305 out of a 81 chevy van.
How much horsepower and torque would I be making?

First time porting job on my 305 heads. Edelbrock eps dual plane intake maniflod.Hedman Shorty Headers to true duals minus the catyletic converters. Summit 224/224 with .465in. and ex. lift Cam.
Competition Cams valve springs to match cam.

 

305 out of an 81' van..maybe 140 horse stock?? maybe.....Porting heads...10-15 horse?? intake manifold another 10 horse..headers..10 horse..cam and what not...15-20? sooo let's add stuffup here. We will say 140 on the high side 10+10+10+15= 140 stock + 45= 185 horse. Now thats just a guess but i would say anywhere between 170 for a low and 185 for a high. Goodluck in your buildup 82..

 

You don't make Horsepower by addition of parts installed on a engine.

 

Wow, those numbers are disapointing. DD2000 said 283hp at 5500rpm's and 309 tq at 4000rpm's. I figured take around 25 off of each of those numbers. So was figuring 255hp and 285tq. Anyone ales have an idea what this setup would make?

 

What exactly are you saying? Swapping out stock for better aftermarket parts will yield some increase in power.

 

Yes changing stock parts will increase Horsepowere. However; just because the Mfg says this part will add 10 HP and another part 20 HP does not mean you gain the total of the two.

 

IIRC that was one of those legendary 305s with the 1.72" intake valves and about 8:1 compression. I seriously doubt it even made 140 HP.

If you want power, look elsewhere. It is a big downgrade to your car: If you think it's gutless now, you'll get a new appreciation for just how gutless a V8 can be, with that motor.

Instead, I'd suggest rebuilding your existing 305, or get a 350, if the short block needs work. It costs so little to get a 350 core, and the difference in the results is so huge, that it makes no sense to spend money on boring, pistons, rings, etc. for a 305 short block, except under specific circumstances, which if you're willing to put one of those old pig motors in your car, don't apply in your case.

If you 305 short block is in good shape, i.e. holds oil pressure and the oil looks OK, don't rebuild it at all. Put a new rear main seal in it carefully, port the existing heads yourself and maybe put larger intake valves in them (they're far better heads than the van ones), put in some other cam besides that one in it because it's way too much for the rest of the setup (I'd suggest a Comp XE256) with new valve springs and reatiners and timing chain, get chassis-specific headers for some other motor than a LG4 such as a 350 TPI with Y-pipe and exhaust to match, skip the true duals as they are very very difficult to get to fit on one of these cars without creating ground clearance or other issues and offer zero performance improvement on a small motor like that, and get a set of 3.42 gears into the rear end. Forget the intake, it's not what's limiting your car's performance right now.

 

You''d be making about 270 horse and about 310 torque with the cam and stuff. My 9:1 350 has a Comp cam with 218/224 headers, exhaust etc. and it makes around 300 hp and 375 lbs torque.

In a SpeedPro catalogue I saw:

350 ci
8.5 compression
1.94 1.5 heads
214/224 @ .050 cam
301 hp
375 lbs torque

 

Pontiacman
How did you arrive at the numbers in your post???

 

I am going by what the quy with the desk top dyno said. I am making more according to one book that I basically followed with a little bit more to my advantage. Becuase you are a 305 and not a 350 it will make a difference.

 

I'll still be happy with those numbers for having a 305.

 

Not a reliable method or accurate way to finalize Horsepower/Torque. However: you can tell people whatever you think it IS.:lala: :lala:

 

There are so many variences though. I doubt with the van 305 you would see even 200 HP, and that's after nearly $2,000 into it, because dual exhaust is expensive. WHat motor do you currently have in your car? What year is it? How many miles? You're best bang for the buck is start building up a 350 and drive your car until the motor is done, then swap it out. Flat out, more cubes = more power potential. With the cast pistons, and weak power numbers to begin with the van 305 shouldn't be an option. Go to a junk yard and you can find running 350's for like $400. Or 350 blocks for $100. (at least I did.)