370 w/S91 spooling question
370 w/S91 spooling question So I got my car running finally and we went out and got her tuned in for the most part on the 7psi spring. The thing that I am curious about is when do people with this setup normally start spooling their turbo? My car isn't starting to spool til somewhere around 4800 rpm, maybe a little higher. It is a little rich right now but not any richer then 11.2ish. I've been questioning that the car is running only on 7 cylinders since out of boost the engine is pretty gutless. The engine was built by LME and has ETP 245cc heads, 8.5:1 compression, with a ported and polished Victor jr. intake/Nickwilliams 90mm throttle body. The turbo kit is one I got from OFI, so it's a tubular header design. Any info would be great. Thanks!
What kind of timing do you have coming into boost? What is AFR coming into boost and at lower boost?
Also with out a boost controller or bigger waste gate spring the gate will be open slightly at low boost making it come in slower.
Also with out a boost controller or bigger waste gate spring the gate will be open slightly at low boost making it come in slower.
1.32 A/R
You should probably have around 25-35 degrees of timing up to 1-2 psi of boost and then start to pulling it out. Something you have to experiment with to find what works best.
A 1.32 a/r isn't exactly a small hotside either.
A 1.32 a/r isn't exactly a small hotside either.
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So I got my car running finally and we went out and got her tuned in for the most part on the 7psi spring. The thing that I am curious about is when do people with this setup normally start spooling their turbo? My car isn't starting to spool til somewhere around 4800 rpm, maybe a little higher. It is a little rich right now but not any richer then 11.2ish. I've been questioning that the car is running only on 7 cylinders since out of boost the engine is pretty gutless. The engine was built by LME and has ETP 245cc heads, 8.5:1 compression, with a ported and polished Victor jr. intake/Nickwilliams 90mm throttle body. The turbo kit is one I got from OFI, so it's a tubular header design. Any info would be great. Thanks!
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You need to keep in mind that 8.5:1 is alot lower than 10.5 (I believe is stock) and will change your spool rpm. The idea of lower compression is to drop detonation...being able to run more boost than a higher compression motor. Also, the turbo's a/r will drastically change spool too. To big will make it laggy, but will make more power. On the other hand, to small and it will spool quick but make less power. I ran a GT4294 (70.1mm) on my 4 cylinder with a .98 a/r and it didn't see full boost until 6800rpm shifting at 9,000. Compression was 9.0:1. But then again, were talking about a 71mm on a 4cylinder vs a 90mm V8. Is your motor stock? You could be pushing the limit with a stock cube motor.
Thanks for all the replies guys! I have also been curious as to why at idle the Afr's from one bank to the other seem to be about 1.0 different at times (one side 13.8ish and the other 12.8 to 13.0ish. I have a fast dual wideband sensor on each bank. I am going to pull the plugs tomorrow to see if it has any signs of not firing on one of the cylinders. But at this point, maybe how rich it's running, and how low of timing we have, we might be able to get a good bit of spool at a lower rpm.
i was hoping for maybe a boost leak but we are going to mess with the springs tormw on the wastegate 
So you are saying that it's gonna be A dog at any given time other then Full throttle in boost?
I actually lied though. I need to get more specifics from my brother before I go and spout off on a thread here. Apparently the timing is at 24degrees until it goes into boost and then it ramps down to 16degrees. We are doing the tune/break in on the street and we're being pretty conservative with the tune to keep it safe and easier on the engine.