thethirdeye88
Well-Known LVC Member
I don't think you'll get as much as you might expect... unless going very radical. I assume you want to stay with pump fuel, so with a small displacement NA V8, you are very limited.
P&P the heads... might get you 30HP if you're lucky... another 20 for the cams; again, if you're lucky. Bump to 11.5 compression (anything higher and you're talking 104 octane)... maybe another 25-30 HP. Exhaust work, 20 HP, intake... 15HP. Tune, another 15. Lets see that's 130 HP over your stock 252... giving you a whooping 387-ish HP at the crank (at best). And this will cost you an easy $10-$15K to have everything done you're talking about.
Reworked heads: $1000-$1500
4 Custom ground cams: $1000-$1500
8 Custom pistons: $1500
8 Billet Rods: $2500
See, you're already at $6000 minimum and you've not even touched labor for building-installing the engine, the billet crank, tranny work, tuning, fuel injectors/pump/lines, rear end work...
You see why Forced Induction is such an attractive route to take with these engines? Ask CammerFE... he's doing exactly what you want to do right now, but with the 4.0L Jag engine (and set-up for turbo). And he's got connections to get this stuff done at a lighter cost.
Look at it this way; street-able HP/cu inch from NA is at best 1.5:1. That means an engine with a 300 cubic inch displacement will generally give you around 450 street-able HP in naturally aspirated form; try for anything above that and you'll be dealing with a severe idle, horrible lower end power and a thirst for high octane race fuel.
The 3.9L is about what, 238ci? That comes to 357HP making 1.5:1 HP/CU IN.
Sorry man, but I think you're barking up the wrong tree on this one; small displacement isn't where you look when you want to build naturally aspirated and get big numbers (at least not for the street). It would be different if you were talking about an engine that has these parts available; Dollar/HP wouldn't be nearly as bad. But in the end, it is your money.
roughly with that in mind what would be the turnout over stock?...