396 Stroker Motor Lacking HP
So I bought a 351w stroker motor about a year and a half ago, the motor is a 1993 block which I wouldn't do again because they only came stock with 200 hp, it's been bored and stroked to 396 cubic inches and was supposed to be putting out 400 hp at the flywheel. The motor has cast iron 1970 351w heads 69cc with 9.7:1 compression ratio, roller cam although it's only like a 206/221 cam, edelbrock rpm air gap intake, holley 670 street avenger carb - do I need a bigger carburetor?, JBA swap headers, x pipe, 2.5" exhaust and side mufflers. So long story short, I take the mustang down to The Mustang Shop in Auburn, WA and get it dynoed on their mustang chassis dyno. Started out with 240 hp at the rear wheels and 319 ft/lbs of torque, added bigger floats to the carb and rechecked the timing which was way off, and the best I got was 283 hp at the rear wheels and 378 ft/lbs of torque. I've heard that you have basically a 20% loss in power between the flywheel and rear wheels so that would put my flywheel hp at approx 330 which is 70 short of what they claim it to have. So right now I'm talking with the shop that built the engine to see what my options are and they want me to take the engine back out of the car, ship it back to them since they are in Spokane and have them put it on their engine dyno because they are certain that my setup should make 400 hp at the flywheel. I don't know if any of you have done a 351w into a 65/66 mustang but it is a pain in the *** and I'd prefer to not have to take the motor out again, ship it back to them and have them give me some BS story that yes it is in fact running 400 hp. So my questions are, I asked the shop if I could get a partial refund on the motor since it's 70 hp shy of what it should have and then I could buy some parts and do it myself which they agreed to but I haven't come up with a figure yet. Or I could have the shop buy some parts and have them shipped to me since they could get parts for much cheaper than I ever could. Finally to my point... I want new aluminum heads and a cam. The Mustang Shop said my cam was way too small and the heads were way too restrictive to put out 400 hp at the flywheel, what brand/size heads would you recommend putting on the motor? And if I replace the heads, what other parts am I going to have to replace? Same with the cam, I want something that has a rough idle and some lobe to it because right now you can't even hear it, but not to where I won't be able to run my power disc brakes. And if I replace the cam that I've got with something bigger, do I have to replace the lifters, timing chain or anything else? I was thinking of some AFR 185's or 205's and then a comp cam 35-770-8 which is their extreme energy cam that has a rough idle and is a lot more aggressive than the cam that I have now. I wouldn't expect that the shop would purchase both but maybe they could get a good deal on the heads and I could get the cam or something. Any advice would be great, thanks
1965 Shelby GT-350 Clone, 351w Bored .030 over, Trick Flow 185cc CNC Aluminum Cylinder Heads, Edelbrock Air Gap Intake, 650cfm Holley Ultra Double Pumper, 3 Row Aluminum Radiator with Electric Fan, T-5, 4 Wheel Power Disc Brakes, Shelby 1" drop, Maier Racing 620 coil springs, Moog UCA's/LCA's, Maier Racing 4.5 mid eye leaf springs, Bilstein Sport Valved shocks, 9" Ford Rear with 3.50 Trac Lock, 2.5" X-Pipe, 3" Shelby Side Exit Exhaust, 17x7" and 17x8" Foose Wheels
Last edited by MUSTANG65FBK; 01-20-2012 at 02:58 AM.
Reason: Added more info