Dynoed my LT1.

**locrian** · 02-16-2007, 03:51 PM

took my 1994 M6 to a dynojet dyno tonight. ran a peak of 234 hp at 5k, and 293.82 tq at 3.5k. it had two misses, one at 5.3, and again at 5.7. i can't get it to miss on the street, i think it is the longer time at high rpms required on the dyno (1st gear on the street goes by a lot faster than 3rd on the dyno). fuel pump or filter? the car is stock except for a cutout. i thought the tq was good, but i was expecting more hp out of an M6 with a cutout? i wasn't running quite right to, so that may be it.

edit:

**BlackLT1Z28** · 02-16-2007, 03:55 PM

How many miles on your LT1? You might want to get a tune up, that might help the misses. And since you have a 6-sp, shouldn't you have dynoed it in 4th gear, since that's you 1:1 gear? And your hp should have peaked at a slightly higher RPM, but that could have been because of the miss you're experiencing.

**locrian** · 02-16-2007, 04:07 PM

Originally Posted by BlackLT1Z28

How many miles on your LT1? You might want to get a tune up, that might help the misses. And since you have a 6-sp, shouldn't you have dynoed it in 4th gear, since that's you 1:1 gear? And your hp should have peaked at a slightly higher RPM, but that could have been because of the miss you're experiencing.

77k miles. new opti, ac delco plugs and wires. anything else to a tune-up? we tried in 4th, but since it is a convertable and the original owner didn't opt for the z-rated tires, the speed limiter kicked in before we could wind it out. what difference would that make? what about an auto? what gear should you run that at?

**BlackLT1Z28** · 02-16-2007, 04:22 PM

Originally Posted by locrian

77k miles. new opti, ac delco plugs and wires. anything else to a tune-up? we tried in 4th, but since it is a convertable and the original owner didn't opt for the z-rated tires, the speed limiter kicked in before we could wind it out. what difference would that make? what about an auto? what gear should you run that at?

Technically, it may not matter. But a horsepower is a function of torque and a dyno measures torque. However, torque is multiplied by the gear ratios, so in a reduction gear, your engine's torque is multiplied by the gear and then by the axle ratio. A higher measure of torque will obviously yield a higher horsepower output. But an auto's 1:1 ratio (for the 4L60E anyways) is 3rd gear, so I would think that it would be dynoed in that gear. But I could be wrong.

**01Z28M6** · 02-17-2007, 04:36 AM

Originally Posted by locrian

took my 1994 M6 to a dynojet dyno tonight. ran a peak of 234 hp at 5k, and 293.82 tq at 3.5k. it had two misses, one at 5.3, and again at 5.7.

This is a good post and thanks for doing it. Your numbers are not far from a stock engine according to other honest reports of 240 to 245 rear wheel hp. Your torque figures are pretty much in line too. Did you happen to get an air/fuel ration reading as well? Your figures will provide an honest baseline for other people who are tuning and modifying their LT1s.

As for other things to a tune up; you may need to clean or replace injectors, fuel filter, coil or icm. I would be looking for vacuum leaks too.

**locrian** · 02-17-2007, 04:42 AM

Originally Posted by 01Z28M6

This is a good post and thanks for doing it. Your numbers are not far from a stock engine according to other honest reports of 240 to 245 rear wheel hp. Your torque figures are pretty much in line too. Did you happen to get an air/fuel ration reading as well? Your figures will provide an honest baseline for other people who are tuning and modifying their LT1s.

As for other things to a tune up; you may need to clean or replace injectors, fuel filter, coil or icm. I would be looking for vacuum leaks too.

thanks man! no a/f.

**01Z28M6** · 02-17-2007, 04:54 AM

The a/f will tell you if you are going lean. The erratic dips in your power curve show right where something is happening. If you would have gotten the a/f reading to go with it you can easily know what to look for. For instance, if it goes rich at those places, you can figure on a spark problem. If it is lean, start checking the fuel supply.

**Firebirdjones** · 02-17-2007, 04:55 AM

Thats decent for an LT1 with some miles on it. A laptop would help to see if you had or have any knock retard, do you know if it was pulling timing out? ,,also check the fuel pressure to make sure it's up to par. New fuel filter is a great idea.
Not sure about the 3rd gear dyno pull,,,that may skew the numbers a bit. Not sure what the cutout would do to the airfuel ratio,,,but I would think on a bone stock car it would go towards the lean side and cause the computer to try and compensate. Running too lean could have caused that high rpm miss you are experiencing. Definately sounds like there is a little more left in it once you get a few things ironed out. Now you have something to go by and work off of. Taking it to the track and comparing your dyno numbers to your track times is something I like to do,,,and I find it very helpfull as well.

**locrian** · 02-17-2007, 04:58 AM

how much would a good diagnostic tool cost that would let me find that stuff out myself?

**Firebirdjones** · 02-17-2007, 05:11 AM

Fuel pressure is easy enough,,,a cheap gauge at just about any parts store can be had to tell you that. Very simple to do.
As far as knock retard,,,thats a little more complicated,,,need a hand held diagnostic tool/scan tool or a laptop with a program for your car. That starts getting pricey. If you have a buddy that may have this equipment and is nice enough to plug it in and go for a ride,,,that would be a great help.

**jimmybling31** · 01-06-2008, 10:01 PM

when my 94 auto was stock i took it to get it dyno'd as a baseline and i got slightly higher numbers. i can't remember the exact numbers off the top of my head and as im 300 miles from my house right now i can't give the exact but it was around 250hp and 310 torque. mine was just in absolutely perfect mechanical shape though. it was maintained by the dealership and the woman who bought it new had only floored it a few times. she bought it because of how it looked. but she sold it to me because being in her 70's now she had trouble getting in it so i got myself a good deal. mine might as well have been new.