Plastic Fantastic 2

[SuperBuickGuy]

Isn't the test (I can't remember who, just it was a yellow C3) with the yarn still on here? - the video - I'll look later, but that was interesting in where the yard was going. I'll have to copy that test once this is stuff is installed

That was JPhil. The pictures are still on here but he never started a topic.

thank you

 

[mfain]

Here are two noteworthy quotes from an old Motor Trend aero comparison of the Gen 1 through Gen 5 Corvettes:

https://www.motortrend.com/how-to/corp-0905-corvette-wind-tunnel-testing/

"Want to see why a fastback is an advantage in a sports car? This C3 has the iconic vertical rear glass with buttresses on each side. The aero effect of this arrangement is to create a low-pressure area that actually sucks air back toward the glass. As you can see here, the smoke is pulled toward the rear glass and against the flow of air in the tunnel. The turbulence created also keeps the air from separating cleanly from the rear of the car."

"Aerodynamically, the C3 we tested, a '70 model owned by Robert Morgan, doesn't differ much from the C2 split window. In fact, with the headlights up, it actually produces more drag (9.09 to 9.73 CDA). The addition of the tiniest rear spoiler, however, did help produce 13.9 pounds of downforce in the rear (shown as negative lift on the chart). This is the only car that was able to produce negative lift numbers."

Sounds like a sloped back window would significantly help whatever spoiler or wing you decide to use on the rear. (Like the old Monte Carlo NASCAR back window). Would be fairly easy to build and could even be made removable. If you can increase the efficiency of the wing, then you have a better chance of creating the downforce you want without adding a bunch of drag. There are also a number of folks experimenting with vortex generators along the top/back edge of the roof to alter the location of turbulent air with respect to the rear wing, but that is probably overkill for the amount of rear downforce you will need. I run the wing on my ACR at a fairly low angle of attack to reduce drag. In the normal factory recommended high downforce mode it produces almost 2000# of downforce at 177mph - more than I ever needed. I probably get 700-900# at 130-140 mph or so where I need it for high-speed sweepers, and I can feel the downforce at 80-90 mph in tighter corners, especially on corner exit. It is easier to create rear downforce than front, so the trick is find a balance so it doesn't push like a dump truck.

 

[SuperBuickGuy]

Here are two noteworthy quotes from an old Motor Trend aero comparison of the Gen 1 through Gen 5 Corvettes:

https://www.motortrend.com/how-to/corp-0905-corvette-wind-tunnel-testing/

"Want to see why a fastback is an advantage in a sports car? This C3 has the iconic vertical rear glass with buttresses on each side. The aero effect of this arrangement is to create a low-pressure area that actually sucks air back toward the glass. As you can see here, the smoke is pulled toward the rear glass and against the flow of air in the tunnel. The turbulence created also keeps the air from separating cleanly from the rear of the car."

"Aerodynamically, the C3 we tested, a '70 model owned by Robert Morgan, doesn't differ much from the C2 split window. In fact, with the headlights up, it actually produces more drag (9.09 to 9.73 CDA). The addition of the tiniest rear spoiler, however, did help produce 13.9 pounds of downforce in the rear (shown as negative lift on the chart). This is the only car that was able to produce negative lift numbers."

Sounds like a sloped back window would significantly help whatever spoiler or wing you decide to use on the rear. (Like the old Monte Carlo NASCAR back window). Would be fairly easy to build and could even be made removable. If you can increase the efficiency of the wing, then you have a better chance of creating the downforce you want without adding a bunch of drag. There are also a number of folks experimenting with vortex generators along the top/back edge of the roof to alter the location of turbulent air with respect to the rear wing, but that is probably overkill for the amount of rear downforce you will need. I run the wing on my ACR at a fairly low angle of attack to reduce drag. In the normal factory recommended high downforce mode it produces almost 2000# of downforce at 177mph - more than I ever needed. I probably get 700-900# at 130-140 mph or so where I need it for high-speed sweepers, and I can feel the downforce at 80-90 mph in tighter corners, especially on corner exit. It is easier to create rear downforce than front, so the trick is find a balance so it doesn't push like a dump truck.

yes but? what follows is a thought process - it may sound like a defense, it's not.... as I respect all of you here, I'm listening to your advice.... even if I don't follow it or seem to be argumentative (which I'm not intending to do so)...

whew - with that disclaimer

I'm 100% certain that if I'm ever at speed - it will be with the rear window out of the car and windows down.... fun fact, with the windows up it and the rear window removed - it'll blow your sunglasses off.... also, I may race with a full kirkey seat - the Corbeau seat is tight, but I don't have any room between my helmet and the roof (I don't touch at rest, but it's too close)... thus window out, windows down and top off should be good enough for my decided lack of ability.... not being mean or self-defacing, just kind of laying out my thought pattern here.

Also, if aero was everything I'd have stuck with my 50 Studebaker truck or bought a Firebird. If I was rich, I'd be racing a C1

In that vein, I've always loved the shape of the C3 but it's not my first choice but it was the first choice of what I could afford. That started me in the C3 hobby - now, I'll make allowances so I can keep racing it.... even though it isn't the best or even a good choice.

 

[SuperBuickGuy]

Just to mention something

I've never had the car oversteer.... understeer, yes, oversteer... never

I also have a plan

I forgot that when I built the frame and upper mounts for the front that I gave myself room to trim and give me more camber. It's enough that, with the new rotors coming (stay tuned) that I won't need a special offset.... I maybe even put more camber in it because that's an option.... and my entire plan for this Sunday.... also it means that I may get neutral or even tail happy (oversteer) after the adjustments.

 

[BBShark]

Isn't the test (I can't remember who, just it was a yellow C3) with the yarn still on here? - the video - I'll look later, but that was interesting in where the yard was going. I'll have to copy that test once this is stuff is installed

That was JPhil. The pictures are still on here but he never started a topic.

thank you

I loaded the images into the tech section:

http://www.vettemod.com/forum/showthread.php?p=135868#post135868

 

[SuperBuickGuy]

Isn't the test (I can't remember who, just it was a yellow C3) with the yarn still on here? - the video - I'll look later, but that was interesting in where the yard was going. I'll have to copy that test once this is stuff is installed

That was JPhil. The pictures are still on here but he never started a topic.

thank you

I loaded the images into the tech section:

http://www.vettemod.com/forum/showthread.php?p=135868#post135868

thank you. Interesting that the middle of the car at 110 doesn't suffer that low pressure rear window issue, but 6" on either side of center does

it's also reaffirmed that I'm building an air intake that comes from the bottom of the windshield... I strongly suspect that the intake I have no isn't large enough.... to the aluminum store....

 

[rtj]

You mentioned h-pipe. Those work, but apparently not as good as x. But x with sidepipes is not really feasible.

Go look on YouTube at helmholtz resonator or 1/4 wavelength tubes. You might even be able to mount them inside. That is what corsa does ($$$$). They really work, test cells use them in their design/constructing.

This might be a good discussion, shows a corsa cut away.
https://ls1tech.com/forums/cadillac...ce-pipes-aka-j-pipes-aka-helmholtz-tubes.html

I think the sidepipes point out to keep oil off the tires. So pointing them in might be an issue. You’ll probably be okay with those dual cones!

 

[SuperBuickGuy]

forgot to post the rule

21. All vehicles must run a complete exhaust system with mufflers (except EV) and must not exceed 103dB at 50 feet if tested. Tested vehicles exceeding 103dB will be immediately removed from competition and given an opportunity to correct the problem. Two noise violations during a single event will result in disqualification from the event and no championship points will be awarded.​

The other 'way' if none of the above works is simply lower the rev limiter.... hope it doesn't come to that - but there is a failsafe.

 

[SuperBuickGuy]

First... nutty dog shot....editedLuigi :waxer:


today was mostly organizing my shop but got started (again) on the gas tank

then lay outedited
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I need to build a die

there it is, just got to get metal tomorrow

 

[SuperBuickGuy]

Big (stupid) wing coming



I bought from CIRO racing. The guy who owns the company races a C3 and has done really well autocrossing. Nice guy too...

Okay so to explain 'stupid' I made a friend a couple years ago now, he's an autistic kid named Anthony.... he is amazing at forced perspective photography.... what is that?

go here and ask yourself 'real' or 'toy'

https://anthonyryanschmidt.com/gallery

some are easier to tell.... truth is, they're all toys. And he's 13. We've become friends - so much shadow of who I was at his age - anyway, his brother is a car nut too.... I think he's 8. But he's a car nut too - likes imports (I'll fix this - I already Anthony saying 'stock is boring') - and I showed him what I plan... his response was "big stupid wing" .... so I explained to him why the big stupid wing and as any good 8 year old, he's fully on board with the idea now. But from here on out, it's the big, stupid wing.

 

[SuperBuickGuy]

the guy building my wing... his car

https://ls1tech.com/articles/c3-r-rick-jung-1968-corvette/

 

[SuperBuickGuy]

New tool

in use

so time to fix 2 problems... first I can't get enough caster but also too wide, this will gain me almost an inch - which, major bonus is the front tires won't rub on the fenders....

quite frankly, this is why I built this in... so now mark... tomorrow cut
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[SuperBuickGuy]

working with a radiator manufacturer to build a radiator with fins that parallel the ground....

 

[SuperBuickGuy]

Sooo, I know, brakes only slow you down....
and I know, no holes

these actually came with the rear when I bought it.... no idea miles but they got me on the road

back is done....

front is going to take a minute since I don't have a 10 mm tap
chop is done

tacked the fronts again.... a bit more grinding but I also need a tap to chase the threads

 

[SuperBuickGuy]

Tap got, reassembled...


gained 2* I need to open up the new rotors a bit then align it.... all by 1 tomorrow

 

[bobs77vet]

I like the alignment tool what holds it in place? does turning those rim clamps put tension between all 4 points and act as a clamp?

I put in a removable rear window in my C3 and i liked the sound presence it gave but didnt really notice any particular air flow either way.

 

[SuperBuickGuy]

I like the alignment tool what holds it in place? does turning those rim clamps put tension between all 4 points and act as a clamp?

I put in a removable rear window in my C3 and i liked the sound presence it gave but didnt really notice any particular air flow either way.

I really notice it when the top is off and windows are down - it cuts down on the buffeting.

Brakes. To catch up, the spindle is C5/C6 corvette - which has a larger hub ring then the Camaro - why, dunno, but it does so a warranty was broken, again

I may not use my lathe often, but when I need it, it really is handy

2.5 degrees camber, 7 degree caster. Drove it today, drives great... I may put shims in it for 'normal' driving and get back to 1.5* and 5 or so caster

bling

trying to decide whether or not to repaint the caliper.... probably won't, but at least I considered it?

It's their rules, but I refuse to invest big dollars in something that I don't need....

$36.00 - I think the speakers set me back $12

 

[bobs77vet]

I did notice that there was less buffeting also . i found it quite pleasant with the glass out. so i guess that really does translate into some sort of air flow

 

[SuperBuickGuy]

time to clean up some wiring and install the radio
easier to just take it apart

one of the really cool things about the Dakota Digital dash is it's 2 plugs to remove it all

and install the chassis

the vent didn't secure to the dash pad... fixing that and that stuff can fall into it

the tabs will hold the duct to the dash pad... all epoxied in place

now no stuff down the vent

 

[SuperBuickGuy]

I'd love to hear thoughts on this (brought up just before the big update)

what about having a radiator built where the cooling tubes are parallel with the ground? (the radiator still would be laid back) I've started talking to manufacturers about building it -figure the C3 and C4 guys would love the extra cooling and the end of the radiator being a thing which lifts the front at speed.... I figure I can use 1" cooling tubes - but 2 of them so it would make a narrow radiator with extraordinary cooling.

The problem - I talked to a guy years ago at a Corvette swap meet who was showing his C3 race car. He had turned the radiator perpendicular to the ground to reduce lift, the problem, he said, was at low speeds it'd overheat because you couldn't get enough air over the shorter radiator to actually work....I have no idea what the fins will look like (wild, I'm sure)....

or am I chasing a problem that doesn't, really exist?