boost for lower compression for same power. But also less heat and stress!!! there for more reliable and more power with lower compression.

Subscribing to this.

Well while subscribing you should give some
input on things as well.

I never seem to see major power differences between low compression (8.5:1) and high compression (9.4:1) dynos. The curve might be shaped a little different, but you can mitigate the effects of low compression by carefully choosing the turbo, tuning the boost control, etc. I personally wouldn't go higher than 9.0:1 rotors, not if you are already spending the money on Rx-7 rotors.

yeah I ended up with the 9:1 rotor...so what do you think about my compressor and exhaust turbines...they don't match up to a GT35 at all.. Well the one side is close just a few mm bigger....but then the other matches just under the GT40..

So I guess that would make it kinda like a GT37 but not...??????

I didn't find specs on the housing but if I'd guess I'd say I was the 1.06 AR from what I've read on the net.

OK. The Renesis is not a lover of over 500 WHP. The eccentric shaft is, how should I say this, less durable then the standard 13B shaft. It has a tendency to flex and and stay flexed. Using heavier rotors is not helping the issue either.
I would not be using any Renesis E shaft in anything over 400 WHP.

The Renesis Apex seals don't like much boost over 15 psi. I just witnessed one go the other day on the dyno. bypass valve was not functioning correctly, froze up or something like that, hit about 18 psi and pop.

On another note. Since your going high boost, I would consider making the exhaust ports open sooner. It can be done. The leading edge on the exhaust port can be ported to open sooner.

Outinnowhere

You should start a new thread with detailed build pics and info on both 8 and 7club.

Not saying you don't know what your talking about.. But I'm pretty sure I was around the 500... There are a few others that claim over 500 and aren't having any issues....

Yes I agree anything over 15 and she will pop. Higher compression, smaller seals, more heat. Yeah everything there makes it weaker on that.

As far as the shaft flexing... your the first to tell me this. I haven't heard anything about rotor slap or shaft problems. Maybe I haven't been looking up the right stuff..but thread after thread about high power I think someone besides you would of brought it up.

So tell me why do you say it flex's and has issues with that?

Mazda used a different hardening and tempering procedure with the Renesis E Shaft.

There is a post here on the RX7club from a prominent member and the issues they ran into with the Renesis E Shaft on the dyno when they hit the 500whp mark.

Anyone running the 9 to 1 rotors in place of the 10 to 1 rotors in an 8?
How does the power compare?
How does the boost limit compare?
What kind of timing does it take; does the RX8 ECU learn this?
What change does the fuel injection need? (more or less gas?)

I think you mis-measured. That is a to4E compressor housing. You cannot fit that big of a compressor wheel in there,, there just isn't enough material. It looks like a Gt35R with a to4E compressor housing.

As far as the Rx-8 eshaft flexing, there are a few people with over 500rwhp without problems, I don't really know where that is coming from...

thank you... alll I know is it isn't a stock or normal turbo lol. I know it's had stuff done to it. Yeah I'd have everything done...but I got laid offa work that's why I haven't posted or really done anything lately. But come first of the year when I get my tax return I'll have more then enough to finish everything...

Something I have thought about doing. But no one to my knowledge has yet to do it.
The RX8 ECU will learn nothing from an internal compression change. You will need an AccessPort to get the full potential of any boost increase. It will allow for tuning.


There is a discussion from Glenn at AZRR that talks about this more in depth. Don't remember where it is on the forum though.