I'm doing research on the greddy turbo kit. everyone says the kit in a stock set up, the boost can peak at 10psi then it will drop off to 5-6psi. Is that because of turbo size or is it because of emange map. what needs to be done to maintain the 10psi and what is the afr at 10 psi? i know people switched to the int x but im talking about staying with emange.

 

Even the int-x users will drop off the psi as the rpms climb:

http://www.mazsport.net/html/movies/rx8dynovideo.wmv


When you say 'emanage' do you mean blue or ultimate? GReddy has replaced the blue and all kits now ship with ultimate. They also offer an upgrade kit for anyone who has blue.

 

yeah i know most guys have the blue and the kit was just released with the ultimate. is there anyone running a ultimate yet? i need to do more research on the ultimate.

My thinking is if the turbo can spike to 10psi it should be able to maintain it. what is the root cause for the drop to 5 psi.

if the int x drops off then can we say that its not the fuel management side but more a mechanical issue? if it is a turbo size limitation, i am thinking that greddy built a kit just to make up for the lack of torque below a given rpm , letting the high end characteristic the same. hopefully creating a broader powerband.

 

I'm running with the ultimate. I would recommend upgrading from the blue. It's a lot better.

The upgrade kit runs about $600.

The only thing lacking on the Ultimate right now is that the 2.0 firmware doesn't pull coolant temps properly. Without the coolant temp, you can't use autotune. Not going to prevent you from using the Ultimate, but it would be nice to tell it "I want 11 AFR across all my maps when the PSI is above zero", and let the car change the map when the actual afr is different.

 

does the ultimate tell you the afr by using the factory o2 or are you using a seperate wide band

 

you can't use the factory narrowband for anything. It's useless.

You'll have to buy an air fuel harness for $20:

http://www.mohdparts.com/emanage/#E-...tional%20Parts

And link your ultimate into your wideband.

 

The turbo is physically too small. It can't flow enough air.

 

Heh. Unless you are magic like I am. Or MadDog. Or a bunch of others.

I run and maintain 11 PSI all the way to redline with outlet temps under 220°F.
My inlet temps are typically 130°F, so that is a compressor temp delta of only 69%.
My manifold air temps are back down to 150°F or so, so the intercooler is doing a great job.

I'll go back up to 12 or 13 PSI soon after I am satisfied with the tuning regimen I employ.

So, Fred, you need to back that up with some real-world data of the type that you are always trying to hold me to!

 

The only way to get to the bottom of this is to create an internet poll. I vote for magic.

 

Jeff, I thought you were using a different turbo than the greddy kit since you did a custom setup, are you using a t618z?

 

The Greddy turbo is too small. Use a better turbo and get the same power numbers at half the boost level. Stop sending a boy to do a man's job and then trying to justify it. You assume that numbers that you see are good and that numbers that people like Scott get with properly designed systems are impossible when the exact opposite is true. Compressor temps tell you half of the story when it comes to making power. They are not the be all end all. There is so much more to is as is proven by a turbo that is so "efficient" barely being able to make an engine capable of 240 hp on it's own having a hard time hitting over 300 hp under boost at over 10 lbs of boost.

Actually when I think about it, for 11 psi of boost, that turbo is efficient. It's just too bad that the flow rate of the turbo at that boost level (that it's efficent at) is not a very good match for the flow rate of the Renesis engine which is what even an efficient turbo running in it's efficency range is still a poor choice for power. If you like running around with a small gain in power but still want to say you are running high boost numbers while extolling the virtues of having an "efficient" turbo, then maybe the Greddy is for you. This brings us back to the problem. The Greddy turbo is too small for the Renesis. That of course assumes you want to make any decent power. That turbo is much better sized for good power on a smaller engine. You would have to pull out all the stops to hit 300 rwhp with that turbo. You might, might get a few more if you really pushed it. It can't flow the required air even though waht it does flow is "efficient". Again it is a kid in a man's world. Give it a kid's job to do. Keep it where it excels.

Keep quoting your numbers and I'll keep pointing out the flaws in only looking at them to base your conslusions.

 

so the amount of air the engine pulls in is greater than the amount of air the compressor can provide at a given rpm. is that whats happening? or is it that exhaust back pressure is choking on the turbine side of the turbo?

 

It's a pretty well known limitation of the Greddy kit. with tunning, you can get pretty decent numbers. but it has its limits.

I dont have a Turbo setup, but I think I've been here long enough(call me a loser) to be able to tell.

 

250~280 whp is a good amount of power for me

Not yet ready for the necessary fuel/ignition upgrades to go beyond that (including time and money required for them), or the amount of power behind the pedal that comes with it. I'm sure many of the GReddy owners share my feelings in that regard.

 

Fred, you keep saying what it can't do based on your knowledge and experience and I keep saying what it can do based on the numbers.
If I posted a 320+HP run with my numbers, would it still be too small?

I'd be a lot easier to silence if you posted a flow measurement for the Renesis at a specific power level vs what the GReddy turbo produces in its efficiency range at a given pressure ratio. I don't think you have it and I'm a bit weary from your speculation.

Scott's numbers are implausible, regardless of the flow rate on the turbo. To flow that kind of air at such a low PR would require cryogenic intake temps. Do the math. The actual math, not the speculative stuff. Don't worry about the wandering VE of the Renesis, it won't account for the extra CFM.

There is no magic. You have a volume a pressure and a temperature and that is it.

Concensus is not science.

 

Have you found a rough figure for the Volumetric Efficiency of the Renesis?