Some of the best tuners upgrade from 9:0 to 9:7 compression rotors for faster spool up and more low end when running big turbos, i.e. T88 and GT42R. Compression is part of the equation but you also have a lot of other factors like ECU control, Tuning, etc. The thing most bolt on kits from companies have to accomplish is a decent power gain without major upgrades in order to keep the price down, i.e. sticking to stock fuel system, how much power the transmission and rear end can handle, what the ecu can handle etc. The compression of the renesis is not the single factor preventing cheap kits from being developed. Nitrous and a large turbo is not all that reasonable for a street driven car because you wont be using the juice all the time.

The GT35R turbo is a good deal smaller than a Mitsubishi/Greddy T78. The GT35R has yet to make more than 490RWHP on a 13B, but is rated up to 600HP. The T78 flows a bit more air but is not too much beyond the GT35R as far as HP per RPM. Of course tuning, porting, engine condition, and other performance enhancements have a pretty good effect on all this...

 

Can't you use lower compression rotors from the 13B-REW or the 13BT?

 

I can't give exact numbers, but I do know from taking to Cam at Pettit that their car max HP came at 8000 rpm. Also a small correction, their car was tested by Motortrend not R&T. Car should be back to Lake Park, FL this week and I hope to drive it. They are preparing 4 or 5 additional units for testing and mine should be on the car by the end of the month. Their car did have a lighter flywheel than the MS unit, but a stock trany.

 

No. The Renesis was designed to use the rotors it came with. What I mean is the difference in seals... aprex, side seals and corner seals are redesigned and now we even have a new seal.. the blow-by. In addition the rotors used in the Renesis are lighter than those used in the 13B-REW and actually have some differences in shape (kinda hard to describe, but if you've seen side-by-side pics you know what I mean). All of this... particularly the rotor weight contributes to the Renesis' 9k redline.

 

WTF, I am not initimately familiar with Pettit's setup, but of course the problem that EVERYONE is running into when F/I'ing this car is the A/F/S management. When the tertiary porst are open, 6 psi is going to be moving an incredible amount of air. Not a problem if you can give it the fuel to match--but nobody has yet cracked the ECU, or developed a standalone replacement. There's only so far you can get with piggybacks on this car, and 6 psi boot with S-DAIS fully activated is not one of them. Besides, isn't the lack of low-end torque the biggest problem?

Also, the 14.2 time is pretty worthless without knowing the atmospheric factors, tires, other mods, 60' times, trap speeds, etc. Jay Goldfarb notes that an ultralight flywheel was installed; unless I am mistaken an ultralight flywheel's lack of inertia would make a supercharged rotary incredibly difficult to launch well--it would be a pretty wicked case of "bog or boil". That's why the 60' times and such would be really important to know.

Peace
policy

 

That's odd, because I heard elsewhere about putting RENESIS rotors into into a 13BT. Does anyone know if the 13B-MSP's rotors are compatible with previous engines, despite a different design?

 

for a guy who claims to know better than a whole lot of people on something fairly complex, asking a non-sensical question like "which turbo will spool faster", not giving any specifics at all like a/r ratio (which will make the biggest difference anyways) or bearing options, or your engine setup or anything (as said by Icemastr) doesn't really reflect well on your opinion.

stick to the stuff that you know, m'kay?

you don't really need a standalone, piggybacks would be sufficient for light tuning on something like a supercharger (supposing you could accurately meter the air being pushed into the motor, something still of a topic of discussion).

the "lack" of "low end torque" (by which you really mean low rpm horsepower) doesn't matter all that much, even dragging. a properly slipped clutch, or grippier tyres (along with a stronger drivetrain *cough*tranny*cough*) and a really hard launch would make up for it. just think about the all-motor p-port draggers that race, they have far less bottom end horses than the 13BMSP does.

no reason to. if you're gonna open up the engine anyway, you could just have the combustion chamber recess machined out a little (increase in volume doesn't have to be huge, 72.5 (9:1 ratio on 653cc chamber) - 65.3 (10:1 ratio, duh) = 7.2cc's), and you're set. you wouldn't have to screw with the side seal clearances, or worry about having the corner seals falling into the side ports ('cause they would, the apex seals are so much shorter with the new rotors), etc etc.

 

yeah, the rotors will work backwards, giving you a nice bit of room to take the intake ports out toward the rotor housing for an early opening streetport, and the smaller seals will seal better (less mass), but the side seals could be fiddled with to get the clearances down to older spec (tighter sealing, 'cause you dont' have to worry about the oil scraper rings and whatever with the perhipheral exhaust port).

the number of teeth on the gear, the size in all dimensions, and all that stuff is the same. they work in older motors.

why would someone want fairly high compression ratio rotors in a turbo motor they're building from scratch?? i have to assume they're modifying the rotors as i pointd out in my above post...

 

Well, piggybacks SHOULD be adequate, but from what I've read about the CanZoomer development, if the RX-8's ECU sees too much variance from what it expects, it will pull it back towards (theoretical) stoich. That's why he had to fiddle with the timing to get a smooth output curve. That's the only reason I said piggybacks don't seem to be adequate for full-on boost applicaitons.

As far as everything else goes, that's exactly why I said I want to know how the car was equipped, and what the trap speed and the split times were.

And yes, by "low-end torque" I really meant "low-prm horsepower". Mea culpa.

Peace
policy

 

for a guy who claims to know better than a whole lot of people on something fairly complex, asking a non-sensical question like "which turbo will spool faster", not giving any specifics at all like a/r ratio (which will make the biggest difference anyways) or bearing options, or your engine setup or anything (as said by Icemastr) doesn't really reflect well on your opinion.

Like i said in a previous post i guess i need to watch what i say and how i say it.I think most who know turbos know the 35 will spool faster.I was really looking for opinions on the give and take of each.I have to really keep an eye out for the quote police.When did i claim to "know better then a whole lot of people on something fairly complex".Im not sure what you even trying to acomplish with this sarcastic ****.

 

WTF no Turbo
I do not know where you got the 3 PSI after 6K rpm from. As usual, people are spouting info not correct which if nothing else will confuse the majority of people interested or not. I have been speaking to 1 of the 3 people at Pettit that have been fully involved in their supercharger progaram. According to him (will remain nameless until he wants to be called) the boost never falls below 5 psi. In addition, the 1st prototype was tested by the magazine and they did not push the test. The 1/4 should will almost surely fall below 14.

 

Cam gave me the info.I cant remember the head sales guys name there,but ive been talking to his "mad scientist"brother to.Didnt push the test?Hmm guess thats why the grenaded a tranny.

 

wow, flaming a mod, that's brilliant. fyi, i didn't put the cape in the pic, or the rotor symbol, or make a total jackass of myself in a thread where i was talking out of my *** about something i obviously didn't know the first thing about. just 'cause a guy at Pettit said something doesn't mean its the absolute truth.

and i'm a very fit 220, thanks for asking.

 

so you photoshoped in the cape and rotor all by yourself to gay it up more?? :D wow thats great, and too even if I get blocked so what. i can still check out the site or get a new user name

thats 220 canadian so whats that like a buck fifty-five american??

 

Ure a f%&#ing clown. Theres nothing more pathetic then attempting to diss someone "virtually". Usually clowns who do that are overcompensating for their lack of a voice in reality.

Keep Dreaming

-Alex

 

Back on topic, sort of: Besides this SC project, does Pettit currently offer anything else for the -8? That is, besides the Protek fuel lubricant, and the pretty sweet red metal rotor shaped oil cap that I bought from them.

 

er...how about that petit sc car? er..um..prretty fast huh? (hehehe)

 

Is this article coming out in the September Motor Trend, does anybody know?

 

Does anybody have a website for Pettit Racing with info on the SCed 8?

 

Leave the thread.. kill ALL the off topic posts. This can still be saved.

Are there any pics of this setup or is it still too hush hush? (or has that already been discussed but I forgot because of juvenile off topic posts?)

 

I tried to email them about this and never got a reply... That was when they were going to California Speedway to test it so I hope they werent pissed I knew.....

dont know...

Is it out in the September release of Motor Trend? Does anyone know?

 

They have a website, but nothing is on it yet. I was with Tyler of Pettit today and they are still doing some additional development work. They are building a new intake to test. Their car is still out west with the company that will be making their ecu for further developement and refinement. I can tell you that the did get about 220 hp at the rear wheel with the sc and intercooler. He couldn't remember the torge, but it was a big improvement. I suggest you contact Tyler for additional information. They hope to have the unit for sale starting in (a guess on my part from our conversation) around mid Sept.
He can be reached at 561-844-2258 Also latest issue of Motortrend doesn't have anything on the car. That issue went to bed before car was retested.

 

Their website is pretty sweet if you happen to be looking to mod an RX-7, tho...

www.pettitracing.com

and their rotor shaped oil filler caps really are pretty cool...and fairly inexpensive if I recall...come in different colors and everything...

 

That TKT Banzai FD is the awesomest. :D

 

Sorry 13, you've lost the spot. Kari is now the best looking.

Back on point. Remember the engine doesn't know where "boost" starts or stops. The engine thinks in absolute pressure. Nobody told it how you print your gauge face. It only thinks it drove below sea level vs up into the mountains.

The reason the roots blowers show a fall off point is that they get so much heat when you force them to go beyond say 5 psi. Below that they are good for a street engine. The rotary is very limited on how much heat it can take. I don't know enough about why, but it is.

A point in the RPM range can be targeted as a design point knowing the curves of both pumps. Meaning the engine and blower. But it is adjustable by the end user. That is the drawback of the roots blower, it uses so much power to drive. Why do you think dragsters break 100 mm wide steel belted blower belts. All the while melting the pistons. Belts last two runs, pistons just four seconds.

That's my $0.02

Richard