WickedVetteLT4

Hello fellas,
I'm looking for a little knowledge regarding high HP and choosing the right primary header size. My car is a built 416 / YSI setup with a built auto trans on e85. On the conservative side (car isn't turned up yet)... it's making mid 800's through the auto as it sits. Car will be around 1000 hp when we turn it up.

I am currently running ARH 1-7/8" headers with 3" catless X through my 3" Corsa catback.

My old setup was a stock block LS3 with cam and a T-trim making 700 or so in which case the 1-7/8" worked nicely. I'm just worried now that i may be leaving some power on the table and that maybe I would benefit by stepping up to 2" primaries.

Anyone here have any first hand experience on which primary size is more beneficial around the 850-1000hp range?

realcanuk

If I was getting headers now, I would go 2 inch, but I don't believe there is enough difference to justify the expense and hassle of changing them out. I am making 1000 through 1 7/8 and the stock 2 1/2 inch exhaust. I don't think I could even notice another 50 hp if it gained that.

WickedVetteLT4

I appreciate the response bud! I'm thinking right along the same track you are. I was trying to justify the expense. I have a buddy down here making just shy of 1200hp with his CTS-V through an auto trans on 1-7/8" primaries but... I didn't know if he was leaving power on the table with the 1-7/8.

I'm impressed that you're making 1000 with the 2.5" system. That right there tells me I should be just fine considering mine is already 3". I figure the power to be gained would be peak hp if anything but I didn't know if my mid range would stay the same or even lose a little. I know bigger isn't always better. The car might show a peak hp gain on a dyno but if it's losing power under the curve, its a wash.

I just didn't know if anyone here had made this exact change at a similar power level and could tell me what gain there was to be had but at this point... I'll prob save the $$$ and stick with what I have.

realcanuk

I am sure someone has made the change and will chime in. I guess if going for every last hp.... it would be worth doing. I would like to see the results also.

lt1z

I would not remove 1 7/8" for 2" now but if I was buying new and planned on a blown 416 I would buy 2" the first time.

WickedVetteLT4

Yeah... It sure would be nice to see a back to back comparison on a dyno but i know that's not very likely. Fingers crossed that someone on here has done it and can share the results though. Lol

Yeah, i agree. Had I known the car was going to get to this level power wise, I would have gone 2" from day 1. But... who knows... power band wise... I'm not even convinced yet that the 2" would be a clear advantage.

Unreal

Made 1090rwhp on 1 7/8". Made a more on 2" but swapped other stuff so can't say what added power. Either way, I wouldn't spend the time/money to swap.

Slo-Poc

I'm still running 1 3/4 lg pro headers making over 900whp. I was thinking of swapping to the two inch. Like the others said it's probably minimal gains for the money, better spent elsewhere. Gl

RicardoFors68

This makes me feel good... OP, my tuner is putting 1100whp, went from 1 7/8 to 2in and didnt feel any gains. I'll ask about dyno numbers.

WickedVetteLT4

Good to hear guys. I appreciate the responses. I think I'll just stick with what I have and spend the money elsewhere.