dr_whigham

iTrader: (49)

Quoted for truth.

Calvinator

iTrader: (5)

I recently ordered a set from DNAmotoring and thought I'd add my measurements. Mine are pretty much identical to the OPs measurements. Overall quality of the headers are impressive for the price. I cut off and welded shut the AIR flanges and EGR because I didn't want to run the risk of it breaking off/cracking over time.

02TransAm/Batmobile

iTrader: (32)

That is what I'm talking about. The welded section right after the inlet probably reduces the inlet size to about 1.5"! Could you measure that cross-section?

The Alchemist

iTrader: (19)

There's no point in measuring the header flange, they are use the same ones.

Calvinator

iTrader: (5)

Just measured the welded section after the inlet. It's 1.627

Calvinator

iTrader: (5)

Yeah, it was mainly just to make sure the caliper was somewhat accurate. It's a cheap one from Harbor Freight lol

AnotherWs6

iTrader: (17)

true, but check out ds98formula's build thread link above. he got pretty good results with these things on a stock motor. 1 5/8 is fine for a mild old school small block, and also true for our ls1's. the difference is that these ls1's breath heavier and want to rev more so the bigger primaries do help, but the smaller cheapies still do pick up some decent hp. they prob arent ideal for a head/intake/cam car, but in any case they are a signifacant improvement over stock. what bugs me is why cant people just make true 1 3/4 that would cost a tad more than the 1 5/8? what would the step up really cost? annoying.

ds98formula

iTrader: (3)

i would like to see some name brand ones checked just for comparison

01ssreda4

iTrader: (96)

Almost all if not all headers are measure OD. You're wasting our time with this foolish thread. And, you're eating $60 to send them back over 1/8". Foolish number 2. Then you will order a brand name header and find out it is measure OD too. Then you'll start another thread bashing them. Foolish number 3.

02TransAm/Batmobile

iTrader: (32)

After I returned the eBay headers, I bit the bullet and purchased some Kooks from Maryland Speed. I measured their ID and it was 1 7/8's with no flare.

People report better numbers after switching from 1 3/4" to 1 7/8"s. Like these guys:

+32/21 - BBK's/Y-Pipe/SLP Dual to Kooks 1 7/8"s/Kooks Dual Exhaust

https://ls1tech.com/forums/dynamomet...l-exhaust.html

+20/15 - Kooks 1 3/4" to Kooks 1 7/8"

https://ls1tech.com/forums/dynamomet...l-exhaust.html

The difference was only 1/8". I may seem miniscule but going from 1 5/8 - 1 3/4 is an increase of 8% [(1.75-1.625)/1.625]= 8%. Going from 1 5/8 to 1 7/8 is an increase of 15% [(1.875-1.625)/1.625]=15%. That is a modest increase.

demonspeed

iTrader: (7)

Awesome! Thank you!

Unfortunately, I measured everything except the wall thickness; however, it was certainly thin compared to anything I've seen with the name-brand headers (as is obvious in the pictures). So, even if Speed Engineering says theirs is also thin-wall and will flow close to a 1-3/4" primary, it's still the same, inexpensive Chinese 1-5/8" stainless that their eBay competitors are selling for a lot less (that they're advertising as a 1-3/4" - which it isn't).

At the end of the day, we need to determine the honest size of the primaries and the gauge of steel they're using. This it the only way to compare the brands at this point since now even a sponsor is advertising 1-3/4" primaries that are actually 1-5/8". I'd love for someone to measure their TSP primaries...

EDIT: I should have thought about this before, but we can determine the gauge because I measured the OD and ID of the collector. At 3.002 OD and 2.862 ID, that leaves us at 0.14/2= 0.07" or 15g ( http://www.engineersedge.com/gauge.htm ).

demonspeed

iTrader: (7)

Did you even read the original post? I measured OD. The brands listed at the beginning of the thread (yes, even a sponsor who advertises 1-3/4") are 1-5/8".

Further, it's not about the $60. It was about how one can save +/-$500 over name-brand 1-3/4" headers by going with -- what we assumed -- were super-affordable eBay headers of the same size..... which we now know are 1-5/8".

With this thread, I think we've determined (in context of price):

Budget: 1-5/8" eBay headers (this includes Speed Engineering for the time being)
Middle-of-the-pack: 1-3/4" Pacesetter, hooker, or even TSP (or used name brand)
All-out: 1-7/8" TSP or name brand

At the end of the day, if one is saving this much money by buying on eBay, they're getting the smallest primaries available, which is 1-5/8" OD and 14g steel

adamantium

iTrader: (3)

This is why i went with pacesetters, not that much difference but i paid $40 more and atleast i know they are actually 1 3/4, or atleast i think they are lol.

dr_whigham

iTrader: (49)

I wouldn't necessarily call TSP middle of the pack. They're definitely well ahead of Pacesetter.

ARH measure their headers by OD as well.

Again, tubing (less than 12" diameter) is measured by OD. Pipe (greater than 12") is measured by ID.

demonspeed

iTrader: (7)

Sorry, that was meant in the context of price -- not quality. I see how you would have inferred what you did, though.

ds98formula

iTrader: (3)

would you mind checking for us

DietCoke

iTrader: (18)

For the record, the headers in question are made by the same company that makes the newer TSP headers.

01ssreda4

iTrader: (96)

I understand ARH and Kooks are top of the line, so with an exception to those two brands, ALL others will not measure true to the stated specs I'd be willing to bet. Its been like this FOREVER. Carry on.

demonspeed

iTrader: (7)

If it's been like this forever, then please provide empirical evidence.

02TransAm/Batmobile

iTrader: (32)

I don't think he could, maybe anecdotal evidence. Either way, he shouldn't be knocking us because we are seeking actual LS1 TECHnical data - the whole premise of this forum.