This is the first big cross road of the project. Until now, I knew pretty much what I wanted to and what I expected the car to do. Previously, I had tried to keep to somewhat of a budget, since the point of the car was to go fast on little money. But, with an engine that is as totally destroyed as mine, I'm not sure there is a real cheap way out. Before a plan can be made to fix the car, I need to decide where I want to go with the project. The main concern is how much do I want to spend on this car. Until now, it was worked great as project while I'm still in school. Throughout the entire process, the car has been driveable and street legal. While this somewhat slowed it's progress, it made it easy to store and transport. I won't be in school forever, though, and presumably I will graduate at some point and get a real job with a real pay check. At what point should I stop spending money on this car, and start saving for something else (that something being a house? real race car? C5/C6?). One of my justifications for using a Corvette instead of a pony car was the hope to avoid sinking tons of unrecoverable money into it to make it fun. Perhaps I should just fix the car as cheap as possible, sell it, and look towards future goals. Or, maybe I should stick with it, and sink that much more into it and make it a Z06 killer. Choices, choices...
After some thinking, I decided I want to keep developing the car and see where it takes me. While saving for a future project (or real race car) is certainly a good idea, I think the C4 needs a chance to show what it can really do. And, quite frankly, I want to keep going fast. While being in school certainly limits how much I can spend on the project, it gives me a chance to build my skills as a driver and car 'builder.' So, now what engine to put in? The choices range from mild to wild:
| Stock, used LT1 | Power: 300 CHP | Cost: $500-800 |
| Rebuilt LT1/4 with head/cam work | Power: 375-450 CHP | Cost: $3000 |
| 383 LT1/4 with more head/cam work | Power: 425-475 CHP | Cost: $4500 |
| Stock, used LS1 | Power: 350 CHP | Cost: $5000 |
| Rebuilt, cammed LS1 | Power: 450-475 CHP | Cost: $6000 |
| 6.0L LSx with L92 top end | Power: 475-550 CHP | Cost: $6500+ |
Please note: all of these power and cost numbers are approximate guesses. I realize your buddy's cousin's roomate is making 11 billion hp from his LTx after spending only $20, but I don't care. I guess the first issue to resolve is to attempt an LSx swap, or leave it an LTx. LSx's are wondeful motors: tons of power, light, durable, and tons and tons of aftermarket support. They really do everything very well. The problem is everyone knows how awesome they are, and thus prices for used parts are high. The main issue with swapping an LSx motor into a C4 is the transmission. The C4 6 speed is called the ZF6. There is no easy way to mount it to an LSx. The differing flywheel sizes means a lot of custom flywheel/starter/bellhousing work has to be done (and no one has done it yet). Thus, the only sensible choice is an f-body T56. While T56's are excellent transmissions, they never came in a C4. This presents some isssues, namely the C-beam. C4's don't use a transmission crossmember, but rather have a large C-beam running from the output shaft of the transmission to the nose of the rear end center section. This beam is what provides the support for the trans. The transmission and rear end have mounts for the C-beam cast in; the T56 does not. There is supposedly a kit available, there has been some debate about its quality. Also, the T56 is longer than a ZF6, and the shifter is not in the same location.
The rest of the swap is pretty straight forward. Swap motor plates and headers are easily available, and the wiring, while tedious, is certainly doable. The real killer, for me anyway, is the fab work. While it certainly is doable, it is more than I can handle right now in my driveway, with no lift or welder. Also, the cost for all the details are a killer. While getting a stock, used LS1 running would be great and not that pricey, it certainly wouldn't be race-ready. I still need to get all the parts to make it reliable: Accusump, oil cooler, race oil pan, freshing bearings and oil pump, etc, etc. Whatever I put in needs to be fresh, and that pushes the cost of an LSx based swap even higher. As sad as it makes me, an LSx swap is out of the picture.
Now, what to do with an LTx? Stock? Built 350? 383? One goal for this project has been to continue to get faster. Throwing in a stock, used LT1 would certainly be the cheapest way to go. But, it will make the car slower. I really don't want to make the car slower. And it comes back to that whole "I really should work on making the car more road race reliable." So, I'm going to build something: 350 or 383? A 383 is pricey: crank, pistons, rods (might as well do 6"), machine work, etc, etc. The stock rotating assembly is pretty good, and should be safe up to 6500 rpms. While a 383 reved to 7500 would sure be nice, it will cost a lot more. So, stock rotating assembly it is. Money that can be saved on the motor while still achieving my goals is more money for the rest of the car. My goal for a while has been to have more power than a C5 Z06. 400 RWHP is a nice, round number, and would be ~40 hp more than a stock Z06. This seems like a nice goal, and certainly reachable with stock head castings and a stock bottom end.
Chapter 22 will detail the engine building process (with pics!), along with the parts I use to achieve my goals (as well as an actual list of my goals). More info to come as this mini-project progresses.
Sources for L92 info:
GM High Tech Performance
Car Craft