No the limitation with a small turbo is two-fold. First the compressor side, the issue is in the aerodynamics of the compressor wheel. If you try to operate it at a non-efficient point, speed&flow, it beats the air up as it compresses it causing it to get hot.

The turbine side is the other limitation. It can cause problems with creating high backpressures, which is a high pressure in the exhaust manifold that acts to cancel out anymore boost you might add. The smaller the turbine and A/R ratio, the more restriction, but the faster spool up you get. A larger turbine and A/R allows more flow, but results in lower exhaust gas velocities and hence less momentum transfered to the turbine. It is a trade off like everything else in life.

The only thing that could be done to help is to get a turbo with a Variable area turbine nozzle that can regulates boost by constantly changing the turbine's flow characteristics. But good luck finding one that is affordable and will work on the 8.

The valve you are refering to is already used on all turbos, it is called a wastegate.

 

A few things to take into consderation about this video.What is the correction factor of the dyno or how come it is not SAE corrected? This can make a car with 100 horsepower at the wheels show 150+ horsepower at the wheels.On top of that the boost peaking out at 12.5 psi is ridiculous.We have never run more then 8.5 psi to make the power me made.Somone is going to blow a motor at 12.5 psi.They got a nice torque gain out of it but it should not have any impact on high rpm horsepower.The third thing is that with the boost dropping off to 5.5 psi there is no way this car is making 290 horsepower at the wheels! The turbo that is supplied witht eh greddy kit is to small to support this type of airflow, period. I am sure some of the other experts on this board would agree with this statement too.

Come run it on the un-biased(we do not own it it is not in our shop)dyno we use and I will pay to see it make this power.Finally you see hundreds of guys on here with Greddy kits that tune them and they dont make past 240 at the wheels running alot more boost.Now this car is making 50 more horsepower on top of that with some tuning and 5.5 psi of boost.And to add to it the A/F mixtures at the bottom of the chart looked really lean.I dont buy it.Take care.

 

I'm not an expert, but...

The corrections don't apply to FI engines

You are using a bigger turbo. more flow rate. same HP with less pressure.

Others have gotten it with the GReddy. One guy in Puerto Rico and another in Brazil who has 300HP to the wheels with it.


Prone to hyperbole, are we? I'd say the norm is 240 HP at the std. 5.5psi and no boost controller.

Not to bring this up again, but we haven't seen the results from your last car yet, have we? Did I miss it? You know what they say about stones and glass houses...

 

how much could the SFR peak at hoursepower wise

 

Wow. And you turbo engines for a living?

 

Scary

 

I'm not an expert, but...The corrections don't apply to FI engines




Yes they do.You have been misinformed.






You are using a bigger turbo. more flow rate. same HP with less pressure.



Others have gotten it with the GReddy. One guy in Puerto Rico and another in Brazil who has 300HP to the wheels with it.



Ok, there is two guys in the entire world and did they make horsepower at 5.5 psi of boost? No. This is my problem with that claim!




Prone to hyperbole, are we? I'd say the norm is 240 HP at the std. 5.5psi and no boost controller.



I would disagree with you based on what others have posted here.



Not to bring this up again, but we haven't seen the results from your last car yet, have we? Did I miss it? You know what they say about stones and glass houses...



280+ WHP out of our first car should give us a little credibility considering we were the first to make this type of power out of the Reneisis motor. Glass houses and stones? I have put together numerous thousand horsepower at the wheels cars so trust me I can make more power out of this stock rotary then anyone else I can think of. Our newset car is almost ready and then the world can see what we can do. Shoot I will even set-up a dyno day on an unbiased dyno here in San Diego and we will run our car against ANY greddy turboed RX-8.How is that for a glass house.

 

Unfortunately, you are basing your response off of a wrong answer. Remember, this particular person said he was not an expert and the fact is that I am. Call Dyno Dynamics, Mustang, Dynopak,etc....... and they all have some sort of correction factor that applies to all cars! This is why you see some turboed cars dyno charts with SAE correction on them instead of ACTUAL horsepower. Actual horsepower is not real because it doenst take into account, barometric,temperature or altitude compensation like the SAE correction does.

Shall I post some examples of turboed cars with SAE corrected dynocharts?

 

What is scary is when people read things(and beleive in them) on these boards that are written by others. who do not have the vast experience and knowledge that we do

 

I'm not one of the members on here that are trying to discredit you, in fact I think you have done some great work, and its nice to have someone developing another system for our car. I'll also be the first to admit that I don't know much about turbos or tuning at all. I think the what most people on here want (and maybe the reason why they give you a hard time) is proven results. There has been a lot of talk about posting recent dyno charts on here for awhile, but nothing actually posted. Let me again say that I support your work, and thanks for dealing with all the people on this forum, but it would be nice to actually see the results of your hard work. Good luck, and keep up the great work!

 

Chrysler had a tricky way to deal with turbo lag. They called it a VNT Turbo (Garrett: http://turbosunleashed.com/shop/prod...33102f954061bc ) . I think it had some moveable nozzle to shoot the exhaust gas across the turbine blades at different angles. The problem was, the moveable nozzles would get gummed up from exhaust residue, then stop moving, which required the whole unit to be replaced to fix it.

I had the misfortune of having one of these cars. When it ran, it ran great (just about no turbo lag). When the turbo malfunctioned, it was time for a new turbo (ka-CHING!). I went thru 2 turbos in 40,000 miles, at which point I gave up & traded the car for a Mercedes E400.

 

I didn't base my response off what someone else said. I based it off the SAE themselves and the fact that I'm an engineer.

Dynojets correct using SAE J1349 a standard that is NOT designed for forced induction vehicles. It says so right in the standard. You will over-correct if you use SAE correction on an FI car. You can show me all the dynos you want, I've seen places dyno FI cars with SAE correction too, but that doesn't mean that's the technically correct thing to do.

You tell me, self-declared Mr. Expert, how a formula designed to correct for atmospheric pressure works when the engine is compensating for much of the loss of pressure on its' own by compressing the air before it goes into the engine. That's why FI cars do much better at higher altitudes than NA cars do. The Formula goes wacky with FI cars because it's correcting for a different level of atmospheric pressure than the engine is actually getting.

There are correction factors for FI cars that various people have come up with over the years that some places use, but there is no SAE standard for FI cars on a dynanometer. The only SAE standard for measing the output of FI cars is J1995 which is a measure of gross horsepower. That doesn't stop people from using SAE correction on FI cars though, which defeats the point because it's going to over-correct and under-correct more or less dependent on the altitude, which is the exact thing that SAE correction is supposed to prevent.

 

Before you get to bent out of shape.......... I am a self declared Mr. Expert in turbocharging cars that weren't designed to be turboed :D So cant we be friends again?

I agree that the correction for barometric pressure is redundant and even altitude to some extent but temperature is not (and I do understand that compression is taking place which raises the temperature). If we dyno on a cold 40F day vs. a hot 100F day then that correction evens the playing field, so to speak, since it uses 70F as a standard For example.....if you dyno on a cold 40F day and make 220 horsepower and then it is corrected to lets say 200 horsepower. Now you do a run at 180 horsepower on a 100F day and it is corrected to 200hp. This correction allows you to make better, much more accurate comparisons.

If you guys want to see actual horsepower and that is all that matters in your eyes, then we will wait till winter hits to dyno our car so we make big numbers :p Just kidding, we are dynoing our car in 110F weather as we speak.

 

The turbo we use is capable of 500+ whp if you run enough boost

 

and how long are the apex seals expected at that level of boost?

 

how much boost would be needed to do 500 hp. how much boost psi wise can be safely run in the RX8
and also how do u deal with the apex seal issue

 

Personally I would think that will 500hp, your apex seals would exit your block shortly thereafter, at a great rate of speed, which most likely would destroy your turbo due to the MSP on teh renesis

 

I am trying not to make this get out of hand like the last thread, but I do have a few points here. I tried to be humble and point out that I am not an expert. But, SFR, you can't just come on here and bash one of your competitors with a bunch of exagerations and expect not to be called-out, especially being so brash about it.

Its your attitude about it that is the really bad part here. Especially when you have not been honest with us about the last car you worked on. Why won't you just tell us what happened? There were weeks with no results, and then some BS story about a broken 02 sensor. You said the car would have a new 02 sensor and would be on the dyno A MONTH AGO. Where the F is it? Come clean, man. This is why people are so hard on you: Attitude+deception.

You still haven't backed--up your claim that Mazsport was somehow fabricating their results. They have documented their results and shared them with the forum. And BTW, you have your facts wrong, it wasn't 5.5 psi that achieved the 290HP. Look again. They never claimed 290HP@5.5psi.

Also, while I am humble about my FI qualifications, you are plainly wrong about the SAE J1349 corrections applying to FI engines. Since the FI is going off relative pressure the corrections over compensate. Period. We can argue about the relative importance, but that depends on the boost as a percentage of ambient pressure. The fact is, SAE J1349 will overcompensate for FI. If you don't understand this, then you are not an expert by my standards.

Since this thread is about the differences between the GReddy kit and the SFR stuff, here is my take.

The GReddy kit is on the market. There are plenty of case studies available. The results with piggyback and quasi-standalone are available for everyone to review. There have been mixed results with the piggyback because of LTFT. If you are willing to reset this, then a good tune job can land you near 250 whp @ somewhere near 7psi. The turbo is small, but spools-up before 3k RPM. It will not provide over 300 whp. A standalone EMS will get you to this mark, however.

The SFR kit is largely undocumented. They achieved 280whp on one car. I have no doubt that this claim is valid. The second car that I know of that SFR worked-on was a forum member. The car went in for installation and the results were never shared. There seems to be a large degree of deception with regards to what happened to it. I seriously doubt that a broken WB02 is all that stood between that car and the dyno. The fact that the WB02 was to be replaced a month ago and we still have no results confirms this (for me at least). The SFR turbo is larger and will provide higher peak HP, at the expense of more boost lag. The SFR kit is more expensive.

 

but if it wasn't about the money which turbo would u guys pick???

Greddy or SFR?

 

lol at this point Greddy. or DIY for extreme results.

 

I would wait until you have more options then pick. Don't surrender to impatience, soon you have a better idea what kit you want because you would have more choices. But if I was to pick ssr or greddy kit, I pick greddy with the standalone ems option. But I seriously suggest you give this 6 more months when there are more viable options out there.

 

^ aye, rushing stuff on rotaries is normally a bad and expensive idea.

 

i would get the sfr if price was around 4500

 

At this point I would get the PTP Motorsports.

 

How come?