Header comparison (1-3/4" vs. stepped)
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Header comparison (1-3/4" vs. stepped) Alright guys, here it is as promised.
My intentions for going from a 1-3/4" header to a stepped (1-3/4" - 1-7/8")header was because of my future plans for heads and intake. I didnt really expect much if any gain. I just figured that since i was swapping headers, I'd do a dyno comparison for you guys that have wondered about the hp difference between the 2. Thats why I posted up my dyno results with the old headers awhile back just for this reason. https://ls1tech.com/forums/dynamometer-results-comparisons/821772-asa-cam-s-updated.html
Old headers: 1-3/4" Jet-Hots
New headers: 1-3/4" -1-7/8" Edelbrocks
Everything else: same (same mods, exhaust, dyno)
Results: almost 4rwtq peak. It was almost a direct overlay of the old graph. It did seem to pick up some on the bottom end (which surprised me). It dipped a little @ 4000-4400 for some reason, but overall its a little better through the entire rpm range.
Overall, I'm happy with the results. Like I said, I did this with heads and intake mind, not because I thought I was gonna gain a lot of hp over the other headers.
My intentions for going from a 1-3/4" header to a stepped (1-3/4" - 1-7/8")header was because of my future plans for heads and intake. I didnt really expect much if any gain. I just figured that since i was swapping headers, I'd do a dyno comparison for you guys that have wondered about the hp difference between the 2. Thats why I posted up my dyno results with the old headers awhile back just for this reason. https://ls1tech.com/forums/dynamometer-results-comparisons/821772-asa-cam-s-updated.html
Old headers: 1-3/4" Jet-Hots
New headers: 1-3/4" -1-7/8" Edelbrocks
Everything else: same (same mods, exhaust, dyno)
Results: almost 4rwtq peak. It was almost a direct overlay of the old graph. It did seem to pick up some on the bottom end (which surprised me). It dipped a little @ 4000-4400 for some reason, but overall its a little better through the entire rpm range.
Overall, I'm happy with the results. Like I said, I did this with heads and intake mind, not because I thought I was gonna gain a lot of hp over the other headers.
Last edited by JBIRD02; Dec 18, 2007 at 04:57 PM.
That is within the margin of error so the conclusion I personally would come to would be "no change." Thanks for posting the results though. This site needs more tests like this. Over the winter I will change headers and post my before and after results. I'm going from FLP 1-3/4" to ARH 1-7/8". I'm hoping for 5 to 10 rwhp gain across the entire curve. (My "entire curve" is from 5200 to 6800) LOL
At least this isn't the typical "I picked up 15rwhp going from brand X to brand X" thread. The good news is you didn't really lose any. My jethots on my last Z picked up awesome power, so this says good things for Edelbrock.
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That is within the margin of error so the conclusion I personally would come to would be "no change." Thanks for posting the results though. This site needs more tests like this. Over the winter I will change headers and post my before and after results. I'm going from FLP 1-3/4" to ARH 1-7/8". I'm hoping for 5 to 10 rwhp gain across the entire curve. (My "entire curve" is from 5200 to 6800) LOL
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I'm happy with the results. I was actually expecting to lose a little on the bottom end and I didnt, so thats good! Btw, my friend picked up 17rwhp over his Mac mids & Flowmaster catback with my old Jethots & TD's!
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I'd be curious to see what happened to your numbers from idle. Maybe the stepped headers hurt your low end? That could signify that stepped headers are bad for a stock cubed motor. I guess we'll never know.
Interesting. I would of expected you to gain atleast 5rwhp on the top end. Maybe if you had a bigger cam you would of seen more gains. It seems that the FLP's weren't holding you back at all.
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Good post, at least people can see how it works in the real work vs on paper. I have a bud switching to 2" primaries on a 402 high comp motor from 1-3/4" primaires, i cant wait for that comparision.
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Exactly, I agree. The heads I'm getting should bump the comp to 11:1, so I did the swap with that and a 90mm intake in mind.
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It was no problem! I see its not as conclusive as many would like, but I figured since I was doing a swap, why not dyno both headers fwiw?
Slowhawk, do you think a stepped 1 3/4-1 7/8 would help on a high comp 11.5:1 384 stroker with a good amount of overlap (24 degree's @ 0.50)? Or would I be wasting my time and stick with my QTP 1 3/4's?
I'm in the same boat as PewterZ28 as far as wanting to test a little larger header on my stroker.
OP, thanks for the comparison
Maybe this will humble some that always say you will lose all low end with a larger primary (on an LSX anyways) 
To me, what it tells me is that the original headers weren't the flow restriction in your current setup and that the new headers didn't hurt scaveging either. The step can only help when you go with a larger cam and headers in the future.
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My thoughts exactly. Like I said, I made the swap with a 90mm intake and a set of heads in mind.
