Rx7Rob

Hi Guys,

At what point should you go with the larger primaries?

I'm looking at the non-emission Kooks (w/SwainTech ceramic coating). In addition to the header, I'm planning on: LS6 intake, cam (probably something like 232/234 at 595/598 and 112 LSA. Undecided if the heads will stay on or get swapped out, and of course full tune.


Thanks!

sunchaser73

Why not swap out the heads?...or at least have them ported. Also...port the intake to match whatever heads you're going to use.

Based on your intended modifications, I would lean towards a header with a 1-7/8" primary. But, it may also be helpful to consult an engine builder/tuner for their opinion.

Hope this helps...

vettenuts

I have seen much conflicting information on this however the person who tunes my car has installed a number of 1-7/8" systems and has told me there is no down side. Since I run Tri-Y's I wouldn't swap to larger but if I had a 4 to 1 system I would consider it.

95rtturbo

My tuner has said the same thing. I have 1 7/8 ceramic coated AR LTs with a catted X pipe. With just that, a Halltech stinger filter, and dyno tune, I put down 386/372 SAE.

WKMCD

Dyno tests have shown that.

Rx7Rob

Interesting, my gut was telling me the larger primaries may decrease some low end torque.

Thought I found the tuner, sent email a couple days ago about getting together to discuss my mods, waiting for reply.

Heads, not sure how much more power I'll get (and $/power). Would be good to see how carbon'd up the pistons are (only have 25k on the car). With the intake and exhaust off, probably isn't too much more work to pull them. With heads off, header installation may be easier.

Damn, with heads off could I drop the pan and push out the pistons? Then I could go forged pistons and add some forced induction (and a clutch)!

Sun, aren't you supposed to go the other way and port the heads to match the intake?

Thanks!

JohnJ@Texas-Speed

I think it depends on the planned modifications. For any car that is going to receive a cam or possibly aftermarket heads I would recommend the 1 7/8" headers.

novajoe

It will be determaned by what you intend to do for mods.

Rx7Rob

JohnJ / Nova, yup - seems like I'm right at the point where it could make a difference, I'll wait to buy until I can reach the tuner (or go with a different tuner).

John, bet you recognize those cam specs!

Thanks

novajoe

Sounds like a plan. If you have any questions please let me know and I will make sure you get the right product. And I am sure John @ Texas Speed will be happy to supply it for you.

sunchaser73

Perhaps I could have said "port-matching." I've read a few threads about port-matching the intake "outlets" to the heads. Toque had his done by SpinMonster. Here's a link to Toque's site (http://www.toquez06.com/). Scroll down to the Fast92 intake install...

I recall another thread on here with some pictures of the before and after. I'll look and see if I can find it...

Here's a link to an article...it is for the C6, but can be applied to the C5:
http://www.vetteweb.com/tech/vemp_08...g/viewall.html