Once again I was glossing through a 5 year old magazine, this time Car Craft and ran across a very interesting Header test I thought a few of you might enjoy.

In this test the magazine took 4 header sizes from the same manufacturer (Hedman) and tested each header on two different motors.... one a "mild" 355 motor and the other a "Hot" 355 motor.

The Headers are:

1 5/8" primaries - 3" collector
1 3/4" primaries - 3" collector
1 7/8" primaries - 3.5" collector
2.00 primaries - 3.5" collector

The Mild 355 motor consists of 10-1 cr, .425 lift 206 @ .050" single pattern cam, L98 Corvette Heads, Edelbrock dual plane manifold, Holley 650 carb.

The Hot 355 motor consists of 9.7-1 cr, .507 lift 244 @ .050" single pattern cam, AFR 190 heads, Victor single plane intake, Holley 750 carb.

Note: All tests were open header test, however they used a slip on 16" or 17" slip-on extension,

Hot Motor Peak HP Test Results:

1 5/8" = 435 HP @ 6700 rpm
1 3/4" = 447 HP @ 6700 rpm
1 7/8" = 452 HP @ 6700 rpm
2.0 = 451 HP @ 6700 rpm

Hot Motor Torque Average from 3000 to 4800 rpm"

1 5/8" = 370 ftlbs
1 3/4" = 368 ftlbs
1 7/8" = 371 ftlbs
2.0 = 369 ftlbs

Hot Motor Torque average from 4900 to 6700 rpm

1 5/8" = 378 ftlbs
1 3/4" = 383 ftlbs
1 7/8" = 384 ftlbs
2.0 = 383 ftlbs

I don't feel its necessary to show the mild motor results simply because virtually all of the test results were within 3 ftlbs and 3 HP of each other with the 1 7/8" headers having the very, very small advantage over the others. (As a note: The HP was between 309 to 312 HP and torque was in the 355 ftlbs range)

As another note: The magazine article declared the 1 7/8" Header as the slight winner in the Header shootout.

My personal opinion.... On a modified motor you probably want to start out with 1 3/4" Headers and if you're more of a strip car than street car, consider 1 7/8" headers.... but lets face it, the differences between the two are almost trivial.

Hope you enjoyed.

Cheers,
Beach Bum

 

I wonder if it wouldve made any difference with the collectors being smaller on the 1 5/8 and 1.75 than the 1 7/8.

 

Thanks for posting that Todd. That's exactly what I've been looking for! I guess I'll go with the 1 3/4's afterall. :cheers:

 

OK we are now definately going to designate you as the tech article guru :D

One that you might want to see done, not to change the subject, but I am going to be getting a larger MAF unit from a member of a different board, the Wells unit that is suppose to be larger in diameter and flow 750 CFM with the screens etc. We are going to make swaps at the atrack and also on the dyno the next time I go, to see if there is any gains from it. :cheers:

 

Ski, I've just had a rare lazy man's weekend where I bummed around at home.... picked up some old magazines and started thumbing through them, to my surprise I found some interesting articles. I used to subscribe to about 10 different automotive magainzes, they would come in so fast, I rarely even opened them up.... maybe I should of, I'm finding some pretty good articles, and have found a few others the forum might find interesting, will post them in a while.

Your test sounds great..... look forward to hearing the results.

later
Beach Bum

 

Beach,

Did they show the full HP and torque curves? I'm thinking that info might be of use to some of the mild motor guys on here. My thinking is, that some people are buying 1.75" headers when they might be better off with 1.625". You didn't race either?

RACE ON!!!
1984 Crossfire
Member NHRA

 

Though I'm not saying that results of the aforementioned test aren't valid, they most likely are given the power output of their "Hot" motor, be careful putting too much weight in those "shootout" articles. There was a test done in Circle Track in the early 90's I believe where they were comparing 6" to 5.7" rods in an SBC. They showed the 6" rod to make more power than the 5.7" rod. Not long after the article was published, the editors found out that the author had the dyno operators tweak the dyno calibration because the "real" test showed no difference, and the myth was that the 6" rod made more power, so obviously their test should reflect that. Well, that author got fired, but this is just an example to warn folks about putting too much in to those tests.

 

CFI,

Yeah, they showed the full curves, but in a nutshell, the smaller header had a small advantage at below 4000 rpm, but very little. The bigger headers had a small advantage above 4000 rpm.... however those 1 7/8" headers actually had as much torque as the smaller ones below 4000 rpm.... weird huh ?

Corvette Z51,

I agree, I don't think anybody should spend money based upon a single test or observation. When I read articles like this, I just take a mental note of it and move on.... but they are interesting, and I personally believe the majority of them are fairly accurate, but not all. In addition, one of the things I have learned is that no matter how identical, 2 set-ups will react differently to the same modifications. Weird huh ?

cheers,
Beach Bum

 

Now that I find very interesting and reassuring.

It's good to know that we should lose very little or no torque down low going with 1 3/4" LTs on a mild 350 SBC.

Thanks much for the info.

 

Beach, i remember reading that article when it came out....in fact, i remember sitting on the beach reading it under a nice umbrella......Ah, the good ol'days.....does anyone in the northeast remember sunshine?

Anyway, i remember noting how the 1 7/8 header worked the best on average.....and even on the milder engine it was right there with the 1 5/8. Unfortunately, not too many 1 7/8 headers available for our cars/heads. Plus, i wonder what effect a full exhaust would have since that's the way we run. It might give a completely different picture.

 

Sounds to me like a nice test, wanna volunteer for it Ralph? :D

I local guy here just built a 406 similiar to mine, and he had a guy build the ones that are 1 5/8 then are stepped up in incriments to 1 7/8 I believe. He said they were over $1K, but he is running way slower than we are with the setup in a totally gutted older camero, I was kinda lookin forward to seeing if he thought the headers were helping him any, but the car is a slug, and he is very disappointed in the times. I think its running 840s-880s at 8X MPH in the 1/8 the last I spoke with him. Not sure if he figured anything out with it, but I know he wasn't too happy, and rightfully so.

From my reading the tapered or stepped headers are best for turbo setups, as it promotes quicker turbo kickin due to the increased exhaust velocity. But who knows till you actually try it on a given setup. That is the tough thing with this sport, nothing is a for sure thing. And it all cost major $ to try :banghead:

 

I dunno Ralph, sure wish on some of these articles they would go to the next step and finish the deal... but, its all we have I guess.

later
Beach

 

Are you using headers on your vette??????
If so which ones......????? And where do you get your smog checks out here????
I want to use them....But...........The Smog ****'s will get me...
thanks
tony
:eek: :cheers: :eek:

 

Are you using headers on your vette??????
If so which ones......????? And where do you get your smog checks out here???? If I were to use them Hooker 2149's...the way to go.....
I want to use them....But...........The Smog ****'s will get me...
thanks
tony
:eek: :cheers: :eek: