305RSlc

Alright, here's the deal. I have very limited knowledge on turbos and power adders in general. I currently have a 305 TBI engine that I am going to replace with either a 355 or 383 sometime soon. Well I know the 305 isn't the greatest thing in the world, but I don't want it to go to waste. I wanna basically kick the crap outta people with it. I remember in the 60's that the 302 was a very powerful engine that could rev to the sky, and I want to accomplish that with the 305 but with a twin turbo setup. I want it to rev easily to 7000rpm, have tons of top end horsepower and a good deal of low end torque. It'll be a daily driven engine so that has to be taken into account as well. My questions are for one is this unreasonable? If not, what kind of turbos should I go with to make power in the 3000-7000rpm range? What kind of cam profile should I run. What psi should I go with? Inductions recommendations(carb or FI?) What kind of rotating assembly would handle the power and rpm? What heads should I used? I want to make around 500-550 RWHP and it'll be mated up to a t56 as long as it holds out and then maybe a turbo400, and of course, a 9" rear with 4:11 gears. I just wanna build my own custom turbo engine, that'll do respectively well on the road, and get me down low in the 10's or high 9's if possible. Any of your advice would be appreciated, just don't bash me too much, trying to learn as much as possible her Thanks in advance!

stevedave454

well i would say if your goal is 500-550 HP i'd get a forged bottom end (does NOT have to be 4340 for that HP goal) with 8.5-8.7 comp ratio, some decent heads (i hear ported heads from an LG4 carbed 305 work wonderfully..according to 83 crossfire ta, and willie) a stock TPI unit, with a 749 ecm (from a sy/ty, it senses boost) and a couple of T4 turbos, should meet your goals, but really on a street motor, with good driveablity a 3000-6000 powerband is much more realistic... on another note the old 302's had a real short stroke and thats why they could rev so high (safely), your 305 has the same stroke as a 350.. lets not let that last comment start a big argument though...

305RSlc

Yeah I was wondering if the short stroke large bore of the 302 made it rev so high. Guess that answers my question. So if I basically got the top end of a Lb9 with a MAF ecm, with a stout bottom end, I'd be set? I still would like to know what type of cam would be best for this application? Thanks for the advice.

83 Crossfire TA

iTrader: (2)

That power band is totally unreasonable unless you want to spend $$$ on rotating assembly parts. The power level is possible with cheap parts if you keep the rpm's down to say 5500-6K tops.

Early '80's 305 heads are OK ported, much better then most of what was made later, but the small chambers will make it very difficult to get low enough compression to run any real boost and a reasonable quench distance. If it was me I'd be looking at some 64 or even 76cc 350 heads to drop the compression some. If you want something seriously trick get a set of vortec heads, slap them on your 305 and go from there. A 305, vortec heads, appropriate cam and a good setup should make your power goal with around 10psi boost and 5500rpm or so.

305RSlc

ok, so I scratched the idea of revving it over 6K. I don't have a lot to spend on a rotating assembly so keeping the rpm down is a must now. Are T4 turbos hard to come by? Could I get them off a certain type of vehicle out of a junkyard? I'm basically wanting to do what Willie did with the 305, only I want to try turbos instead. So vortec heads, some T4's, a pretty good rotating assembly, and a decent cam for the boost should do it? What about ignition, should I upgrade my factory system if or when I drop the motor in? I was gonna go with a 6AL box from MSD and a better coil to begin with, but anything else to help combustion? Thanks for the help.

jon_volk

all you would need for a 305 reving under 6k would be two decent t3's. Unless you use some farily small exhuast a/r's on the t4 i would think a pair would be kind of laggy on a 305.

conman962

im wanting to do the samthing with my 305 but mines a tpi and i was goin to go with garretson turbos off the turbo diseals would that work?

305RSlc

I was just gonna get some T3's and do a T304E upgrade to them.