MARK 99STS Posted November 14, 2005 Report Share Posted November 14, 2005 Ok guys I took the car to the dyno this weekend for some baseline numbers before I turbo charge it. Now that I can control the air/fuel trim I wanted to experiment. Got some interesting results. 1st pull was running stock program. As expected the A/F was very rich(typical GM) at about 11.8:1 (251 HP, 252 torque). 2nd pull I backed off the fuel and it ran fairly lean at 13.8-14:1, but the HP and torque stayed nearly identical (250HP, 250T) 3rd pull I split the difference and got the fuel trim to 12.8:1 and as you can already guess the HP and Torque stayed the same. The guys at the dyno said they had only seen this happen with a Cobra Mustang running the 4.6l doubleoverhead cam motor. Very wierd. We did a final run unplugging the IAT sensor which made the computer think the air temp was -40 in hopes to increase the timing but the results were still the same. The only other dyno results I have seen for the STS were from Corsa when they compared their exhaust with and without. Their results were 206 HP and 227 HP, so I am significantly higher than that. Anybody have any thoughts as to how the HP does not change with a change in A/F ratio? MARK 99STS TURBOCHARGED Link to comment Share on other sites More sharing options...
speedyman_2 Posted November 18, 2005 Report Share Posted November 18, 2005 Hmm..Let's see. More gas going in. Same HP. Not enough Spark for more gas to make a difference?? I Dunno. Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted November 18, 2005 Report Share Posted November 18, 2005 What gear was the dyno done it? Could the torque management be a factor here? Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
MARK 99STS Posted November 18, 2005 Author Report Share Posted November 18, 2005 Hi Bruce, What happened to the rest of this thread? To answer your question, it was done in 3rd gear. We took it up to 6500rpm right at the shift point. At 6500rpm in 3rd gear it was at 130mph and it hit cutoff at the same moment the guy let off. I know the car shifts automatically at red line from 1st to 2nd and 2nd to 3rd regardless were the stick is locked, but does anybody know if it will shift to 4th automatically if the stick is locked in 3rd? We didn't test this theory as he backed off at 6500. By the way the sampling was started at 3800rpm in 3rd gear as to make sure it would not downshift on us if we started at to low on the RPM band. MARK 99STS TURBOCHARGED Link to comment Share on other sites More sharing options...
danbuc Posted November 18, 2005 Report Share Posted November 18, 2005 I take it you have the H-rated 130mph cutoff then Mark. I would imagine that if redline was reach in third gear at 130mph like you said, that it would shift automatically regardless of gear selection. If it would go to 150, it would have to shift. What mph was the sampling started at? 2nd gear runs out at about 80mph. If I can get my car on the dyno at my school, I'll probably run it in 3rd gear as well. Second would work, but you would have to bring the speed up above 35mph. At this point, it won't downshift to 1st either, since 1st run out at abotu 42mph. The RPM's are similar to that of 3rd gear at a abour 60 or 70 I think. On a side note, your dyno number are somewhat interesting. Just as a comparison, the Grand Prix GTP we have put's down about 206hp, while making about 240 at the crank. This makes me kind of wonder about the dyno results listed on Corsa's website. With the GTP, this works out to just abotu 15% loss through the drivetrain. The same amount of loass on the N* work out to about 255hp at the wheels. Even a full 25% loss is still 225hp. MArk, say your making about 325hp or so at the crank right now. Your dyno number show a loos through the powertrain of about 22%. Add that loss to the stock 300hp, and your still left with 234hp. I'm starting to think that the dyno sheet listed on Corsa's website is somewhat flawed. There chart shows a loss of about 31%. That's pretty darn high, even for a complicated tranny like the 4T80E Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted November 18, 2005 Report Share Posted November 18, 2005 Hi Bruce, What happened to the rest of this thread? Dunno, Is some missng? Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Scotty Posted November 18, 2005 Report Share Posted November 18, 2005 Hi Bruce, What happened to the rest of this thread? Dunno, Is some missng? Link to comment Share on other sites More sharing options...
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