Ford Mustang Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
9,175 Posts
Discussion Starter #1
I have a 94 cobra with a stock low mile hyperutectic piston shortblock. I want to do all of the bolt-on stuff like afr 165's, E-303 etc. I have already installed the Pro-m PIH kit and A9L computer. I also put a crane HI6-TRC with timing retard. I want to get a powerdyne supercharger but am having a hard time deciding on the #6 or 9#. I've seen posts of guys with the free flowing alum. heads/cams etc. say they are seeing #4lbs with the #6 kit and approx. #6lbs with the 9# kit. Even the #9 kit seems fairly safe if #6lbs. is what I would net. I'm not building a race car, but want it to run strong. At the same time though, I don't want to break my pistons. What would you recommend? Thanks
 

·
US Navy Active Duty
Joined
·
652 Posts
Though I don't have a Cobra, our mods are very similar with my Cobra intake, GT-40Y heads, etc. I mentione this because I'm sure your car would be able to make very similar hp numbers to my car when I had my old Powerdyne. What I did to get a bit more boost out of the 6lb BD-11A was add a larger crank pulley (not sure what size the stock Cobra one is) and a powerpipe. Before those mods, I saw about 4.5-5psi with 6lbs of boost. After those two mods, I saw a solid 8-9psi. I mainly did this to keep the 2 year warranty and make a bit more boost without overspinning the blower (the internal belt thing). Anyway, I dynoed a best of 400.3rwhp/386.6 rwtq with my old set-up, not mind boggling but good power for a street car. Though I was unable to track the car in that condition, it ran good, even during the hot summer months of Virginia.

Just my .02. Good luck.
 

·
Registered
Joined
·
9,175 Posts
Discussion Starter #3
95 GTS, I think they told me that the #6 & #9 have the 2 year warranty as long as you don't remove the pulley that comes with it. Have you ever figured how high you are spinning the blower with the #6 pulley and 7" crank compared to the #9 pulley and stock crank. Most of the posts with 9# powerdynes are showing approx. #6 at the intake. So I assume maybe you are spinning it a little higher than the stock #9 setup. Are you still using your stock 95 shortblock? Do you use boost retard? I think your horsepower figures are impressive. 400 rwhp sounds awesome to me. Thanks
 

·
US Navy Active Duty
Joined
·
652 Posts
I believe the formula for determining how high you are spinning the blower is:
crank pulley diameter/sc pulley diameter x blower internal ratio (3.05 for BD-11) x engine rpm

So when I had that blower I was spinning it about 41,057rpm at 6000rpm. The rpm limit of the BD-11 is 42,000rpm so I wasn't overspinning the blower. So if you had just the 9lb pulley, you would be spinning the blower at about 40,597 assuming your stock crank pulley is 6.5". As far as my experience with the larger crank pulley goes, it didn't give me a whole lot more peak horsepower or torque, but the low to mid range gains were impressive.

I'm not using a boost retard because supposedly my chip handles that for me. Still using the stock block and going through tuning problems with my new set-up.

By the way, CurtC on this site, made 361rwhp/362rwtq on his 95 Cobra with a 6lb Powerdyne, complete exhaust, maf, and chip. The rest of his Cobra was stock. On top of the horror stories concerning the Powerdyne's reliability, I had heard they couldn't make power. After reading about Curt's car I went for it and made 381rwhp/367rwtq on 6lbs of boost and ran a horrible, miserable [email protected] on street tires.
 

·
Registered
Joined
·
746 Posts
I saw 7lbs. with the 6lb. pulley with a stock engivne except for 73mm MAF and full exhaust. That was at 6000rpm. Since you already have a timing retard, I would buy the 6lb kit since it's alot cheaper, and if you want more change the pullies. You can make your own bypass valve with a little homework. Make sure you add a bigger fuel pump.
 

·
Registered
Joined
·
9,175 Posts
Discussion Starter #6
DewyR. I talked to powerdyne and they said that if I wanted the 6# kit they would add the bypass kit to it. I already have a 190lph in-tank and T-rex external. I also have boost retard so if I were to change to the #9 pulley in the future, I'd be all set. I just kinda feel that the #6 would be plenty of power and a little safer for the internal belt and my hyper pistons. Thanks
 
1 - 6 of 6 Posts
Top