HughG

I want to rebuild my stock 1984 Corvette to get more horsepower at a decent price. The person that has done past rebuilds for me is trying to talk me into getting rid of the Crossfire and the heads, saying they are both junk. I do not want to take things so far that I have to bypass the stock computer, I want to leave the crossfire and I am not objecting to getting new heads but the costs may prohibit that. I am looking for any advice that will increase horsepower but not cost an arm and a leg and will not be in conflict with the stock computer. What size cam can I use that will work with the computer? Would a new stall converter help (and if so, what size?). Will flat head pistons give me anything?

I have new injectors and a new fuel pump on it now (car didn't run too well when I first got it). I drive this car everyday, so I am looking to get more hp, but I am not going to be racing it... just occasionally when I have to prove something to a Mustang or some of the other people that have Vette envy. Oh yeah, I got rid of the CAT and put a dual exhaust on it.

I realize that the 84 Vette is kind of the bastard Vette, but I really enjoy driving this car. Just want some more power... I mean it is a Vette. 205 stock horsepower for a Vette is almost embarrassing. It deserves more.

Any help from people that have done this or have knowledge is this area is appreciated. If you have places to buy the things you are talking about please give me links. This rebuild is going to take place in approx 2-3 weeks, need to know my options as soon as possible!

James93LT1

Listen to your builder, he knows what he is talking about.

HughG

I'm not eliminating the crossfire. I don't want a carb and it will cost way too much to go to TPI. The crossfire works fine now, I have actually tune it really well and it runs good and I get decent gas mileage.

Calderone

That's cool but you won't have 300 hp out of that setup
Heads,intake and exhaust are a must if you really want that power

rodj

Maybe this and a decent set of heads

http://forums.corvetteforum.com/c4-t...crossfire.html

or a 100 shot of NOS

The Green Rocket

Actually I think that '84 Corvettes are cool, and I like the Crossfire. I remember when they were new, I was working at a large Chevy dealer at the time - I read everything there was to read about the car, its engineering and technology. It was a groundbreaker and I became a big fan of the C4. It took eleven years before the planets came into alignment and I finally became a Corvette owner.

Okay, here's the deal on the Crossfire: it is cursed with puny intake manifold runners and equally small cylinder head intake ports. The Crossfire actually runs good up to the low 4,000 rpm range - then the party is OVER.

Replacing your heads with aftermarket is easy enough - its the intake manifold that will give you fits. The factory Crossfire intake is not so easy to carve up. One alternative (if they are still available) is the X-ram. If you have access to machine tools and you are a good aluminum welder you could use a lstandard low rise single plane intake manifold and make your own. Or you could wait and see if the new performance Crossfire intake manifold become a reality.

Or you could find a vintage Smokey Yunick Z28 style cross ram http://i40.tinypic.com/v6ulcn.jpg and adapt your top plate.

Success on any of those will push you beyond 300 hp.

Thomas

Frizlefrak

Let's get back to basics here.

The 84 Corvette uses a Gen 1 small block Chevy engine. It will respond to all the "normal" mods like any other SBC engine. The real inhibiting factor is the intake, but that can be overcome as well. What it all comes down to is what you want to spend, and if you're concerned about ever getting that money back out of the car when you sell it. If you aren't concerned about that, then mod it like any other SBC..... heads, cam, headers/exhaust, X-Ram, torque converter, and a 7747 ECM will do wonders. But it won't be cheap. And you won't (in all likelihood) get the money back when you sell. But it will get you in the 300 HP neighborhood, and will help squelch those pesky pony cars (at the track, of course). And of course, you MUST leave the Crossfire Injection badging on the car, just to add insult to injury when you beat them.

If you are concerned with money, change titles. Yes, sell the 84 and buy an LT1 car. Bam...instant 95 HP increase without ever getting your hands dirty. Your goals will then be met.

I love the 84....I've owned one for 12 years now and bought it out of nostalgia, but I love it warts and all. And I'm fully cognizant that modding it to perform like a newer Corvette will probably cost more than selling it and buying a newer Corvette. Something that you might want to factor into your decision making.

Good luck whatever you decide....we're here to help

GREGGPENN

Seriously, there's a good chance you'll spend less in the long run -- and have the car with less wait. Even if it costs a bit more now, resale will be more -- which is where you'd come out.

50ithSILVERz06

TPI set ups shouldnt be that overly hard to find or super high priced.......700 usually gets u everything for a complete swap..........except heads.......

TJM

[QUOTE=HughG;

Hugh, fill out your personal history so we will know more about you.



Based on what you said, I recommend changing your rear end gears.

With an automatic a 3:07 - 3:45 ratio will make a good deal of difference. Your DANA 36 won't take much more than that.

Gas millage will suffer, but either you get insulted by Mustangs or you pay something.

3:07's are common on the forum. Getting it out is easy.

Anything bigger is custom and will run about $350.00. A GOOD mechanic should set it up for $250. oo if you go gears.

Then headers and free flow exhaust.

But spend $100 on a FSM, it will pay for itself.

TJM

LD85

Changing the ECM is not the end of the world, but regardless, you need to specify a budget.

If you HAVE to keep the crossfire, buy new heads, headers, and port the intake to the max, and you have what you have.

LD85

Changing the ECM is not the end of the world, but regardless, you need to specify a budget.

If you HAVE to keep the crossfire, buy new heads, headers, and port the intake to the max, and you have what you have.

I agree 100% with the sell it and get a LT1, you will never regret it.

Muffin

Speed costs money, how fast do you want to go? Old saying but absolutely true.

rodj

And a TPI makes how much HP even with alum heads ?

JLeatherman

300 chp out of a crossfire isn't exactly impossible. But it's gonna require major work. Porting the stock intake/removing the EGR provisions, new heads, cam, larger injectors (GM454 90# injectors), modded 7747 ECM with tuner (Moates ostrich), headers, etc. Do you want to open the motor up? A number of guys on the crossfire forum built 383's with good numbers in the 300 chp range with the stock ported manifold. You're looking at a minimum of ~$3k and some real work.

You do know that changing the stall speed doesn't actually add any engine hp right? And the '84 already has flat-top pistons. If you change heads be careful what you get, 67cc on a stock L83 longblock will give you too much compression for a DD car.

I am not telling you to sell it. But, you can't just open a catalog and buy a couple things to get a crossfire into 300 chp. It's just not supported like that in the aftermarket world.

Also, I'll throw this out there, but I don't think you'll be happy with a real high stall. The L83 is a torquey motor, and with the intake restriction it runs out of air real fast in the higher-revs. A higher stall might feel fun at launch, but on a DD car with the crossfire it isn't real practical. If it's an auto it probably has 2.59 gears. Get a D36 with 3.07's and it'll definitely make a world of difference.

Honestly, keep it stock, enjoy it in the corners, and don't be so concerned about numbers. The 84 is a good driver, great handling, and fine looks. They can become money-pits when you get into the "I want X-hp from this the hard way" approach.

kangi

Yeah, the intake is one of the bottlenecks in the Crossfire setup, however its not that big of a deal to port it out. I did it over the winter as well as porting a set of '113 heads. Many will say these heads have too small of a combustion chamber, and will drive up the compression ratio too much. This is not necessarily true, selecting the right cam to produce an acceptable dynamic compression ratio is the key to being able to use these small chamber heads. There are a few good DCR calculators to be had online, just do a google search.

In addition to the porting of the heads and intake, I'm installing a new cam, long tube headers and dual exhaust. I'm not ready to say what kind of power my combination will make, I'll be putting it on a dyno after its all together and broken in. I can, however, tell you that the stock setup made 175.5 hp at the wheels.

I guess what I'm trying to say is that I too wanted to squeeze some more hp out of the ol' '84 and I think there is plenty capacty for improvement with the stock setup. Good luck and have some fun with it!

qws

Think I'm gonna get my .02 cents in here as well.

Converting to a TPI first is a complete waste of money for the gain you get.
You can be in the neighborhood of the gains you want pretty easy. I know I've done it.
13.3 @ 99 mph on the track. Only differance was I used a Xram as opposed to porting the intake. Whats the differance between a ported intake and Xram. Not very much. You may see better gains with the ported intake.

This is what I had when I got that time.
Xram
Dart ss heads (cost was $625 for the pair)
1.6 rr's
D44 3:45
mild 2040 cam
2500 stall
2"tb's with 90 lb injectors, 15 psi

So are your goals within reason? Most certainly are.

qws

[QUOTE=JLeatherman;1573436454]
. If it's an auto it probably has 2.59 gears. Get a D36 with 3.07's and it'll definitely make a world of difference.

[/QUOTE}

All 84 autos came with a D36 with 3.07 gears. None that I know of came with 2.59's

j-vette

LD85

I know it is hard to grasp, but sell it and upgrade to a 1991 or newer.

You will spend at least $5k if you by heads, cam, headers, gaskets, etc, etc, etc.

Your can and $5k can get you a nice LT