14.2 quarter for the Road and Track people.Forget FI to make it faster.Easier to drive yes,but after 6200 rpm threshold 3psi boost.I said it once and ill say it again...this engine will not like boost.5k or so price point available by xmas.

 

Are you saying a supercharger isn't a form of forced induction? $5,000 for 3 psi? I could get an air hose and spray 6 into the intake! Sheesh. Well, at least they're trying. You can't entirely say the RENESIS is un-boostable. I believe Phoenix's Power's RX-8 is proof of that.

 

this in the latest R&T?

 

If they are only getting 3 psi of boost there is one of only a couple of things going on. The first is that their supercharger is too small and can't keep up with the airflow requirements of the engine. This has nothing to do with whether or not the Renesis will like boost. Second, they have only designed the system to give a low end boost. This too has nothing to do with whether or not the engine will like boost. Third, they could have tuning issues with the ecu that is prohibiting them from making more power at this time. Again this has nothing to do with whether or not the engine will like boost. It would be an ecu issue.

The Renesis is no different than any other engine on the entire planet from the standpoint that it is no more or less friendly to forced induction. It will like forced induction. We just haven't seen anyone do it properly yet. Be patient. I predict we'll see the first 300 hp RX-8 within the next 6 months and the first 350 hp within the next year. The more everyone learns about these cars, the closer we get to a good power upgrade.

 

yea the wait is killing me.

 

Didnt explain myself i guess.I maybe thought most out there would have understood.6 to 7 psi until 6200 rpms.We know what happens then right?After the 6200 rpm is hit they have to back it down to 3 psi.Anyone that thinks they can run any kind of substantual boost at high revs really dont understand this engine or do not care about reliablilty.Compression or porting must be changed for boost,its that simple.

 

Also, that 14.2 tells me absolutely nothing about how much power that car is making. What kind of trap speeds did they see in the 1/4. What were the cars 60' times. For all we know its making decent power but not getting out of the hole properly. We need more info before we can judge this car.

 

Good thing you clarified that WTF. 3 psi would've been down right nutty.

 

there's a distinct possibilty the drivetrain just cant take a launch under boost like that. upgraded clutch, gears, slicks whatever...we might have us a low 13's car. thats sti territory and the sti has 300/300 at the crank and AWD.

i dont know the details of the system (someone could be so nice as to tell me) nor much about SC'ers but that makes the most since, especially if its built for power down low.

 

Yeah whatever dude. You just keep on thinking that. I guess I have no idea what a rotary really likes. Since I obviously don't understand it, please fill me in with EVERY possible detail as to exactly what the Renesis can't take any "substantial" boost above 6200 rpm. Why is that the magic number?

 

Well, I wouldn't flame him for making that Super Street-type statement.

 

Hes probably thinking about positive displacement superchargers where generally they are maxed out at about 7500 since they are on a 2:1 ratio thats 15,000RPM. If you look at positive displacement supercharger dynos on other small displacement motors you will see the torque beginning to significantly taper off around 6000RPM. So he he isn't completely wrong.

 

Guys cmon.RG i respect your knowledge of the rotary no questions there,but you for from know everything.I even believe it was you that made a post about 4 port being eaier to turbo then 6port.@6200 rpms when the last ports open, the engine does not like boost.Ive heard this from more then one person now and thats why most have even scrapped FI projects.The side ports are causing problems with FI period.Thats why i stated that new porting and or shaving rotors to drop comp needs to be done.As this engine sits now a SC or mild turbo to help bottom end is about all your going to see from any reputable company.


Ive had 2 7's and just bought my 3rd.Ive given up any type of FI project for awhile anyway.RG on another note i got a question.Spooling on a gt35 compared to a t-78.Is there a big rpm difference between these 2 for boost?Ive been reading and there is alot of mixed feeliing about both just looking for more opinions.

 

honestly, i still fail to see how something that increases airflow makes the motor 'not like boost'. all the ports are side ports, its just one(two) more opening up.

 

But that has nothign to do with the motor liking or not liking anything. That's simply the way they designed those blowers to work, and in those applications the purpose was to give a bump to the low end. If you wanted it to have more of an effect on the top end, I think, at least with that type of blower, you'd need to gear it such that it would end up making less ofa difference on the low end. Maybe that's exactly why the Pettit unit behaves like that. Everyone has a different idea about how they want it to work, I wouldn't assume those design decisions were necessarily mandated by limitations of the motor.

jds

 

I think your answer for this question lies here.

www.rx7club.com

www.turbobygarrett.com

http://www.mhi.co.jp/gsh/eindex.htm

 

Many months ago I was considering a supercharger and almost sent my 8 to the West coast to fab one up. Due to a communication breakdown I decided to hold off. In the interim I did some calculations and they indicated that each pound of FI boost was worth 16 h.p.+/-. With most early projects limited to 5 pounds I decided to go for a 50 h.p. nitrous kit. Most of you are following that story. My current set up at 55 h.p. mimics the Petit set up in terms of output and is working quite well. In addition, I have a bunch of other mods. I have even used the 75 h.p. shot a time or two. The point is that the 8's drivetrain can handle that which I have thrown at it so far. The only reason I don't use the 75 shot is because of detonation at mid to high rpm's. SSR mentioned a while back that they were seeing some intake manifold ballooning at 5 pound levels. I wonder if the manifold issue is why Petit limited their high rpm boost to 3 pounds. I would like to do a side-by-side with nitrous versus FI just like in some NHRA classes.

Charles

 

There is a fairly large difference between the response of the T78 and the GT35R. The GT35R used by A-Spec on the RX-7s reaches full boost usually around 700 RPM's sooner than a T78 and has better reponse.

 

That gos along with most of what ive read.Where the info seems to fall off is top end differences.Will the t-78 deliver alot more hp up top?Seems to me the 35 is a no brainer unless your looking for 500 plus hp.

 

Yep think ive been down that road with 2k post on rx7 forums.Turbogarret does not even offer a rx7 single set up on that site.Nopistons.com also has good 7 forums.

 

Compression is the main issue.Ill try to spruce up my terminoligy from now on.I will call it "blowing up" instead of "not liking it" from now on.

 

I would think anyone with the r&d time they are putting to these will try to market max performance.

 

Off topic: WTF, I believe the TRUST T-78 is a larger turbo than the GT35. Nevertheless, making power is based on how you tune your engine. Hell, you could even go with a GT3037S, make just as much power, and it will spool faster than the former.

 

Don't forget that some racers use a larger turbo and them make up for the lack of low-end response and spool up time with a small nitrous boost. Perhaps a hybrid set up will be the way to go. Do I sound like a nitrous salesperson? I hope not.

Charles

 

compression yes. but 10:1 is 10:1. be it on 4 ports or 6. yeah i know, more rpm more heat etc...but if compression is the only problem, lets get some machined rotors in there. the 50hp that some of these kits are claiming isnt even worth blowing the motor over. 150? maybe, but not 50.