i am sorry but i am new to this whole car thing and i want to learn, so nwith that said i want to ask a bunch of questions. i am sure some will be dumb and some will be repetitive but i will do my best to search for the answer before i ask. so with that said i have looked for the answer to this question and i can not find the answer. here it goes.

1991 rs camaro. 305 v8 tbi injection with the 5 speed tranny.....

i am wanting to beef up the original power plant and want to know if i can put any set of heads on the car that are for a 305 as long as it is the 86 or newer heads?

thanks mike

 

hey mike ,welcome aboard ,lots of good people and answers on this sight. if youre looking for stock bolt-ons look for 083 or 416 last 3 #s on head #.there are alot of aftermarket heads out there too.afrs are great heads .im sure these other guys will chime in with more info. than me, but hope this helps ,later jimmy

 

afrs!... i am off to summit! be back in a few with more questions i am sure!

 

ok here is another question that i need explained in ENGLISH!....

what is the difference when it says 58cc / 170cc intake runners...?
what do i have now stock?
how big can i go?

 

you more than likely have the 64cc LG4 heads. this number is the size in cubic centimeters of your combustion chamber, the area above your piston where air and fuel is compressed and ignited to power the engine. 58cc heads have a smaller combustion chamber, allowing you to squeeze the same amount of air and fuel into a smaller area, compress and ignite it, thus producing a more forceful explosion and more power. Hope this helps.

 

Okay, let's straighten a few things out.

'91 RS TBI would be LO3, not LG4. The heads most likely are 191 or something similar swirlports. The chambers are 58cc, meaning the portion of the cylinder combustion volume in the heads is 58 cubic centimeters. The '87-later "better" non-swirl heads are 081 castings - 58cc chambers, 165cc intake ports.

The intake port volume is exactly that - how much volume the heads have for each intake port. Generally speaking, the larger the volume of the intake port, the more it will flow (but not always).

416's are the '86-earlier 305 heads (58cc). They were on LG4's, LU5's, and LB9's. But, the intake mount bolts are all at 90 degrees, whereas the center two mount bolts on each side of your heads are at 72 degrees. Not a problem if you're putting on some intake other than a TBI replacement, but if you're sticking with TBI, you should look to stay with heads with the 72 degree bolt angle (although not something that is a must-do).

Most aftermarket heads are 64cc or more, intended for 350 or larger engines - which means you don't want to use heads made for a 350. 305's have 58cc chambers in order to keep the compression ratio up - which is what you want to do. Aluminum heads should have even smaller chambers, because heat is lost more quickly through aluminum than iron, which reduces power - unless you raise the compression ratio, which restores the power.

The TBI forum has a lot of good information about beefing up your type of engine. Start by looking over the stickies at the top of that forum.

 

oops, i missed the year of his car!! my bad.

 

Generally, the best way to modify these cars to get rid of the bottlenecks 'one after the other' is in this order:

- Tune Up - Do a full tuneup on the car if you haven't already, just to bring everything up to par to give you a good base to start with. New spark plugs, air filter, fuel filter, PCV valve, distributor cap and rotor, and ignition wires. This will freshen up the engine and get everything working as it should. Check the condition of the cooling system at this time too. Can't hurt to change the oxygen sensor in the driver's exhaust manifold too, if you're up for it.

- Air Cleaner - Find either a dual snorkel (has two big scoops on it) from an earlier carbureted car, or the cheaper and easier solution is get a generic parts store 14x3" open air cleaner.

- Exhaust - the exhaust GM put on these cars is quite poor, even with the top-of-the-line engines like the TPI 5.0 and 5.7. Your car will have the smallest V8 exhaust if its the stock system. Changing out your exhaust manifolds for some shorty headers, with matching Y-pipe, and 3" catback of your choice will free up a very noticeable amount of power. The good 3" aftermarket catbacks are usually sold "for 5.7 TPI".

- Cooling System - change to a 160* or 180* thermostat from the stock 195* thermostat. If you live in a cooler climate, stick with the 180*. 160* will run very cool if your cooling system is in good shape and you aren't living where its rediculously hot all the time.

You won't gain anything changing your cylinder heads untill the above has already been done. The stuff I listed (except maybe the thermostat) are power bottle-necks long before the heads are. Cylinder heads are a pretty massive undertaking for someone unfamiliar with the car too... the above mods will familiarize you with the car quite a bit.

 

ok... great help guys. let me see if i can clear some thing up a bit....

the tune up has been done. was not as hard as some made it out to be. i changed all 8 plugs,wires, cap and the rotor. i also put a new air filter in there.

the cooling system... this is where i get excited. when i first got the car it ran 220 degrees and hotter... i put the 180 thermostat in there flushed the radiator out twice and got some fresh antifreez in there. and i also put in a jet thermostat switch in to turn the fan on a bit sooner. the hottest it gets now is 220 and it only lasts for about 5 seconds!

as far as the exhaust goes i have replaced the muffler with a flowmaster and put some different tips on there. i do need to change the headers and do a different y pipe. i thought about doing this when i changed the heads out. they will need to come off anyways.

as far as the air cleaner goes there is a vacumn line and a sensor hooked to the air filter. if i change to an open element filter what would i do with these two things? plug the vacumn line and just not worry about the sensor?

 

The sensor is the Inlet Air Temperature Sensor, and the computer needs that information. If you go with an open element, get it mounted in there.

Other tune-up items are fuel filter and O2 sensor.

The whole LO3 exhaust is terrible. It needs to all go, and if the Flowmaster you put in there is for the LO3 application, it needs to go, too.

 

lo3 is meaning the 305 motor correct? the exhaust that i put on there was just the muffler. i would have to change that? or should i change the cat to something different?

 

If the Flowmaster muffler you put in there fit your exhaust pipe, then it's too small for much use for more power.

When we say "the whole exhaust", we mean "all" of it. From the exhaust manifolds to the tailpipe tips. Stuff made for the '86-'90 TPI single cat application is a good place to start. If you need emissions, I'd suggest Hooker 2055HKR headers (come with a great y-pipe), Catco 9118 catalytic converter (or similar direct-fit high-flow replacement), then your choice of cat-back system (Dynomax for the TPI application above is decently quiet and good-flowing).

 

Just the 305 with the TBI system... TPI and carb'd 305 engines have different engine codes.

 

083's would be bad news on a LO-3 btw

 

If you have the right tools (and friends in my case) you can modify that Flowmaster to fit a bigger exhaust system. I did and saved myself $100 for a new muffler.

 

I just picked up a RS of the same year and am trying to figure out what to do as well. I have been doing alot of research online and I found an article from popular hotrodding where they used a set of stock vortec heads from a 96-00 pickup with a mild cam(cant remember which right now). With a reflashed EProm that combo made 150 HP at the flywheel over baseline. This was on an engine dyno so it wont put that to the wheels but it sounds like a good place to start.

I then found another article about using the vortec heads on a 305 with similar results. I think you need to have the heads milled .030 to reduce the chamber volume a little so you dont lose compression.

 

If the muffler has the 2-1/4" inlet, you can modify the 3" pipe going to it to fit it, but it will be a restriction.