diabolical1

iTrader: (3)

well, to be honest, those are my thoughts, too. however, i don't know how to make it work with stock ignition setup. i've seen Rx-8 guys running the HKS Twin Power for amplification, but i haven't seen any running Crane. i also haven't seen anyone running aftermarket coils. this is not to say they're not out there, but to be honest, my interest in setting up a turbo Renesis is pretty newfound, so i'm still looking at setups out there and gauging efficacy to see if it's something i'd want to muck with on my 8. it's still a bit new to me and as i said, i haven't had the chance to pull a Renesis apart yet so i'm happy just getting to know my 8 and enjoying the smooth N/A power right now while doing some homework.

Roen

iTrader: (2)

I had been told that the REW irons/block was the best for making peak NA power?

BLUE TII

iTrader: (9)

Well, prior to the Renisis the REW had the best bearings, thrust bearings and oil system so it stands to reason that it would be the best starting block for the high rpm needed for NA power.

The upper intake manifold is very nice too for a strong dynamic effect in the 2ndaries.

And the ports are nice for top end flow with plenty of room for porting.

I have heard of as high as 240 hp claimed out of a streetport NA REW, which doesn't sound impossible if 210 RWHP is done as low as 7,800rpm on the S5 TII NA hybrid.

Ctrl

When I switched to rx-8 spinny bits I also did a lot of other things at the same time so I can't give a fair description of rotors only. But I've got them, and it's a better engine than the blown stock 6 port I took to the shop.

What I have now is:

street ported 6 port irons
ported fd tt rotor housings
fd tt oil pump
rx-8 eshaft, thrust assy, and ceramic coated and clearanced rotors with 3mm seals.
550cc secondaries
rb underdrive pulleys alt/main

Given the mods it's hard to tell how much power is being made by what component versus a stock component,

For me a lot of the reason was the weight and inertia of the engine.
I had the money for rx-8 rotors at the time, I already had an aluminum flywheel from the stock engine along with a road race rb exhaust. If you're going light flywheel you might as well go light everything.

I can say this tho, I know the compression makes some difference because I can feel it in the engine braking.

Roen

iTrader: (2)

got dyno?

61620B

I am using non rx8 rotors nor e-shaft on my race motor.Just 8 stationary gears and a set of GTU rotors with 2mm seals on an 85 GSL-SE Block.Also fuel injected Alky fuel with aftermarket management.

I have spun my motor to 12K Rpm with no problem and making plenty of HP throught the rpm.The key is the right porting and exhaust porting also with a good tune.That is on a P-port design.

I am going to try the Rx8 rotors soon just to see hopefully some better results,going to stay with the stock 2mm grove for now also.

Here is a link to my personal best record run at the 1/4 mile.NA power!!

You could see from the videos that i stumble a bit on the launch but it pulls like a

turbo car once it goes past 2nd gear.Estimated HP around 380 RWHP to push 2100 lbs car.

http://vids.myspace.com/index.cfm?fu...deoID=22105355

crispeed

Rene.
RX8 rotors suck big ***** .
You're better off with what you have. Just lighten them if you want and the rest will fall in to place.
There's a huge difference between static and dynamic compression with those rotors and it gets worse over time especially in this type of application.
Just ours and a certain other All Motor racer's experience.
We never gave up on them but after all the trial and error we were still down 20 to 30 rwhp from where we were with the 9.7's. Can only imagine what the results would have been once we switched back to what works.

61620B

yeah i know,it came across my head a few times.I just have to see for myself.

Roen

iTrader: (2)

Can you explain the difference between static and dynamic compression, and how the change in the two during operation affects both the 9.7's and the 10.0's?

crispeed

I know how you feel. You're like me have to figure it out for yourself to be sure.
When you know 'who' told me not to try it you think I listened.
During the off season that certain person's car at the time went from a 10.30's to a 11.0's I asked what was the deal. He said that **** don't work. 'I tried everything and you see what's the deal'. We went from 10.40's to 10.80's! Everyone was going backwards.
First time we tried it on the dyno the difference was immediate. We said to hell with it let's see what happens at the track where it really matters. First pass was off by four tenths and at the end of the run the catch can over flowed and oil was every where. To be exact it lost almost 2 quarts on that run. At the time the longer, cut to fit side seals were not available so we went with what was available and as suspected the excessive clearance was not going to work in this application. Then finally the long side seals came available. Had to make a new jig offcourse to clearance those things. Even then the match was not as how I would like it. Re-assembled the motor with the new stuff. Checked compression and it was way better than before but still not as close to where it was originally. At the track some time was gain but still not close to the original level. The one good thing was that the catch can was back to an acceptable level after every run.
I'm not going to mention how many I cracked trying to lightened them! Not worth it for a 1/5th of a pound.
In the end we knew what we had to do but the accident happened and the story ends there. I'm going to miss it a lot. For me as a tuner and engine bulider it was the biggest challenge. Like they say it's time to move on!
I hope you have better luck.

crispeed

In laymans terms.

Static or cranking compression pressure is what each cylinder/rotor
experiences when the starter motor is turning the engine or when
the engine is running at idle RPM. In other words 10:1, 9.7:1, 9.5:1 etc.
Dynamic compression is the pressure seen at the gauge when checking cranking compression. For eg. 100psi,120psi etc.
Dyanamic comprssure ratio is actaually the important factor.
This explains it more in piston termology but you will get the general idea.
http://www.empirenet.com/pkelley2/DynamicCR.html

dave20bpp

I guess i should enter this thread as i have just completed my engine with rx8 rotors and i will say i am very happy with how they have come up but the hassle of all the machining is not worth it, the car will be on the dyno soon so i will have some numbers for you all guess proof is in the numbers. Side seals are an issue i just hope people see how different they are if they are going to play.

here is a vid of the engine they went in http://www.youtube.com/watch?v=h8sKu...eature=related

cheers dave

ps CRISPEED i have 2 question for u did you run the oil scraper on the rotors or not?
and what gearbox did you guys run in the rx3?? just looking for options for my capella??

cheers

crispeed

The RX-3 had a G-Force 5-speed clutchless tranny.
No I did not use the scraper because a copule of people who used it had serious wear patterns in a very short time.

crispeed

Good luck on the dyno Dave.
The engine bay is sweet and it sounds the same also.

Ctrl

Interesting thread. Here's my newb question... how does lighter weight and higher compression give less results? To my layman's mind, in theory it should be opposite.

Roen

iTrader: (2)

the difference between static and dynamic compression (apparently) as quoted above.

Compression ratio is a big deal, but I can understand, if your engine only produces 90 psi all faces, an older 9.7:1 CR engine that makes 115 psi on all faces will probably make more power than your engine.

Ctrl

I understand that and thanks for pointing it out. I got a compression tester here, I'll find out my PSI level and post it. What's the best plug hole for it? Trailing or leading? [edit] Nm, found the info.

BlastinSideways12A

I would guess that the RX8 rotors' seals aren't able to seal as well if the dynamic compression is lower. Perhaps the side seal configuration is not as effective? If you are machining the apex seal grooves and using the older 13B apex seals then the apex sealing shouldn't be a factor.

j9fd3s

iTrader: (3)

diminishing gains.... the rotors arent that big a % lighter.

my pet theory is that the 10:1 is fine, but to do it the combustion chamber shape isn't as optimal as it could be. you can see it in some older piston engines too.

Roen

iTrader: (2)

in that theory, gains are still gains, and shouldn't equal to losses....right?

Ctrl

Since I went 3mm seals and had machining to do anyhow we had to properly notch the corner seals ala FD style. I don't know all the reasons why, I was just the customer, but adam (rx7specialties) and I did have a discussion about the corner seals and had to modify some.

j9fd3s

iTrader: (3)

yeah, seems like the combustion shape/size = a small loss

dave20bpp

thanks means alot for someone like to you to compliment me on my car especially knowing the cars that you have build/worked on mate

Yeah i heard the same sorts of stories about the scraper so i scraped it too, just wanna say how much i loved the Travieso Racing rx3 it was one of the inspirations in building my car, hope you dont mind me picking your brain a little more about the gearbox setup somewhere done the track when it comes closer to the time for me to get one.


cheers dave

crispeed

No problem Dave.

crispeed

That has also been discuss to a certain extent.