Any way to get good downforce front and rear without breaking the bank? I'm not so concerned about low drag coefficient, just trying to keep it on the ground.

 

Out of one of my ragazines a 70 vette has 230 lbs of lift on the front 55 lbs at the rear at 100 MPH. Obviously at higher speeds the lift would get worse, you will be doing good if you can just get rid of lift.

70 camaro has 325 lbs of lift front, 40 lbs rear at 100 MPH.

 

I didn't have my friend take good pictures of my 78 out racing. But with body rake............. you can get lot's of downforce. Here is proof. By the flag stand in the mid 150 mph with my foot on the floor. The front and rear are compressing the body down to the tires. It would take 1000+ pounds to compress my front just one inch and about the same in the rear.

 

ive read that the factory spoilers were actually functional in creating the downforce and less drag

 

I thought this was a major problem on C3's? Anyone know where you can buy a front and rear spoiler not just for looks but one that gives some heavy downforce?

 

Autocross guys around here are going to Tap Plastics and buy acrylic sheets to build see-through wings then bolting them onto their decklids. Front spoiler "bib" can be extended downward to keep air from getting under the car to help with front lift.

 

It is a major problem. Without appropriate measures being taken to shift the air pressure differential equation in your favor, the C3 has inherent lift issues at speed. As you've already surmised, a proper air dam and spoiler package is a good place to start; the dam serving to limit the amount of air that gets beneath the nose of the car and the spoiler "trapping" air on the top of the tail. Lowering your ride heights and having a little body rake will further help.

For pre-'80 bodies, the Pace Car dam and spoiler are functional in design, but the rear spoiler may be somewhat less effective on pre-'78 coupes, which are the least aerodynamic of all C3's. However, the factory dam will need additional bracing for much use over ~80, as it's a bit too flexible to maintain its shape over time at speed. Aftermarket versions don't seem to suffer this problem. I don't have pressure differential data from which to extrapolate lift/downforce numbers as of yet, but the sensitive instrument on which I sit can attest that the PC package (claimed to yield about a 15% reduction in C/D) significantly improves high speed stability in long, fast sweepers. Other available designs may be more or less effective, but the PC design is legit.

Among other in depth discussions of C3 aero you should be able to find on the CF, here's a recent thread you may find somewhat interesting...

http://forums.corvetteforum.com/c3-t...ics-et-al.html


TSW

 

I have body rake and the racing 1981 twin turbo front end which was used to race in places like the 24 hours of Daytona up around 200 mph on the high banking.

the front nose back has an aluminum pan and a air dam under the radiator to create a low pressure area under the hood

Yes, I have the L-88 fender flare kit to install now. In this picture I have 295/35/17 hoosier slicks and rears are massive NASCAR rear road racing slicks

 

George, that shot really makes those tires look even more huger. Hope you keep that color when you get it flared. BTW, haven't heard in a while how that other little vintage racing project is coming along.


Charlie

 

Optical illusion The rear wheels have 2 inch adapters on each side and the rear wheels are 12 inch width with 6 inch BS. So compared to stock Vette I have 8 - 10 inches more rear wheel track. on the front I have an additional 6 inches . It really helps going around the turns.

I got pretty dorked up from the flying motor pieces while operating the dyno last november and was out of work for a month. So I lost two months. Anyway it's basically done and the body is going in the paint booth. The plan is to take it to Infinion (Sears Point) and spend a day with a world class driver shaking it down to get a bases line with numbers. Then the boss and I will have a go at it. I hate that race track because if you screw up the car can get destroyed.

I told the boss that i would rather just buy the guy a plane ticket and we could do it here or Thunder Hill where it is very safe. Even Laguna Seca. In December one of our Brabhams F2's went of into the tires and it tore off the rear suspension on one side and the wing. It was probably a 10-20 thousand dollar wreck. I'm still putting it together for a 2 liter challenge race coming up weekend of March 7th

 

Must have missed word of the dyno disaster, but glad you're OK. Agree Sears can bite and that Laguna is safer, and so enjoyable a challenge, and so close to the 17 mile drive and to the aquarium, and... (Think anyone will notice I kinda like hanging around Monterey? )

Post up with results (here in C3, too).


Apologies to the OP for catching up on your dime. Got anymore Q's or comments we might can address to help out?


TSW

 

Where can I buy a bolt on front air dam and rear spoiler that will work?

 

Your profile doesn't say where you are located or year of vette. The ecklers 80-82 front body panels are somewhat of an improvement.

But I would find a local speed shop and have them fabricate the front chin spoiler out of a non-breakable material.

rear wings you can buy. How fast are you planning on driving?

 

I'm in Southern Calif.

 

CRAP, George, I missed hearing about that too.....

what happened to YOU??


Glad you on the mend, anyway.....What blew??? engine, mods. hoped for HP...etc.....

 

How did it happen on Nov 1st. to me? I work at an exotic historic race car shop here in Reno. We had rebuilt a jaguar racing motor for some billionaire in South America. My job after assembling them is to put them on the engine dyno. Where you break the motor in and run it numerous times making adjustments for maximum power before shipping them off to get installed in a race car somewhere.

We had run this one several times and it was the last run before boxing it up to ship. Well it had a faulty brand new damper from Jaguar England and it broke into three equal pieces just as it was passing through 5400 rpm on the test stand with me at the operating console. It is right in front of you not in a dedicated dyno room. So this 3 pound chunk of metal bounced off the cement floor and hit me right below the knee cap on the outside of my knee. So it was like somebody hitting you with a baseball bat and it shattered my Tibia Platue (lower joint) and tore up the cartilage. The shop owner right next to me and did not get hurt at all. It took me off my feet and the pain was kind of over whelming. My leg wasn’t on straight anymore, so we knew that it was not good. Any way after the orthopedic surgeons I was laying in bed for a month with my knee imobilized. I limping better everyday.

We are so fragile when you think about it. If I would have been standing farther back and took it in the chest throat or chin it would have killed me.


So I'm looking forward to driving a March F2 in Historic races this year. The entry fees are reasonable. typical 2-3 day event is @ $500 for HMSA events. I only want to do the West coast events. F-2's with great drivers can be right there with the fast times at any event. With 1:30 laps at Laguna Seca.

 

this is a very similar car as to what I've been restoring. this actually a March formula Atlantic car with muffler for the 108 db or so racing at laguna. That's our GT-40 behind.

 

Holy crap, George. That sounds downright painful. Glad you're doing better now. I can't wait to see pictures of your C3 with flares on it. I've always thought that would complete the look of your car. Good luck to you on your knee recovery.

 

Are you sure the car is being compressed? I understand that when a dragster starts spinning its rear wheels off the line , the centifigal force gives the tires a larger diameter. Wouldn't his happen at +150 mph?
Not saying yes , not saying no. Just wondering.

 

years ago i competed in some Nevada open road races. When you try to average 150 mph for 93 miles I took my tires pretty seriously.

I came across some posted data on goodyear road racing tires and recommended tire pressures for different speed ranges and they did have a section on tire diameter growth out to 200 mph. Just do some digging. It was really minimal.

Where as Drag slicks (Wrinckle Walls) have light weight construction and no side wall stiffness. They really grow just doing a 150 mph rear wheel speed burn out