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Discussion Starter #1
I am building a 94 cobra which will be used mostly for shows and street driving. We want to do 165 AFR's/ E-303 for a nasty idle and put a powerdyne ( with FRPP label on it so it looks a little more "Fordish". My question is that i hear about powerdyne belts braking if spun too high. Option #1: 165's with the 61cc ( which gives 9.3-1 comp) chambers and a #9 lb pulley or #2 165's with the 58cc chambers ( which gives 9.6-1) with the #6lb pulley. I just wondered if I ran a little more compression the motor would be a little stronger before getting into boost and then I wouldn't have the make as much boost and spin the blower as fast. Most guys with heads and cam say they are only seeing #4lbs with the#6 pulley and 6# with the 9# pulley. Which way would be best. I have to be careful because I am running a stock shortblock 94 with hyper pistons. Don't want a meltdown. What do you recommend?
 

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Option #1 with a good (safe) tune.

When adding compression/boost....you will always make more power adding boost rather than compression.
 

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Discussion Starter #3
Do you think if I run the 9# pulley and end up seeing approx. #6 in the intake, that I will be O.K. with hyper pistons? I have just installed a Crane HI6-TRC with boost retard ignition. I also have the 190 lph in-tank pump and T-rex external. If you net #6 at the intake, would you need much timing pulled out? Powerdyne told me in the past if you put their #6 kit on a stock 5.0 you will see #6 at the intake and say to set your initial timing at 10 degrees and no retard is necessary. Is a free breathing 5.0 with a 9# pulley netting #6 the same as a stock 5.0 with the #6 pulley netting #6. Is one more likely to detonate than the other. I assume the aluminum heads that situation a little. Thanks
 

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What I would personally do, is to set the motor up with the lower compression and the 9 lb. pulley on it. I would be very conservative on the tune and would make sure not to go WOT until you were on the dyno with a wideband. The fuel system sounds like it will keep up as long as you have an adjustable FPR so that you could make fuel pressure adjustments. You already have the Crane ignition which is a good thing. What injectors and Mass Air are you going to be running? I would probably suggest some 42 lb. injectors (without an FMU) & a 80mm Mass Air if you don't already have them bought.

What kind of intake are you going to be running? If you were to have a free flowing intake and heads (which the AFR's are), I doubt you will see any more than 6 lbs. of boost with the 9lb. pulley.

I wouldn't worry about the hyper pistons too much as long as you have a good tune!! Make sure that when you get the combo together that you run 91-93 octane (the best out-of-the-pump gas you can get in your area) and that you resist the urge to abuse the car until after you get it dialed in on the dyno.
 

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Discussion Starter #5
My intake is a GT-40 tubualr upper and Fox-Lake fully ported lower. 65mm FRPP TB, 75MM mass air, (30# inj.w/6-1 FMU) FRPP shorties, Kirban FR. The only difference between the #6 unit and #9 unit is the pulley on the blower itself. Would I be smarter to get the #6 and then add the #9 pulley in the future if it doesn't make enough power to keep me happy? ( TOO MUCH POWER IS JUST RIGHT!) Thanks
 
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