JungleMan

I have a 91 Firebird with a 305 TBI...and like pretty much every 305 TBI owner on this board, I'm looking for more power. (Please don't suggest a 350 swap-- I'm enough of a newbie as it is and doing heads/cam work on my 305 will be enough of a challenge, I'd be way over my head in an engine swap.) I want 300 at the crank...enough to run with those new '05 Rustangs running around.

In the next month or two I'm taking the first logical step (besides Open Element...) and tacking on a full exhaust replacement. Headers, y-pipe, high-flow cat, and catback. Most have said this is a necessity for doing any engine work on a 305 since the stock exhaust/manifolds hold it back a lot.

My next step however (and the one I'm posting about) is upgrading my heads/cam/intake...I am aiming for 300 at the crank for this car. I'd like for you all to suggest ways to get it done on the 305 TBI, parts to use, etc...and preferably from anyone who's done engine work on the 305 TBI.

I can get a VERY good deal on an LT4 cam with a custom chip, but is the LT4 aggressive enough for my goal or do I need something bigger? I have heard that the Vortec heads are a great choice to go with on the 305. I have barely done any research on intake stuff. I have a somewhat decent budget, not entirely limited, but I don't need a monster machine, and I don't want to blow up my 700R4 in the process (which is good for about 325HP).

I already have 3.23 gears, posi, 275 series tires, and brand new shocks/struts, so getting it all to the ground efficiently shouldn't be a problem. Thanks

del91_305

Well in my opinion im sure it can be done. Of course you will need better heads bigger cam, and you will need to do something with your induction. Are you planning to stay TBI? You will Definitly need to get into some chip tuning. I am in the process of doing a Head/Cam/Intake/Carb swap, am i am hopeing to put out about 280 at the crank and that is with stock TPI heads, But i am switching form TBI to Carb.

JungleMan

I'm probably going to stay TBI yes. I'd like to retain fuel injection, and TPI is too complex/expensive most likely. I assume I'd need a bigger TBI unit though.

Just curious, what cam are you using for your setup?

V8 Slayer

FULL Intake
FULL Exhaust
Underdrive Crank Pulley

Internal stuff...

JungleMan

Never thought of underdrive pulleys...but I'd probably do the real engine work before doing "minor" tweaks like that.

Any idea how much HP we could be talking with underdrive pulleys?

Gunny Highway

iTrader: (1)

Not alot. I haven't heard of any good gains being made with them.

As far as 300hp, I believe Chevy Hi Performance reached that, but tuning was a bitch and the cam was huge. If you want to make 300hp out of a 305, it can be done, but I just hope it's not your daily driver.

You should be able to find the article on Chevy Hi's website.

. . come to think of it, I think they kept cam specs a secret

TonyC

iTrader: (1)

I'd bet some worked vortecs or mild AFR's (milled) would do the trick with the right cam. I'd just call up Comp Cams and see if they could recommend something that'll make the power you're looking for with those or similar heads and a good intake like an Edelbrock Performer RPM Air Gap.

v8nate92RS

Ditto what gunny said, check out the Chevy HiPerformance '92 RS they did the Vortech head/manifold swap on. They used a big custom ground cam, high-flow Turbo City TBI with all the mods including injectors, and tuned the hell out of it. Its gonna be A LOT of work, but if you have the time, $, and patients I'm sure you'll be at least close to successful.

Gunny Highway

iTrader: (1)

But didn't they have to mill the crap out of the heads too? I think Trick Flow now makes a 305 head, so it might actually be cheaper in the long run to get those rather than the vortecs; also it would allow you to run a lot more manifolds.

Dewey316

Here is the key to a 300hp LO3...

ShiftyCapone

iTrader: (7)

What is your budget? There are many heads that you can use but many need "extra" work to really make them work on a 305. You should be able to get 300 hp out of the following heads

Prepped 081's or 416's
World SR torquer 305's
Prepped vortecs

By prepped I mean larger valves, port work, and cut guides for larger lift cams. The same applies to the vortecs yet you would most likely want to mill about .020 off the bottom to bump your compression back around mid 9's:1.

The trick flow heads are nice but are better suited for a mild 350. The cahmber size is at 58cc but because they are aluminum you would want to run more compression than 9.3:1.

del91_305

The cam im using is 214/224
Lift is 442/465

Ronny

iTrader: (1)

nice lookin trunk! whats that ugly brown thing there? a pool cue from 1901?

IROC-Z28_CAMARO

iTrader: (4)

Dewey what do you run on the spray. I am just about to install my kit, by the way thanks for the help a while back, and would like to have some thing to compare to.

Thanks

Dewey316

I'll let you know in a couple of weeks. The track hasn't been open since I installed the spray.

Assuming the new ECM fixes my issues, I'll be dyno'ing and running at the track in the next 2 weeks.

--John

Gunny Highway

iTrader: (1)

I was under the impression that the "Nawwwss" kits don't work well with our systems.

Dewey316

Mine works well.

Although it is not your average TBI kit.

NOS Super-Power shot plate + intake studs


TBI Adaptor sits over that


Not exactly a bolt on TBI kit, but it fit my needs.

Gunny Highway

iTrader: (1)

Does anybody actually have the TBI kit on their car? I could have sworn our systems had issues with the computer compensating for fuel and timing or something to that affect. . .

Dewey316

The computer does not compensate fuel or timing for the nitrous. If you use a wet kit, it will inject fuel and nitrous together. For timing, I have a chip in my car, that pulls 4* of timing out at WOT, when I plan to use the nitrous, I use that chip

Ronny

iTrader: (1)

IOW. YOU USE THAT CHIP ALL THE TIME?

TonyC

iTrader: (1)

I have the NOS kit, works juuuuuust fine . Because I have the Promnator, I have one bin set with 4* pulled out and one bin with full timing, so I can just flip the prominator switch to the 4* retard bin when I'm on the bottle, and when I'm off, switch it back to full timing.

njspder

300hp from a 305 is easy work.
holley tbi intake, holley or 454tb, mild heads(think torquer 305's or cleaned up L98 vette heads), LT4 hot cam, tuning, and full exhaust with !cat.
tunign is where power lives. get that right and the rest is easy.

later
tim

IROC-Z28_CAMARO

iTrader: (4)

Wow, Tonyc I like that setup you go going there. How is the bracket mounted to the floor.

Dewey316

Tony, how is that legal, I see no blow-down tube.

TonyC

iTrader: (1)

Gimme a break man, I'm poor, haven't bought the blow down yet . The bracket is bolted into the seat belt bolt holes (where the seat belts used to be) and it rests on the hump in the front, piece of cake to make, looks great.

Gunny Highway

iTrader: (1)

In GA, if I did something like that, the Cops would probably impound my car with no questions asked.

cali92RS

So those 10's make about 100 HP each?

TPI-454

"Crane custom-ground cam; 0.510/0.520, 210/214 at 0.050, 114-degree lobe separation angle..."

TPI-454

Dewey316

Nope.

but my stickers do.

Or should I take that as a challange to race?

cali92RS

We can race anytime...
100m sprint sound good, or you want a 40 yard dash?

Dewey316

I'm a smoker. We better stick to the 40yrd. I might not make it 100m.

kirkm76

Anyone know where the first article in this series is? I have the rest, including where they put the 6 speed in, but not the first one. I've gone to a 350, but most tof the info should be the same. The only thing I hated on that article was how they kept the tuning secret. I know, some things are trade secret but they could have done it themselves and figured it out and really helped folks out rather than having a pro do it and not really helping anyone. Yes, I can do it myself too, but why buy the magazine...A tech artile should show you how to accomplish something, not how to do it 90 percent. Nonetheless, I want the article. End of Rant