I have an 86 trans am with 161k miles on it and I want to supercharge it, but I'm fairly new to this kind of stuff so I'd like a bit of advice. I was planning on rebuilding the engine first, then adding any upgrades to it so the supercharger doesn't blow it up. I don't know if it'd be better to replace the engine with a lower mileage 305 or to upgrade my current one. I'd prefer to keep my current one. If that sounds doable, can y'all give me some suggestions on what I should replace in it after rebuilding it? And any links to those? I would also like to know what kind of supercharger I should get and any links to where I could buy it. I would really just like to learn more about supercharging as a whole and get help with finding parts and needed upgrades to my current engine.

 

Cue the "upgrade to a 350 for the same price" comments in...3...2...1...

 

A supercharger on an otherwise stock 305 will make approximately the same power as a built 350 without a supercharger.

You would be better served just putting in a built 350 with 8.5 compression and adding a supercharger later if that's not enough for you.

GD

 

I've considered doing that and I might. But I just want to explore down this route before making any decisions.

 

"Rebuilding" a 305 is a waste of time.

What's the budget? You're going to need more than you think.

GD

 

How much $$$ do you have for the project? Who will be doing the actual work? If it's you, what is your experience level with engine building/tuning?

Bolting any kind of power adder onto a 34-year-old, 160+K mile engine is not likely to turn out well.

 

 

I turbo’d my stock 131k mile 305.

things i learned, you want to make sure you have fresh valvesprings and good ignition components.
also may want to have heads resurfaced and do head gaskets now. Mine started pressurizing the coolant system, somehow. Lol. In boost the heater core started leaking. No turbo it was fine.

other than that i wouldnt be too concerned about the mileage. But the tuning has go be spot on and doing that with a bolt on kit with a fmu type fuel delivery may not be what i would recommend. Needs to have a boost referenced fuel system like 2-3 bar map sensor or perhaps a larger maf sensor to read the airflow increase. I like map based

 

Put the supercharger on the 305.

Have some fun until it grenades.

Then swap it for a 350.

 

Yes you can supercharge a stock 305.
As long as you avoid detonation you can add a lot of power. You'd be best to add a cam and valvespring set to let it in and let it out.. The stock oem 305 cam will really limit supercharged performance.
And suitable hyd or solid cam on 110 lsa or wider is fine.. The lil 142-144 roots blowers and the Eddy 122 H E-Force blowers really shine on a 305.
If you want you can swap heads to a open chamber 350 76cc head (1.94" valves) to drop the compression even more to allow more agressive boost on pump gas
7.5:1. Even better if you home port the heads.
The pre1975 76 cc castings are best for this eg 441-487-920-916 etc
Use a 750++ cfm carb. A hei diz can be modded for a blower friendly spark curve and or running a boost retard also.. The stock motor will take lots of boost but engine knock detonation under boost must be avoided.

 

 

Chevy L-31 vortec heads also work very well on budget supercharged 305's. They breathe a lot better than stock 305 heads and the 64cc chambers lower the cr a bit too... With vortec heads be sure your supercharger kit includes a vortec style (port location and bolt pattern) blower intake manifold. Do not try to adapt other style intakes to vortec heads. Both Edelbrock and Holley/Weiand have Vortec compatible kits.

 

so yes you can supercharge a 305....i did....and after the stock bottom end seized up.... i upgraded all the parts to a forged long block....the 305 with 10 lbs of boost made 350hp at the wheel...you can get a built 350 to make more than that.....i don't know what kind of fuel system you have, but it will need to be upgraded as well, if you are looking for big numbers

 

I bought a 1987 Z28 with 305 TPI with 100,000 miles in August of this year. The first plan was to leave it alone. Smoked on start up so I decided to change the valve stem seals, which led to new pistons, rings and bearings. A friends brother had a ATI Procharger for a Camaro and I was going to buy that and put it on the stock 305 and call it a day. He ended up selling it some time ago.

Now I am building a AFR headed 383 stroker.

I was in the same frame of mind as you at the beginning, but now its a 383.

As much as I always hated hearing "put a 350 in it".......in the end its the same money, more power, and less hassle.

It is a real shame a SBC 305 doesn't respond to mods like the same sized SBF 302. There are hundreds of thousands of Mustang head/cam/intake 5.0s running around that make more power than head/cam/intake SBC 350s.

My 2 cents

 

Buy a nitrous kit, leave the 305 stock, Have fun
Blow it up.
Buy another 305
Repeat.

Way simpler and cheaper than a supercharger

 

put the charger on the 305 have sum fun .mean time build a 350 time and money etc etc when the 305 gives up put the charger on the 350 drive on !

 

I would not rebuild the 305.. (a compression test will tell you if its still healthy) The most I would do to the short block is a ring and bearing freshen.(ball hone) and only if needed. If you do do that then file fit the new standard rings. Open up the top ring end gap for boost. (about 40% bigger ring gap).. The heads got to go.. The cam s got to go. any perf head with a 1.94" valve and 64 or bigger chambers is good (67-70-76cc). Extra bonus points if you port these heads. You want to lower the cr and also improve port flow in 1 hit. Now it is blower friendly. I like the Edelbrock Enforce 122H blower kit for this one.
The shorty headers that fit easy are fine for this.
Any 218 to 226 in 236 to 234 ex cam on 110 to 114 LSA is fine... EG crane HMV278-2 EG Comp Xe262H-10 or Xe262-13 or the summit 224-234 .465-.488 114 cam. or similar cam is great. (elgin, melling etc)
Even a Summit 278 222.467 110 lsa cam is fine
104/116 Install.
Use a 750+ cfm carb The edelbrock 800 avs2 carb is just right.
Add a 10" high stall and 3.42 to 4.10 gears and you are dragon slayer ready..
Yup you'll need a hood scoop or a 3"-3½" cowl hood.

 

What heads are on it now OP? Is it a tpi car?

not sure i would invest in finding different heads just to do this to a stock bottom non roller 305 and i would go centri blower to make it easier

I would have new gaskets and proper valvesprings in it, a roller conversion ideal but flat tappet can work just gotta be extra careful on oil additives and such.

 

The heads prep is a critical part of this. stock 305 heads will really limit this combo.. By doing another set of budget heads up you minimize down time , install all all at once and address the breathing, compression ratio and valvetrain for the cam all at once.. This combo will out perform a built N/A350 or 383 if built to my spec... Too many cooks spoil the broth. The centrifical is neither easier nor cheaper..

 

I guess it depends on his goals. Stock bottom end 305, if all you want is a mild gain in performance, run 8-10 psi and be happy.
my bone stock 91 305 went 110 mph in the 1/4 on 8 psi. Thats 2 mph faster than my bolt on ls1 trans am. Stock cam stock 305 Tpi heads. With valve float lol. Thats pretty good power gains considering it is a 90 mph car if its lucky n/a.

Idk what castings he has but they are plenty for mild performance gain, let boost do the work. Just refresh them with good valvetrain components, fresh valvejob and deck, new gaskets etc

centri would be a bolt on affair. If he has a tpi car its much easier. If hes tbi then i suppose you could go either style blower but i rather would keep everything under hood with a centri kit. Even if you could adapt a basic torquestorm kit on it be fairly budget.

 

Look at Pro Charger for a super charger kit for your car. The same kit will also work on a 350. If you want to play with the 305 have fun it will work well. If you decide to go bigger in the future then build what you want then.

A supercharged 305 making 350 RWHP would be fun and it would be more street friendly then a 350 CID engine making 350 RWHP in N/A form.