I'm throwing this out as a Friday discussion thread. Believe me when I say I've searched and read daily for months the debates on one engine over the other. This is more intended to clarify some things in my head and work through a bit of theory.

Everything I've read (with few exceptions) and logic tells me a 350 should always be used over a 305.

However, let me throw some thoughts out and pick your brain.

First, the car is intended as a weekend warrior third car that I'd like to be able to drive anywhere (a.k.a. reliable). It currently has a 305 in it (carbed). My thoughts are:

- built lower end w/forged pistons
- 9:1 compression to keep some throttle response down low
- 113 casting heads
- TPI intake with siamesed intake (already have the intake)
- single turbo (I'll look through the maps to determine size - probably a PT70)
- 700r4 trans
- 3.23 gears

I know the 305 has the limitation of shrouded valves, but I'm fairly comfortable with the turbo working through that limitation. I've been dealing with shrouded valves for a long time (4.6 Ford).

My rationale for using a 305 is:
- lower cubes generally = better mileage
- the TPI intake and 113 heads won't be as much a restriction on the 305
- not as much parts-breaking torque from a 305

Why limit myself with the intake and heads you may ask? First, I already have the intake, so that's a plus. Second, I'm doing this on somewhat of a budget. The intent is to not break the bank while building this. The overall goal for the car is very low 12s or high 11s on drag radials. The suspension will be focused on straight line performance vs corners, so that's not really an issue.

So, what say ye?

 

Not much of a conversation piece, I see. It must be too played out.

At any rate it's OBE, because I picked up a 4-bolt 350 from my brother-in-law.

 

You could still run the 113 aluminum heads on the 350. If its a weekend warrior you might just want a built turbo 350 tranny. Cheaper to build. Higher gears would be good.
**Edit**
Didn't see you wanted to drive it anywhere and still run 11's. Better keep the 700r4 then for milage, but at least step up to 3.73 gears(unless you have the 3.23s for now). You stock TPI base is going to hold you back. I would hold off on a turbo and get a better aftermarket intake setup with a 150 shot of NOS to go with it.

 

The 113 heads work great on the 350's with some porting, so you can totally use those heads on either size motor. I also have to agree that NOS would be a wayyyy cheaper route to running 12's than going with a turbo. If you're doing this build on a budget, forget about the turbo. You're talking major amounts of money to set up your car properly for a turbo. Also, the 3.23's wouldn't be near as much of a hinderance with the 350 because of the increase in torque over a 305, so you wouldn't necessarily have to run 3.73's with the 350. Just my .02.