Hi everyone,
Hope you are all doing good and flying down the 1/4 mile listening to that sweet symphony of good old american muscle.

Anyway, I am after people's opinions on my setup and if you think it is worth upgrading the headers to the larger primary 1 7/8 size.

Here are my engine specifications:

LS2 408 short block fully built with forged internals and high end gear
CNC LS3 heads 60cc chambers 12:8.1 static compression ratio
236/244 .626 .626 114LSA camshaft from Patrick Guerra
Fast 102mm intake manifold
! 3/4 4into1 long tube headers with 3 inch merge collectors
Dual 3 inch cat back exhauust (full stainless)
4.5 inch body heavy duty ballistic cats with 100CPSI
3200rpm high stall converter
3:91 rear gear
This engine runs on pump e85
The engine is making 510rwhp which is very healthy for an automatic.

I feel though, that my power may be hindered by the smaller primaries though.
The engine is crazy fast, but I feel when foot is planted, it feels like the engine is being choked as the torque curve is there but its not intense. I can't properly describe it.
Its just the sensation I get.
Another reason I think it may be the primaries, is because, you have got all that compression, the extra rich fuel mixture running e85, plus all the flow of the heads etc, the 1 3/4 may not be enough header to deal with all this. Plus the 12 degrees of postive overlap from the camshaft.
I have seen numerous posts where even on stock LS3 engines the 1 7/8 headers have gains with zero losses down low.
I contacted Patrick Guerra and he said to me in all his testing on LS3 engines, the 1 7/8 has always made more power everywhere and these heads seem to prefer the bigger primaries.
I have noticed there are also many others who have claimed to have lost power and torque going to these but they seem a little suspicious.
Would appreciate anyone's input and advice. I can also be contacted at bortous85@gmail.com
Cheers

 

Absolutely upgrade. You'll be surprised how much power the bigger headers are going to be worth.

 

Sure if you have that kind of time and money even though you have a good set of headers then yes by all means. If I was starting from scratch or my old set was rusting out then it would be a no brainer, otherwise it's not worth it IMHO

 

Hi, so how long is the primary pipe ?

Lance

 

Go straight to 2 inch if available.

 

BortIve there have been at least one test showing 1 7/8 headers gain ~ 5 hp over 1 3/4 headers on a stock LS1. I think your set up would gain a whole lot more.

Often 2 inch headers do not fit as well as 1 7/8 if the car is a 4th gen fbody with a stock k-member. If you have an aftermarket k-member then 2 inch would likely make more peak power.