91BigRedZ28

I have a beat-up 305 TPI in my car right now. In my garage, I have a 305 TBI with 27k on it. It's from a Caprice. I want to put the good 305 in my car, but first I'd like to upgrade.

I have 600 dollars to spend. Exhaust is all taken care of (I hope). The TPI itself is still good. People have told me to keep the TPI. I was thinking about a cam. What else could I do? And what cam?

Transmission too...should I get a shift kit? Is an aluminum driveshaft going to contribute to HP gains at the wheels? Enough to spend $360 on it?

Sorry for all the random questions, but I know you guys can help. Thanks!

'91 Z28 305 TPI
Weld Pro Stars w/ Mickey T's

iroc22

For the cam, you should look at TPI specific cams. They're designed to work with TPI's long runners.

I would port and polish the stock heads, if that's what you are running.

I would invest in a shift kit. As for the aluminum driveshaft, it's more of an exotic thing. You will obviously see gains at the rear wheels because of the less rotating mass, but keep in mind that the faster you go, a heavier driveshaft will generate a higher force to the rear wheels. Granted the engine will have to create more torque to get the heavier driveshaft turning.

91BigRedZ28

Thanks. Couple more questions...

Is there a shift kit that you recommend? And as for porting and polishing the heads, how much would that cost? And I'd need new valves, right? What should I get? I hope I'm not asking too much...I've just never really done anything like this.

One last question...how much bang for the buck will I be getting? In terms of HP gains, what should I see? The good 305 has a little over 200hp I think.

Thanks again.

iroc22

I would recommend B&M's stage 2 shift kit.

You could port and polish your heads yourself with a dremel tool. It would be a good idea maybe to practice on a set of old heads first and then step up to yours. You wont need new parts for your heads, but you might want to replace them if you think it's necessary.

You could squeeze anywhere from 250-270 from the little 305 with ported heads and a decent sized cam.

egmonster

I say you can push 300!!! (at the flywheel of course) with good tuning, siameseing your intake base and porting your upper plenum and doing your heads. If you have an auto get a new torque converter. You will see pretty big gains with a new one. Take the rest of that money and get a decent set of headers and an eprom burner... read how to do it yourself on the PROM forum right here. THere is a really good sticky forum for newbs going on over there (and in the TPI section). Torque Converter - 250, Porting Kit (assuming you have a dremel already) 30 bucks, EPROM burner + proms + adapter - 210, headers 300? I know you'll be a bit overbudget but man your car should be in the 13's without too much problem . Also pickup a corvette servo for your tranny for now. That will make it seem a lot more responsive. They're only around 40 bucks. You can invest in a shiftkit later and perhaps sell the servo that comes with it or keep it as a backup. I am assuming you are on a tight budget and already I have put you over sorry!

RSCamaroGuy92

Diong what each of these guys have said will greatly improve your 305's performance. Anyone who can get 1hp for ever cubic inch of a motor has definitely done something right. I'ld see 300 horses on a streetable 305 as quite an accomplishment. These mods should put you around 300horses. That is just about all the 305 can do and still be very streetable.

egmonster

If you already have headers then do what I said plus get a cam . LT4 Hotcam or something of that nature will suffice... you will definately need to burn your own proms though .

91BigRedZ28

I'm not so sure I trust myself with this PROM burning thing...I read the tech article twice and I'm frightened and confused.

Would it be possible for me to just junk the whole computer system and bolt on a 4-bbl intake and carb? Good idea, bad idea? This would mean new ignition setup, and new gauges, right?

iroc22

Yeah, you could put a carb on there. Really the best way to go is keep the TPI though because it will make more horsepower and torque. Your 91 is a MAP system, which shares the same system as my TBI and my combination has run fine so far with the stock chip. Don't worry too much about about getting a custom PROM. Just keep the LSA on the cam high when the duration gets higher.

five7kid

iTrader: (14)

Not TBI heads. The swirl port design is intended for low-end grunt and gas mileage, not high flow.

If you port stock heads, do it to TPI-type heads (087 castings).

iroc22

Yeah he wasn't clear on which heads he was going to use, but no way should he be trying to work with the 187 TBI heads.

Most common TPI casting #'s for 305's is 081.

91BigRedZ28

Thanks guys...

So the computer chip isn't TOTALLY necessary? Or will it just optimize the improvements?

I saw on Crank and Chrome, some computer chip that you bought for like 250 and when you ordered it you told them what mods you have done...and they program this thing. And if you do any more mods, you send it back and they update it for free. What is that, and is it worth it to do that instead?

One more question: how necessary is it that the cam be TPI specific? I can't find any, so I imagine they're pretty expensive.

iroc22

No a custom chip isn't necessary. Though, I only get 8-12 mpg with my stock chip, because it's running too rich.

What they did on Crank and Chrome is just get a custom chip burned for their application. That's what you would have to do.

Check out Comp Cams. They carry specific TPI cams that aren't expensive or hard to obtain.

egmonster

personally I'd highly recommend a chip.

http://ice.prohosting.com/moates/gmecm/hardware.htm

You can order an adapter so that you can easily change your PROM without much hassel from this guy Craig Moates. His product is of good repute. Also I suggest ordering the Flash PROMs from him as you probably don't know exactly what to look for . Understand that normally you need to erase these proms with UV light. Flash PROMS can erase themselves which allow for easy reprogramming and updating. The adapter he makes plugs in easily where your PROM once was. It will become apparent what needs to be done once you get it open and have read the instructions carefully .

You will also need a scan tool to obtain readings from your sensors so that you know if you are running lean or rich. Many of the tools available that you can buy at your local auto parts store will do the job, but not all. Some are just basic code scanners and what not, and that is not really what you want although they are useful diagnostic tools as well. You need something that will also get your O2 readings. I cannot personally recommend one as I have limited experience with them. I use my laptop computer (p233, 64mb, 2gb color 12.1" purchased for 120 bucks US on ebay), with an ALDL cable so that I can plug into my harnass (cost me 70 dollars Canadian) and use Tunercat (a useful program that gives you your readings AND lets you modify your EPROM settings with an easy spreadsheet format and lets you burn them onto your own chips with a chip burner! cost 70 bucks US). There are also good freeware programs that include the necessary files for our cars. I can't say I have much experience with them though.

Pocket Programmer Plus - 150 dollars, it's exactly what you need.

http://www.xtronics.com/memory/EPROM.htm

Xtronics is a very pleasant company to deal with in my experience btw.

I realize this is a pricey endeavour but I personally think you will be rewarded with better fuel mileage and higher performance . Also please note it is really handy to have the laptop as you can drive around in various conditions and obtain readings at various engine loads and rpms. And then you can burn your chips right there! But if you don't have a laptop don't fret you can still use your computer but you will have more hassle getting the data into the chip, but of course it is still very possible (with a scan tool obtain readings, just hook up the prom programmer to your pc). Of course you can also play it by ear and not use a tool at all, but I don't really recommend it.

Also I thought you had a TPI setup, misread my bad.