ablkbrd

whats the deal with 58mm throttle bodies and lt1s? i hear horror stories lol. i know y need to port the intake.. some say drill the butterflies.. but i also hear about tranny problems on autos.. something about line pressure.. will my trans performance button help that?

96capricemgr

Shouldn't hear any horror stories.
Far as drilling the butterflies that is WRONG the drilling needs to be done low between the blades to replicate the IAC bleed in the stock TB and the IAC circuit on the back of the TB often needs to be sealed as well. This is because the aftermarket seems to have just reused the castings they had for the old TPI stuff and the LT1 is VERY close but the manifold design necessitated a separate IAC distribution circuit that the aftermarket TBs don't seal to properly. The drilling the hole needs to be customized for the engine setup too so I guess the aftermarket not drilling it can be excused based on that. The stock TBs had a different size hole L99 to LT1 and as you mod the engine and idle air requirements change so does the bleed hole size need to change.

The tranny thing is just a matter of the line pressure being scaled off of a number of factors including throttle position. Well a larger TB allows in more air for a given throttle position, more air is more power and the tranny needs the line pressure raised to compensate.

If you think all this constitutes "horror stories" then you need to enjoy the car as is and pay someone else to do the maintenance. This is annoying little crap that requires a little understanding, if you think this is bad what are you going to think when you hit an actual problem?

ablkbrd

thank u for the info : ) but no need for the lashing ; ) ive turned every bolt on every car and bike ive had since 17. "as is" just isnt in my blood and as far as horror stories , they are all over many forums and can be googled, not asking would constitute bn an idiot. esp since ive never had a problem with 52s. oh.. did i mention thanks for the info? : )

shawngamblez28

i've had a 58mm on my car for 3 years an have never had a problem

96capricemgr

Most guys just don't realize the aftermarket TBs screw up the idle. The potential for A4 tranny damage can be resolved with reprogramming or a shift kit and is slow if neglected not immediate..

james55

How much does the A4 tranny line pressure need to be increased. I have the software and cable to program and found mine is set at 90 default. Please let me know. Thank you.