Which Headers? 1 7/8 or 1 3/4?
 

Hello everyone and thank you ahead for your help and suggestions. I recently was fortunate enough to get my very first corvette however I have been reading and studying up about them for a while now. It's a 2005 Corvette and all stock. I have in mind what I want to do, Long Tubes, catted or o/r x-pipe and borla stingers. So my concerns with all this which size I should get for the headers? Any insight will be greatly appreciated.

IMO whether to install 1 7/8 or 1 3/4 headers depends on what level of power you want to match. Below 500rwhp do the 1 3/4... over 500rwhp go with the larger.

Just a general marker - of course there are many variables.

1 3/4 works well with stock to moderate horse. Will give you a little (not much more) torque. 1 7/8 works well with bigger horse numbers. If you plan on S/C or cam, head work then go the bigger ones.

Thank you very much for replying quickly. I am looking at an intake which I cannot make my mind up about and also gonna purchase a hand held tuner b/c their isn't any speed shop around here at all to get a proper tune.

Don't do the handheld tuner. Search up Chuck Cow for a mail order tune.

:iagree: If you are just planning simple bolt on mods and a tune, then 1 3/4.

You can actually lose performance from too large an exhaust system.

Bigger does not always mean better.

Thank you very much Blorton and Marc. The only reason I was questioning about the 1 7/8 is due to me finding a set of Dynatech headers and x-pipe on ebay for $1,000. They are brand new and the x is catted. I've heard bad things bout a smell with o/r x. I also am wanting a set of kooks so I may just suck it up and drop the $1,700 since this is the best I have found so far.

From my understanding even with FI the 1 7/8 gains over the 1 3/4 are at a very high RPM range but the 1 3/4 will be a restriction at some point. After several talks with Anthony from LG he has me going with the 1 3/4. I was going to go SC this summer but not it will be longer. Even if I do I will prob leave the 1 3/4 on I'm not worrying about a few HP when I have 550.

I've got American Racing 1 3/4" headers. Zero regrets on not going with a 1 7/8".

Ok another question, I never plan to supercharge my car or add nitrous so main concern is if I still decide to go with the 1 7/8 will it be a bad thing, like cause any issues? I found a pretty good deal on a set of dynatech's and compared to performance gains they give you with kooks etc, its an awesome deal considering I would be saving around $700, thats a few more things I could do to the car. My immediate plans with the car are the Vararam intake(still debating), borla stingers, and whichever header/x I can decide is best without problems. That will be pretty much the extent of performance mods maybe add a few more but nothing major at all, and thank you very much for your thoughts and help with this.

IMO with the mods you plan to do, 1 7/8 headers will give you less power. Go with the 1 3/4.

Think of it like a garden hose...

If you have a lot of water thrust (power) a larger diameter hose is better to let all that water out faster. Less water thrust will not do well in this larger hose; it will dribble out - not a pretty sight :lol:

If you have less water thrust, a smaller diameter hose is better because it accommodates the existing power better.

Listen!
 

Listen to the man, he is giving you some VERY GOOD ADVICE AND IT MAKES VERY GOOD SENSE! :cheers:

An example where EXCESSIVE size (1 7/8") might apply to a SC and could be determental. Too large of an exhaust system will cause blow through of A/F mixture into the exhaust and be improperly burned (need some restriction). Too much of a thing is NOT always good! Therefore, as some have noted, you have to look toward the WHOLE PLAN, just not parts - plan ahead for the final results. The whole system needs to be balanced to each other! Think of the whole picture, NOT parts!

This has to be the first thread where I agree with everyone's response so far!:cheers:

I have 1 3/4" LG super pro headers and here are my results with some mods...
http://forums.corvetteforum.com/c6-t...nd-videos.html

Here's my other car that also had American Racing 1 3/4" headers on a supercharged car...
http://forums.corvetteforum.com/c6-f...od-cutout.html

Anthony@LG also recommended the 1 3/4" header system to me too.

I know I'll get flamed for showing the OP this, but here's another cheaper option than the ones he's considering....:eek:

If I had an older vette that I was doing a budget build on, I'd look into these a little further. I still want to view a set in person to see the quality first hand.
http://forums.corvetteforum.com/c6-t...s-in-here.html
http://forums.corvetteforum.com/c6-p...-05-09-c6.html

There is a lot of good information in the replies you have received so far and I agree with them. With what you are doing the 1-3/4" with a 2.5" x-pipe w/cats is a better fit for you.

On a dyno you may see that the larger diameter headers make a little more power (1-2hp) but it will be way up in the rpm's and not usable.

Here is a link, http://www.bbexhaust.com/car/corvette/c6/, to our c6 page on our website www.bbexhaust.com where you can read more about our headers, x-pipe and exhaust.

You mods get the 1 3/4, I had my C5 with 1 3/4 at first, I went to 1 7/8 headers on my blowin setup and gained 15 rwhp and 18 tq, my loss down low was about 5 rwhp, you could not tell the difference on either end, but then when you have over 700 rwhp it takes alot more/less to notice a differencehttp://i29.photobucket.com/albums/c2...rican_flag.jpg

Thank you VERY much!
 

Thank you VERY much! Don't forget about AutoCal!

Here's the deal, for many years I only installed 1 3/4 cause guys usually didn't go that wild.....

Years later, many of those guys came back for cams and blowers and such and we wished we had gone with 1 7/8 pipes.

Truth is, as the driver/owner you're not gonna see much difference if at all from where you sit.

SO, going forward we decided to give everyone 1 7/8.

You won't really gain or lose anything until you get to 5 or 6 hundred HP worth worrying about.

That's how we do it.
Chuck CoW

It's been proven to use 1 7/8 with no loss down low.

Mine made less down low, but at my levels you could not tell, the Dyno did not lie:rock:

Maybe if you're comparing between cheap headers that use an inferior design!:rock:

Might want to check out the more expensive comparisons that actually use true 32" long exhaust primaries in their header design....that is where the tq gain will come from.:thumbs:

http://forums.corvetteforum.com/c6-t...p-results.html

Just swapping the 1 3/4" to 1 7/8"...
1 3/4": 582.5 / 512.9
1 7/8": 584.2 / 512.2

So just swapping them, you stand to make about the same power. Honestly, we've seen dyno sheets on an identical call, 3 or 4 pulls in a row, and they can fluctuate just as much as the difference you're seeing in this comparison.

PowerLabs had it further tuned for the 1 7/8", getting:
587.7 / 518.4

Gain of 5rwhp/6tq...

PowerLabs posted..
So, from what I take from all of this:
- If you've already gone with 1 3/4" headers, just stick with them.
- If you're in the market for headers but aren't going to go F/I, stick with
- If you're going F/I but don't plan on going past 600rwhp, stick with the 1 3/4" unless the pricing is identical for the 1 7/8"
- If you're going above 600rwhp, go with the 1 7/8"

I will be sticking with my 1 3/4". :cheers: