Ahh, I see you went with the larger primaries, and you will lose torque by doing so. I know they recommend the larger primaries for forced induction, but I wonder what would have been the results have you bought and installed the 1 5/8" version instead.

IMO, I reserve the 1 3/4" primaries for the GT500 5.4L, and power greater than 500 RWHP. The quote below was taken from the S197 forums.

IMO, the 1 3/4" primary is too big for a 281 CI engine. We used a 1 3/4" primary for the LS1 engine, but it's 346 CI...much larger than the 4.6L. The upgrade for us was 1 7/8" primaries.

anyone else have knowledge in what I am talking about here? I really would love to know what difference it would have made. I'm guessing the 1 5/8" primaries wouldn't have sacrificed as much torque.

 

you are right, i should of went with the 1 5/8" headers. now i am chasing to get back what i already had and didn't know it, cause i did it all in one day!!

 

I found a 3.25 6 rib on ebay for $60 about 6 months ago. It bumped me up to 12psi and 500rwhp on a 1st gen whipple.

 

diab! what exhaust are you running? i was at 11 lbs. with stock exhaust and ford tune!!! the addition of kooks headers lowered it to 10 lbs. and i lost low end torque.

 

i just called ford racing and they told me the injectors are 32 lb. and they are from the gt-40!!

 

Talk to the experts and ask them about using a smaller pulley. I've heard that 12 lbs. is the max boost you can run with stock internals, and that's assuming a solid safe tune. You will get your under the curve power back again, and the peak will perk up as well.

 

i am thinking a 3.2 or 3.25 should do it. damn, i am so tired of making the wrong choice on what performance parts. shaftmasters, DS vibration and still have some sort of vibration, umi performance, uca and lca, uca roto/joint was loose 1 full turn and was causing a thunking noice, hurst shifter, 1/4-20 bolts fell out and the shifter just fell apart, my friends did the exact same thing and there much more!!

 

If you are having a problem with your drive shaft, call Shaftmasters asap. They have great customer service and will be glad to help. I know what you mean about buying the wrong part and having issues. That's why I read for weeks before I buy ANY part. I visit multiple forums to get the general consensus everywhere to see if it's a good buy, or I'm throwing my money away.

 

32lb at what delta? Their website lists 39.15psi IIRC. There is no way a Ford GT makes 550hp with the injectors operating at 32lbs. Take the delta up to 54psi and those 32lb injectors are 38lb.

Here's the conversion factors. If I'm reading it correctly the high and low slope correction factor is 1.19 at 54psi.


http://fordracingparts.com/parts/ics/m-9593-mu32.pdf

 

I have stock exhaust from the manifolds to the axle and Flows out back. I also ran almost 11psi with the stock (3.375") pulley.

Agreed. I wouldn't have bumped my boost up if I didn't 100% trust my tuner, and even now I realize I may be running on borrowed time. I keep a reserve fund in case she pops.