Hey all!

I am about to possibly purchase a 58mm BBK TB. Will I have any idleing problems??? Will I need to adjust the idle screw, these have one, correct??
Also will I have any other installation issues. I hope this is a *true* bolt on.
FYI, I plan on boring out the intake to match, w/ Brent Frankers page.

Will I have any tuning issues??? I have heads, cam, LTs, all the goodies, etc.
and LT1 Edit. I shouldn't have any BLM or fuel changes w/ this, right?? I currently have a 52mm. BTW, if this makes a difference, it is an LT4 intake.

Thanks!

 

You will need to check the TPS voltage and make sure it is ~.50-.60v at closed throttle. Also check that it gets ~4.5v at WOT. This can be done with the key ON (engine not started) and watched with a scan tool. You may need to slot the mounting holes in your TPS if you need adjustment. Normally the TPS does not need adjusting.

If you have the 4L60E, you will probably need some reprogramming for shift points.

 

a 58mm has no benifit to a 350-355ci motor over a 52mm tb. that much air is not needed. also, on the intake, the lt4 intake is only around to match up with lt4 heads. the angle where they meet is different than lt1s.

 

I wonder how much it would affect my shift points?

There is no such thing as an easy bolt on!

I have a Scanmaster in my dash to check for TPS. That is what I was going to go by. I also have LT1 Edit if needed.

Thanks shoebox!

 

Do you have proof of that first statement?

I mentioned the LT4 intake b/c of the heads that I have, Stage II GTP. I know it is the angle only that is different than the LT1 intake. I just made that reference b/c of my heads, sorry for the confusion.

Thanks for the reply though.

 

think about the numbers you need for the car to run. with a 58mm and a 350 or 355 you are going to see some boging down low. i have seen it on a few cars. most people sell the 58 and get the 52. start off right, and get the 52, you wont be sorry.

 

I had my stock one ported out to 52mm. Works great.

 

I have a 52mm right now. I don't see how 6mm more on each side could bog me down so much. That is the first time I have heard this. I know that bigger isn't always better

Do you have a dyno sheet, or more info on that?

Thanks for the input though!

 

I'm surprised this hasn't been brought up yet:

Yes you're going to have installation issues. If you just slap a 58 MM TB on to a stock manifold, you're going to have a "step" where the manifold openings are. The stock Manifold is only a 54MM opening, so each hole is going to have a 4MM smaller diameter than the 58mm TB. It will bolt on, but any gains you were going to see will most likely be negated by the turbulence caused by the step into the manifold.

 

I wasn't going to slap on a 58mm TB. I don't have a stock manifold, and it is
being bored out on the car 6mm each side, via Brent Frankers install page. Also, the stock manifold is 52mm, barely. Put a mic on it, and it is like 51.8-9.

I also have LT1 Edit to take care of tuning issues.

 

Man do any of you guys read before you reply? She said she currently has a 52mm. She said she's going to bore the intake to match the throttle body.

I do recall of hearing of some issues with the 58mm tb's, but i've never really had any experience with them. You'll have to play with the adjustment screw and the TPS to get your IAC's where they need to be and get the sensor voltage correct. Have you talked to Jeff Creech about the 58 I'm sure he's had some real world experience with them and could probably tell you what to do about the shift points.

Richard

 

Just wanted to make sure.

 

Since the t/b is only a door for air, tuning will remove any bog that would occur.

 

a max effort 355 can outflow a 52mm tb

 

um lol like opening that intake well its like on the car and stuff is a very umm bad idea! i did mine at my familys machine shop and those threded disc's on the bottom of the intake you have to remove them after and clean the hell out of it