Looking for advice...
08-03-2007, 08:12 PM
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Car: 1987 IROC-Z
Engine: 350 TPI
Transmission: 700R4
Looking for advice...
87 tpi car, running 6E bin w/ tunerpro. lt4 hotcam, vortec heads, 9.6:1,
My original engine burned a lot of oil (3+ quarts in under 1000 miles)...the best i did before on the same tune was 13.81 @ 100, with a 2.09 60'.
I replaced that crate engine with the same setup, only this time i have ported plenum and descreened MAF.
Recently I ran my car and got 4 solid datalogs out of it. Unfortunately, on my best run of the evening my laptop died.
I ran consistant 99.5-100.3mph all night, 60' being the deciding factor of ET. While I was ok with that MPH, i think its got a lot more in it.
Timing through the whole run sat at 31.99, with 7 counts of knock by the end causing a max of 2.5 degrees retard. MAF read out to be 225 g/s at the end of the run, TPS at 4.4. My fuel pressure at the beginning of the night was at around 48 psi, and my O2 voltages sat at .950s (stock O2, not a wideband). I began to drop my fuel pressure each run, about 1.5-2 pounds per run. O2 voltages stayed in the .9-.950 range still. My 4th run it was in the mid 8s, so I bumped fuel pressure back up .5 lbs and stayed there. Its sitting around 45 psi.
My 5th, undatalogged run, I got a 2.000 60', and only managed a 13.83@100.xx.
With the previous engine, i shifted it myself at around 5500, and had TCC lockup come in around 75 mph. These recent runs, I let the trans do its job and shift at 5000, TCC lockup coming in at 85 mph. The previous engine had 1 MPH better through the 1/8 mile (79mph), I assume because of the lockup coming in sooner. Once through the traps before, the vehicle pulled hard still. This time it felt as though the car was struggling through the traps at 100.
Any advice on where to start would be appreciated.
My original engine burned a lot of oil (3+ quarts in under 1000 miles)...the best i did before on the same tune was 13.81 @ 100, with a 2.09 60'.
I replaced that crate engine with the same setup, only this time i have ported plenum and descreened MAF.
Recently I ran my car and got 4 solid datalogs out of it. Unfortunately, on my best run of the evening my laptop died.
I ran consistant 99.5-100.3mph all night, 60' being the deciding factor of ET. While I was ok with that MPH, i think its got a lot more in it.
Timing through the whole run sat at 31.99, with 7 counts of knock by the end causing a max of 2.5 degrees retard. MAF read out to be 225 g/s at the end of the run, TPS at 4.4. My fuel pressure at the beginning of the night was at around 48 psi, and my O2 voltages sat at .950s (stock O2, not a wideband). I began to drop my fuel pressure each run, about 1.5-2 pounds per run. O2 voltages stayed in the .9-.950 range still. My 4th run it was in the mid 8s, so I bumped fuel pressure back up .5 lbs and stayed there. Its sitting around 45 psi.
My 5th, undatalogged run, I got a 2.000 60', and only managed a 13.83@100.xx.
With the previous engine, i shifted it myself at around 5500, and had TCC lockup come in around 75 mph. These recent runs, I let the trans do its job and shift at 5000, TCC lockup coming in at 85 mph. The previous engine had 1 MPH better through the 1/8 mile (79mph), I assume because of the lockup coming in sooner. Once through the traps before, the vehicle pulled hard still. This time it felt as though the car was struggling through the traps at 100.
Any advice on where to start would be appreciated.
08-04-2007, 09:18 AM
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Re: Looking for advice...
It would seem that the times are simliar, within tenths between the two (identical) engines.
Two unknowns are the number of miles on the new engine (takes time for them to loosen up), and the weather conditions. I do know that it has been hot here on the Eastern seaboard for the last several days.
Struggling to pull on the top end is (typically) too much timing, and/or fuel delivery dropping off.
RBob.
Two unknowns are the number of miles on the new engine (takes time for them to loosen up), and the weather conditions. I do know that it has been hot here on the Eastern seaboard for the last several days.
Struggling to pull on the top end is (typically) too much timing, and/or fuel delivery dropping off.
RBob.
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