what gear ratio should i run with a 408, 550-600hp, tko trans and an irs. the dif now has 273. the ford motorsport gears are out of stock in 373 so do i go 410 or 355. street use only and i never speed or drag race on the street.......
You should take into account what type of cam is in your engine. Some long duration, high lift cams reduce the bottom end torque significantly. If you keep those gears - you probably will have to leave it in 4th on the highway and slip the clutch a lot to get it going. Your engine might have a lot of torque - but it's at 2500 RPM.
Hopefully someone has a similar engine/cam in their car and can give you advice on what gears to use.
I have a 302 with an X cam and I switched my 2:73's for 3:27's. But I am a long way from testing it out to give you some input on how well it works.
Uh Trevor, you probably have never driven an FFR with a stroker 351W. My buddies 408 w/450RWHP&480lb/ft of torque has 327's in the rear and any place that it is running in 1st gear, including idle, a stab of the throttle results in tire smoke from the 315/35/17 Yokohama A032R's. The FMS X303 cam is a big cam for the 302, I have it in my 342 and it works very well with the extra 40 CI. I would go with 3.27 gears because the motor will produce more than enough torque at freeway speeds (The above 408 made over 400 rear wheel lb/ft of torque from 2000-6000 rpm)
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