LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Went to the track...

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Old 10-01-2009 | 06:35 PM
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Default Went to the track...

disappointed again. Couldn't run quicker than a 12.9@105. With all my mods that time is way too slow. Not sure why the car runs so slow. It feels strong and hooks without a problem. I logged the car and looked it over and the only thing that look out of the ordinary are:

1) Left Short Term counts vary from 4% lean/rich at WOT even if BLM locker is used.
2) Timing is set at 33 in my tables and varies from 36-37 in the log. I have heard though that this is not uncommon.
3) Wideband afr ratio when lean in the mid 14s ran quicker than when rich in low 13s

Anybody have any ideas what could be happening?????
Old 10-01-2009 | 08:21 PM
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Whats your 60' time ?
Old 10-01-2009 | 08:28 PM
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Originally Posted by dlk1950
Whats your 60' time ?
high 1.7s
Old 10-01-2009 | 08:40 PM
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I dont know what to think...with those mods I would think low 12s - high 11s.
Old 10-01-2009 | 08:47 PM
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definitely should be quicker. i'm scratching my head too. its like all the power is missing but the car still feels strong. weird thing is about 3 rare times during regular driving i have given it gas and its like it finds all the missing power for that one quick instance.
Old 10-01-2009 | 08:50 PM
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What about your 330 and 1/8th et and mph?
Old 10-01-2009 | 09:08 PM
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330' 5.284
1/8th 8.215 @ 83.11 mph
Old 10-01-2009 | 11:57 PM
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knock retard?
Old 10-02-2009 | 12:49 AM
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nope no knock
Old 10-02-2009 | 01:01 AM
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How much does it make on the dyno.
Old 10-02-2009 | 01:13 AM
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Have you dyno'd it?Whats it make?What was the DA or Elevation?Sounds like maybe it's blowing thru the converter.If your having Full power randomly that sounds like Fuel or Spark issues.Are you still running an Opti?Is it good?Could be failing at high RPM's.Are your plug wires good?Any missfires detected while logging?Also you may be floating the Valves the Springs could be worn out or were never strong enough to hold.I had that same problem with about 15k on my springs the car felt slow so I dyno'd it,It was losing about 30 or 40 RWHP on the dyno from 4000 rpm on,I replaced them and got all the power back.With those mods you should be in the Mid 11's.

Last edited by LS1iFiEd; 10-02-2009 at 01:21 AM.
Old 10-02-2009 | 09:09 AM
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Originally Posted by earl lee
How much does it make on the dyno.
I was going to ask the same thing. If it hasn't been dynoed yet then make sure you go to a known dynojet, not some odd dyno where you really don't kkow how the numbers compare.
Old 10-02-2009 | 10:55 AM
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Thats way to lean. Check your fuel pressure. Pump may be gettin weak..
Old 10-02-2009 | 11:45 AM
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Originally Posted by LS1iFiEd
Have you dyno'd it?Whats it make?What was the DA or Elevation?Sounds like maybe it's blowing thru the converter.If your having Full power randomly that sounds like Fuel or Spark issues.Are you still running an Opti?Is it good?Could be failing at high RPM's.Are your plug wires good?Any missfires detected while logging?Also you may be floating the Valves the Springs could be worn out or were never strong enough to hold.I had that same problem with about 15k on my springs the car felt slow so I dyno'd it,It was losing about 30 or 40 RWHP on the dyno from 4000 rpm on,I replaced them and got all the power back.With those mods you should be in the Mid 11's.
i did dyno it and it made 452hp one run and in the 370s all the rest. That was weird since it made 396 on the old setup which was less powerful. Don't know where the 80hp went. The dyno curve was smooth and didnt show any signs of spark or valve issues.

Im running and MSD opti. Don't know if it is failing as the dyno curves looked good and at the track the logs showed the timing was okay. I checked the plugs and wires they are good. I didnt feel any misfires but then again i dont have a crank sensor that checks for that since mine is a 94.

The springs are less than 2K miles old and have enough pressure on the seat for the cam and its lift numbers.

DA was really low like under 100 since the elevation at the track is only +5.
Old 10-02-2009 | 11:52 AM
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Originally Posted by matt94z
Thats way to lean. Check your fuel pressure. Pump may be gettin weak..
when i set the afr to be what i want it to be it is a lot more lean. to get the afr in the low 13s i had to command 11.77.

at idle i have it set a 43.5. what should it be at WOT? how do i check the pressure at WOT. my gauge is behind the manifold on the schraeder vavle. i dont want to have my head and hands all in the engine bay while its at WOT.

the logs show the trims at 128 on the right side but the left side is a little erratic if switches from rich to lean throughout the run.
Old 10-02-2009 | 11:52 AM
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Def. way down on power, 105mph is awefully slow - car is jumping off the line and then sleeping down the rest of the track, I ran within 2mph of your 1/8th and 1/4 speeds with a stockish car. I agree, the tune looks like it might be the issue, an afr in the 14's, if the gauge is reading right, is way off.

If the banks arn't running even, maybe you've got a goofed up injector.

Specifics on the heads/cam?
Old 10-02-2009 | 11:57 AM
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My Vette did the same thing. It would 60' ok but just felt slow and only ran 12.90 @ 107 mph. There was no miss or sudden drop off in power just slow all the way down. All i did was change the fuel pump and BAM 12.03 @116 mph. It felt like a whole new car.
Old 10-02-2009 | 11:59 AM
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Originally Posted by acammer
Def. way down on power, 105mph is awefully slow - car is jumping off the line and then sleeping down the rest of the track, I ran within 2mph of your 1/8th and 1/4 speeds with a stockish car. I agree, the tune looks like it might be the issue, an afr in the 14's, if the gauge is reading right, is way off.

If the banks arn't running even, maybe you've got a goofed up injector.

Specifics on the heads/cam?
injectors were cleaned and flow matched and they turned out to be fine.

heads are stockers ported & polished 2.02 1.6 valves. cam is a comp 224/236 574/572 111lsa.

the afr is tricky since i have to command a way rich afr to get something in the 12.7 range. id have to command like an 11 afr. on the dyno the car always made the big numbers at 11.8.
Old 10-02-2009 | 12:13 PM
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sounds like a fuel issue. You shouldnt have to command 11's afr to get 13's. Check fuel pressure!
Old 10-02-2009 | 12:21 PM
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Originally Posted by Vettestir
My Vette did the same thing. It would 60' ok but just felt slow and only ran 12.90 @ 107 mph. There was no miss or sudden drop off in power just slow all the way down. All i did was change the fuel pump and BAM 12.03 @116 mph. It felt like a whole new car.
my very first time on the dyno on an older setup i went to a tuner and my pump was bad it kept leaning out throughout the run. i got a racetronix kit on there now. id have to check to fuel pressure at WOT to see if its bad again.



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