dragonZ28

iTrader: (32)

Okay, I know that of course in theory the 1-7/8" primary LT's would yield more power. Well, as you guys know, the price difference between Pacesetters and QTP's, for example, is huge. Is the HP gain worth spending the extra cash?

I think that for the price, Pacesetters are the best bang for the buck reagrdless of them being 1-3/4" primaries. These are going on my SDPC 408 soon, and any info would help. For example, has anyone gone from 1-3/4" to 1-7/8" with extra cubes? If so, what gains were noticed? Thanks guys.

Mr. Luos

iTrader: (9)

I went with Kooks 1 7/8" for my 402.

'01 WS6 TA

iTrader: (5)

I went with the 1-7/8" for by cam only car....

DONAIMIAN

iTrader: (18)

I want to pull my jet hots off for some 1-7/8 QTP's on my cam only car.

Mr. Luos

iTrader: (9)

You guys planning on spraying??

1 7/8" longtubes will more than likely make a little less power than the 1 3/4" on a stock cubed N/A car.

xaon

iTrader: (12)

my car gained 15rwhp switching from 1 3/4" FLPs to 1 7/8" Grotyohann's. Stock motor, TSP 231/237 cam.

I personally couldn't see myself spending a bunch of money on a motor and then skimping out on the headers.

Mr. Luos

iTrader: (9)

Really?? That is awesome!

I have heard people losing power with the stock cubed motors running the bigger headers. Guess it really depends on the setup.
I completely agree with the statement about not going cheap on the headers. I am working on finishing up my 402ci and I decided I didn't want to put my SLP LT's on it. Kooks 1 7/8" for me.

Mooobunnny

iTrader: (1)

1 - 7/8 gets my vote for head/cam 346 or a stroker.

01 Red WS6

iTrader: (4)

1 7/8

QTP are worth every penny.

V6 Bird

iTrader: (15)

Have you not read the CarCraft Article.....They tested this theory and 1 7/8 tubes on a stock LS1 made the most power all over. Might want to rethink your theory. I use the Edelbrock stepped race headers and they work well for me.

Mike

JakeFusion

iTrader: (7)

For a 408? 1-7/8 at the very least. A stepped 1-7/8" to 2" or a 2" outright would be ideal, especially if you are going to rev it beyond 6500rpm.

383ss

iTrader: (14)

I have dyno proof on my 408. I went from 1 3/4 to 1 7/8 and ONLY gained from about 6000+ and it was only 8hp. I LOST everywhere else. lost 20lbft of tq down low. I posted a graph in they dyno section a few months ago

technical

Header gains are not comparable with diferent cat-backs. The system needs to be evaluated before you can decide where the gain came from. Going from 1-3/4 to 1-7/8 with a cutout(s) might not net you much gain. Conversely going to bigger headers with a performance cat-back that flows pretty good might show more gain under the curve.

lsevenl

iTrader: (5)

h/c 346 here with 1 7/8 kooks. Fastech has been using these religiously over 1 3/4 for h/c car. Low end torque suffers, but who the hell races in low rpm. HP gains are just as good as 1 3/4

bigdsz

iTrader: (1)

Technical, perhaps there are details that I'm missing but if the guy had a minimal gain from 6,000 rpm up then what is the real point of upgrading to 1 7/8 headers unless you are like full race? When I go to a 402 there is no way I'll go to bigger unless there is a substiantial hp gain.

technical

If he had a fairly open style exhaust or cutouts there wouldn't be as much gain with the larger headers because the rest of the exhaust is providing extra power vs. someone who has a more restrictive exhaust (and less HP to start with) and switched to larger headers. Two different ways of making power.

It's analogous to the gains you see from headers *only* vs. the gains you see in combination with a cam and/or heads. Remember that power is derived from the "system" of parts including the tune... Cam size, compression, etc. all play games with the numbers.

bigdsz

iTrader: (1)

Sorry man , it must be because I''m on my third cocktail, I just don't follow your logic, maybe someone else can clarify your reasoning. Thanks.

383ss

iTrader: (14)

for clarification, my results were on open header setups.

technical

Proof for my point. He was already making more power with 1-3/4 headers than most of us because he had no exhaust. Therefore his gains with bigger headers was smaller than someone who has a full exhaust. There's no hard number that represents the absolute hp gain from installing a part. e.g. "makes 5-15 more horsepower" claims by manufacturers.

TXCAMSS

iTrader: (60)

1 7/8 headers on a bigger cubed motor is hands down a worth while mod. I went from 436rwhp with 1 3/4 to 459 rwhp with the 1 7/8 Kooks and added a 12 bolt at the same time which should have costed me about 15 rwhp over the 10 bolt. This was on a 383 Stroker and through a single 3 inch cut-out. I don't recall the TQ gains , but there was no loss.