Hello everybody. Does anyone know if a stock c4 tranny for a 250 will draw or not transfer all HP to the rear wheels when a built 302 is installed instead? The dynojet showed 208 hp at the wheels and 234 torque. Very dissappointing. Will be thankful for any info.
any trans will use some hp to turn it. i believe a c4 uses about 20-25 hp to spin the internal parts & overcome friction. 208 rwhp doesnt sound too bad for a relatively stock motor or a mildly modified one. i think bone stock 302 in 1975 was rated about 175 or so if i remember correctly.
Maybe I took it wrong,sounds like he wants to know if it will hold up behind the v8.If it was working good before it should hold up fine.
208 sounds spot on for a 302, unless it's some kind of fire breather. Accessories eat up a lot of power. We used to figure it took about 40 ft-lbs to turn all of the accessories, plus the drag on the short block. 40 ft-lbs at 6000 rpm is about 45 hp. So if your 302 is pumping about 300 HP, which is what most aftermarket people advertise for the right cam, intake, carb, etc. You take off 45-50 for the water pump, power steering, alt, A/C, etc. Now you're down to 255-250. That's the difference between gross and net HP. Before '72 everything was measured gross, which made them look a lot better than they were in real life. Take off another 10 because the tune isn't 100% perfect. Now you're down to 245-240. Take off about 15% for the transmission, torque converter, rolling resistance, and rear end and you're at 208. The dynojet tends to read high too, because the inertia dynos need to use a "fudge factor" to compensate for transient engine performance, so it might not even be as good as it says. A true water brake or electric resistance (mustang dyno) will give you actual numbers.
