mtcraigco

I am looking at purchasing a set of headers and exhaust from a forum member and have two options to choose from

A) Headman HPC coated headers with 2.5 inch mandrel bent stainless exhaust and flowmasters (probably delta 40s or super 40s from the pics)

B) Hooker SuperComps (painted) with 3 inch mandrel bent pipes and bigger flowmasters. (probably delta 50s from the pics)

I am not terribly concerned with the tail sections and flowmasters, I can swap out the muffs and tail sections later if I don't like the sound,

I am more concerned with

A) the fit of the Headmans vs the Hookers, the headers will get wrapped no matter what so HPC is noce on the headmans but not a deal breaker, fit is more important

B) The correct size pipe for my engine,
(I don't want to go too big with the 3 inches and kill scavenging)

These will be running on a zz454 short block with zz502 heads and zz502 cam. Intake will be a performer RPM air gap with a 750/850 carb of some sort.
I figure HP/TQ will be very high 400s or lowish 500s (crank of course)

So, will the 3 inch pipes be to big and kill scavenging? I don't want to kill low/mid range TQ for high end HP, this is going to be a STOUT street car, not a strip car.

How about the fit of the Headmans vs the Hookers? How about flow of the headmans vs hookers? I am not sure of the primary pipe size but they look like 1.75s I'll find out for sure before I pick which set.

Thanks in advance.

MotorHead

Over 500Hp I would run 3 inch you are on the borderline, this is just one opinion though

69427

I wouldn't lose sleep over the scavenging thing. Headers are what are supposed to do the scavenging, and all bets are off when you cork them up with several feet of exhaust pipe and mufflers. The 2.5s will probably fit better, but the 3 inch setup should have less restriction.

427Hotrod

Go for the 3" for sure.


JIM

LT1driver

3" is my choice.

midyearvette

i like your build up...the 502 cam will kick things up a notch....good call....my 454 ho has the 211 cam and with a 288 low keisler and a 336 gear. it gives me all i can handle with 235 70 bfg's from a dead dig to the top of any gear. if i would change anything it would be the camshaft which after 5500 falls off. the mill will go to 6000 easily but the grunt is gone....combined with the oval heads and higher compression i think you are taking full advantage of the gm stuff....just a thought , have you considered the 392 head with the 2.19 intake valve?......both the oval heads work best under 6200 rpm .....the smaller intake valves are still large enough to handle more camshaft and would enhance torque....jmho....anyway great build for the $$$..........

FRSTR90

Based on you intake choice and carb choice, I think you saw that article I posted in another one of you threads... Well, there was another test done on the ZZ454 comparing 2.5 and 3 in exhaust. The ZZ454 gained HP and TQ with the 3 in. So, I would definitely go with the 3 in. I would post the article right now, but I'm too lazy and tired to find it. If I have time tomorrow, I will post it.

Also, I forgot to mention my Heddman's have 2 in. primaries. I would think those would as well.

mtcraigco

Thanks, seeing as how the zz454 hits 490 with just some bolt ons, I figure the zz502 cam and the zz502 (2.25 intakes) heads should put it just over 500 without a doubt. The heads are a done deal, they're actually off of a 502 ram jet and have never been fired up, the price was right and they are the same heads I was about to pay $979 to scroggin dickey for, cost me less than that and got them off a guys hands for him. Definitely a win/win


Yes I did see that article and yes it was a major factor in my looking into the zz454, I did lots of other research as well and everybody seems to feel they are under rated by quite a bit AND respond very well to upgrades. I'll be in it for $1500-$2000 less than a zz502 kit (counting slightly used heads) and the 454 short block and make as much or a bit more power.
I would like to see that exhaust article, I didn't see that one.
And yeah the Heddman's do have a bit larger primaries, so they are probably 2 inchers.

Thanks to all for the feedback, I was leaning towards the 3 inchers anyway. And thanks for the reminder that it's the primaries that do the scavenging, not the downstream pipe.......... DOH!

mtcraigco

Never mind on that article, I found it


http://www.hotrod.com/techarticles/e...tem/index.html

Ganey

3"

The Hookers may be 1 7/8".

corvette744

Here is something you might enjoy.http://[/URL]

turtlevette

I looked at the article. How do we know its not all in the muffler? What would the 2.5 inch pipe have done with the 3" muffler?

c3 Vettes are so low and there is just no room to tuck up pipe under there. Those massive 3" sewer pipes are going to look like hell, drag on everything, and add more weight. I don't think its worth the incremental HP gained if there really is any.

The really bad part of the c3 exhaust is where it passes under the diff. There's just nowhere else for it to go. It scrapes on everything and some installs don't even tuck it all the way up against the strut bracket which makes things really bad. Then you see a lot of people jack up their rear end to compensate which makes the car look stupid and ruins any handling you hoped to achieve. My muffler shop suggested going to an oval pipe transition right under that area.

Another interesting test might be 2.5 vs. 3 pipe all the way back without mufflers. Remember Hotrod Magazine is in the business of selling aftermarket systems for their paying venders. Bigger systems bring in more money.

I think we all lose sight that we need to build comfortable and reliable all around performing C3s that we actually want to drive. Some of you guys with these loud systems sidepipes ect. get in your C3 and drive it for a few hours on the weekend then jump right back into a modern car because your friggin ears are bleeding.

I don't know. Just the other side of the coin. Not every friggin thing on the car needs to be optimized with an engine screeming at 6000rpm. How many times do we go there on the street anyway.......those of us that still have a license.

FlyViper

Question on this topic (sorry to interject here MtCraig): I'm also doing a SB-ZZ454 swap. I have 2.5" exhaust and plan to keep it that way. Can anyone recommend which headers would work well/fit this setup? I've been looking at tons of them and either can't decide which would be better or not sure if they would fit correctly?

I'm also worried a bit about ground clearance on full length headers. Am I going to be scraping this things all the time and should therefore look into some kind of shorty or block hugger headers?

Also, Holley's website says the following:

Is this just CYA, or should I really not even think about putting new hookers on the ZZ454 prior to breaking it in? I really want to avoid buying used headers, installing them, breaking in the engine, then pulling the used headers off and installing the new ones I really want. Thoughts/comments?

EDIT: I'd definitely be interested in buying a used setup that would work for my application if anyone knows of someone who has that.

MotorHead

Seems to back up what I said

mtcraigco

You make some good points and I tend to agree with most of it. If I were building from scratch I might very well run 2.5 all the way to the back and then jump up to 3 inch muffs on just the tail section.

However the mantra that any car article is a joke and full of lies just because they want to sell something is kinda old, so get off that horse, OK??

It's just that I have two custom built very nice systems to choose from and either one is a bargain.

I understand the clearance issues and you're right about there probably not being THAT much diff between the two.

On the other side of MY coin, I DO tend to run hard and don't want to leave 20 FREE HP on the table. No I won't use it everyday, but I'll use it often enough to make it worth the discussion.

The oval pipe thing IS a good idea though, especially right there at the diff.

Just a bit more thought on the subject.

mtcraigco

Standby a day or two, and there should be a nice set of 2.5s with headers included as I'll prolly go ahead with the 3 inch set up, I've just got dibs for the moment

And big deal on interjecting, I've been following quite a few of your posts on the subject as well.