ptindall

Got a guy claiming to have a race prepped '85 that weighs 2225 lbs that he built for less than $12,000. He claims making a C4 this light is cheap but that making a C5Z06 that light would cost 2-3 times as much. What's the real story? Can his car possibly be that light? How exactly is a gutted C4 significantly lighter than a gutted C5 Z06?

69427

Not saying yea or nay, but doesn't a stock '85 weigh about 3200 pounds? I assume he removed the a/c, carpeting, spare tire, and power seats but there still seems to be a long way to go to get to the 2200# neighborhood.

FAUEE

I've seen some C4s stripped. Down to 2800 pounds or so. 2200 would be a major deal, 2800 pound cars have replacemwnt hoods, no windows, moat conveniences removed, fuel cells, etc.

Scooter70

Anyone know what this guy's target weight is?

http://forums.corvetteforum.com/auto...build-log.html


Edit: In post #76 he says he's shooting for 2500lbs.

Look at that build and then compare it to simply gutting a race car. No way a simply stripped out car anywhere close to 2200lbs.

froggy47

Ditto, I don't believe 2225# ask to see the weigh slip.

ptindall

The car has an LS6 swap, 700r4 trans, and lexan windows. If its possible to make a C4 that light and complete the entire car for less than $12,000 like he says, that's impressive, but seems hard to believe. And equally hard to believe it can be done with a C4, but not with a C5 Z06. The car is an X prep autocross car.

rfn026

I would love to see his print out. I'm at 3024 lbs. Gutted interior, one race seat, no spare, no a/c, etc. I just don't we how he did it.

A guy in Michigan had an entire body made out of carbon fiber and got down to maybe 2500 if I remember right.

I might not even believe a print out on this one. I would have to actually see the car on the scales.

Richard Newton
Car Tech Stuff

spazegun2213

Wow, this sounds like a good story, but I'd want to see the car on scales.

2200lbs is stupid light for a corvette. I wonder if the ~12k included a lot of free labor and fabrication. I'd assume you'd have to remove lots of the frame and weld in lighter parts to achieve that weight.

Then again I've seen striped out c5's with light wheels, lexan and carbon everything hit around the 2500lbs range (I'd assume that was a dry weight as well). I'm sure that car cost him a small fortune, and I could not fathom taking another 300lbs out of that car....

froggy47

I was thinking the same thing 2500# is believable dry.

UniqueDoug

bspvette

Alright Guys. I'm the one the OP is talking about. Apparently he is on a mission to prove himself right at all cost.

The last time the car was officially weighed was earlier this summer at 2,362 wet. Since then, parts have been changed & removed to the tune of 137lb. That brings the weight down to 2,225lb on paper. Probably not going to get it officially weighed again until spring, since there are other things I plan to do over the winter. We are planning to replace the old 700R4 with a lighter manual tranny (Like a T56, beefed up T5, or 3-speed Jerico) which should lighten the car another 30-60lb. Then we can worry about strategically adding weight to get up to the minimum of 2,226lb.

But the OP keeps asking how this is possible, and it seems that you guys agree that it seems impossible. I said the same thing when the season ended last year. I had been running at around 2,650lb with what I considered a "gutted" car for quite awhile. But my new co-driver challenged me to see how close we could come to minimum weight. So we started working to find every spare ounce last November, and didn't quit until we had to button everything up for the 2013 season.

To get to the 2,650, I had done all of the standard "gutting". Plus, I had changed to a 5gal plastic fuel cell. Everything was removed, including ALL wiring harnesses, that were replaced with the basic wiring needed for racing. The doors were gutted, but the steel was still there. Replaced the windshield with an 1/8" Lexan piece that I made. I had a 600hp SBC with single 4-barrel, lightweight Real Wheels with Hoosier Bias-plys, and all heim jointed rear suspension that I put together myself. I added a standard 4-point roll bar that I custom bent, and had a friend weld in place.

So with that baseline, we started removing things to get down to 2,362. I don't have exact weights for most things, since we just took removed parts each day & put them in a bucket to weigh at the end of each day. But most of the stuff was very small, like misc weatherstrip pieces (very light stuff, but it adds up), unneeded bolts, redundant brackets, large chunks of door supports. We paid attention to a lot of things like 8 long bolts attaching the aluminum rear bumper support clip to the main frame. We reduced it to 4 bolts.

Extra flanges of material on the bumper covers was removed.

Removed the frame from the clear roof, and just bolted the plastic panel to the A & B pillars (13lb).

Then we removed a bunch of metal from the front & rear bumper support areas.

Cut all structure out of the hood (Left hinge supports) 26lb

Removed hood support, and upper wheel well pieces.

Removed rear wheel well pieces.

Removed second cooling fan.

Removed side mirrors.

Changed from stock type transverse leaf to coilovers. (don't know if that was lighter or not.)

Added small tranny cooler to old license plate location for better weight distribution.

Replaced SBC with stock LS6 sourced from Craigslist. Running a single 4bbl intake with the MSD spark box for the LS coils.

Then hand fabricated an aluminum splitter for the front.

I fabricated aluminum covers for the headlight holes.


Since the weigh-in at 2,362lbs, I have:

Replaced the rear window with 1/8" lexan (36lbs).

Switched to lightweight brake rotors (11lbs).

Cut out the rear cargo area & replaced with flat .031 aluminum sheet. (18lbs). All that plastic was surprisingly heavy.

Removed door bars & lightened hinge hardware (18lbs).

Changed to a lift-off VFN fiberglass hood (40lbs).

Changed to VFN fiberglass nose (14lbs).

There are lots of things we've done for my AutoX car that you would never be able to do on a RR car. For example, my windshield starts to buckle at about 75mph, so it would be completely inadequate for RR. And you would be crazy to remove front & rear crash structure on a track car.

I'm sure I've probably forgotten about some things, but it really is an honest weight.

BeerMan

bspvette

Oh, and I've think I've saved a lot of weight by staying with 16" wheels & original brakes. Most guys want to bump up to the large dia wheels & big brake kits. But for AutoX I found the small stuff to be more than adequate, especially with the lighter weight.

BeerMan

bspvette

You are right. It was a major deal. We spent countless hours looking at every part to determine if it was really important. And then removed the stuff that seemed unimportant. It's not that we removed MOST conveniences. It's that we removed ALL conveniences.

I was quite nervous at the beginning of the season, because I figured we probably miscalculated on the importance of some parts. But I was surprised that the car ran great all year. No failures of any kind. This was the first time in several years that I had no mechanical failures.

The only small issue was that downforce from the splitter pulled the nose away from the front of the car, due to all the removed structure. I'll have to fabricate some supports for the new nose this winter. That will probably add 3-4lbs.

BeerMan

UniqueDoug

Well there you go BeerMan, great post.

bspvette

I followed this guy's build. Wish he would finish it to see where he ends up. He says it is going to be more economical to do the Ecotec/Turbo thing than the LS, but that's hard to imagine. I'm in the Turbo business, so I have an idea how much THAT stuff can cost.

IIRC, he works for a turbo house also, so he's probably planning to call in some favors to keep costs down.

I think it will be really cool to see how it ends up. Corvettes are such an underdog in XP, which is dominated by Lotus, Mr2, Miata, RX7, etc.

BeerMan

bspvette

Correct. It includes a ton of my free labor, and a little bit here & there from various friends. It also includes a few favors, as well as a bit of bartering to get parts I didn't have the money for. And one of the best things is that this project has caused me to develop some pretty nice metal fabrication skills.

We removed a lot of excess frame material, but none in the main box area that supports key structures of the car.

BeerMan

drivinhard

With no cage or a smallish 4 pt rollbar, I can see it. My car (C5Z) would be right about that if you tossed all the ballast and cut the cage out (about ~130 lb). OEM body panels except for the hood (ACP carbon @ ~15 lbs).

He is right, it's all in the little bits and pieces, there is no big heavy silver bullet. It's just real little stuff at quantity of 500

RX-Ben

You guys and your aluminum C5 test mules!

ptindall

Thank you for actually explaining, beerman. Now can you explain how similar work could not be done to a C5 Z06 without spending double the money? There is very little in your list that actually costs money at all. As I said, it's almost entirely the removal of parts, which costs the same on any car; nothing.

drivinhard

Yeah and I'm sure with your whole body for sale and that you probably just put on ANOTHER stock body , that you have a pig heavy turd