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A 90 vette, 245hp should have a 113 L98 aluminum head, 1.94"/1.50" valves int/exh, 64cc chamber, maybe 58cc, not sure. Flow around 200cfm(ish). Not a bad head really, but not great one either. A vortec head would flow better, but intake would have to be replaced vs. stock.
You could be correct on the rpm which stock I would assume is around 5,500/5,600, maybe not. So 5,800 at least may not be out of the question on that motor I wouldn't think, let alone 6K. With the timing where its at and current fuel, the motor will not achieve its potential IMO. The timing is off at WOT. If you don't think that is a problem, then I don't think I can help. A mail order tune is never a good solution and will need tweaking and that's the truth, but what do I know? I only went to EFI University tuning school. Good luck with your tune.
I appreciate your input but the only thing you are telling me is my timing is off at wot but by how much and where.
I have studied your tune and your data log and I have some comments.
-It appears to me that the log you posted #3 you started out in 2nd gear and what appears to be a gear shift is actually excessive tire spin where you lifted on the throttle and then got back on the throttle after the tires hooked. The RPM of the engine and the tire speed of the car work out to a second gear launch and spin and then the drop to 18 MPH is when the tires hooked and you got back on the throttle. The car shifted to third gear at 72 MPH. You need to find out why the car is taking off from zero in second gear?
I also looked at your tune and it appears OK to me, your low RPM timing is at 22 degrees and your upper RPM timing is at 30 degrees. This appears a little conservative but not bad. You also had some knock retard at the shift so it may not help much to add more timing. I would try more timing and see what it does but in general the tune looks OK.
I have attached a more detailed graph of throttle application and MAP reading to show the 2 nd gear launch.
I have studied your tune and your data log and I have some comments.
-It appears to me that the log you posted #3 you started out in 2nd gear and what appears to be a gear shift is actually excessive tire spin where you lifted on the throttle and then got back on the throttle after the tires hooked. The RPM of the engine and the tire speed of the car work out to a second gear launch and spin and then the drop to 18 MPH is when the tires hooked and you got back on the throttle. The car shifted to third gear at 72 MPH. You need to find out why the car is taking off from zero in second gear?
I also looked at your tune and it appears OK to me, your low RPM timing is at 22 degrees and your upper RPM timing is at 30 degrees. This appears a little conservative but not bad. You also had some knock retard at the shift so it may not help much to add more timing. I would try more timing and see what it does but in general the tune looks OK.
I have attached a more detailed graph of throttle application and MAP reading to show the 2 nd gear launch.
Thank You that was very helpful. With my work schedule right now it may be awhile before I can do some more pulls to test 1st gear. I now in the past I have manually shifted the trans through all the gears with no problem. I would like to get it on a dyno one day also, just not much time right now.
04-20-2017, 04:55 AM
