I'm still trying to find it again, but while I was surfing the web I found a comparo on these two headers. It was done in a speed shop in Detroit. They had two cars, A highly modified tpi 383 camaro, and a bone stock tpi 305 camaro. On the 383, the SLP's made more horsepower above 5000 rpm, however, it wasn't much. Under 5000 rpm, the edelbrocks made more horsepower and torque. On the 305 camaro the edelbocks made more torque and horsepower throughout the entire power band, which was only to 4500 rpm. So it really depends on your application which headers are better. I think for most of us, the TES would be the better choice. It's just the rust issue that is a problem. I'll have you know, my buddy has had uncoated TES headers on his car for three years now, and they just have the usual surface rust. He takes care of them and wipes them down with SuperClean every once in a while. The headers are thick enough that I don't think rusting through will be a problem. It's just the "looks" issue that comes up. He is so happy with them that I just bought a set and they look very well engineered. They are a great deal for $300 considering they are CARB legal. I'm more worried about economical performance gains than show winning looks.
I'm still trying to find this article again. I let you guys know if I have any luck.

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'88 IROC TPI 355, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp Roller Rockers, Comp Cams TPI cam, fully ported '90 speed density TPI with '86 base so it fits older style heads, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
Won bracket races at Numidia Raceway with my '70 Nova
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

dyno numbers do not directly equate into in-car performance.
There is a very big difference between the actual performance of TES and SLP's.
I have measured a 6% power gain from swapping to SLP 1 3/4" shorties. That number is based on trap-speed VS vehicle weight.

ODB

 

If your testing wasn't done on the same day, w/ every other setting on the car identical then your in-car performance tests aren't going to be an accurate guage of which header is best. Not that I'm questioning that 1 3/4" SLP headers probably do make more power than the 1 5/8" TES.

Which headers were tested IROCZ28, both 1 5/8" primaries or were the 1 3/4" SLPs also thrown into the test?

I would think a dyno test showing more power at every rpm under 5000rpm for the TES would be about the best proof you'll ever get about performance. But when you say more power are we talking about a very small 2-3 hp gain or something where they are in reality more or less breaking even? I'd be real surprised if they weren't so close it really doesn't matter...

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

 

I don't know if the testing was done on the same day. It probably was though. I do recall that the difference in horsepower was very small, to the point that it probably doesn't matter. I don't recall the size of the primaries between the two headers. What they were basically saying is that the Edelbrock's were the best bang for your buck. If I had extra money I would buy the SLP's because of durability. With a little work, and some inexpensive por-20, the edelbrock's will perform just as well as the slp's, and last just as long if they are properly taken care of.

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'88 IROC TPI 355, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp Roller Rockers, Comp Cams TPI cam, fully ported '90 speed density TPI with '86 base so it fits older style heads, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
Won bracket races at Numidia Raceway with my '70 Nova
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

BTW, the only thing changed on the cars were the headers. All else was left alone. The tests were done inside on a rear weel dyno, so the atmospheric conditions had to be consistent.
I think I saw it on camaroZ28.com. Someone had it as a link. Still no luck in finding it though.

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'88 IROC TPI 355, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp Roller Rockers, Comp Cams TPI cam, fully ported '90 speed density TPI with '86 base so it fits older style heads, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
Won bracket races at Numidia Raceway with my '70 Nova
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

I was referring to OBD's post when I mentioned testing needing to be done on the same day, w/o changing any other settings.

I was implying the dyno test showing the differences between the two done by a mag comparo has got to be wayyy more accurate than track days that are a month or more apart w/ who knows what variables including temp and traction each day, and dozens of possible tuning changes over the time between runs...

I hope you can find that comparo, I'd really like to see the details about this test.

------------------
Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

 

I wouldn't have posted that info if I wasn't sure it was right. I'd put more faith in my test data than anything from a dyno any day.

 

How can you say that knowing the variables between even track runs on the same day, much less weeks (months? how long was it between testing)? Yet you've got it figured down to 6% increase huh, all attributed to the SLP's alone, forget any tuning, whether, launch variances, etc...

I would put alot more faith in direct, back to back (w/ every factor the same) testing on a dyno where we can see the whole power curve, and eliminate launch/driving/shift point factors in our findings.

I'm not saying you're not right, the SLP 1 3/4" headers probably did yield the improvement you saw, it's just open to too many factors to put it above direct dyno comparisons. (especially since the article is probably 1 5/8" vs 1 5/8"...)

------------------
Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited March 13, 2001).]

 

Interesting... I'll still take my SLP's over Edelbrock's any day, every day, and twice on Sundays.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Well Ray I can really understand your doubts about joe shmoe posted their so called test results up here. I think if you saw how I conduct my tests and knew me and my car that you'd think a little differently about their validity.
My car is dead consistant and I've made it that way precisely so I can get good test data. I do not rely on the track for my test data because there are too many variables that I cannot control there, plus the track adds roll-out to your time measurements & more error.
Even as bad as the track is, my last two runs at Gateway Int. Raceway varied in E.T. by .003 seconds and 0.000 MPH. I was also using my Vericom2000 at the same time to get current corrections, and I use a Davis weatherstation for air density corrections.
I was just stating my results with my 383. Obviously results will vary on different cars & hopefully everyone knows this already.