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Do headers really help flatheads make horsepower

Discussion in 'The Hokey Ass Message Board' started by minks garage, Feb 21, 2012.

  1. PackardV8
    Joined: Jun 7, 2007
    Posts: 871


    The older I get, the faster I wuz. FWIW, a 286" flatmotor making 240hp would be very competitive in the classic classes at Bonneville. Most of mine made 150hp, 175hp costs money and 200hp cost beaucoup bucks.

    jack vines<!-- / message --><!-- sig -->
  2. jguff
    Joined: Jan 14, 2009
    Posts: 134


    In the June 1953 Hot Rod Magazine they did a series of dyno tests to see if dual exhaust systems created more rear wheel horsepower on stock engines. In a few cases they also tried headers along with the duals.

    A stock 1953 Ford flathead generated 68 rear wheel horsepower at 3000 rpm. With dual pipes it generated 71 and with duals and headers it was also 71.

    A 53 Merc had 70 rwhp at 3000 rpm, 72 with duals and 73 with the headers added.

    A 53 merc with Merc-o-matic auto trans had 72 rwhp at 3500 rpm, 76 with duals and 75 with headers and duals.

    It would seem that a stock flathead at modest rpm does not produce much (if any) more power from the headers but gained mostly by freeing up the exhaust flow from the manifolds back by replacing the single exhaust with dual pipes.

    It could be quite different with a modified engine with heads, carbs, cam etc. operating at higher rpm.

  3. Well Jack, this was a motor that Earl Evans had built for Land Speed stuff, As I mentioned on the headers that were tested. I might be a little off on the numbers, again it was 40 years ago. But this was a very healthy motor. Cam was an Isky 433 and it was somewhere just under 10.1 Compression. The block also had some very extensive port work.

    Of course us being smart ass high school students, we laughed and said we'd be embarrassed if that was all the power our small block Ford's and Chevy's made (even though most of them probably didn't)
  4. PackardV8
    Joined: Jun 7, 2007
    Posts: 871


    Then you and I agree it would be competitive in the flathead class at Bonneville. Any recollections of what years and what classes it ran?

    jack vines
  5. No, it was run before my time and the car was long gone. The guy just had the complete motor, trans, and rear end. Unfortunately I wasn't really into this old stuff at 16 so I didn't pay much attention to it. But I remember playing on the Dyno like it was yesterday as that was Fun
  6. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,796


    Like anything else, it's got to be part of a set of upgrades, to REALLY see a difference.
  7. gots to make a difference....

    both 1.jpg
    Joined: Dec 3, 2002
    Posts: 1,043


    From my experience headers and dual exhaust (with glass packs) definitely help the little flatty engine. I've had a couple more since I posted last time and my experience is the same. It's pretty cost effective, sounds better, looks better, is better. Do it!
  9. Pete1
    Joined: Aug 23, 2004
    Posts: 1,678

    from Wa.

    Back in the 50's when we had a Clayton dyno in the shop, we used to run a lot of engines for good customers for a jug of moonshine or a couple cases of beer after hours.
    Some were 304's and most were 315's or bigger. One of the most consistent things noted was the difference between the common swept back 3 into a collector type header and our W type was at least 10 hp more for the W's. These were 2 inch down pipe with reversion dams and a baffle in the center just above the 3 1/2 inch collector flange. The ports were matched and faired. (Often overlooked on the exhausts)

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