Originally Posted by Outlaw47

If you get it all done, 8-10psi of boost is do able with a GOOD DYNO tune...no mail order tunes or any of that other stuff, its not something to skimp on.

You will also need 42lb. injectors, bigger MAF and a bigger fuel pump as well.

Originally Posted by Outlaw47

42's can be found on lightnings and 03-04 cobras

It will not run at all once you put the 42's in and the bigger MAF, it would just foul the plugs since it would be severely rich. Most cars ive helped dyno wont even start until you re-program all of the air/fuel charts in the computer.

Originally Posted by White_Thunder

10 works, 8 is probably safest number worth running.

39lb are on cobra 42lb are on lightning.. either will work.

255lph fuel pump. 90mm maf

Originally Posted by TechMike

Fuel - 42# injectors and 255 lph fuel pump.
Plumbing - Air intake to turbo cool side. Exhaust to Turbo hot side.
Tune - Get one close - Main order from VMP. Enough to drive onto a trailer.

Boost - 8 - 10# max on stock internals. Closer to 8 the higher the mileage.

GET A DYNO TUNE!

Originally Posted by 6Pack1999

if you want to run low boost yea... if your gonna run 8- 10 you need 39-42# injectors plus upgrade the fuel pump... perty sure

Originally Posted by CHADD

psi on the engine is all depending on type of tune you have.

You can run up to 8psi with a FMU as long as you dont race it.

10psi can be ran on a good dynotune.

More boost you run on the engine, then more fuel you will need, but ignition and heat plays a big part also.

Ideally you would want to run 6-8psi on stock engine with a good dynotune, and not a mail order tune. anything higher could remove the reliability of it.

The more hp you make on an engine not designed for it, the unreliable it will be.

Originally Posted by Outlaw47

CHADD pretty much nailed it right there.

You can always go by more boost = more heat...too much heat = detonation = BOOM!! To break it down into simpler terms

I'm still running an FMU with stock injectors and MAF which is why im only runnin 4psi because that is the most you can run with a completely stock engine and fuel system. My A/F is right on the money but everything is flowing at their max rate.

Originally Posted by b2therad

Dude... wtf. I just took the time to explain to you that the "stock fuel system" can do what ever the **** it wants. It has nothing to do with making boost. Boost is a measurement of the mass of air being forced into your intake. You can run 648 PSI on the stock fuel system if you wanted to.. but it wont be able to keep up with the fuel air ration.And besides.. after he has spent 5k on this sick turbo or s/c set-up then who really cares about getting new injectors or a different fuel pump. All that stuff is minuscule comparatively to the work, parts, and prices involved in a custom set-up, which is exactly what any kind of FI would be on a 4.2. And just because he has a 4.2 doesn't mean he cant make good horsepower or torque. Who told you that you can only run 4PSI anyways?

Originally Posted by Raptor05121

guys, lets not forget that making a truck fast isnt all about power. you also have to have more stopping power, more traction, lower the CG (hopefully) for a more stable ride at higher speeds and also cuts down on air resistance. it gets expensive after a while