Question: C4 tune up

[warren s]

If I had an 84, I would just try and restore it to mint condition, just as a classic in my own mind, being the first of the C4s.

As for performance, a low end crate motor like the GM 290hp 325ftlbs motor. It would be a major increase in performance, and a platform able to support more modifications without a major overhaul. And its not going to shred the trans or rear end.

 

[vetteboy86]

And calling it a 'mule' hurts my feelings. Thought you guys were supposed to be helpful, not discourage some one and make them seem like there a complete and total idiot. Isn't that what a forum is for... guess I came to the wrong place, you stick a man and their cars together in one place, this time a forum, and it all becomes an e-peen war, thanks for the help all...

There are many good running crossfires still in existence. At their time they served a purpose, just as the L98 cars did, and the LT1 cars. All things lead to what we have today. When introduced the C4 was an amazing car, and for those that still own one still is.

Facts are facts though unfortuantely. 1984 was one of the highest production years for corvette, if not the highest. It's possible 1979 might have produced a thousand more or so. Collectors value on these cars, are only going to amount to something it is an absoulute survivor in perfect condition.

What most are saying is do some research. You may find that you would be better suited starting with a different platform to achieve your speed goal. Use the 84 as your cruising car, because I'm sure it still gets excellent fuel mileage if everything is working correctly, and it is still a corvette.

 

[warren s]

1979 53907
1984 51547

 

[boomdriver]

And calling it a 'mule' hurts my feelings. Thought you guys were supposed to be helpful, not discourage some one and make them seem like there a complete and total idiot. Isn't that what a forum is for... guess I came to the wrong place, you stick a man and their cars together in one place, this time a forum, and it all becomes an e-peen war, thanks for the help all...

Dude,
nobodys bashin or running your idea down, if anything, they are ALL trying to be very REAL with you. Keep in mind there are people here that have been doing this for all their lives. I have been in a C4 since 1988 and have learned a great deal about what can be done and whats a total waste of time.

It cost LOTS of money to step past 300 hp.

Here, I'll give you some price quotes and I'll supply the links if you need...

Rotating assy, forged pistons, crank, I-beam rods-----> $ 2400

Heads---- bare anywhere from $600 to $1500 EACH
Cost me $1100 for a bare stock head a few yrs ago, new.

Add all the springs, guides, seals etc...

Cam-- $250 Lifters (hyd roller) $250 for GM parts

Thats the basics...and you;re around $5500 so far with no machine work YET, or the details...

Porting, another few hundred,. CC runners/intake & port match, few more hundred.

Now, add a turbo or charger? then fuel goes with that. Fuel inj $300.
The turbo, small twins can be had for $150 each or from a junk yard but you have to rebuild them and thats not cheap,. If you do not have machine tools and are able to deal with micrometers in shaft/bearing size, you cannot rebuild at home. Turbos are very delicate little machines...oil supply lines, oil catch cans... oil accumalators etc...

Hell, lets say you got a pair of turbos for FREE !

now you have to fabricate an intake duct that means piecing aluminum tubing together in small 2" or smaller sections to make the curves and bends and tig welding all that. You got to add a wastegate/blow-off somewhere and a controller. And finally, if you want it to run without knocking to death, you MUST have an intercooler, so the duct that you were building just got 5 times more complex...where do you put all this stuff? brackets have to be fabricated of aluminum,. machine work, it takes weeks if piecing odd parts together.

You could just go buy the KIT, but thats several thousand $$$$$$
No wonder the single turbo is so cheap????? its not even 2% of whats needed.

Then, when you have the engine together and installed, there is the exhaust...thats gonna be $1500 for any POS system thats able to handle turbo flow.

Guess from experience, 350HP. and $10,000

My buddy did a new crate motor, pro-charger, good induction & coolers, the tunes and chassis mods and he gets just barely over 400hp and he spent more than $10K.

If you want a real taste, look up threads in here from Marv...he just built a motor with a HP goal on a budget. He will tell you first hand it ain;t cheap as it started to be. And he did not add turbos, either.

If you want support and advice, you;re in the right place but you cannot come in the doctors office and start telling anyone how to operate...

What we all want, and what we can have are generally different things. Unfortunately, too many of us reject the advice of those that have tried, or been there, because its not what we want to hear. Then we'll go out and waste a fortune, not be happy with the results and be mad at the car or others that "should have said something"

Remember when you go down HP road with these advertisements, Most claims do not apply to you. When they say they will add 20hp by bolting their product on your car, its sure tempting and you want to believe. Its simply not true. They might have gained that much HP in their engine when tested, but they never tried it in YOUR engine, or mine. The results are always less becasue their test controled the results from the beginning...

You CAN build a damn nice motor but you have to be realistic. Start with a solid bottom end, and if there is a budget, forget about chargers or blowers or turbos. The best bang for the buck would be NOS as long as the engine is set up properly. Thats why a forged bottom end is a great way to start. That gives you a solid foundation that you can build on later.

Good Luck, and please don't be offended by those that have already tried.

trust me, I spent big $$$ on every gimick add-on thing there is when I got my first c4...and filled a dumpster when I moved. Also filled somebodys pockets with my money. Thats what advertisements for MORE POWER are designed to do....not make your car faster.

 

[aklim]

And calling it a 'mule' hurts my feelings. Thought you guys were supposed to be helpful, not discourage some one and make them seem like there a complete and total idiot. Isn't that what a forum is for... guess I came to the wrong place, you stick a man and their cars together in one place, this time a forum, and it all becomes an e-peen war, thanks for the help all...

1. We can be blunt and perhaps save you money, time and heartache

2. We can tell you what you want to hear, have you buy the parts and waste money, time and still not get what you want.

Pick one.

 

[93Rubie]

I have a solution for you, and it will require less money than turbo, supercharger, etc...or even heavily modifying your L83 Crossfire engine. Yank, that iron puppy and store it in a corner and drop in a $1500 GM truck LS-based 6.0L V8 with about 360hp or so. Might be some more work but with an auto trans. it is a fairly straight forward swap. I think you would be happy with this.

LS Engine Swap for C4 Corvettes | Corvette Central Blog

An easier swap would be to a LT1 which you can make 400+, pretty easy. Or more with some more $$$.

FYI, 350-400HP in a Cross-fire is doable but $$$. 300HP would be much more realistic. Heads, cam, intake, tune, should get you close to 300HP without too much trouble.

An engine is an air pump that is way L89 are better than L83's, and the LT1 is better than the L98, LS1 better than the LT1,and so on...later engines breath better and make more HP. Not necessarily torque but much more HP.

 

[bartric]

Found an LT1 for sale for $600, thinking about getting it. How complicated would it be to change my car from an auto to a 6-speed?

 

[warren s]

The trans swap is doable, but it needs a later model trans – I think the bell housing for the 92 to 96 is required. Trans mount may be slightly off. The LT1 will trash the early C4 manuals. The hydraulics would also need to be installed.

You will need the full wiring harness and ECM for the LT1. ( sticking an air filter on the end of the plenum and leaving it run in open loop looses a decent amount of power) The engine mounts and tranny mount may need to be changed. The sub frame connectors may need to be changed.

There may be kits available for this conversion. I remember seeing a few early C4s with LT1s and LS1s.

 

[bartric]

Warren, all of that knowledge you just filled me with, says that this costs a lot of money to do, like, A LOT... Also, I was thinking about getting a 6 speed, then gearing it so that it's top speed will be around 130 but improve it's acceleration, I've yet to ever have a reason to go over 120, so I figure 130 would be a good cut off, since it's above most other cars, and about 20 mph above most 1/4 mile runs. Just seemed like a good cut off speed, plus, I figure with a decent bit of hp, and six gears, that should make my hp band easier to fit correctly so that it keeps closer to optimal acceleration. What do you think, what would it cost, how hard would it be to do?

 

[billyz06-2003]

c-4 power

I have a Lt-1 stock and it is a real nice running car, if i was you leave it alone. Save for while and get a z06, 505 hp's are coming down and you will c-5/c-6 tech. then you will have a great machine. Just my 2 cents worth.....................................Billy

 

[Highway Man]

Feedback

That's a lot of feedback. Anyway my conclusion about bolt-on horsepower gains is that they are probably going to be minimal at best. There are things that a person can do to make a car run more effeciently such as air intake, exhaust, and possibly a performance chip but as far as significant horse power gains it probably just isn't going to happen. A motor is stock condition only has so much capability in it and you can't put ten gallons of water in a one gallon can. A change in one component affects all the others. The best intake in the world is going to be hindered by a poor exhaust. That's a no brainer. From my perspective I think the best thing to do is to build the performance incrementally with improvements to the overall system rather than try to overload one end while neglecting the others. It all comes down to money-how much a person has and how much they are willing to spend. If you're on a budget like me you do what you can when you can. If money is no object then why not just take the car to a high-performance shop and go for the big one? Personally I don't see why a person needs to take a car that will go 140 miles per hour and make it into a car that will go 200 miles per hour. How many times is a person going to have the opportunity to unleash all that power? Performance manufacturers love this kind of stuff-that's how they make their money. Don't get me wrong because whatever a person does with their car is their business but what is the motive? Just what is it that I am trying to gain. Personally I'm not out to impress anyone as I like my car and I am doing some small things to make it run more effeciently but the bottom line is is that it doesn't matter if anyone else likes it or not. If I'm happy with it that is all that matters. Dude when someone looks at your car they don't know if it will do 100 or 300 miles an hour so what does it matter? I know there may be some who don't like my conclusions and they are entitled to their opinions and I am not trying to step on anyone but to me this is about having fun not my car is faster than your car. There have been a few times when I spent money that proved to be unproductive and then I wondered why I did what I did. Anyway what you do with your car is your business and I think what has been said in this thread is from people with experience as to what will and won't work. I'd just give it a lot of thought before I launched out and started spending money. Hope it all works out.

 

[warren s]

Warren, all of that knowledge you just filled me with, says that this costs a lot of money to do, like, A LOT... Also, I was thinking about getting a 6 speed, then gearing it so that it's top speed will be around 130 but improve it's acceleration, I've yet to ever have a reason to go over 120, so I figure 130 would be a good cut off, since it's above most other cars, and about 20 mph above most 1/4 mile runs. Just seemed like a good cut off speed, plus, I figure with a decent bit of hp, and six gears, that should make my hp band easier to fit correctly so that it keeps closer to optimal acceleration. What do you think, what would it cost, how hard would it be to do?

It will cost alot of money. A few grand at least. The type of transmission you have will not be a major factor in top speed. Even though the 6 speed has 2 over drive ratios, it doesnt mean the engine can "pull" in those gears. The 84 stock will be close to hitting 140 in a very long run as it is now.

To get your car into the 13 second quarter mile range, and have a usable top speed in the 130 mph zone, (Usable meaning it can go that fast in less then the space of the bonneville salt flats) It would need all the so called bolt ons and a cam change.
The crossfire injection system would have to go on the shelf for safe keeping.

 

[warren s]

That's a lot of feedback. Anyway my conclusion about bolt-on horsepower gains is that they are probably going to be minimal at best. There are things that a person can do to make a car run more effeciently such as air intake, exhaust, and possibly a performance chip but as far as significant horse power gains it probably just isn't going to happen. A motor is stock condition only has so much capability in it and you can't put ten gallons of water in a one gallon can.

That all depends on what platform you are starting out with. Some are VERY receptive to bolt on components. The LS1 for example. With long tube headers, a cold air box and “tune” the engine can pick up close to 50hp. The performance envelope from the factory has a pretty large range for improvement before things start to break.

. A change in one component affects all the others. The best intake in the world is going to be hindered by a poor exhaust. That's a no brainer. From my perspective I think the best thing to do is to build the performance incrementally with improvements to the overall system rather than try to overload one end while neglecting the others. It all comes down to money-how much a person has and how much they are willing to spend. If you're on a budget like me you do what you can when you can. If money is no object then why not just take the car to a high-performance shop and go for the big one? Personally I don't see why a person needs to take a car that will go 140 miles per hour and make it into a car that will go 200 miles per hour. How many times is a person going to have the opportunity to unleash all that power? Performance manufacturers love this kind of stuff-that's how they make their money. Don't get me wrong because whatever a person does with their car is their business but what is the motive? Just what is it that I am trying to gain. Personally I'm not out to impress anyone as I like my car and I am doing some small things to make it run more effeciently but the bottom line is is that it doesn't matter if anyone else likes it or not. If I'm happy with it that is all that matters. Dude when someone looks at your car they don't know if it will do 100 or 300 miles an hour so what does it matter? I know there may be some who don't like my conclusions and they are entitled to their opinions and I am not trying to step on anyone but to me this is about having fun not my car is faster than your car. There have been a few times when I spent money that proved to be unproductive and then I wondered why I did what I did. Anyway what you do with your car is your business and I think what has been said in this thread is from people with experience as to what will and won't work. I'd justgive it a lot of thought before I launched out and started spending money. Hope it all works out.

Its all about you own personal perception. Like any hobby it’s the small differences that make the big difference in your mind. Like spending $1000s on a camera when you can take pictures with a $30 cell phone. The list can go on for ever.

 

[bartric]

@Warren S, Would there be a way to change the 6 speed so it only has one overdrive gear? Cause like I said, now I think I'm quite set on getting an LT1, building it, and putting in a manual transmission and I really want to drop down the gearing ratios so that it'll keep a top speed somewhere between 120 and 140, and since I'm cranking out more hp, it should still have a good pull through all the gears, or at least, I would like to think so. And then pull out the Crossfire and rebuilding it and cleaning it up (the people before me didn't take such good care of it). That way when I sale it I can be like, power or stock, your choice, or just sell both engines with it (although, I don't really plan on selling the car anytime in the foreseeable future).

 

[bartric]

It will cost alot of money. A few grand at least. The type of transmission you have will not be a major factor in top speed. Even though the 6 speed has 2 over drive ratios, it doesnt mean the engine can "pull" in those gears. The 84 stock will be close to hitting 140 in a very long run as it is now.

To get your car into the 13 second quarter mile range, and have a usable top speed in the 130 mph zone, (Usable meaning it can go that fast in less then the space of the bonneville salt flats) It would need all the so called bolt ons and a cam change.
The crossfire injection system would have to go on the shelf for safe keeping.

Also, I read that the '84 stock's top speed is 149.

 

[warren s]

I dont believe its possible to modify the trans in such a way, however you can change the rear end gears to a differnt ratio for better acceleration at the expense of top speed. There is good chance the Lt1 will stress the stock rear end anyway.

The real question is, How much money do you have to spend on this project Vs the possible gains you can achive?

 

[Toms007]

Bartric, your attitude has changed dramatically since the start of this thread. From "I will not replace my Crossfire fuel injection system." to "Found an LT1 for sale for $600, thinking about getting it. How complicated would it be to change my car from an auto to a 6-speed?"

My personal opinion would be, figure out what you want from your car, if the 84 doesn't fit, then sell it and buy the car that fits what you are expecting....the L98, 85-91's, the LT1, 92-96 or the LSx, 97 and up. In the long run I believe that this would be in your best interests and easiest on your bank account.

You have received a lot of good advice here. And what it boils down to is horsepower costs dollars. Yes, each of the little things that you can do (bolt on) helps a little, but if you really want serious HP, it means digging into the internals and spending money on parts, machining, assembling and knowledge. I know this because I was once young and went through many of the same growing pains...actually I'm still learning those lessons and I'm not young any more.

I do hope that you can figure out what you want and can afford to do.

 

[bartric]

@Warren S, that was the type of modifications I was talking about, changing the gear ratio's so that my redline in 6th gear ends up being between 120 & 140. My money, well, lets say, my tree is slightly wilted, I'm 19 (which explains my attitude that it must be my way, lol, or at least that was my attitude), work at a fast food restaurant making minimum wage ($7.25 since it's probably been a while since you guys have gotten paid minimum wage), and about 400 every two weeks. That's my budget... lol. I know, pathetic.

@Toms01, Yeah, my attitude changed, mostly because I realized the ease of just an engine swap, and the benefits of having a powerful engine along with the stock crossfire engine as far as long term goes and selling benefits. Getting my ideal car would probably be easiest on my bank account in the long run, but seeing my pay check would make that hard to do. I would really like one of the LT engines, like possibly a '90-'95 with the LT5, that'd be amazing, but I doubt I have that much money, and I would be more than satisfied with an LT1. I want to stay with a C4 though. I don't want real "serious" hp, but I also don't consider 350-400 to be too serious. Now if I was going for 600-800, that's serious hp.

Does anyone else have any better suggestions? Should I just try to find one with an LT engine, or just try to do a drivetrain swap?

 

[Highway Man]

retrospect

That's a lot of feedback. Anyway my conclusion about bolt-on horsepower gains is that they are probably going to be minimal at best. There are things that a person can do to make a car run more effeciently such as air intake, exhaust, and possibly a performance chip but as far as significant horse power gains it probably just isn't going to happen. A motor is stock condition only has so much capability in it and you can't put ten gallons of water in a one gallon can.

That all depends on what platform you are starting out with. Some are VERY receptive to bolt on components. The LS1 for example. With long tube headers, a cold air box and “tune” the engine can pick up close to 50hp. The performance envelope from the factory has a pretty large range for improvement before things start to break.

. A change in one component affects all the others. The best intake in the world is going to be hindered by a poor exhaust. That's a no brainer. From my perspective I think the best thing to do is to build the performance incrementally with improvements to the overall system rather than try to overload one end while neglecting the others. It all comes down to money-how much a person has and how much they are willing to spend. If you're on a budget like me you do what you can when you can. If money is no object then why not just take the car to a high-performance shop and go for the big one? Personally I don't see why a person needs to take a car that will go 140 miles per hour and make it into a car that will go 200 miles per hour. How many times is a person going to have the opportunity to unleash all that power? Performance manufacturers love this kind of stuff-that's how they make their money. Don't get me wrong because whatever a person does with their car is their business but what is the motive? Just what is it that I am trying to gain. Personally I'm not out to impress anyone as I like my car and I am doing some small things to make it run more effeciently but the bottom line is is that it doesn't matter if anyone else likes it or not. If I'm happy with it that is all that matters. Dude when someone looks at your car they don't know if it will do 100 or 300 miles an hour so what does it matter? I know there may be some who don't like my conclusions and they are entitled to their opinions and I am not trying to step on anyone but to me this is about having fun not my car is faster than your car. There have been a few times when I spent money that proved to be unproductive and then I wondered why I did what I did. Anyway what you do with your car is your business and I think what has been said in this thread is from people with experience as to what will and won't work. I'd justgive it a lot of thought before I launched out and started spending money. Hope it all works out.

Its all about you own personal perception. Like any hobby it’s the small differences that make the big difference in your mind. Like spending $1000s on a camera when you can take pictures with a $30 cell phone. The list can go on for ever.

What I wrote was based on what the man has-an 84 crossfire. There again are those particulars that crop up from one engine to another. Like one person said the technology is constantly changing.:W

 

[bartric]

Well, like I said, what would be best?

I found a '92 Corvette for 9500 (seems a bit high since the kbb is only 8100 and since it's a '92). What would be the chance I could offer my 'vette + maybe 3000 and he'd take it?