Car seems down on performance from last year

[JoeliusZ28]

As the title states - Im wondering if anyone has any ideas for things I can check on that might cause such a thing. Last fall, i could drop to second gear at 55 mph and lay stripes on command. This year I'm lucky to spin in second much at all. Granted, the tires have been upgraded, so it "could" be a mental thing but even so it does not seem like it has the same gut that it used to and even watching old videos it doesn't seem like im pulling through the gears as quickly as before. The car runs and drives just fine, there is no mis-firing or anything like that.

I am wondering if worn piston rings could be a factor with my added compression and original 100k mile bottom end. Ever since ive done the cam, the car has burned some oil at full throttle. That said, in 3000 miles of relatively hard driving im lucky to notice a change on the dipstick reading and the oil stays pretty clean.

I figure I will check the spark plugs to make sure none have come loose and maybe re-lash the valves. Any other suggestions or possible explanations? I don't expect this engine to last forever but hopefully its not getting tired just yet.

[ezcruisn71]

Did you ever check your exhaust for possible plugging (bad catalitic convertors)?
Hook up a Vacuum gauge to the Engine then start the Engine.
At 800 to 1200 rpm watch the gauge.
If Vacuum gradually drops then this could be excessive exhaust back pressure (plugged muffler or catalytic converters).

[JoeliusZ28]

No catalytic converters, and I have 3" duals so I don't think there is any restriction there

[1BADAIR]

Mph at the track

[mcalus]

Hope you get it figured out Joel. I'm in the same boat, my 1/4 mile times are not even coming close to what they should be at.

[JoeliusZ28]

Mph at the track

Only problem is i wont have the same wheels and tires as last year.... ive got some lighter 16s and heavier 18s than the 17s i had before. Hopefully going to the track soon though.

[DETROITMUSCLE]

those wheels won't affect your mph much, I went to a drag setup and didn't gain any mph. The problem may be the LS1 air lid setup just realized its out of place.

[JoeliusZ28]

The problem may be the LS1 air lid setup just realized its out of place.

Why didnt I think of that? That must be it, close the thread

[MunsterZ28]

you got a boat anchor for an engine. lol maybe its just new tires and the fact your used to your car? mine is slow but to me feels like it moves out like a prius.

[1BADAIR]

like jeff said wheels wont make a big diff. although if you dead hook now the MPh will go down unless you absolutely killed the tires before.
some wheel spins increases mph

[JoeliusZ28]

OK well i haven't gone to the track yet, but like i was saying in another thread that after yesterday I am 100% sure something is wrong. Saturday it was running considerably rougher than normal at a cruising RPM as well. It seemed i was better off in a lower gear than normal. I also think the bearing in my A/C delete pulley is toasted. I'm going to check things out later this week.

[MunsterZ28]

OK well i haven't gone to the track yet, but like i was saying in another thread that after yesterday I am 100% sure something is wrong. Saturday it was running considerably rougher than normal at a cruising RPM as well. It seemed i was better off in a lower gear than normal. I also think the bearing in my A/C delete pulley is toasted. I'm going to check things out later this week.

lol so in a round about way you just called my car slow

sounds weird, i know mine is killing for a tune. yours is too.

[Kwazrollinz28]

140k on my bottom end and still running strong, i just pour in a can of RESTORE and she purrs like a kitten.

also seen your car at m&g i didn't notice you changed you wheels, it looks really good I like the shifter and gauges, and the car

I know my car is crying for a good tune though, But doesn't matter this block is stock i'll put money into a good tune on a fast motor

[JoeliusZ28]

lol so in a round about way you just called my car slow

sounds weird, i know mine is killing for a tune. yours is too.

Not at all, your car moves out for a hotcam. I do think im lacking some top end right now but it cant be that much. What im talking about surfaced more after the show when the four of us cruised up to woodward.

[MunsterZ28]

hmm does it miss at all in the top end? i know when 1 of my optis went it was flat on the top end and had a miss like 4k and up from time to time.