Been thinking about this for a while. I remember reading on the forums that using a 5.7 head will increase RPMs a bit and also reading because of the larger camber compression ratio would also drop a bit. I know the limitations of the 305 but isn't lower compression and a increase in RPM good a thing for a turbo? I know the cars limit is around 400ft-tq plus 6000rpms before things start to break and proper replacement parts start costing a bit.

I have a 5.7 I was going swap out to but I want to give it a nice and proper rebuild before it gets a turbo. Just since I was going to buy Vortec/L98 heads for it anyway why not try them out on a 305 and drop a turbo as well. All the upgrades are interchangeable between the blocks. Boost is also a universal love so much wouldn't change between the 305 and 350.

So question is will a L98/Vortec head on a mild 305(headers, exhaust, plus appropriate cam, and FI) work as well as I think it will? Or would the compression drop to much and RPMs be negligible. I don't plan on blowing anyone's doors off if anything I would be blowing parts up before that. I just wanna show a couple friends that with the proper mods my 305 will wipe the floor with his Turbo lancer. Always saying you have double the displacement and cylinders yet I can't beat it. Even tho I try to explain that the LO3 wasn't made to perform.

 

Vortec head is alot better than stock L98 head. 083 L98 head wont give you much in performance on the 305 over the stock 081 LB9 heads. Both are similar just different valve size and chambers. If its 193 swirl port tbi heads then there is minor performance gains to be had. You dont need extra swirl in the port of a forced induction motor

But goin to larger chamber would make it more boost friendly for high boost. But stock compression ratio with mild cam is more than safe with an intercooled low boost setup. It will easily make 400 crank hp with 10-12psi

Ditch tbi and get a good port injection or blow thru carb on it

 

Ooh boy, here goes.

Different cylinder heads will not effect capable RPM range or power band because of a larger chamber. Using a larger cylinder head will lower the compression ratio making it safe for a boosted application. Old school guys will tell you around 8.5:1 is ideal, but you can get away with in the 9:1 even 9.5:1 with tuning. RPM range is only as good as your valve train is. a stock bottom end probably shouldnt spin faster than 6K if you want to keep it together

2)Im not sure if you can swap vortec's on, it wouldnt suprise me if you could seeing they have the smaller valves. The only concern i would have is different compression ratio for one, and two, if you launch the short block, it will likely destroy the head. On a plus size, Vortec's are really cheap and any valve train mods can be swapped over (assuming your not swapping valves) Though boost is "boost", a turbocharged 5.7 will not create the same amount of boost a 5.0 will

Proper valve train, a cam and tuning will get you to where you need to be. I would not let .7 liters effect your plan. I know someone whos running a procharged 305 on meth making 380rwhp and well over 400 ftlbs.

 

Hehe, this kind of thinking really takes me back. Don't think you're automatically going to wipe the floor with the Lancer, especially if it is built. There is more to RPM than you think, so get the traditional thinking out of your system, and fast. RPM, gear and tire size dictates your speed, weight and horsepower dictates how long it takes to get there. Traction wins races. If the Lancer can rev higher, it potentially can be faster, but horsepower and weight dictates how fast it will get there, so if your friend knows what he is doing, you may very well lose, especially if he has AWD. You have a long road ahead of you...

These guys street race by me, an oldie but goodie matchup, enjoy...