Ok, since i got my new engine running i raced a bone stock ls1, which i hung even with up until 90 where he pulled me. After that i a raced a 5.0 with intake, headers, cam, and gears, which i beat by about 3 cars. Tonight i race a freind who has a bone stock bmw 328, and its not a m3. It's bone stock and runs a 1/4 of 14.7. Anyways we raced and it was dead even from any roll we went from and it was dead even off the line. I barely pulled him, everytime he was just at the cab. Now my question is why is it so much slower? I had 2 other people in the car that had a combined weight of about 350, but i don't think even that would justify how much it slowed down... I really now i should be able to smoke this car and it was dead even, and to be honest i feel like selling the truck now if i can't find a major problem. I did change somethings with my editing software, but i don't think it would make enough of a difference. All i did in the editing software was change my a/f from 12.8 to 12.5, and then pulled a degree of timing, and increased my shift point 200 rpm. The only thing i can really think that could cause the decrease is a clogged cat (which i doubt because i think if anything they would just be blown out) or a problem with one of the cylinders (which i doubt). I was also thinking maybe a fuel filter because i am getting the slightest bog on top, but i don't think that either. im at a loss. I don't know what is up but this thing is a turd now for some reason. Any ideas? Engine has about 3000 miles on it

 

Just a guess, maybe your friend's bimmer is not stock. Does your truck feel slower or the same?

 

first off, 5.0s r wildcards... u never really know what theyre going to do so u gotta throw that one outa the equation. keeping up with the ls1 was pretty good... however, was it stick/auto? z28 or SS? lots of differences there, ive seen those cars driven completely different by different people. the beemer is kind of a shocker, wouldnt expect that to keep up. not only that but i question those things running 14s stock anyway...

all u gotta do is race one of the shos uve already raced, thatll tell u if things r the same or if infact something got slower. just common sense in figuring it out... ohya btw thats where a gtech comes in handy

 

it was a z28 stick, raced one of the sho's-put about 5-6 cars on it if not more.. but those 2 cars where before i messed with my tune. tonight i put the tune back to where it was before i started tweaking it and thats what it was. I don't know why but i screwed something up somewhere with the spark or fuel... so it was just whatever i changed in the tune, oh ya and i had a clogged fuel filter

 

probably a case of not really knowing what the hell ur doing on the tune

 

ya, gotta learn some how

 

Do you not have access to a 1/4 mile drag track???????????? So you went from a 5.3 to a 383? If so could you feel a difference in SOTP when you did the swap? I hope so!

 

He has a 98 so I doubt he had a 5.3L in there before.

 

Ok then its even worse- whatever he had he shouldnt see any power loss going to a 383 or not be able to tell a difference. What is your setup man?

 

no he feels a difference, hes just saying it seemed like the tuning made it slower.