i have a 85 trans am with the LB9 paired with a 700-r4. I am having a rough time deciding what to do with it at this point. The car runs 15.0 @ 91.5 (last year), and of coarse i want more performance. I ran desktop dyno and the program says that if i through on a set of World torquer 305's, headers, and a mild cam, i can pull 290hp at the fly. my other option is swapping out my engine for a 350. I found a LT1 for sale very cheap, but i know that the swap is going to take a while and be very hard. Do you guys think those numbers on desktop dyno are correct? because if they are i would be getting better than LT1 performance (i thought they were rated at 275hp) out of a 305. I always thought there's no replacement for displacement, but i could be wrong.
thanks

 

If you think LT1s put out 275, that must be at the rear wheels, so that would be more than your 290 at the flywheel by about 50. Im guessing on the math there. Why not put a more than mild cam in? If you get the LT1, remember that you need all of the electronics as well.

There is replacement for displacement, see that movie the fast and the furious?

 

The LT1 swap would not be woth the time/money IMO. 275hp at the rear's "if thats what it is I dunno" loosely translates into 325 hp at the flywheel. Considering the cost of the engine itself+wires,ecm, that junk & the time to install it would be wise to get a zz4 crate or if you like cheaper retailers of reccon sell HO 300hp engines thats the figure with stock acss and thier only 1200$. "I will not use a reccon but you might"
I dunno, just not worth the LT1 pain factor to me.
SSC

 

To be different I would do one of the following:

Build the 305 with a RHS 334 Stroker kit and get a nice 270HP they claim or;

Build a small block 400.... I would skip the whole 350 thing cause everyone has a 350, but how many 400's 383's, or 334's do you see at the strip?

 

You only talk about h.p. numbers but you don`t mention torque.Even if you built a
305 with the same h.p. as a 350 it would
probably be at a higher r.p.m. and would
make about 40-50 less ft/lbs of torque.
I agree with Brian k. a mild 406 will
still make 350-375hp. at a reasonable r.p.m.
and make tons of torque.This means you can
use stock torque converter and stock rear
gears with no trouble.

 

In my club that runs at Bandimere:

400's: 2 in early El Caminos. One runs mid-15's, the other mid-16's (neither should admit they're 400's, in my opinion).

383's: 1 in '57 Nomad, runs 13.10's almost every week, 1st in current Club Clash standings. Another in '36 Chevy Pickup, roots on top, smooth idle, runs 13.40's, 1st place in ET Series; uses it to haul trash from his shop during the week.

334's: No known. It will take as much to build a 334 with your 305 block as building a 383 even having to buy a 350 block - why bother?

Other displacements: A few 305's (all slow), some 350's (some respectable), three 396's (high 14's to low-15's), several 454-502's (low 15's to low 11's).

Apply the .9276 correction factor for 5800' Bandimere to compare to your sea level times.


P.S.: Only a couple of these are 3rd gens.

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

Not to flame or anything But usualy I see 396's & 402's spanking the crap out of 454's and 502's.
SSC

 

When I ran desktop dyno torque rating was around 350 ft/lbs peak with the 305. Like i said it was with heads, headers, and cam. 290hp, 350ft/lbs from a 305? I think the program is somewhat accurate, because they said i have somewhere around 200hp, 275ft/lbs now. i think thats pretty close to stock ratings for the LB9. So ya think i should build the 305? I didnt really want to tear open the bottom end unless i had to so i wouldnt want to use a stroker kit.
peace

 

The 396's are in 3800-4000 lb street driven cars, while the 454/502's are race-prepped trailer queens.

 

85, what paramaters are you using for DeskTop Dyno? I've used 9.5:1, low heads, TPI intake, stock manifolds, what I beleave is the correct "peanut cam" specs, and I too get about 200 hp at 4000 rpm, but my torque levels are like 330 @ 2000 rpm. I too wish to simulate more accurate data.
I tried the setup of 305 torquer heads, small tube headers, a compucam 2030, and it shows 300hp @ 5500 rpm. I like that combo.

------------------
Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.

 

85TransamTPI

It all depends on how fast you want to go. Remember that you always want more. In addition to your heads, cam and headers I would go for a set of 1.6 rockers, port and gasket match the heads and intake setup and rig up some king of ram air set-up if you can.

Again, it all depends on how fast you want to go.

 

the 305 will never have as much max power as a 350. I;d say go for the 350, and you could always stroke it 383 later for some massive power.