Here we go.... I have an 84 that has 98K miles original. The car has sat for 5 years, and I just recently pulled the engine and put all new seals/gaskets in it. I am getting the TPS and MAF code, but I haven't got around to measuring the voltage or replacing them yet.
Here is my question. I want to know if replacing the injection system with a different intake and mechanical carb is a valid idea?
Am I opening a huge can of worms by doing so. (computer, dash....etc...)
And,


Thanks!
Shawn

 

Lot of guys have carbed them, some guys have modded the cfi system by heavily porting the intake manifold & increasing the fuel pressure. I switched over to a 2 bbl. tbi & reused the stock wiring & ecm. This allowed me to use any carb intake that would fit under the hood. You have to be careful with your cam section, cfi systems like to have a cam that makes good vacuum.

 

So how about leaving it stock, but swapping intakes? Would that setup be ok? I would rather just modify my intake and fuel system. I don't really want to modify the internals of the block.

Shawn

 

There is a lot of info on the net about your system. Here is one of the sites that some use:http://www.crossfireinjection.net/

 

Why?

 

First thing you probably want to do is replace your stock fuel pump with a new 1985+ fuel pump as the 1984 pump is weak.

I'm planning on putting a Renegade intake on my 1984... that alone is supposed to be good for 20HP according to the advertising. If you've seen the runner size in the stock Cross-Fire intake you'd see why. The Renegade is as far as I know the only replacement Cross-Fire compatible intake currently being made, the others like the X-Ram aren't in any of the catalogs anymore.

I'm planning to go a little further than that though, I am planning on also replacing the stock smog heads with aluminum heads with 64cc chambers, 180cc intake ports and 2.02" intake valves, swapping the stock flat tappet cam, lifters and stamped rocker arms for a retrofit hydraulic roller setup with roller rockers and a double roller timing set. I will also install headers to complement the cat-back exhaust system that is already on the car. I already have a Super 65k HEI distributor and a new set of 8.8mm Accell plug wires I plan to put on. At some point if it needs it i may get my throttle bodies bored to 2", have 68lb/hr injectors installed and upgrade the ECM to a newer/faster one...

Anyway, I'm hoping that all that together will get me up to around 250 HP or so... that should at least make me competitive with L98 Vettes with TPI. I have no illusions it will make it hang with an LT1 car, let alone a C5 or newer... but it should be a big improvement.

 

There is an old Corvette magazine that built up a Crossfire. They did headers, chip, underdrive pulley, flowmasters, K&N filter and possibly some other things. I have not read it in a while, but I think he hit 13's. Will have to try to find it.

I would not change to a carb, I personally feel like it is going backwards. Crossfire cars are dependable and deliver good mileage.

I do find the TBI setup mentioned above an interesting alternative. I have a 92 GMC truck with TBI and I like how it runs.
Shawn

 

Unless you enjoy spending money, you FIRST want to have a reason to change the pump; that would be, that the pump isn't meeting the demand. A pressure gauge will show that readily. No need to change a perfectly fine working pump.



This is true. IF you can find one, the Renegade is a direct replacement, bolt on. A great upgrade, if you can get it.



You need to have more confidence in your mods. You should be able to get about 250 hp from a ported intake (or Renegade) and tuning alone. With your proposed mods, and appropriate tuning, I'd EXPECT it to beat LT1's and possibly LS1's (stock). Here is a vid of an '84 L83 racing a '94 LT1.

L83 Mods:
*Ported intake
*No cats
*Converter
*free tuning (fuel pressure, base timing)

LT1's Mods
*Long tubes
*Exhaust
*52mm TB
*License plate CAI
*Gears

LT1 in the close lane, CFI, far lane. W/regard to the numbers, keep in mind this is in UT; 4500' elevation and likely a ~7000' DA. That CFI car would go 13's at sea level, w/all stock long block. RIP, CFI-EFI.

 

The reason I say to change it first if you've still got a stock 1984 pump is it is barely adequate for a stock L83. Once you start doing any significant upgrades "barely adequate" isn't going to cut it.

I was not under the impression they were hard to get anymore, most of the Corvette vendors claim to have them in stock and ready to ship.

I dunno... seems pretty optimistic to me. Even the Renegade only claims "up to" 30 HP and that is on a modified 383. On a 350 I would think 20 would be a pretty strong estimate and maybe 5-10 HP from tuning on a stock motor... that only gets an L83 to 230 which is where the lowest L98s are stock.

That would be great, but I am not going to hold my breath.

There can be other things that can play in here... the driver, tires, etc...

 

I agree the '84 pump is marginal, but it can and has performed. The '84 in the vid I posted was running a stock pump. Why not test before $pending $$?? Everyone loves to recommend new pumps for 84's before the old pump has proven to be in need replacement. For SURE, if the old pump fails to meet demand, upgrade to a newer style pump during replacement. But to replace for no legitimate reason? Kooky.



I've heard that too...but not seen any reports of anyone getting one recently. Last report *I* heard was a vendor who claimed to have have one is stock, didn't.



Did you watch the video?? W/tuning and porting you SHOULD be able to out do an L98. Why? Two reasons;
1. tuning (timing) is incredibly conservative on all CFI motors, and large gains can be seen from nothing other than base timing increase.
2. The PORTED intake (or Renegade) has a reasonable runner cross section (the major handicap of the stock engine), but does NOT have a long runner design that hurts high RPM power, so you end up with a decent cross section and a nice, mid-length runner intake (think HSR length) with a great RPM range.

Here is a personal example: MY CFI car was an '83 Trans Am, so it had only a 305 (CFI). With these mods:
*Edelbrock "headers" and Y
*Increased fuel pressure (on the stock pump)
*Advanced base timing
*160 stat
*Electric fan
*smog pump removed
*T-5 trans (car was originally an auto)
...the car went 14.5/95. How many hp does it take to get a ~3400 lbs car to go 14.5/95? About 230 or so (remember, 305). My car was originally rated at 170, so that is pretty strong evidence that a little tuning goes a long way on the CFI set up.



Don't drag track much do you? Trap speed tells the story. Doesn't matter what tires, driver, or etc. you have, car is going to trap what ever hp it makes. That mildly modded LT1 trapped a very small, 1.5 mph better than that mildly modded L83.

.

 

I agree with this. Too many people advise CFI owners to change the pump. But why? Unless you're seriously modding your CFI, the stock pump works fine.


^^ THIS ^^
With a slight timing advance over the factory setting, I noticed an immediate increase in not only acceleration, but also throttle response and gas mileage.

So many people have hate for the CFI cars, I wonder how many have actually owned one?

 

Why not? Its a $50 part and these are 35 year old cars. Sure maybe leave it if the pump has been replaced recently... But why start to make mods to a car with a part that is known to be a weak link? I want to start with a solid base line personally.



I own one right now. No hate, but I want to be realistic about the gains I expect to see from mods. If they turn out better I will be happy to be pleasantly surprised. If they only do what I expect I will be happy. I'm only going to be disappointed if all the people who told me to sell my 1984 and buy an L98 car or a much more expensive LT1 car were right. I don't expect that to be true. I'm figuring I should be at least competitive with stock-ish to lightly modified L98 cars and that is good enough. If I can compete with LT1 cars that would be great, but I don't expect that.

 

Why not? Because, I guess if that is your reasoning, why stop there?? Why not replace all your ball joints? Even if they're not bad. Why not rebuild your engine? Even if it's not worn out. I mean, you said you want a "solid foundation" for mods, so that being the case, you'd need to build a short block, a transmission/clutch/converter, go through suspension, the brakes, rebuild virtually the whole car. OR, get all the service life out of each part, and replace when the part's performance warrants replacement. Some people have enough money to rebuild cars that don't need it. Most people don't, and I'm one of them....so I TEST before I replace. Not sure how you can continue to argue that logic.

Copy you on your expectations, and that makes some sense. Definitely better to be happily surprised than to be disappointed.

 

Expecting a L83 CFI to compete with a LT-1 is a stretch.
The CFI give up 95 HP, and a boat load of technology vs the LT-1.

If you want LT-1 performance, just buy an LT-1 Vette, or Camaro/Firebird if funds dont allow a LT-1 Vette.

By the time you buy the CFI Vette and spend the money needed mod it to 300+ HP, you could have bought a LT-1 car.

I love my CFI Vette, and I know and accept its limitations.
When the time comes that I tire of it, I'll sell it and purchase a newer, faster Vette.

But the one thing I wont do is hack up a classic Vette because its "not what I want".

 

Wow, this current batch of CFI owners is a major downer. Have some faith! Did you see the vid above of a ported/exhaust/converter CFI matching a mildly modded LT1 car? I wonder if anyone has watched that vid?? If I were still a CFI guy, starting out w/mods....I'd be pretty jazzed to see that, and get an idea of what is achievable.

I got my CFI car (which remember, started as a 305) to just about 300hp for around $1500. Want the parts/price list? For ME, that included changing the engine, since I was starting w/a 305, not a 350. Admittedly, I used a lot of used/junk yard parts, but it all worked out nice, and it ran for a long time for me, before I sold it. This was 15 - 20 years ago, so parts may have been cheaper, but it was also back when people were plowing new ground w/CFI, and many still believed that you couldn't port the intake b/c you'd lose all your low end tq.

Getting to ~300 hp should be attainable with intake/intake porting, heads/head porting, exhaust, injectors, cam and tuning. Been done enough times, that there shouldn't be a "mystery" to it. Viewed another way, it should take the same thing it would take w/an L98, minus the ~$1000 required to spend to "fix" the L98 intake.


.

 

Don’t get me wrong, I love my CFI Vette, and yes, with enough time and money, it can run with a L98, maybe even a LT-1.

To me though, it just isn’t worth the investment.
Id rather enjoy my car as is, rather than chop it up for the sake of a few more ponies.

I don’t take my car to the track, and my street racing days are long behind me.
So why do I need to butcher a classic car just for the sake of more power?
My L83 makes more than I can use on the street (sanely) as it is.

But thats just me, Im sure others feel differently.

 

I wouldn't consider the mods I'm planning on "butchering" it... In fact basically the only ones that will really be visible will be the headers... and the aluminum heads, but if I sprayed those black on the outside even that wouldn't be that visible. Well, the red distributor cap and slightly different coil cover on the Super 65k HEI if someone knew to look for it I guess... But the rest of the mods are all internal or like the Renegade will be covered up by the air cleaner cover...

And yeah, the mods I have planned will not be cheap... but around here a 1984 is so much cheaper than even a 1985 usually (in the same condition, similar miles) that I'm not really that much over where I'd have been had I started with a L98 car. And LT1 C4s around here are usually that much more expensive than an L98 too...

 

Just out of curiosity, what do you perceive as "enough time and money"?


So which is it? The "money" issue?? Or that you're satisfied w/the car's performance as is?? Although I'd hardly call your car a "classic" (too many made, not worth much, not specifically collectible), I agree you don't need to modify it. No one NEEDS to, and don't think anyone in this thread said otherwise. OP asked how to do it, you came on and said that it makes more sense to sell and buy an LT1...which is pretty questionable. If you dig your car the way it is (and I totally "get it" how you would or could -it's a FUN car!) then that is fantastic for you...don't mod it.

 

I may be branding myself as an old geezer but I don't generally consider any car made after 1972 to be a "classic"... I'm not the only one either... several of the classic car groups around here have 1972 as their cutoff for what cars are allowed to participate in their events. Unfortunately since I sold my last car that qualified (a 1972 Chevelle, so barely for that one even) when I bought my 1980 C3 a number of years ago... I don't have anything they'll allow anymore.