Asylum839

How much boost can the stock supercharger and engine handle before I start running into problems? On an 03 cobra

freewilly

upwards of 16psi, but you got to get it tuned by a tuner. i got 15 psi with ported eaton, thats with a 3.00 upper and a 9.00 lower. before with port and the 2.75 upper pulley and the stock 7.50 lower crank pulley i was getting 13.5psi boost. thats good at first, then you want more. im sticking at 15psi .anymore you'll be pumping heat into your motor. my car now breaks tries at will just by stabbing the gas.which i must cure.

GTPGuy

Question about dropping pulley size (sorry for the off topic)

I know in my car there was a lot of mods I needed to do to stay away from knock Retard. Same thing for this model cobra or can you drop with a exhaust mods only?

freewilly

you got a gto? you can do just exhast without a retune,i did on my 99 cobra.ran good almost beat a big bad vette. he had 335 rwhp to my 291rwhp.[:@] now i got a 03 cobra ,where's he at now?

GTPGuy

No, I have a grand prix GTP. Two years from now I'm planning on buying either an 06 GTO or an 04 Cobra. I think if I do go with the GTO, I'll miss the supercharger; that's why I'm leaning toward the Cobra at this point.

03InDisguise

I agree with free *****, anything over 15 psi, and you'll be pumping heat into your engine. Personally, i would stick to around 13-14 just to be safe. Heat=ineffiancy (sry bout spelling =P)

freewilly

well i got back from dyno testing . im running 20psi boost now it drops off to 17 psiat the higher end ,but make 60ft tq more at 3500 rpms 576 compared to 511. it was good for another 30 hp too.

AllVenom

I see about 17-19lbs with a 2.93/6lb lower and ported Eaton. It does drop boost but only down to about 14 and that's after about 4500-5000 RPM. The torque is through the roof too. The difference in boost for me is weather related, here in NC the humidity sucks the life out of the Eaton worse than a ho downtown.

freewilly

now i need another hilton over lay for boost gauge the one i got goes to 16 psi. they make a 24 or a 26 psi one too.

CobraBob

I'll assume you're talking about a street setup for daily driving, with an occasional trip to the track. Take my advise and don't go over 14-15 lbs. of boost with an unported Eaton. 16-17 lbs. with a ported Eaton. Over that and you're seriously overspinning the blower and producing a lot more heat. Heat is a killer with these motors. Even a safe tune isn't going to help eliminate the heat related issues. It will hopefully prevent detonation, though. Give Bob Stiegemeier a call at Stiegemeier Porting and he'll fill you in. He has been porting these blowers since 2003. As a matter of fact, I was one of his earliest customers. The blower is not rated at 14,000 RPMs for reliability reasons, but for efficiency (the blower heats the intake too much at higher RPMs). Which is porting the blower raises the efficiency of the blower, allowing for a couple of addtional pounds of boost.

If you want to see the relationship of boost to blower rpms, take a look at the Boost Chart on my FAQ page. http://stangshiftergaskets.com/2003_...m#_Toc35092360