fireyautocrash

Everone has their own style, ive always wanted to get a 3rd gen 305 carbed car and use it as a super budget race car... The idea involves a cheapy turbo setup and lots of weight reduction. When the motor blows buy another on ebay for 100 bucks and start over again. The smaller bore should have better detonation resistance and a set of 76cc 350 heads should drop the compression low enough to have a margin for error in the tuning department... Hp is a compressive load, rpm's are what destroy stock bottom ends (mostly rod bolt weaknesses) Theroetically you could make 4-500 rwhp below 5,600 rpm with a properly sized hot side (at over 20psi!). Lots of people would ask why buid such a thing, the answer is because its fun... Theres no real investment so i wouldent be afraid to beat on it (be courteous though, wear an engine diaper at the track).

As far as a normally asspirated 305 goes budget should be the name of the game. Stock home ported heads, used lt1 and l98 cams are not a waste of time in my opinion. No matter what you build someone out there is faster. Why not spice up a 305? If your goals pass what the stock 305 bottom end can handle a 350 would me a much more economical choice to build.

Zepher

L98 cam comes in some of the 89-92 LB9 305's already, the ones with 230hp.

I converted my 86 Trans Am LG4 305 into an LB9 Tuned Port motor (top end swap and a semi-large cam).
this is how it sounded,
http://youtube.com/watch?v=nGTLJ9nS2aI

and literally smoking a 72 Chevelle on the highway,
http://youtube.com/watch?v=iJ8DqoSvQ9E

briggsbuilder

Iam in the hospital for a day, and this is what the thread turns into??????
You guys

spice up a 305, have fun with it..... blow it up with nitrous and then drop in a 350,383 or even a big block .........WAT EVER FLOATS UR BOAT.......

ws6transam

One thing to consider is that the bottom-end of a 305 is essentially the same as a 350. They both have the same crankshaft stroke, they both use the same connecting rod, and they both use the same size main bearings. The crank throws are balanced differently due to piston mass. If you wanted to make a turbo 305 and make it last, the cast 305 crank is probably strong enough to make 500 HP+, based on the fact that there are cast stock 350 crankshafts out there living happily under those kinds of conditions. A turbo 305 would need a better piston than the cast aluminum ones you find in a stock 305. I'd suggest that a 305, with nice forged pistons, and a good set of ARP fasteners on the rods and mains would most likely handle hundreds of horsepower's worth of nitrous or boost. You can now go back to the debate of how to get air into and out of that small bore.

Kevin91Z

L98 cams come in all 90-92 305 TPI engines. They only come in '89 TPI 305's with the dual cats and 5-speeds.

rik89gta

Yes, between 90-92 the 305 5 speed cars all came equiped with the L98 camshaft. However the 305 A4 combo came with the peanut camshaft.

Kevin91Z

No, the 305 TPI automatics from 90-92 also came with the better L98 camshaft. There are no peanut camshafts in any 90-92 TPI engines.

rik89gta

Yr Model Trans Engine
code/type CR Displ. HP Torque Induc-
tion Manual
std. Manual
opt.
(G92) Auto
std. Auto
opt.
(G92


91 RS M5,A4 LH0 V6 8.5:1 3.1 (191) 140@4400 185@3600 MFI 3.42 ---- 3.23 ----
91 RS M5,A4 LO3 V8 9.3:1 5.0 (305) 170@4000 255@2400 TBI 3.08 ---- 2.73 ----
91 Z28 M5,A4 LB9 V8 9.3:1 5.0 (305) 205@4200 285@3200TPI 3.08 ---- 2.73 ----
91 Z28 M5 LB9 V8 9.3:1 5.0 (305) 230@4200 300@3200 TPI ---- 3.42 ---- ----
91 Z28 A4 L98 V8 9.7:1 5.7 (350) 245@4400 345@3200 TPI ---- ---- ---3.23


GM Stock Cams
Model Number .05" Duration 1.5:1 Lift 1.6:1 Lift Lobe Sep. Notes
14093643 202/207 .404/.415 .431/.443 114.5 87 350,305man
10088155 179/194 .350/.384 .373/.410 109deg 87 305 auto
10066049 207/213 .415/.430 .443/.459 117deg 88-89 350,305
10111773 202/207 .413/.428 .441/.457 114.5 90-92 350,305

Well if it isn't the peanut cam... then why is one 305 tpi with either the A4 or M 5 combo rated at 205 horsepower while the other 305 that's only available with the 305 and M5 rated at 230 horsepower? I know there is an available G92 option, but I can't understand how an extra catalytic converter and an oil cooler would add 25 horsepower... Something isn't adding up here!

redneckgames

uh they look exactly the same. You could always say that that 350 is a 305 and unless they run the numbers, they wouldnt know.

Zepher

You could look at the balancer.

ws6transam

Except that would be lying and cheating. ...and some street racers carry guns.

redneckgames

first you cant always look at a balancer.
second how many hard core street racers you know that run 305s?

DAKMOR

I hear 5.0L BMWs are pretty fast.




lol.

Marc 85Z28

The biggest problem with the 305 is not its bore size. It has two main problems hurting it:

1. The SEVERE lack of performance in a stock application. Sure the later G92 LB9s moved nicely, but your average 305 is a lazy, sub 200HP engine straddled with emissions that doesn't really respond until the entire top end is replaced. Which brings us to number 2...

2. Replacing the entire top end on the 305 is just not cost effective. The SBC family has better options out there that will make more power for the same or less cash.

The only other reason is that most people don't build 305s right. Parts are horribly mismatched, or are budget parts that make budget power. I've seen my fair share of low 12 second NA 305s that were built right. AFR used to make a cylinder head solely for the 305, and may make a current 195cc head with small valves (1.94/1.50) if you ask nicely Couple that with 10.5-11:1 compresison and a cam (low-mid 230s duration roller) and intake (Victor Jr - forget TPI) that is capable of peaking above 6000RPM and you'll make plenty of power - small bore or not.

burnin_rubber_irocz

I love this thread because of all the great info i'm getting from it about what I could do. I also like the fact that some people are finally being positive about the 305. Most posts have someone ask a question about a 305 and it ends 2 comments later with "Buy a 350." I want to build mine up also and am looking for suggestions about what to do and this thread has helped ALOT. I have read every comment from the start. Especially the part about somehow not being able to make 500hp 305. Yes of course I would probably find it easier to drop a 350 in there but I want to deal with the engine I got and make it the very best I can and do something good with it. I love driving and do it for fun and am addicted. I'm not drag racing or racing period (unless provoked) but am looking for the best performance with what I got and be proud of it. Especially if i made 500 or over with it. Is there anybody out there with a supercharged 305 that could tell me their setup and how they got it that way? my car is 87 not 88 messed that up