i have a 1994 pontiac firebird formula, V8 lt-1 engine with a supercharger, headers and exhaust. runs the 1/4 mile in 13.5. i have been told my several people that i should be in the 12 second range, do you think the supercharger is hooked up wrong? could it be the stock wheels, suspension or computer? any suggestions comments?

powerdyne supercharger with 6 psi boost, stock gears, no the pcm hasnt been tuned, it does have a FMU, edlebrock shorty headers, high flow cat- exhaust, not alot of traction on the launch

corvette tranny

 

60ft times are huge at the end. If your sucking wind out of the hole, your losing a lot at the end. What kind of 60ft's do you get? You should also get a tune too. Your probably leaving some on the table without one. Is it an auto or 6spd car? I would guess with a 60ft improvement and a good tune, high 12's would be pretty easy.

Ken R.

 

it is an auto, im getting approx 2.2 60 foot times mph is 103

 

What's your MPH ??

I had Edelbrock headers, borla exhaust, and a procharger @ 7PSI and ran 12.6 @ 118MPH on stock tires, stock gears, 6-speed though ..

--Sean

 

mph 103

 

Do you have a boost gauge? Are you showing boost at higher RPMs? If so, how much?

How many miles do you have on your car? Fuel pressure gauge? What's that show?

What plugs are in it? How long has it been since those have been changed? Wires? Optispark?

Are you at some really high altitude?

Tell us as much as you can so we can try and help solve the problem..

I ran faster MPH than that without the blower ..

 

no boost gauge 77,000 miles no fuel pressure gauge, stock plugs are in it nothing new, im in new york, a camaro ran faster with a cold air, headers and exhaust.
somthing is not working correctly im on all orts of forums to try and find out why. dyno tuning seems to be the number 1 problem

 

Dyno tuning is not your biggest problem. Look at my post above, those were all my mods.

Get yourself a boost gauge and see if you have boost, how do you know that you have 6PSI if you don't have a gauge telling you that? How do you know that you have enough fuel pressure and your FMU is working correctly.

It is very hard to diagnose problems when you don't have the tools to do so.

 

Sean is right. You need those two references to start with. The powerdyne uses a internal belt drive. That could be broken and therefore no boost. The fuel pump might be unable to deliver enough fuel at WOT.

 

how do i get a boost gauge? how do i check the FMU??? the car did run faster when i added just the supercharger. but you guys have good points . im just trying to find out the problem.
i guess i need a boost gauge let me know where to get one. also how do i check the FMU???
thanks ed

 

sheeesh, someone's in over their head ....

 

our cars are alike what times do you run?? do you have any problesm like i have? let me know ed

 

ok, sorry to be a wiseass but I was really shocked to hear those questions. You can find nice autometer boost gauges in a Summit or Jegs catalogue, get one of the low reading versions for the boost so it will be easier to read and not have a lot of wasted needle sweep area. The fuel pressure gauge is even more important. Without the fuel pressure gauge, a Scanmaster, or logging software, you cannot know you're getting enough pressure while driving. Honestly even a Scanmaster or logging software won't tell you this, but you could at least know you're not going lean by observing your O2 voltage. The FMU that comes in the PD kit is an 8:1 if I'm not mistaken (I don't use mine anymore, I use larger injectors and LT1 Edit), which means for every 1 PSI of boost you should see an additional 8 PSI fuel pressure. With the 6 PSI kit you should see around 80 PSI fuel pressure, this is how you will know your FMU is working properly. If the diaphram fails in the FMU or there is a loose vacuum connection you won't see full fuel pressure and could go lean, causing detonation and subsequent cracking of ring lands ...you don't want that. Some risk not knowing their vitals, but I wouldn't dare to....it's too critical for a supercharged application, especially on an engine that's not optimally designed (high C.R. ... and loose quench) for it.

My guess is your internal belt is broken and you're not getting any boost. Either that, or you're going really lean and detonating, causing massive amounts of knock retard which is killing power via reduced ignition timing. DO NOT proceed to drive it at high throttle % anymore until you find out what's going on with the fuel.

 

cool, im trying to learn as i go, i called the place i bought my powerdne and they told me it is only a entry level supercharger it wont give me a ton of power like i want, is this true? did i make a mistake in buying?
thanks ed

 

6psi should put you at a lot higher trap than 103. Stock cars regularly break that. You difinately have some issue. I am going with faulty S/C belt as well. I think if you were going lean enough to get THAT MUCH retard, you would clearly be able to hear the pinging.