lnuxhakr

iTrader: (2)

My son bought a 02 Z28 last month and it already had a P&P heads, rebuilt transmission, trans cooler, 3k stall and shift kit installed, basically full bolts-on and suspension.

He never got on the car hard because it had a pretty harsh engine sound at the time but the trans shifted well and hard with the kit. Last week he did a cam swap (VRX5), top end refresh, and we had the car dynoed and tuned and its idling well, except its absolutely dead after 60mph.

In [D] the car will down shift at 55mph and pull slightly, but nothing like what one would think. He's putting 416hp to the ground. After 60mph the car barely even accelerates in [D], but runs hard in D (3rd).

Any ideas?

Thanks in advance!

BoricuaHec01

I wish my dad was into cars like you lol.

lemons12

iTrader: (71)

Buddy had this exact problem, converter was mismatched and about shot.

With that big of a cam you need a 3600 minimum, I would recommend 4000+. And a quality converter, ptc yank vig circle d etc..

Not saying this is your problem, but definitely a possibility.

FirstYrLS1Z

iTrader: (4)

what rearend gears are in it ?

JRENIGAR

iTrader: (37)

either trans slipping or converter is about shot. I ran a car like this and beat him from a roll with my bolton car. I couldnt understand it either at the time.

floodofnoise

I am no expert, so I could be way off here but.... from what I hear these automatics have a deadzone area in that mph range you are talking about. If I punch the throttle at 50-60 in my a4 trans am, i don't get near the quick acceleration that I get if I lay the pedal down at a slow roll or stop.

I believe with a tune (I am ordering a frost tune eventually) he can turn off torque management in the automatics that will give you more pull in that range. Also, I've read that different gears will reduce that deadzone. It sounds to me like you may be possibly experiencing the same thing I do in my automatic.

JRENIGAR

iTrader: (37)

If Im not mistaking: Toruqe management only happens for a split second while the trans is changing gears. Its designed to keep the clutches from slipping until all the hydraulic pressure is engaged on the apply pistons. what hes talking about kinda reminds me of a slipping trans, I know its got a conveter thats designed to slip but thats only till it reaches full stall speed. What brand is the stall?

floodofnoise

Ok, thanks for clarification on that torque management, I'm in no way a car tech.

lemons12

iTrader: (71)

Flood I'm assuming you are a stock or bolt on car. Most 400+rwhp cars don't have the normal dead spots and certainly don't fall on their face, especially with a larger converter.

floodofnoise

Correct, my car is stock. Just learning.

lemons12

iTrader: (71)

That's what I figured

Lower gears and or a larger converter, along with a cam especially like the ops, sgouldnt ever feel like it just stops pulling unless there is a problem. Not to mention it does fine while In D.

Who tuned the car?

JRENIGAR

iTrader: (37)

No prob, and Im sure theres more to it than that but thats just my understanding...

floodofnoise

I know it's probably annoying, but my style of learning new things is to ask questions in the form of a statement. So, when I say "I've read it could be this", I am really asking "Could it be this?" "Could this problem be related to something I read earlier?" because I want to know for myself.

I'm hoping someone with more knowledge will chime in and correct me because if I'd never mentioned the torque management or deadzone spot in the auto trans, then I would be still questioning it in my mind.

I do this frequently with more experienced engineers at my job, and have benefited greatly from it. Like I said i'm not an automotive tech, just happen to love to drive and would like to learn more.

Good luck to the OP, i will follow this thread because I want to know what the fix ends up being!

lemons12

iTrader: (71)

I picked up on it.

Plus, if right you look more knowledgeable on the subject than you might be! Lol

floodofnoise

Ha, yes thats why i start out with "I'm no expert, but..." lol. Then the experts come in and i sit back and watch

lnuxhakr

iTrader: (2)

Thanks for the input thus far everyone. I forgot to mention the car has 3.73 gears in it.

lemons12

iTrader: (71)

brand converter?

lnuxhakr

iTrader: (2)

That part we don't know. It came with the car!

lemons12

iTrader: (71)

Who tuned the car?

lnuxhakr

iTrader: (2)

Vengeance Racing...