2ktransam

iTrader: (12)

I have a ls2 402 in my car with ported 243's and texas giant cam. It makes 505rwhp na and I'm needing a little more for a na class I want to run. The car has 15 year old Jet Hot 1.75 headers going into a custom ypipe and 4" cat back. I'm debating on stepping up to TSP 2" headers and switching to e85. How much of a gain could i hope for out of both?

jetech

You didn't provide enough information for anyone to give a good answer.
Sounds like this is a street car that you are drag racing...? I would keep the 1 7/8" tubes
Running E85... need more info about the engine. CR is? Carb or injection ? Fuel injector flow rate ?

Jtm2085

iTrader: (1)

He is running 1 3/4, not 1 7/8. You would pick up some horse power for sure by going to a larger header, but not sure if it's the worth the time and money to you. Who ported the heads?

01ssreda4

iTrader: (96)

Go 2 inch! I ran the 2/3.5 on my H/C LS1 and was super pleased with them.

big hammer

Kfxguy

iTrader: (1)

hearders? lol

SoFla01SSLookinstok

For a 402 the 2'' hearders should take a load off the motor from the 1.75" tubes. Less pumping losses. I'd say go for it.

G Atsma

You beat me to it!! LOL!!

99 Black Bird T/A

iTrader: (4)

This maybe on interest. May not match exactly with an LS but probably in the ballpark.

Mopar Engine Dyno 1 3/4 vs 1 7/8 vs 2 inch primary headers

505 whp is fairly close to ~600 flywheel hp

I think this is a decent article, a set of 1 3/4 vs 1 7/8 vs 2 inch headers are tested on a ~600 flywheel hp Mopar.

1 3/4 vs 2 inch ~15 to 20 flywheel hp

E85 tune probably depending on tuners skill to a degree: 10-20 flywheel hp

20 to 35 whp - would be my wild guess for both mod's

andrewzpsu

If you decide you want 2" headers, we can give you a great deal on Kooks! Call us @ 610-628-1563

https://www.cspracing.com/kooks-2-x-...-ls1/22412600/

JakeFusion

iTrader: (7)

That is a nice price on those Kooks.

sxc Z28

2'' primaries and X-pipe be worth 35+rwhp for you. Probably more. E85 gains gonna depend on comp ratio and tune.

qweedqwag

Your intro says 2"hearders, whatcha hearding 2"cows? 2"chickens? What?

fastsspr

iTrader: (49)

Hi, your Ls1 have factory compression ratio with the 2" headers?

Kfxguy

iTrader: (1)

It’s 2” hearders.

G Atsma

I HEARD that! lol

wannafbody

iTrader: (2)

If you are stepping up to 2 inch headers, I'd suggest stepping up to some larger port and valves heads if you can for your class. TSP 237 or 247 heads might work.