I recently purchased a set of Thorley headers For my 69 F-100
390FE. They are equal length 1-7/8" primaries,4 into 1, 3/8 flange, and 2-1/2" collector. The rest of my exhaust is 2-1/2" through twin turbos out the back with a crossover. The cam will be a solid grind clay smith 292 advertised, 240 @ .050, 108 lobe center .570 lift. 2000 to 6000 operating range with a c-6.
Did I make a bo-bo with the 2-1/2" collector? I figured that
if I had a 3" collector and was necking down to 2-1/2" pipes
I would be losing velocity and flow, but now I am stuck with 2-1/2" pipes.
Also, how about this:
IMHO I hear a lot of pickups that sound like a noise maker is attached (glass packs or somthing) but can't seem to accelerate very well. Reminds me of when I was a kid and would put a piece of cardboard in the spokes of my bike with a clothespin. I would rather be in front of these people ( where I always have been} and don't hear the noise. Course they never accept getting beat
and roar past me at the next light popping my eardrums and picking up there speeding ticket a half mile down. Well I thought about those warrior mufflers that you can un cork for fri night drags but how do they sound corked?
Also anyone ever wye pipes with covers out the side, and does this cause turbulance when capped for the street?

 

hey olddude,the headers you have are perfect for the engine you have.2.5" exhaust will give you the best perf. 3." would make you have to run closer to that 6000 rpm all the time cuz you would lose all low end torque.LaMar