stock bottom end LT1's with boost (8 psi), what timing are you running at WOT?
Greg Carroll got me setup with an ostrich, tunerproRT and a great base tune. I did have success tuning WOT fuel ratios on the dyno w/ wideband (by using first the % enrichment vs. coolant temp table, and then the %enrichment vs. RPM table). My S/C is an intercooled (procharger intercooler) P600B making 8 psi boost. Im running about 12.0 to 12.3:1 AFR at WOT.
Im still wondering what I should do for spark advance...Everyone knows that the time honored spark advance for chevy v8 (naturally aspirated) is 36 degrees at WOT. Obviously it needs to be lower under boost.
What should I be running under boost? Some people have told me no more than 20 degrees. However that seems too wimpy.
Im running 30 degrees (at WOT) until 4500 RPM, where it goes to 28 and then at 5000 RPM, it goes to 26 degrees. Im having good luck with this. Im not sensing knock retard, but I need some better resolution scanning software before I am 100% certain that no knocking occurs -at any point under any full throttle runs.
Im still running stock computer, so Im limited to 100 kPA being 'full boost' condition.
I know a lot of people act like supercharging a stock bottom end and compression LT1 is a bomb ready to go off. Thats fine, gives me excuse for a forged, lower compression, higher boost rebuild!
It sounds like your timing is pretty good with your base tune. 26 degrees is always what I found made the best power with my blown lt1 firebird. It however had forged pistons. You might consider changing the "%Throttle position for WOT" table to 20% across the rpm range. That way you don't accidentally boost it up while computer is still shooting for 14.7 AFR. I would shoot for 11.8 AFR when you are tuning the PE tables. It will make a little more power at 12.5 but it is on the edge of detonation.
Methanol and boost go very well together. If you want that stock motor to last and get a real kick in the pants order a methanol/water injection kit for it. That will keep it from detonating and drastically lower your IAT's.
You might consider changing the "%Throttle position for WOT" table to 20% across the rpm range. That way you don't accidentally boost it up while computer is still shooting for 14.7 AFR. I would shoot for 11.8 AFR when you are tuning the PE tables. It will make a little more power at 12.5 but it is on the edge of detonation.
Steve
Steve, thanks for your suggestions. I did go in and lower the '% TPS threshold for WOT' from 4000 RPM and up. It was set around 80% to trigger WOT from 4000+ RPM.
There have been times when I was not able to get traction at 100% throttle, and was only able to accelerate at app. 80% throttle. I could have had leanout problems if I was trying to accelerate beyond 4000 (under boost) with < 80% throttle!
I always lock the BLM's in cell 15. This cell is the last cell before the computer goes into WOT mode. This will give you a more predictable AFR at WOT. Some cars will get split BLM's in this cell and then when it goes into WOT mode one bank is leaner than the other.
Tunercat made this change to their software upon recommendation from me and many other tuners. Its just a simple check box. On or Off. Don't know if TunerproRT has this.
BTW if you have a Wideband on the car you don't really need to go to the dyno every time. Just find a stretch of highway where you can do a good WOT 3rd gear pull from 2000 to 6000 rpm.
I always lock the BLM's in cell 15. This cell is the last cell before the computer goes into WOT mode. This will give you a more predictable AFR at WOT. Some cars will get split BLM's in this cell and then when it goes into WOT mode one bank is leaner than the other.
Tunercat made this change to their software upon recommendation from me and many other tuners. Its just a simple check box. On or Off. Don't know if TunerproRT has this.
BTW if you have a Wideband on the car you don't really need to go to the dyno every time. Just find a stretch of highway where you can do a good WOT 3rd gear pull from 2000 to 6000 rpm.
Corvette Store
stock bottom end LT1's with boost (8 psi), what timing are you running at WOT?
