I was told by a reputable machinist/porter that he has done R&D on porting LT1 TB's.... and came to the conclusion that there are none/very small/if any gains from porting an LT1 TB......

He mostly ports ls1 style TB's and he has seen upto 9 RWHP on bone stock LS1's......

Any comments.......

 

The gains with a larger TB on a fairly stock LT1 is negligable.

The stock 48mm TB on an LT1 should be fine untill you do heads/cam/stroker/etc.

You would probably see some decent gains on a heavily modded one.

But a stocker is fine until then

 

I have a 52mm. I got mine from a friend who upgraded to a 58mm. Why who knows. I swapped the 48 and 52 mm's at the track, and saw absoulutely no gain with only bolt on's. I personally don't think you need to upgrade unless you do a stroker. Unless you get a good deal on one, then I'd put the money to better use.

Z

 

Did you Port The Intake as well? the intake opening for the TB is only 48 as well....im pretty sure...get it opened up and then you should see a big gain...the reason you arent seeing anything is because you have 52mm trying to go through 48...it still gonna be the same amount of fuel depositing.. if you dont wanna go with porting your intake...go with the LT4 intake...its set for 52...somebody please correct me if i am wrong..

 

Just what i was thinking.... I wonder if the gains would be greater; IF the intake was also port matched to the TB size....

Can some one please tell my why it is that LS1's gain as much as 8 RWHP just from porting their stock TB..... This is on a BONE stock car all the way to the paper filter....

 

Stock LT1 and LT4 intake openings are 52mm. No modifications are needed for a 52mm throttle body to fit the stock intake. Anything larger than 52mm the intake bores require opening.

 

He is right. And no you probably wont see much gains with a 52 over a 48. Espesially if you are stock.

 

why is it then that bone stock ls1's gain an average of 8 RWHP......

 

what about if i get my heads ported to 2.020" Int. and 1.6 Exh., think a 52 would be big enough? how much increase would i see?

 

My cam/LT car lost power and torque with a 52mm TB.

 

IT's becasue of thier intake design.


You won't need a bigger TB on yout LT-1 untill it's out of breath... unless you have a Big ol cam, nice ported heads... or bigger displacement, your LT's isn't choking just yet.
Your cars only gopign to take what it needs. And if you lspa on a 58 over a 48...when the 48 was sufficent enough... there's not going to be an increase in hp.

 

Because it is a completely different engine design than an LT1 and breathes better up top. You can't compare the two engines like that.

 

If your car doesn't need a bigger TB it won't gain HP from one. You will only see a gain after you do heads or a cam.

 

What Im Asking....

Do you think my car will be fine with a 52 after i have a good port job done (2.020 Int. 1.60 Exh.) and maybe a GM847 or Hot Cam? im also looking into a set of 3:73's

 

Yes. I don't think the price of an upgrade to the 58 is worth it, unless you plan on stroking it.