Taijutsu

Forum: I think most would agree that our C3 needs some better aeros.

I believe a front splitter is better than a front spoiler?
But who has made a splitter for our cars other than BJ?

On the rear I was looking at diffusers and their effectiveness.
Has anyone tried to put an effective diffuser where the spare tire carrier is?

The big question is: Does it work? lol

R

C3DeedlyDee

Are you looking for downforce or trying to minimize drag?

Kevova

I would Google Greenwood Corvette. His company led the way in C3 aero.

mobird

I think on the front, I wouldn't want to mess with the aero much because the C3 uses that front little splitter to suck air up to the radiator.

On the rear, I could definitely see where a diffuser would be useful! Especially for the people like me who have removed the big rear bumper brace and spare tire carrier, there is a big area under there now that is like a big fiberglass parachute haha. I could see where just a bottom plate or something to help direct air away from the hollow rear bumper cover could be useful...

keep in mind, lowering your car makes a difference in the drag coefficient. Lower car means less air going under the car (effectively what a front splitter is doing). You would probably have to pretty much have your car slammed to the ground to make a difference though.

What speeds are you running at? At normal speeds aero will not make a difference. If you are doing half mile events, high speed road courses, or have a heck of a motor under there and you are going 120+ in the 1/4, I would say it is worth looking into Aero.

Keep in mind, aero goes both ways. People on a road course are usually applying aero for downforce (to use the wind force to press down on the front and rear tires to give more grip) which actually LOWERS the car's top speed.

While on top speed runs, you more often see aero to make the car more "slippery" and have less drag to reach a higher top speed.

gkull

A true splitter creates frontal down force. An air dam keeps air from under the car, the lower air pressure induces downforce.

I can't find the c-3 GT1 photos, but they installed a rear diffuser like what you see on your typical Porsche 962 that I worked on.

Taijutsu

I want to run fast enough that more downforce would be nice! lol

The autocross guys have a plexiglass panel they bolt onto the rear spoiler.
The driver said he couldn't run as fast w/o it.
He also had to take it off for the road course events.

I want to run the silver state and feel safe.
For now I'm thinking the PC aero kit to start.
The diffuser looks reasonable for a car w/o spare tire carrier?

I notice that the serious cars spend time cleaning up the undercarriage!

R

mobird

What kind of power is your car currently making? And what suspension mods and wheels/tires are you running? How about weight savings?

All of those things will make a MUCH bigger difference than aero. ESPECIALLY good wheels and sticky tires. If your bushings haven't been replaced, replace all of them, your car will handle MUCH better.

Let me put it this way, if your car is stock (or near stock) the old 15" tires aren't nearly as grippy or stiff as modern tire designs and compounds, so you are probably giving up the most time on the autocross course there. Second, if your suspension is original, you have a TON of time to gain on the course there. On a budget, a composite leaf spring, new front coils, Bilstein Sport shocks all around, and new bushings will put you in a different league from an original car.

Also power and drivetrain will make a huge difference. If you are running an auto with a 3.08 rear gear, you are probably rarely in the right gear or area of the powerband when you come out of the corners. Consider re-gearing so you can get on the power out of the corners.

All of those things will make a TON more difference than aero, and there is alot more you can do after that (adjustable control arms to give you better caster, weight savings which improves every aspect of the car, better brakes so you can brake later, etc...)

If you know all of that already, than I apologize for reiterating it! You just didn't give much info so I assumed. Basically, until you are at the point where your car is set up perfectly (and you are a VERY good driver) and looking for those last couple .10's of a second, aero isn't really going to make a difference on an autocross course.

If you are running a half mile event or something high speed, then yeah I would look into aero. I wouldn't want the nose of my car lifting at 150 mph.

Bikespace

Put on a front clip from a 1980-82. It will still look "stock", and does work a bit better. There are several mullet corvettes floating around the Forum, like the 1975 that just found a new home with a new forum member. (I can't paste a link with my phone...)

Gale Banks 80'

I did the Silver State in 1993. I don't see what Year or era of C3 You have. When I was threw with the SS I came to the conclusion that what I had done to my C3 wasn't really the best set up. I had done the usual Suspension enhancements and wider Tires or what You want for Autocross. 17 x 9.5 Rims with 275 Tires which was way wide in 1993. The Hwy 318 was in very worn condition from the Trucks at the time, and driving with those Tires at 140 mph was not ideal. My car was is a late C3 which has a little bit better Aero than the earlier cars. I ran the popular side skirts and front chin spoiler of the time and I guess it did OK it didn't take flight. Two Aero mistakes I made was that I didn't disconnect the Headlights so after running 10 minutes with out any vacuum ( Turbocharged Engine ) they opened. I also didn't get the drivers side window up in time at the start and the Vacuum sucked it out for the rest of the race.
If I was to do it again I would build a Plastic Front Spoiler as low to the ground as You dare and not plan on having much of it left by the time you get to the finish. I would find out what condition the road is in before hand. I would set the car up for fast straight away speed and not worry to much about cornering there are a couple of 90mph corners in the Canyon and that's about it. A slow steering box ratio would be a plus. The safety regs will dictate your speed class and I doubt that it will be fast enough to where wide wheels and tires will do any good at all. The most common frailer is Tires take the freshest set you can get. When one blows it destroys the car it was on. Have fun it was a Blast for me something I will always remember.

gkull

Like gale banks 80 said. I was in the 150 mph class which limited me to a maximum of 175 mph. You are trying to hit right on your 150 mph average for the 90 some mile course so your passenger is monitoring the stop watch for known times at the various road markers to tell if you are on schedule

for your application you need your racing experience and licenses held. I'm out of the loop, but the SS race had a two year waiting list years ago it was just the main event out of about 4 in Nevada. The Pony Express was one that my friends entered

all I did for my first event was a custom chin spoiler with a 4 inch rubber bottom right down to the pavement. Body rake with the front end way down 550 front springs rear wing and 500 pound rear spring . I also spent a bunch of time calculating the best gears
you want to limit the amount of air coming in the front grill area. You don't want so much air going through the radiator that you build air pressure and front end lift I had plenty of testing before the Silver State event

my experience induced me to buy my 1981 daytona front end and QA1S with 700 pound front springs

Taijutsu

Forum: Thank you for the info and support.
The SS is on my bucket list for sure!
I didn't know about the other events?


I want a track car I can drive hard to and from the event.
The idea of a short blast down a drag strip is OK.
But I want Max bang for my buck.
Auto-X is a possibility for chassis tuning?

I am much more interested in driving very fast for 90 miles. Eek
I understand I would have to get some instruction/certification.

Not sure how much sack I have these days? lol
But I would like to find out! OMG

Thanks

R

gkull

This is what Wikipedia says the modern rules are. They skipped over the tire requirements. I had to have a SCCA cert cage, all SFI stuff including drive line hoop, onboard diver and engine fire system, and I see that they dropped my class top speed to 165.

Rick it is not all that bad, Just a sunday drive in the country for about 45 minutes in the 120 mph class

1. Touring Class (Speed classes: 95, 100, 105, 110 mph)

Stock street cars with regular 3-point seatbelts may be run in this class. A handheld fire extinguisher must be fitted, while gloves and Snell approved motorsports helmets must be worn by drivers and navigators. First-time drivers must run in this class unless they have appropriate motorsports experience. At no time may the car exceed the Tech Speed of 124 mph (200 km/h).

1. Grand Touring Class (Speed classes: 115, 120, 125 mph)

In addition to a handheld fire extinguisher, gloves and Snell helmets, the car must be fitted with 5-point or 6-point harnesses and (from 2007) window nets or arm restraints for the driver and navigator (if present). Open cars must have a rollbar fitted. At no time may the car exceed the Tech Speed of 140 mph (230 km/h).

1. Grand Sport Class (Speed classes: 130, 135, 140, 145, 150 mph)

In addition to the above equipment, all cars must be fitted with a rollbar or equivalent roll-over protection. Drivers and navigators must wear fireproof racing suits. At no time may the car exceed the Tech Speed of 165 mph (266 km/h).

redvetracr

this has been converted back to being a `70 w/rear clip on trailer), the suspension consumables need to be updated but with a good motor & trans it will get you what you want, really nice SCCA legal cage already installed, send a PM if you or anyone else is interested

.

Taijutsu

George: What are the other 4 events you mentioned?

I have considered the Virginia City Hillclimb.
My big tq SB "315 rwtq" w/M-21 should get right up the hill?

I want to ease into this before I take the big leap! Eek

Any advice?

R

gkull

I've done the Ferrari hill climb out of Carson City Nevada towards Virginia City. I would not recommend it unless you have a death wish. People seem to die there most every year in mega buck machines. You miss a turn and you are sailing off the mountain. Or you slam into the rock road cut and then bounce off and out into space and land on the rocks way below. It is also kind of invitation only after you apply.

The Silver State classic dropped the unlimited class because of all the deaths.

Silver State Classic Challenge

Nevada Open Road Challenge

http://lonestarcorvetteclub.com/cont...odule_id=84720

don't know if they run this one anymore.

http://www.roadrunnerdon.com/html/pony_express.html

gkull

They have added guard rails and made the hill run shorter because of the two deaths in a Viper and I think that it was an AWD racing Porsche death.

Here is an example of the Virginia City hill climb. Pro drivers used to bring out full on TransAm racing Vettes and Camaros when TransAm was a full series in the mid 2000's. After competing in my RR Vette back in the mid 2000's. I went to the tamer volunteer worker for the event because I worked at the local Ferrari shop.

This is an example of the course.

https://duckduckgo.com/?q=virginia+c...ai=gYJycPV51ZQ

Taijutsu

George: I was hoping for some laps at Buttonwillow on an open track day. lol
The wife would frown on death and destruction!

gkull

You have two relatively close tracks. Sonoma which is fun, but somewhat dangerous. There are some turns where guard rails are a possibility. Thunder Hill is a very safe track. big run off areas and you would really have to work at it to ever hit a solid object. I would look at the thunder hill race track schedule and find out when they have a test and tune open track day or join the SCCA and start at the bottom taking all they classes and work your way up to getting out on the big road courses. As a SCCA driving instructor I got to ride along with a few scary people that should have never been allowed out on a high speed track. They should have never been passed auto-X solo driving.

NewbVetteGuy

THIS. I am just consistently shocked that there's no rear diffuser options for these cars. Like Mobird said, after you remove the spare tire carrier the rear bumper is just a giant parachute.

Taijutsu if you find anything, please report back.


Adam

mobird

I'd be interested as well. But I am more of a DIY guy (read: cheapskate) and most likely wouldn't purchase one unless it was pretty cheap. HOWEVER! I am planning to fab one up later this year. It's easier in my case since I have side pipes, so there really isn't much I have to avoid back there and it would basically be a sheet of aluminum from the bottom of the rear bumper cover to the diff housing area. Can't imagine it would be very difficult, and I could paint if black so it doesn't stand out.

I'll make a thread and take some pictures when I get around to it. It is one of those things that is kinda "theoretical" since it will be difficult for me to get any actual data to show any improvement it might give. But I think of it as more of peace of mind that there isn't a glaring flaw like that on my car haha.