402. 1"3/4 headers good enough?
402. 1"3/4 headers good enough? i have a tsp 402. stage 3 prc 6.0 heads, texas giant cam, fast 90/90 and so on..... this is on a 2001 corvette so i naturally have true dual exhaust. im running stainless works 1" 3/4 long tubes and 3 " all the way out with stainless works 3" catback.* no convertors.* is it nessacary or worth stepping the headers up too 1" 7/8????? thanks for your opinions.
i understand. i just dont wana go throuh the hassel over 5hp. but if im really gonna see faster track times and more rwhp i'll do it. i know its all part of the puzzle. just wondering if anyone has tested this.
I have debated the same thing with my 408. Since I already had 1 3/4 headers from my head and cam setup I decided to keep them rather than spend that much money for a small gain. If I didn't already have the 1 3/4's I would have bought the 1 7/8 headers.
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Joined: Dec 2001
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If they are LGM 1 3/4" headers, I wouldn't worry you may trade off a few peak hp, but the longer primaries will pick you up in tq, which with a cam that big you are going to need. You are probably on talking about a couple of HP peak right now with a swap.
Ideally based on the math of the cam grind and the engine size it shows the theoretical optimal header to be
30.876 inches long on the primaries
2.041 inch tube diameter
Ideally based on the math of the cam grind and the engine size it shows the theoretical optimal header to be
30.876 inches long on the primaries
2.041 inch tube diameter
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I have the LG 1 3/4 and couldn't be happier with the robust amount of torque in the lower revs (413 @ 2,800) on my 402.
My buddy Robert whom also has a 402 switched from the LG's to AR 1 7/8 and lost 19ft lbs peak and around 4-5 throughout the curve, while only gaining around 3-4whp across the curve...
A better quality set of headers may make more power regardless of size (Kooks/LG)..
I am personally sticking with my LG's....
My buddy Robert whom also has a 402 switched from the LG's to AR 1 7/8 and lost 19ft lbs peak and around 4-5 throughout the curve, while only gaining around 3-4whp across the curve...
A better quality set of headers may make more power regardless of size (Kooks/LG)..
I am personally sticking with my LG's....
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We have 2 cars here that have 402s and run our 1 3/4 HVMC headers. One a 402 with a 200 shot that weighs 3700lbs runs 9.95 strong. The other is an all motor 402 that also runs our 1 3/4" header. That runs 9.88. If the car drives on the street, that is another reason why you do not need to go with a 1 7/8. As long as your 1 3/4 headers are of good quality no need to swap to 1 7/8. Hope this helps you out.
At what CI/HP level is it recommended to go to a 1 7/8? I have 1 3/4 Kooks on my LS2 but I'm building a 416 or possibly a 427. I would think a 1 7/8 would be necessary at this level.
If you search around I remember some time ago when someone did a before and after dyno from 1 3/4 to 1 7/8 headers. this was his only mod swap. I believe the guy gained 18hp and 10 or 12lbs of tq from the swap.
That is pretty much on par with what we have seen on going with a 1 7/8 over a 1 3/4 on strokers.
If you are worried about loosing low end TQ, a great compromise would be the Eldebrock stepped header, 1 3/4 to 1 7/8, with a race merge collector. Not to mention it is 1/2 to 1/3 the price of the other metioned headers. Good luck.
