Ok well I have had the feeling that my car gotten slower which I know is usually just getting used to the power or owner paranoya syndrome haha. Well I went to the dyno and well I was right, I was indeed down 18rwhp. Now the question is where did it go? Looking for any suggestions as to what happened etc.

List of things which have changed since previous dyno of 343rwhp:
- Swapped plugs from NGK to AC/Delco iridium tipped from dealer
- Full Loudmouth catback instead of Cutout w/ stock exhaust
- Torque Thrust 2's 17x11 with 315 tires

After spinning the rollers twice I had a best of 325rwhp and after data logging the pull and looking everything over from the log it was EXACTLY the same as the 343rwhp pull as far as everything was running great and tune was still dead on with good AFR's.

So LS1 guru's where did it go? Could plugs affect it that much and added weight from the new wheels? I highly doubt the cutout to loudmouth switch effected it that much maybe a few hp but either way let me know I want the power back or at least just know my motor isnt going to let go or something catastrophic haha.

 

Don't worry about it. Weather differnces could acount for nearly that much hp if there was an extreme differnce. Anyway, weather probably is going to account for 5-10 hp, and the heavier wheels & tires will account for 5-15 hp.

 

well that makes me feel ALITTLE better haha but the weather was almost the same but it was actually alittle colder out. The thing is though when hopping on it with some buddies around here that i usually pull from pretty substantially 4 cars +...Now im only pulling about a car or so. Well im most interested in making sure the motor isnt going south on me or something and well that 18 hp can definately be fixed when i put in the new cam.

 

Weather shouldn't matter, dynos almost always have built in corrections for weather conditions.

Dynos are only to be used as a tuning tool. Try to make it back to the track and see how it runs. While at the track weather WILL be important, of course, but it will give you a better idea than anything else.

You will lose some of it through the extra rotating mass of the tires. They will also slow you down a little bit in the real world.

 

Different or bad gas? Heavier wheels? Need new wires maybe? Fuel filter clogged?

There's a lot of little things that can change HP small amounts.

Maybe your buddies aren't telling you that they have modded their cars, or maybe it's your imagination.

Or maybe your car is just posessed.

Go back to the track, that will give you the real scoup. Peak power means very little in the grand scheme of things.