C3 front end lift (aero) question.

I have seen this before, at what speed does this happen?
would you get enough air at a slower speed? In town?
would a 69 act the same way, with the different grills?
 
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COLE SWEAT said:
I have seen this before, at what speed does this happen?
would you get enough air at a slower speed? In town?
would a 69 act the same way, with the different grills?
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Somewhat interesting for a side view, but nothing unexpected, what surprised ME was the same thing done years ago on my '72 and it's not what anyone thinks either.....not even close....I have a flat/SB hood with an aftermarket BB hood bulge on it, and the interior under the bulge cut out, for other reasons than anything aero.....and so I taped some tags on it, without any rear hood seal, and even hung over the back open edge of the bulge....tagged everything that made any sense and visible when driving....

up to 100 mph or so, the tags were just about totally still, just laid there, meaning NO LIFT from under the hood, not the main section, the only lift you get from the hood, is forward of the radiator.....the engine compartment is about neutral in airflow pressures....but one thing to note, I have Dual Spal fans and so they are not blowing back through a stock shroud creating an under the main hood pressure.....put in a stock setup, I dunno and damn sure not betting......

:clobbered::nuts:
 
I've had few laps at WGI on the long track and have not had any issues with front lifting at 140 or so (Garmin) and i didnt want to abuse my welcome...

1. not stock body
2. lowered suspension
3. 26" tires in front, 28" tires in rear.
4. increased the body rake a degree or so by removing spacers from the body mounts in front and adding to the rear, sectioned/shortened the radiator support and lowered the radiator to compensate
5. Brake ducts behind the grilles and a massive rubber (conveyor belt) air dam

Granted the rake increases drag but a C3 is more like a brick than a streamliner and about 150 horses shy of keeping up with my AMG
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84rzv500r
Looking really good - and running too!
Just curious - do you have any pics "stickered up?" Are you running just open track days - or?

TIA Cheers -- Jim
 
phantomjock said:
84rzv500r
Looking really good - and running too!
Just curious - do you have any pics "stickered up?" Are you running just open track days - or?

TIA Cheers -- Jim
Click to expand...

Mostly SCCA autoX in XP class and some runs at the local 1/8 mile strip... getting ready to go again tonight hence the new tires and window nets.. :sweat:

I had a hard time picking up the pepper shaker this morning at breakfast so my racing days are over (motorcycles AMA flat track 69-75, Road race AMA/CCS, Formula USA, WERA, GPpro 83-92, road race 2000-2011 vintage and track days on my 4cyl 500cc two stroke yamaha and XR-1000 Harley) :mobeer:
 
84rzv500r said:
I had a hard time picking up the pepper shaker this morning at breakfast so my racing days are over ...
Click to expand...

Carpal Tunnel? I'm going in for a release following a weekend at Daytona. Post recovery - back to the boat for 6 months do the right hand on return.
84rzv500r said:
Mostly SCCA autoX in XP class ...
Click to expand...
Hmmm, XP class - I was wondering where my "Elvira" would fit in.

Hope the drag racing went well.

Cheers - Jim
 
What about the 79-82 Trap Door Shroud added to the mix?

Anybody have an idea of how this would affect the pressure forward of the radiator/nose lift issue?
 
"What about the 79-82 Trap Door Shroud added to the mix?"

Can you post a photo or describe it?
 
MetalKid - long time no hear/here.

Paint me a picture - the photos are great - but does the flap open down - towards street side?

Seems like it would increase under hood pressure if that is the case. Might change front end lift by getting some air from under the nose - at the cost of more in the engine bay - which is a lot of drag.

If that air could be evacuated through the hood - would improve both -- less nose lift and less drag internally.

Cheers - Jim
 
Hey Jim! :yahoo:Good to be somewhat active again after a way too long hiatus that occurred after being transferred from Las Vegas to Phoenix, in March of this year.

The flap opens down, with the leading edge dropping below the normal bottom of the shroud, (almost in a scoop like fashion) the theory is that at high speeds the pressure built up in front of the radiator, because the engine driven cooling fan can't move the air fast enough, causes the flap to drop open and dump the excess air. Returning to slower speeds, reduces the pressure, and gravity causes the flap to close.
 
Richard D said:
I realize this thread is pretty old but I'd like to see more...
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Not so very long ago I got a very large engine oil cooler it's about a foot square and almost 2" thick, I managed to move the radiator to the rear by adjusting the mounts, and getting good mount/clearance to the a/c condenser and the radiator, and note that the auto trans does a good run in HOT weather and the trans comes into the garage at 130f on the pan temps.....can't bitch...

:drink:
 
I've spent much time thinking and seeing other solutions to this issue - the next C3 I build I'm going to try a vent above the radiator then use electric fans to pull enough air through to cool the car. With a decent spoiler to keep the air out of the underside (belly pan plus opening the side vents), I think the issue with bottom breathing could turn into an attribute. The key would be keeping the air either going up in front of the radiator or going out the sides... but as with good keyboard-warrior theories.... we'll have to wait and see .
 
SuperBuickGuy said:
I've spent much time thinking and seeing other solutions to this issue - the next C3 I build I'm going to try a vent above the radiator then use electric fans to pull enough air through to cool the car. With a decent spoiler to keep the air out of the underside (belly pan plus opening the side vents), I think the issue with bottom breathing could turn into an attribute. The key would be keeping the air either going up in front of the radiator or going out the sides... but as with good keyboard-warrior theories.... we'll have to wait and see .
Click to expand...

I may have posted here long ago, but with the rad fins aimed toward the crank pulley and electric fans in the same plane....there is basically no air under the main part of the hood....and my yarn proved me correct, now what happens on the side scoops on MY car, I dunno, never placed any yarn...much less see it at 100 mph.....

I just wish it wasn't such a plumbing nitemare to get water free cold air into the intake mani....I tried once, and found water in the bellows rubber from a rainfall, not even a storm....so THAT concept was scratched...:gurney::clobbered:
 
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This chart is interesting. You can see the c3 improvement in aero. If you had frontal areas for each gen, Cd could be calculated.
 
Here's a car, sort along the lines of the silver car above. I'll have to do an image match search to see if there is more info on this one.


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