Headers vs Rams horn

[Bill75]

Getting ready for ZZ4 "implant" to replace the L48 and I'm not really a fan of installing headers but I ran across this site that someone mentioned on another forum. Looks like standard exhaust manifold with modified ports for increased flow. First thought that I had was to take mine and have them machined to open them up and save $400 +-. Just wondering what you guys think about this approach and if makes any sense.

http://www.castheads.com/corvette_systems.php#pipe_kits

Bill

[pgtr]

All the above 2" and 2.5" both flow quite well. Then they can be further ported. Personally I'd probably go with 2.5s and leave it at that w/o further machining. FWIW the place you referenced does have an excellent reputation.

Hope that helps.

[Bill75]

Originally Posted by pgtr

All the above 2" and 2.5" both flow quite well. Then they can be further ported. Personally I'd probably go with 2.5s and leave it at that w/o further machining. FWIW the place you referenced does have an excellent reputation.

Hope that helps.

Thanks. So his "Stock" manifold which has a 2.5" port opening isn't really a "stock" GM replacement? He's machined them bigger? I don't know what mine are now.

If that's true I wonder if I can't just have a shop machine mine to 2.5" if there's enough extra meat on them.

Bill

[Jack]

Some earlier vettes than yours came w/ OEM 2 1/2" outlets ... the vast majority came w/ OEM 2" outlets. Your 75 almost certainly has 2" outlets.

The BRP manifolds are real nice ... but don't miss what their intended purpose is: It is for lower class circle track cars where their rules REQUIRE an OEM-like cast iron exhaust manifold ... where headers are not permitted. BRP's manifolds are almost certainly a "replacement" grade.

The implication is that BRP's manifolds are the next best thing to conventional tube headers.

Tube headers, like em or not, will do as much or more than the cheated up BRP cast stuff ... and for a lot less money. A decent set of ceramic coated tube headers are $250 or a bit less (eg Dynomax) ... and will net you more performance. Most tube headers have an inlet of at least 1 1/2" x 1 1/2" and you can run whatever size pipe you wish.

Some later C3/C4 came OEM with short tube headers w/ outlets in about same position as cast rams horn ... and some are stainless. Someone else here will know which years.
JACK

[pgtr]

Originally Posted by Bill75

Thanks. So his "Stock" manifold which has a 2.5" port opening isn't really a "stock" GM replacement? He's machined them bigger? I don't know what mine are now.

Most stock rams horns are 2" including all those used in C3s (yes yours are 2") but they also made 2.5" for some C2s which are still available (less than cost of machining your 2s which if too thin can crack). I'd either go with the stock 2" rams horns as is or purchase a set of 2.5" before I'd mess with the machining. As Jack said those machined jobs are really for circle track racing that require a factory style manifold.

Short of Tri-Ys (which do not fit in C3s) I'm a fan of Rams Horns over equal length headers in a street driven car.

[Bill75]

I understand about the BRP's now, I'm glad you guys responded, thanks.

I'll look around and see what's available.

Bill

[bobherr46]

I think you can buy aftermarket 2.5" rams horn manifolds for about $100.00 each. They obviously won't have the machining of the BRP product but they would surely be an improvement over the 2". Also,I think they will have a big klunky looking generator bracket cast in to them but a machine shop could cut this off and you could smooth them out with a grinder. i am hoping to do this for a winter project. - Bob

[bobherr46]

Just looked at them. Check out the 1AAuto online store. $89.95 each. - Bob

[Rowdy1]

If you're going to a ZZ4 I'm guessing you want more power than what you have. A set of long tube headers will give you the most performance and allow it to breath better and scavenge the way it was meant to for maximum flow.

[Bill75]

Hi Bob and Rowdy,

I'll check the manifolds out you suggested Bob, thanks very much!!

Just did: Man that bracket is ugly, but it could be machined off and refinished OK.

Yes Rowdy, I do agree with you about the headers, Jack mentioned the same thing. I live on a dirt road and I'm concerned about the ground clearance, every set I've seen installed hang down a little more than I like. Also chasing loose bolts in the headers, although I guess a set of stage 8 hardware would solve that issue.

Thanks for your suggestions.

Probably the last ride of the season today. It's going to be a nice 55 deg day here today, they're talking about snow Thursday

[Rowdy1]

With the right headers you won't lose much if anything on ground clearance, I just put a set on the 62. The header bolts are not a problem either, they make a set of locks that run around $40 that doesn't allow the bolts to loosen up.

[pgtr]

Thanks for the website reference. I see what you mean about that big ugly bracket.

I 'thought' there was a 2.5" rams horn that did NOT have the big ugly bracket - but my memory may be in error.

[Bill75]

Originally Posted by Rowdy1

With the right headers you won't lose much if anything on ground clearance, I just put a set on the 62. The header bolts are not a problem either, they make a set of locks that run around $40 that doesn't allow the bolts to loosen up.

Any suggesdtions on brands? I can feel myself starting to give in to headers. There is alot to be said for the ceramic coating keeping the temps down in the summer also.

View of CT River today up in Massachusetts

[Jack]

Alotta folks are reasonably pleased with the ceramic coated Dynomax long tube headers ... $250 or a bit less.
JACK

[Bill75]

Originally Posted by Jack

Alotta folks are reasonably pleased with the ceramic coated Dynomax long tube headers ... $250 or a bit less.
JACK

Thanks Jack!