Slyno96

my buddy has a 01 z28 that has a magicstick3 cam, headers, and exaust. Before he had it tuned he raced our buddy's 01 z-06.... it was close but he pulled on it (slowly) the whole time. He just recently had it dyno tuned and edited to fix idle issues, bump up the rev limit, and such and the original hp on the dyno before the tune was 365 and w/ the tuning it brought it up to 386rwhp. The dyno graph was real jumpy so we put in tr-6 plugs and msd plug wires. Well.... we took it out tonight to see how big of a difference the tuning and the new wires and plugs made and the vette pulled on it pretty bad......... Does anyone know why it would have made it do this?

Slowhawk

iTrader: (12)

The car could of been dyno tuned for the most "dyno" hp.Then when it is on the street it has too much timing/lean A/F causing KR which makes it lose power. A pretty common thing to happen.

Now this is just an idea I'm throwing out.

jimmyblue

iTrader: (11)

What might the Z06 guy have done to his car, meanwhile?

Slyno96

nothing.... he's a really good friend and he's been to busy trying to get our friends 408 ss and his 99 turbo TA running to have done anything to the vette. I just don't know how 20hp of raw power can make it slower.........

hc_performance

iTrader: (4)

Do you have any way to data log? If so next time you guys go out data log to see if it pulling timing like slowhawk was saying.

Slyno96

yeah.... we might have to try the data log. I bet you were right about the "dyno power" so, we might have to get it retuned.

2xLS1

iTrader: (25)

Yea, blame the tune without any data to support it other than someone posting that here. The car is not the same as it was on the dyno. Even if it was just a plug and wire change, things can get screwed up even doing something as simple as that. Crack a plug installing it, A bad wire even when new. If Jeff is unhappy with the tune, tell him I'll relfash his stock file in the car and refund his money. The tune was a good tune. Here is a before and after with the datalog.

white2001s10

iTrader: (4)

It's true that dyno and track tunes are not the same, but seriously how controlled of a test was that?
I know at least the Z06 is a manual car and if there wasn't an even start there was absolutely not even a hope of consistency. You're better off rolling dice to see who wins.

Slyno96

Im not saying you didn't do a great job tuning Glenn, its obvious you did.... he gained over 20hp. We were just trying to figure out how he could lose his street performane when he did gain hp from your tune. The first time the two raced before the tune, the z06 actually got a jump on him and he caught it. Then when we ran them the other night they both hit it at the same exact time and the vette pulled the whole time. Im just curious if bumping up the rev limiter is causing him to shift out of the cams powerband. We were just trying to find an explanation as what the problem could be. We will be in OKC sunday for the test and tune at Thunder Valley so maybe if you figure something out we can get it all worked out. You did just fine tuning it cuz it fixed a lot of problems he was having w/ the car. I didn't complain once about the tuning being bad on here, we just couldn't figure out why it would do that. Thats the only reason i posted this.... to get some opinions.

AKRA

What was your before and after track times? Your comparison was totally un controlled. Where you at the same exact speed both times? Where you both in the same gear both times? A 20 hp increase from the dyno tune is what it is. Thats only about a 5% increase. It helps but it's not going to be a drastic differance.

Good luck,

Al

CuNfUzEd

iTrader: (14)

It's because the driver couldn't drive probably! Or was he grabbing your crotch instead of the shifter?!?!?!?!LOL

Patman

20hp is pretty drastic actually, that's enough for about a 3 tenths improvement in the quarter mile on most cars (unless you're talking about going from 500-520 hp that is, then it's not worth as much)

Running three tenths quicker in the quarter mile is enough to beat a car by three car lengths (if you previously both ran the same time that is)

Iron Sights

dynocar

There are too many variables in a street type grudge race, not very scientific. However, you could be getting into knock retard on the street but not during the dyno tune causeing less street HP. I have seen many cars tuned on a non load controlled dyno that have shown a lot of KR on a load controlled dyno. The more that you can simulate the actual street/track load that the engine will see on the dyno the more better the tune. As previously mentioned, monitoring such things as KR could help diagnose your problem if you have one.

AKRA

I have found that with a 3500 pound car with a baseline of 400 hp you will actually see about 0.1 sec and 1 mph improvement per ten hp.

Go to this web sight and check for your self. http://www.rpmoutlet.com/dyno.htm

Anyway, even three tenths of a second improvement in the quater is hardly noticable with the SOTP meter.

Plus the point I was trying to make earlier was if you were not in the same rpm range both times that you raced you will not have the same toque applied to the rear wheels. If the second time you raced (after the tune) he was in his optimal torque range and the first time he wasn't it might have been his performance that changed. The only way you can use that race as a comparison is if you race a set distance from a stoped position both times.

Al

white2001s10

iTrader: (4)

I think you meant to say "mo betta"

dynocar

Right on, bruda!

CuNfUzEd

iTrader: (14)

I still say he wasnt shifting the right ****! Where you at Mike?

H8 LUZN

This is why you need a programable mustang dyno....

You need to get as close to road load as possible, which an inertia dyno cannot adjust.