LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Just had my first dyno run....NOT GOOD!

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Old 07-21-2003, 09:27 AM
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Angry Just had my first dyno run....NOT GOOD!

Hey there everyone, I need all your expertise please.

I just did my very first dyno run on Saturday. It was about 93 degrees and about 50% humidity. Here is what I got:

Max Power: 255 HP
Max Torque: 275.8 ft lbs
Air/Fuel Ratio Average: 13.2
Average Coolant Temp during runs: 185 degrees

This is what it measured at the wheels! Yuck! I expected a much better run than that. They did a total of 3 runs, all within .2 HP of each other. They did tell me two things:
1) My car is running a little lean (I did notice a quick little puff of black smoke when she got above 5500 RPM).
2) The drivetrain loss for an auto is around 20%.....so I have about 318 HP at the flywheel. Is that right?

OK, now here are all the mods so far (all bolt ons):

1) TPiS Air Foil
2) Trick Flow Elbow and K&N Air Filter (stock housing)
3) March Underdrive Pullies (both alt and crank)
4) Mac Performance Complete exhaust (y-pipe, hi-flow cat, complete cat back.....also new O2 sensors)
5) New 24# FMS Injectors
6) Bosch +4 Plugs and Hypertech Coil
7) CATS Tuning (basically just the Hypertech program at the moment in the PCM)

So, now what can I do to help this? They said if I increased my fuel pressure, that would help a bit on it running lean. Can I do that with the CATS tuner? What else can I change in that program to help my power....there is a lot there I do not know much about and I am not into just changing numbers around to see what happens.....what has anyone here done?

Let me know what you think, please! Any and all advice is welcome!
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Old 07-21-2003, 09:50 AM
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Well you have a stock cam and heads so thats about right. They have about 240 at the wheels stock.
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Old 07-21-2003, 10:11 AM
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So, the numbers from GM are flywheel numbers when they say these cars are 285 HP? It sounds like with my mods I have gained about 33 HP over stock at the flywheel and 15 at the wheels, right?

So, what kind/brand of cam should I get for this stock motor? It does have 111k miles. Can I just do a cam and get gains from it? Can I do this myself or should I get it done?

Let me know what you think, thanks!
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Old 07-21-2003, 10:17 AM
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I would be leary of going to all the trouble of putting a cam in a 111k motor.
I have 135k on mine and am just gonna wait till I build my new engine.
Lots of people do it though, so go for it if you want.
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Old 07-21-2003, 10:25 AM
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A little disappointing, yes, but you don't even headers, do you? (Unless they are the Macs)
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Old 07-21-2003, 10:29 AM
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The only thing I see on your mods list that would really raise power is your exhuast. I would say those are pretty standerd numbers. You need to get yourself an intake and some headers. Then those numbers would look alittle better.
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Old 07-21-2003, 10:32 AM
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I wouldnt be too disappointed.You are at a high altitude which accounts for the low numbers.The air is thin.Less air= less power.
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Old 07-21-2003, 10:33 AM
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Yeah, you dont even have cold air. With that alone you will be in the mid 260s.
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Old 07-21-2003, 10:50 AM
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Dump the hypertech.

Otherwise it looks relatively normal to me. You don't havwe much in the way of performance modifications yet...
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Old 07-21-2003, 10:51 AM
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I think those are perfectly OK numbers for your mods. Keep adding some real mods.
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Old 07-21-2003, 10:57 AM
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Originally posted by joeSS97
I wouldnt be too disappointed.You are at a high altitude which accounts for the low numbers.The air is thin.Less air= less power.
The numbers should be "SAE Corrected" to standard conditions, including temperature, pressure, humidity and sea level. That fact should be stated on the dyno sheet. That way, the numbers can be compared to everyone else's no matter what the altitude or test conditions are.

If you look at the mods, and throw some numbers at them....

1) TPiS Air Foil - a couple HP
2) Trick Flow Elbow and K&N Air Filter (stock housing) - 5HP for the K&N, "0" for the elbow
3) March Underdrive Pullies (both alt and crank) - a couple HP
4) Mac Performance Complete exhaust (y-pipe, hi-flow cat, complete cat back.....also new O2 sensors) - 15HP
5) New 24# FMS Injectors - 0HP
6) Bosch +4 Plugs and Hypertech Coil 0HP
7) CATS Tuning (basically just the Hypertech program at the moment in the PCM) - HPP tuning can cost you 5HP without the 160'stat and lower fan on/off temps.

He gained about 25HP. 285+25 = 310flywheel. Allowing for a more realistic 18% loss on the 4L60E...

310 x 0.82 = 255HP
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Old 07-21-2003, 10:59 AM
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airfoil = 0 hp
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Old 07-21-2003, 11:08 AM
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Originally posted by FacelessZ
airfoil = 0 hp
I'm giving him the benefit of the doubt , and the numbers off the dyno tests at ws6.com:

airfoil - 2.4HP
u/d pulley - 0.7HP
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Old 07-21-2003, 11:21 AM
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well u have a a4 w/ not many power mods...so its not far off if at all
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Old 07-21-2003, 11:23 AM
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Well, OK.....thanks everyone.

So, this is what I am hearing:

1) I know I do not have the Mac headers, did not want to chance an exhaust leak, so I did everything else.
2) I also have a LT4 KM
3) Dump the Hyptertech? Already did that, copied the program into my laptop with CATS. Returned the stock program via the Hypertech and then sold it. Copied the stock PCM program to the laptop and then flashed the PCM back with the Hyptertech program. So, now......what can I change in the PCM using the CATS tuner? Should I go back to the stock PCM tuning and start fresh? I know I want the fan on/off temperature lower, but what is best? After that, what should I adjust? The fans kick on at 182 degrees and off at 176 degrees....does that sound about right?
4) What about the air/fuel ratio? How can I get more fuel without changing anything?

OK, what else can I do the help this? Any ideas from all you experts?
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