I've got a mildly modified 92 C4 LT-1 automatic and am trying to decide whether to keep the car or pursue additional performance upgrades. What engine swaps are possible with this car that could be accomplished without the need for significant chassis and/or drive train modifications? I'm on the fence between keeping it and building the LT-1 to the extent possible, buying a new (or newer Vette) with a bigger power plant or doing some sort of engine swap with the C4. However, I don't have any idea about what kind of swaps are even possible. Any and all comments and suggestions are appreciated.

Thanks ........... WS

 

Nearly anything is possible, and "significant modifications" means different things to different people. Do you have a budget? What kind of power or times are you looking for? How long can the car be apart? Will you do the work yourself? More questions than answers at this point. After market block with all the goods and turbos. LSx block NA or FI. There are many many possibilities. What do you want?

 

Speed costs money. How fast do you want to go??

You really didn't say how much of a performance increase you want. One thing that would provide a good increase would be a supercharger. Build a nice strong bottom end and a blower (depending on the boost level) could get you something like a 200 HP increase. Also consider more displacement over stock. Going to 383 cubic inches or even something like 406 is doable with you r LT1 block. Add a larger cam, long tube headers with dual exhaust, some head work or even aftermarket heads can result in a hefty power increase.

Don't forget a performance tune. You didn't say what mods the engine has, but a good performance tune can easily add HP and torque to what you already have.

One of the things that lots of people either overlook or wait until there are broken parts is a strong trans and diff. You didn't say how many miles are on the car, but definitely save funds for building a trans that will handle the power you're after. Same with the diff. In your case, swap the existing D36 for a D44 and then look at a variety of gear ratios.

 

I'll try to answer the questions and suggestions raised in the previous two posts in the order presented ...

Do I have a budget? - Not really. I'm prepared to spend quite a bit of money to build the LT-1 if I think the ROI is favorable. If spending more on a newer Vette will give me more what I'm looking for, then that will be the choice.

What kind of power or times am I looking for? - Times are more important to me than dyno numbers. I'd like to get the car into the low-to-mid 11 second range. Let's say 11.50 or better.

How long can the car be apart? - I'd like to get it done within 6 months.

Will you do the work yourself? - No, none of it. I am 62 years old and just now learning how to turn on my computer. Everything from start-to-finish will be farmed out. There are several competent and reliable Vette techs and engine builders within 2 hours of where I live. They've worked on a lot of Vettes in the local area and they're all flying.

How fast do you want to go? - See above. Low-to-mid 11's provided the car is still street-driveable.

How much of a performance increase do you want? - Again, I'm looking for a street-driveable car that will run low-to-mid 11's. I want whatever performance upgrades will get me there. Since the option of adding a supercharger (either now or later) is definitely on the table, rebuilding the bottom-end is part of the plan.

Considering more displacement over stock? - Yes, definitely. Since the bottom-end will be rebuilt, now is the time to do it ... "there is no replacement for displacement".

Considering larger cam, long tube headers, head work? - Again, definitely yes. Right now, the car has a 430hp Trick Flow top-end package which includes TF's version of the LT-4 "hot cam", American Racing headers, 3.54 gears and a 2500 rpm converter. I've spoken to Lloyd Elliott - his preliminary recommendations included extensive work on the heads and intake, a much bigger cam and a 3400 rpm converter. Lloyd does not perform bottom-end work, so we didn't discuss the supercharger option.

Performance tune - My current set up is running a custom tune from Ed Wright. Lloyd suggested that I stick with Ed. He also suggested talking to Ed about upgrading to a later model OBDI or OBDII system with a MAF for better tuning options and results. I'll have my tech talk to Ed. The two of them used to work together for GM.

Transmission & Differential - If I add a supercharger, the existing tranny has to go. If not, I'll stick with what I have until it needs to be replaced. The car has a D36 diff, so I'm limited to 3.73 gears. Once the tranny goes, I'll switch over to a D44 with whatever gears the "experts" recommend.

Engine Swap - Another option that I am exploring. I don't know if it's possible and, if so, what would be involved, but I'd be thrilled with a LS-3 376ci / 480 hp motor. If that could be done along with a supercharger all other bets are off. However, I doubt the LS-3 is a viable option for a C4 without a LOT of extra work. We'll see.

I hope I covered everything ......... WS

 

WS - since you are in Maryland (and you said within 2 hrs), the only person I would even consider doing my car is this man:

https://www.corvetteforum.com/forums...essdriver.html

He has done cars/motors for several forum members and I would trust anything he told me 100%.

Matthew

 

Thanks for the suggestion. I contacted "rkless" last week, but these days he's doing engine work on a very limited basis. He suggested I contact Maryland Performance Center and praised the quality of their work. Right now, I've been talking to Lloyd Elliott (Texas) and Karl Ellwein (Southern Maryland). Both of those guys have extensive experience with LT-1 motors. My local engine tech does very good work, but spends of his time working on LS motors. Also, he does not offer machine shop services so all his machine work is farmed out. Depending on the customers wants and needs, he sends heads and intakes to either Lloyd, Karl or Advanced Induction. He uses a couple of different local machine shops for bottom-end machining, but does all final engine assembling himself.

 

You could just buy my car! I just finished this project and Im considering selling. Its a 1992 zf6 car. It has alot of modifications! The suspension is all dual adjustable coilover set up. It has a fully built, forged 383 lt4 with huge heads and a procharger D1sc on it! As of now with a very very conservative tune it makes 545 RWHP and 540 Ft/lbs. It has only been to the track 2 times and has been 11.21 at 131 MPH. It will easily run tens with more seat time and after the suspension is dialed in. The car has 60k miles on it. The build has maybe 2500 miles..

 

Thanks, but that's not one of the options under consideration.

 

No problem. Sometimes buying a car that is done is ALOT cheaper than paying to have one modded.

 

No doubt about that. What are you asking for it?

 

Im not sure. I have over 20k in parts on the car alone. All receipts and documentation. No labor included in that. I did it myself.

 

Nice job covering the questions. The LS-3 is doable. Several have gone to an LS. Ch@os is one of them. Here is an EROD LS swap. I'm not sure how much of their original dash/guages work. I think putting the engine in would be the easy part. As for the LT engines, a large CI 383, or 396 and a supercharger should be like the easy button. No changes in wiring or guages and it may pass emissions. Greg @ Blowerworks is still doing kits for your car and can also help with tuning. The LT would not have the flair the LS has, but it could get the job done. Mid 11's should be no problem if the whole thing is thought of as a system. One other item to consider, are you wanting to keep the AC?

 

Well, in that case you're a pretty talented and knowledgeable guy. It adds up pretty fast, doesn't it? But then no one ever said going fast would be cheap.

 

This sounds encouraging. As for the gauges, I was thinking about swapping out the stock ones for something like this ...

http://vettaid.com/ReplacementGauges...ePackages.aspx

I'd like to keep the AC, but giving it up wouldn't be a deal breaker. The car is just a toy that I like to play with, so I'm not concerned about how any of these modifications might impact its future value. When it comes time to give it up, I'll just take the best offer whatever that might be.

 

A C5 will be much cheaper. Sorry to all of the C4 guys (I'm one, by the way), but if you aren't married to the C4 platform, can spend a little more money, and really want performance potential, a C5 will give that.

Reasons:

1) LS engine is already there! (If you're looking for 500 hp or more, you've already saved money going to a C5.)

2) Better chassis; the C4 is great and has a very visceral feel, but the C5 is stiffer and provides better suspension geometry.

3) Better resale!

In short, a $5k C4 with $7k in modifications (engine swap) will probably not match the performance of a $10k C5 with $2k in mods. As the mod numbers rise so does the disparity between C4 and C5 performance. There are two main reasons: first, the C5 has an LS, which more easily makes a lot more power, second, the C5 just has a stiffer chassis. With enough money you can put an LS into a C4 (which would cost more than selling it and buying a C5), but you'll never bring the chassis up to the level of a C5.

So, if you love the C4 styling, like I do, and really want to make the most if its platform, go for it! Spend the money, make it great, tell us about it. But if you're really not committed and are looking for the best sports-car value out there, by a C5.

Obviously more than 2 cents.

 

Sounds like you have an awesome set up already. But the LS's have so much potential, that it's impossible to ignore. I vote LS, then boost it which ever way is your preference. Here is my Z51 LS ZF6sp. I've had TT C5's before, IMO this is the best of both worlds. So again, my vote is jerk n sale your motor(which should be easy), then drop a LS, and start making real power. O, and all my gauges work, just use the Dakota box.

 

Decisions, decisions ... you guys are absolutely killing me!!! Just kidding. I really do appreciate all of the comments and suggestions. Right now, all options are on the table. My C4 is my first Corvette, so there probably is some level of "romantic attachment" that I'm dealing with. I'm normally pragmatic about most everything, so I'm sure when it's all said and done logic will dictate the final decision. Tonight, I looked at a nice 2008 C6 with the 376/430 motor and 4LT package. It only has 17000 miles and I can get it for $30K ... the seller is in a financial bind. If I buy it, I would almost certainly toss in another $10K for a supercharger and intercooler. That would easily put it at around 600 to 650 hp. Right now, I have around $22K invested in my C4 and trying to get that car to 650 hp (if it can even be done) would easily cost another $20K for a new bottom end, supercharger, transmission, etc. And that's for a 23-year old car. I like my C4 a lot, but at some point common sense and logic must prevail over a juvenile "romantic attachment". In the mean time, the search for the Holy Grail continues.