Just doing some thinking ahead. Sure a carbed 351+ stroker would be fun, but with the price of gas, we all know mileage is a slight concern especially for a 95% street, 5% track car. I'm thinking of possibly doing a stock engine + turbo setup possibly(if I buy a certain 5.0 I'm looking at). Correct me if I'm wrong, but around town, easy on the gas, it would still get 15ish+ mpg, right? I use to beat the piss out my my stock engine + S-Trim, and filled up about every 220 miles. If I pumped 14 gallons(probably less in real life) thats almost 16mpg. I was never driving that car easy either. My 3 mile drive to work saw 8psi and triple digits most days.

So, as to mileage, I think the fuel system would be a big aspect. With my S-Trim combo I was running 36s, no FMU, and no tune. It ran great. Everyone is quick to say, "just get 42s!" I know my 36s held up to 8psi, and pushed my little notch to an 11.9 without and headgasket problems. Would 36s be able keep up with 10, maybe 12 psi from a turbo? Would 24s with a FMU get better mileage over 42s?

 

Mileage depends on the tune not the injector size. Shitty tune=shitty mileage.

 

ditto.... and HOW you drive lol

 

Like they said only on your question above...It's not about boost it's about HP and efficiency. I don't know what a stock 5.0 would crank out at 10-12 psi. But you need to start reading and forming an opinion on HP. Many people use .55 Lbs fuel/hr per FWHP as a rule of thumb for fuel usage on blown engines. Most don't want to run their injectors at over 90% of max. So your 36'rs X 8 X 90% =259 lbs/hr of fuel. Divided by .55 Lbs fuel/hr per FWHP is 259/.55 is about 470 at the flywheel. That aint bad but the 42's would equate to more like 550 FWHP. I've seen people post much higher #'s than that on 42's, but that brings your stock block strength into question.......

 

I fubarred my bottom end with 36 lb injectors and 13 psi boost, so don't try to duplicate the same stunt. I thought I could make up for it with more base fuel pressure and race gas, but 3 ring lands let loose in one race weekend. Running a set of 42s with a proper tune should make your fuel consumption no better or worse than, say, a 2003 Cobra (given similar gears, weight, etc.).

Mark