For your absorption and contemplation I bring you a rumination of the reverie of burnt cats on toast

[SquareRoot]

Well ****. Doesnt look like they make 2.5 to 2.5...wtf?

Maybe search in the lawn mower section. 2.5" lol

 

[Swearbody]

Maybe search in the lawn mower section. 2.5" lol

:**** Eater: 2.5 collectors for life dog

 

[Catbox]

Man you are making me pull out all the cool stuff.

Check these out...
https://gbemandrel.com/shop-for-your-parts/ols/products/2-12-aluminized-steel-marman-flange-assembly

You must be registered for see images attach

 

[Bextreme04]

Ive emailed them already. If not ill just keep using the double chamfered 2.5 gaskets ive been using for years.
Every set of headers ive had were cheap no names with 2.5 collectors, but were always on the truck when i got it, except these stainless ones i bought. I actually thought it was the more common size due to having 5 sets of them but again...ive only owned cheapo headers that were "period correct" aka "cheap,rusty, and old". This is my first truck to really drop $$$$ on.

The cheapo flowtech ones I had on the 350 in my 74' were a 3" collector and the flowtech 454 ones I'm about to put on my 80' are also a 3" collector. All of the headman and hooker headers(obviously not cheapo) I've seen were also 3" or sometimes even 3.5". It's funny that all the cheapo ones you've ever seen were 2.5" and all the cheapo ones I've ever seen were 3"... must be a regional difference

 

[Swearbody]

The cheapo flowtech ones I had on the 350 in my 74' were a 3" collector and the flowtech 454 ones I'm about to put on my 80' are also a 3" collector. All of the headman and hooker headers(obviously not cheapo) I've seen were also 3" or sometimes even 3.5". It's funny that all the cheapo ones you've ever seen were 2.5" and all the cheapo ones I've ever seen were 3"... must be a regional difference

yeah my brothers hedmans are 3" collectors and the collectors on my camaro were 3" as well iirc but both have larger primaries.. Im pretty sure one of those 2.5 i had were jegs headers. all them had tiny primary pipes.

 

[Swearbody]

Man you are making me pull out all the cool stuff.

Check these out...
https://gbemandrel.com/shop-for-your-parts/ols/products/2-12-aluminized-steel-marman-flange-assembly

You must be registered for see images attach

I found something similar that just came with the flange. Would be nice just to bolt something between the pipes without having to weld on new flanges.

 

[Swearbody]

Man you are making me pull out all the cool stuff.

Check these out...
https://gbemandrel.com/shop-for-your-parts/ols/products/2-12-aluminized-steel-marman-flange-assembly

You must be registered for see images attach

Just watched a video on these. IM definitely sold on the idea now.

 

[Catbox]

yeah my brothers hedmans are 3" collectors and the collectors on my camaro were 3" as well iirc but both have larger primaries.. Im pretty sure one of those 2.5 i had were jegs headers. all them had tiny primary pipes.

I had a set of Blackjack headers that were 1-1/2 inch primaries and had the small 2-1/2 inch collector on them.
Usually what I have seen when you have 1-5/8 and above for primaries the collector typically comes as a 3 inch unit.

 

[Jwernatl]

Who in the hell is "they" and why should I believe "them"?????

I don't know - but 'they' say you should. It's like you see it on t.v. - it's gotta be real, right?

 

[Jwernatl]

I heard if you stick butter up a cats ass you can scavenge some burnt toast. I heard it here so it must be true.

yea - right. - hmm, ya know my neighbor has them damn cats over there...hmmm

well, scratch that - Im outta butter.

 

[Camar068]

on this topic, is there such a thing as an exhaust size calculator that includes an X/H pipe option?

My concern is at the bottom end of recommended size, will x/h add TOO much back pressure.

 

[Camar068]

GMSB link for more info:

https://www.gmsquarebody.com/threads/h-pipes.27951/

 

[Frankenchevy]

on this topic, is there such a thing as an exhaust size calculator that includes an X/H pipe option?

My concern is at the bottom end of recommended size, will x/h add TOO much back pressure.

The H pipe only equalizes pulses and maximizes scavenging based on all tests. Worst case scenario, the pulses can flow right on by if the velocity dictates. Nothing in an h pipe forces the gases to change direction...

 

[Camar068]

got that from an article I'd read. stated that an H pipe has more back pressure than an X resulting in higher low end torque between the 2. I've got a stock 5.3 LS with 2.25" exhaust is why I asked.

By what the article said, I don't know where I'm at on the limit of back pressure since I'm under the typical 2.5".

After reading the link I put above, I think I'll take it to my exhaust guy and have him throw one in and go from there.

[edit] found this after I posted.

https://www.aa1car.com/library/exhaust_backpressure.htm

 

[Swearbody]

got that from an article I'd read. stated that an H pipe has more back pressure than an X resulting in higher low end torque between the 2. I've got a stock 5.3 LS with 2.25" exhaust is why I asked.

By what the article said, I don't know where I'm at on the limit of back pressure since I'm under the typical 2.5".

After reading the link I put above, I think I'll take it to my exhaust guy and have him throw one in and go from there.

It doesn't "create" backpressure. It just so happens that an x has less backpressure than an h. Either will reduce backpressure significantly.