performance gains from headers
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Junior User
Joined: Oct 2004
Posts: 78
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From: South Williamsport, PA
performance gains from headers
What kind of performance gains can i expect if I put on a set of heddman headers with dual exhaust? I have a 351m in a 79 f-250 4x4. Will I get any better gas mileage?
Senior User
Joined: Jun 2004
Posts: 155
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Should gain about 15-20 hp. I would guess that if you keep your foot out of it, you should gain 1-3 mpg cruising at light load. I gained 4mpg loaded with mine when I changed, but I run a modified 400. You might see less with a stock 351.
Posting Guru
Joined: Dec 2002
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From: chicago burbs
get the smallest diameter tubes you can find if you want to see mileage gains, they will also improve power and driveability. the cam is prolly the single most important factor concerning mileage, but a few other factors need to be matched to the cam of choice for optimum results.
Senior User
Joined: Sep 2004
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From: Stanton,Ne
another good thing to do is put a H pipe in your exaust between the two tubes ahead of your mufflers. This will help with scavenging and equalize head pressure. It's also worth a few horses but I couldn't tell how many for sure
