SpeedCat86

I have a '86 305 TPI that I would like to get the most power out of. I want to keep it street-legal, and daily drivable.
What kind of mods will I need to maximize my motor?
I also don't want to do anthing that will involve removing the engine from the car. Same goes for nitrous or forced induction.

So, can I build a 300+ horse 305 with primarily bolt-ons?

current mods in sig:

TBIfly

I'm sure it's possible to manage that, but I dont think you can get there without pulling the engine.
Considering my TBI stock is about 170 hp...

things that will help:
-new intake manifold
-exhaust manifold (make that puppy breathe)...push for 3in. all the way back
-if you feel froggy, jump on some larger injectors for the TBI (Ive asked around and called TPI specialties whom stated that even a 52mm throttle body would be too much for the 305 to handle, i think we have either a 42mm or 48mm, dont hold me to it though)
-bigger cam
-TBI spacer
-heads
-stg 2 chip
-proper timing

Im just guessing here, but you may get close to the mark! good luck to you and dont forget the traction for all that action.

Dan91Z

TBIfly.. he has a tpi, not a tbi

afr 190 heads or world s/r torquer heads, headers, 1.6 rocker arms, and possibly some aftermarket runners should get you there with what you already have.

TBIfly

my mistake, still....go for everything i said, disregard the TBI-specific mods

Zepher

iTrader: (1)

Heads, Cam, Throttle body, SLP runners, AFPR, 22-24lbs injectors, full exhaust, and Custom Prom.

With those parts, you should be near if not over 300hp.
Gonna cost about $2 grand or so, probably more.

gruveb

YES!!!

The biggest knock on the 305 is that it is smaller than the 350!

Of course you can get 1hp/1ci displacement in just about any engine.

To get about 300 horsepower out of a 305 will take a new cam of course, exhaust, and some head work. Same as improving any engine. It can be done rather easily, just do your home work.

There are lots of people on here getting well over that amount out of their 305's. Mine is still in the process, but I would definately be there if I had done my exhaust already. I'm running carbed, not TPI, but none-the-less, it is do able.

Willie runs a supercharged 305 and he will eventually break into the 11's in the quartermile!! That's probably close to 500 rear wheel horsepower.

Do a little home work, find out what your budget is and it can be done.

SSC

Well if you dont want to remove the engine than your kinda limited. Its much easyer to pop the sucker out and go from there. If you want to get that power with a minimal amount of work your probably going to have to get some forced induction AKA supercharger. A supercharger will get you there with a minimal amount of hassle of course a CSC isnt going to do much if your stock intake cant flow.
SSC

iroc5speed

I'd say you'd probably be better off pulling the engine, and putting in some high compression pistons, then throw on the AFR heads, maybe even an LT1 intake, that would be sweet.

five7kid

iTrader: (14)

The LB9 already had flat tops. What are you calling "high compression pistons"?

Although more expensive to do with TPI, the 1HP/cubic inch is still possible. You've got to do something with the heads, cam and exhaust, then the TPI work. You don't have to pull the engine to do any of this, but it is probably easier in the long run.

AFR heads are designed around 4" or larger bore. Although probably better than stock factory heads, they probably aren't the right way to go for a 305.

LT1 intake on a pre-LT1 setup? Doesn't sound too "sweet" to me.

Zepher

iTrader: (1)

LT1 Intake on a TPI car looks awesome.
A buddy of mine has one on his car and he can modify one for you for about $100 or so.

GRENDLE

heads , you dont have to go all out aluminum , or total race parts, just either hog yours out, intake, exhaust, and bowls or get a better set than what you have (oem are still cheap and still good) (if you want to practice get a dremel and ask a bone yard for a bad chevy head you'll return, have fun and see just how far you can go before you trash it, test the limits, or get a book and just practice a bit, it's not too hard) go with a better cam , work the exhaust system (chevy's need it) and also work the intake. look at the mods people are doing to their intakes and start there. also get a g-tech ( you need something to judge if what you did is working). the rest is a lot of tuning. 300 hp out of a 305 isnt that hard it's the attention to little things that makes the difference. or you could go the other way and spend $550 on a nos kit , and add 150 hp real fast.

SgtSkip

Check out the March issue of Car Craft. They made a 325 HP 305 from bolt ons. They spent about $1500.

Chevy83Z28

I'm in the same situation, I have an LG-4 w/ 86k miles on it (carbed...not TPI.) If I were to start swapping heads, and putting in a bigger cam and intake manifold... is it likely for my rings to start blowing? By increasing the compression in each cylinder (mostly due to new heads,) can't this start blowing rings? Then the engine would need a complete rebuild, and I'm sure at that point I'd spring for a new 350. Is it considered to be worth it to work a high-mileage 305?

The only reason I'm going to work on my 305 is because the parts are interchangeable. If I blow the 305, I'll just transfer the cam/intake/headers/ignition/etc into a 350. I may have answered my own question here but just looking for more opinions on it...

un4givin89

325Hp for 1500 dollars, was that TBI and an LO3?? Cuase I'd like to achive that goal.

I was planing on new vortec heads, cam, intake, exhaust, headers, new tbi

Little GTA

.

SgtSkip

They started with a stock LG4 from an 782 'maro w/ QJ and dyno'd out a whopping 145 hp. Added headers, dual 3" pipes w/ flowmasters, L31 vortec heads, holley 750 double pumper, Edelbrock super victor intake and comp XE262H-10 cam. Ended up with 324.7 hp

burntblues

I agree with everyone else, you gotta do the cam and the heads. Go for a fairly mild cam since you aren't going to want anything that'll keep tripping the knock sensor, you won't get anything that way. The heads and the intake will be a good change too. Edelbrock makes a performance kit that you could use that has almost all of that stuff, but I would probably swap it out for the World Products Torquer II heads.

I agree that you gotta change the exhaust too, the main problem between a tpi camaro and the old rustangs was that the stangs had exhaust manifolds that should have just been called headers while we got stuck with these manifolds that can't feed an ethiopian oatmeal.

Before you start squeezing everything out though, maybe you should look at some suspension upgrade stuff to get everything to plant a little better...

-=-Mike

SpeedCat86

Ha Ha! I knew I wasn't that crazy!
300 seemed like a nice round number to aim for, and now I know about what kind of expenditures to plan for.

The power boost will have to wait untill the chassis is done. I gotta get it lighter and tighter so I can keep up with the BMW's in E Street Prepared

burntblues

nah, its definatly possible to get the power out of the 305. The important thing is to get it to the ground. Unfortunatly with our suspensions (which suck) its a PITA. The first thing is to change the torque arm and then the rear suspension components. Afterwards look at the front end stuff. The torque arm is probably one of the biggest things though... I've got well over 350 horsepower going through my car now, and the wheel hop that you get in our cars, even with POSI, sucks. The torque arm just cannot handle the power. Go with some polyeruthane bushings and swap out that stuff first.

Always do your rebuilds from the bottom up, the power is only as good as what yo plant it with...

Mike