Does anyone have dyno graphs from different primary sized headers of the same design- on similiar and/or the same motor?

I'm looking to do a little comparison of things...

I've noticed more & more people are putting 1-7/8" and 2" headers on very mild 346cid motors- and this just seems against anything I've ever done with the older motors...

Has anyone run 1.5" or 1.625" LT's? and with what result- compared to larger tubes...

 

The best type of header to run on an LS1 is an 1 3/4 stepped to a 1 7/8 with 31 to 33" primarys and a 3" to 3.5" collector, are far as midlenghts go the macs are 1 3/4 by 26" they will keep up in peek horsepower but they lack about 8-10 flbs of tourque down low, they do better with the collector mod.
Done ever use shorty headers on an LS1.

 

Thanks, but I'm really looking for some raw data to do a blind comparison.

By the by- a friend picked up 14rwhp/19lb-ft using Edelbrock TES shorties over stock manifolds on a blown car. And he still passes CA inspection in LA 100% legally. So I'd say if used in the right application- they aren't as good as long tubes, but they certainly have a use.

 

I wanted smaller headers (diameter) when I was looking. Everyone preached bigger is better but would not provide proof. I still believe that a 1 5/8 would out perform a 1 3/4 on a stock engine, but on even a mildly modded engine (bolt ons) that is seeing upwards of 400 hp at the crank you are borderline on the 1 5/8 vs. 1 3/4. The major hang-up I was having was that I was accustomed to crankshaft hp #'s and everything in the LS1 world is RWHP so add about 15-18 %. Example 430 crankshaft hp = 365.5 rwhp. At 430 hp you are starting to limit the engines breathing if you install a 1 5/8 vs. 1 3/4. There is a Vette longtube that is a 1 5/8 that is also made in a 1 3/4 (if my memory serves correctly). You could look it up and see what the dyno results were.



I did quite a bit of research trying to find the header that was the closest to equal length and the over all tubing length. The problems when you do find the header that is the closest to equal length is that the may all be too short (rarely ever too long). So that is not a good measurement on the LS1 headers. Also look at the collectors. I think that the SLP has horrible collectors followed by TTS. The Grott and Hooker styles has a nice long collectors with good transition area. Also I have seen one shop say that they picked up power by going to a Hooker over a FLP and then another shop said the exact opposite, so take the results with a grain of salt. There are a few headers that I would steer clear of. I would stay away from the SLP and the Pacesetter. The SLP's hang too low and have a horrible collector. The Pacesetter & TPIS have IMO some tubes that are way too short. The TTS again has a collector that is too short and cost too much. For the money it is going to be hard to beat the Flowtech.

On a side note if TTS would change their collector and have more transition area it would be the best IMO.

I know you wanted concrete data but I just wanted to help in any way I could.

Later,
Bart

 

I dont have any dyno info yet but my car is getting Kooks stepped stainless with y-pipe and cats installed right now to replace my TTS headers with y-pipe and cats. The TTS headers were starting to rust badly. I heard that TTS made a revision to there cats later on after I bought mine so they would flow better.
The stainless should last A LOT longer than the 3 years the TTS did, hell the TTS coating started to come off within the first 6 months.

 

Bart-
Thanks, sounds like you did a lot of the research I was starting to do already.

I actually have a set of Hedman 1-1/2" to 1-5/8" stepped/coated headers on the way (hey- they were $200- and Hedman makes nice stuff- so worth an experiment). Going to be interesting to see the results. Could be good (great low-mid torque) or bad (lower across the board)...but we'll see.

Anyone seen the new edelbrock victor series headers? high velocity collectors are standard... There is some neat stuff coming out for our cars for reasonable prices now.

 

z28hokie,I've seen some pictures of Edelbrock race headers 1 3/4 to 1 7/8 stepped primaries with awsome collecters, the guy that posted them on this thread was real pleased with the quality, I beleive you can buy them for under $400.00 but they're just painted maybe you can get them coated too.

 

You have a part # for your header?

As far as the Edelbrock they are just a copy of the Hooker with a merge collector. My headers are hooker copies with merge collectors but mine are 1 3/4 alll the way and are not stepped.

BTW what mods do you have? Hedman is owned by Holley which also owns Hooker and Flowtech so I am pretty sure it will be a hooker copy so it will pretty easy to get a general idea of how the smaller priamries affected your power band. Also what size collector do your headers have? I am very interested in your results. Good Luck.

Later,
Bart

 

Bart-
The part # from Hedman is 66534
If you put HED-66534 into the "part #" on Summit it will find them... I have a discount coupon on "any exhaust product" so that's how they landed @ almost $200 even (they are $263 I believe)

It's a 3" collector, no idea in terms of length or style, I've yet to see any pictures of them. Just got a postcard saying they are backordered till 4/1...so we'll see...

 

FYI I looked at Jegs website and they list the same header as a 1 5/8 to a 1 3/4 step instead of a 1 1/2 to a 1 5/8 step. I am not trying to be argumentative just did not want you to have a huge suprise. My bet is that they are the 1.625-1.75 because of the 3 inch collector.

Also what mods do you have currently and do you plan to dyno before and after?

Later,
Bart

 

Yeah... I've seen conflicting information them too.
Jegs has the 1-5/8" to 1-3/4" listed
While Hedman has 1-1/2" to 1-5/8" listed here: http://www.hedman.com/pages/hedders/pass-chevy.html.

It'll be interesting to see which one is actually correct, I'm going to assume Hedman's though (but we'll see).

Let me get back to you on mods (I'm going ground up...so just the suspension is done)...right now I just have a lid, performance wise. And I'll probably dyno, properly tuned before...then properly tuned after...

 

Hmm they also offer a non step 1 5/8 header. Looks like somone would make a 1 5/8 for the truck market for more low end torque.

Later,
Bart