So been reading the "Headers by ED" site. A major proponent of true equal length headers. Have to admit though....he really never says why. Looked and looked....no answer.

Many years ago I read an article by David Vizard about exhaust systems and he didn't think egual length headers were necessary at all. Especially on a V8 because the firing order just doesn't support the scavanging. In fact, he stated that not only don't we know what length to actually make headers, but that un-equal length headers will make the torque band broader.

So to those of you with tons of dyno experience......does it really matter? Do you see significant differences?

The Hookers on my car are far from equal length....but at the same time are a very nice quality header. Coated they cost too much to replace at the present time.

I'm talking big blocks here BTW......

Comments?

ron

I remeber seeing an old CHP article that did some dyno tests. The equal length was worth much, maybe 5-10hp. Torque picked up a bit and flattened out. So unless your building an all out race car the equal length probably would be overkill.

Steve

I was just re-reading Smokey's book and he pretty much says the same thing that Vizard said. Equal lenght headers are tuned to a narrow rpm range. Something like 1000 rpm. Outside that range they will cost power over an unequal length set.

Also, when looking at equal length headers, you can't just measure the lengths. Every bend adds length to the primaries. The tighter the bend or the more degrees it turns the longer the pipe appears to the exhaust gases. I use to run into this when figuring static pressure in HVAC systems. There are charts that give the length added by each bend.

I've often wondered why only the header companies have discovered this speed secret - making avery pipe a different length to make the power band wider. Imagine the results if the cam companies would get on the bandwagon - have each lobe ground to a different duration and lobe center so you cold match the headers.

Jere Stahl has said that on average, equal length headers seem to work best in the 4000 - 5500 RPM range.... once past 6500 or so there isnt any more power to be had with equal length vs unequal length.

Howerever if the equal length header due to the engine / chassis combo... if some primary tube(s) have flow restrictions built in , in the attempt to make them equal length, then that can really cost you power.... It would be better to have an unequal length that flows closer to the same, than an equal length that had restrictions that couldnt flow nearly the same.

Interesting topic ....69 above is correct about equal length theory from Jere Stahl and of course Jere Stahl and "ED" would tell you primary tube and collector diameter is the most important thing then equal length ... remember Stahl builds headers for primarily race applications so equal length has value. when you buy Stahls he really wants to know your use.. race or street and rpm band and HP and he goes to great lengths not to have flow restrictions , hence some tubes outside the frame rails on early BBC Chevelles... so no compromises for fit... but I can tell you plug clearance is excellent so equal length can be done and still fit reasonably well

BTW Headers by ED tape on header design is well worth the $$ it really gets you thinking

equal length can be done on most any car if you compromise. I have a 454 in my s-10 Blazer with equal length headers by ED. but I can't steer very far anymore and my mufflers are visable from the side. I have done a bunch of research and found good arguments for both sides. I decided to go equal length and got all 8 tubes within an inch or two of the 38" www.headerdesign.com (http://www.headerdesign.com) told me with the 16" collectors.

http://www.greatlakesdragaway.com/gldforums/vbgarage.php?do=view&id=982

When I bought my equal length "Headers By Ed" he sent an article along (Car Craft I think) that tested several headers on a 350 chevy, including his. His 1-5/8" equal length headers made some 40 ft-lbs more than the non-equal length 1-5/8" headers.

I just wished somebody would come out with a cheap set of 1.5" diameter, four tube, long headers like I think used to be made for smaller motors..

Maybe even a cheap set of 1.5", Tri-Y's...

I remember they were out there when I was younger but I expect everybody wanted the "race motor" look that bigger tubes gives so they got dropped..

pdq67

Hedman makes 1.5" long tube header for the GBody. May work in a Chevelle with a little massauge.

Steve

The thing that most people forget about Ed Henneman and Jerry Stahl is that they honed their craft on the dragstrip in the 60's when stock and super stock classes were king. :cool: Their Ideas are based on real world testing... not computer simulations. These type of cars had some real limitations on cylinder heads, cam, induction, etc. The gains that they got from a better header translated into some real E.T. improvements. Now that said... I think that a lot of our cars are along the same lines.. Those with 13.5 to 1 compression and triple stages of NOS only need four big tubes dumping into a coffee can :D

i think theres an about 12" difference in my lemons. coupled with the fact that 4 of the tubes are fender well and the 4 corner tubes are in the frame. i may try a set of slip on collectors with longer primary sides and see if it dosent pick up some. Dave

I gotta!!

Anybody remember the cast aluminum, long race factory exhaust manifolds that either came out on the '63 or '64 SS Galaxie Fords or maybe Big Cat. or -Prix Pontiac's!!

From what I have read, they dripped molten aluminum at the starting line as they took off...

Carry-on...

pdq67

Originally posted by pdq67:


Anybody remember the cast aluminum, long race factory exhaust manifolds that either came out on the '63 or '64 SS Galaxie Fords or maybe Big Cat. or -Prix Pontiac's!!
Smokey Yunick had stainless steel four tube headers made for Fireball Roberts Pontiac NASCAR effort. They even had a pontiac part number. NASCAR impounded them and I believe they are still in the museum at Talledaga.

Yes, I can believe Smokey would do something like that after reading about the 7/8 sized car thing!!!

pdq67