looking into getting the lt4 intake, i would like to get a 58mm throttle body as well, i know the 58 wont fit on a stock intake, how much better is the lt4 intake than the stock lt1? is the sizing where the throttle body meets up the only difference?
-Jason

 

also, can u use a lt4 intake manifold on stock heads? will it bolt up?

 

The LT4 intake won't work on LT1 heads. I would also suggest NOT putting a 58 mm TB on. If you really want a bigger TB, go with a 52mm. The intake is already matched to 52mm so you won't have to port match anything. The 58 is only if you are making SERIOUS hp. I put the 52mm TB on, but it wasn't necessary at all. I got it cause I got a good deal on it. Anyways, you won't notice much at all with the 52mm TB on, and unless you are making some high hp numbers w/ nitrous, blower, etc. I wouldn't do it.

 

The LT4 isnt much better than the LT1 if at all. It is only meant to match up with the LT4 heads unless you machine the LT1 heads to fit correctly. The 58mm TB WILL fit, its just that the bores in the intake are only 52mm and need to be opened up. Unless you're making in the neighborhood of 550rwhp (level of needing a 58mm TB or monoblade has been widely debated) or a 52mm TB is just a plain restriction, a 58mm TB is not necessary. Too big of a TB can lose you ponies.

 

He's right. A guy in our F-Body club slapped a 58mm TB on, and I believe he lost 8 or 10 hp on the dyno.

 

thanks guys

 

There really arent too many reasons to use a 58mm TB. If you do the calculations, the amount of air flow made even in most blower applications dont require a 58mm TB. If there is a restriction, in most cases, it isnt the TB. A monoblade is an ungodly amount of overkill. I've seen people running maxed out s-trim blowers on 383 LT1's using the stock TB. It flows just fine, though it does look like crap. So, IMHO, dont bother getting a 58mm TB. Stay around the 52mm and any airflow need you would possibly have regarding the TB will be taken care of.

 

Ya, I know the TB bores in the intake are 52 mm, but I wouldn't bolt up a 52 mm TB without opening up the bores to 53.0-53.5 mm. Realize the TB is lined up on the intake with studs, not dowels. Studs/bolts mean there is bolt/stud hole clearance in the TB. Bolting up a 52 mm TB to a 52 mm hole, will all but guarantee a mismatch of some sort. FFT