Cobras wanting to lift at high speed.

ac andy · #1 (**permalink**) 09-20-2002, 10:28 AM

I have heard lots of talk about cobras getting light in the front end at high speeds and i was just wondering if the big block cars stayed on the road a bit better because of there increased engine weight or do they still want to lift off, but a higher speed. Can anyone shed any light on this?

agro1 · #2 (**permalink**) 09-20-2002, 10:42 AM

They still lift, and with the added weight up front, when they do lift they are harder to control...Not by much though. They both start to lift around 140 or 150. Steering starts to get light and you can feel the front tire's contact patch getting less...Not the most confidence inspiring situation. Olthoff Racing has developed a front air dam to reduce this effect but the Cobra still has the aerodynamics of a brick...If you want to just go really fast get a Viper or a Vette. If you want to get going really fast extremely quickly get a Cobra, and hang on.

Excaliber · #3 (**permalink**) 09-20-2002, 03:01 PM

The problem is not so much the Cobra lifting,,,,,,it's the DRIVER that needs to "lift"....ha ha.

Ernie

bonyhadi · #4 (**permalink**) 09-20-2002, 03:54 PM

LNP reports that at 165mph on ERA 535 the windshield cracked and he was forced to get off the cell phone, put down his mighty 64oz. BIG GULP and concentrate on the road ahead. He was also
looking out for Creeper and his pals.

Chaplin · #5 (**permalink**) 09-20-2002, 04:11 PM

Bony-
When are we going to see pictures of 535, cracked windshield and all, in your gallery?? I miss looking at that beauty.

Mike

bonyhadi · #6 (**permalink**) 09-20-2002, 04:49 PM

Mike,
When I get it back from the shop, I will have to take some snaps. Getting new tires, alignment
and polish out the paint, plus detail.
After Pat cracked the windshield he replaced it, so I can just tell his tale of speed.
God Bless America,
daniel

Spanky · #7 (**permalink**) 09-20-2002, 06:10 PM

ac andy,

This situation(problem) was discussed at the speed shop when we were at the SAI open house last spring. At least a partial solution, which they used, was to design the oilcooler shroud, oilcooler and radiator at an angle to increase downforce.

Spanky.

casaleenie · #8 (**permalink**) 09-20-2002, 09:02 PM

Say What??? Whadda you mean they "lift".
If my wife reads this kinda stuff I'm a deadman....
I'm having enough trouble selling her on this thing...
I'm going to keep her off the internet until the deal is made...
Jeezz

ac andy · #9 (**permalink**) 09-21-2002, 03:00 AM

Spanky,
Having the radiator at more of an angle sounds like common sense to add to the down force, but does this then open up overheating problems due to the smaller surface area of the radiator that the wind is hitting, or does the shroud force the air in enough to fix this problem?

750hp · #10 (**permalink**) 09-21-2002, 05:31 AM

Spanky - how did they think the radiator angle would help? I'm only guessing, but if the radiator was laid back at the top then air could spill across the front surface of the radiator then hit the underside of the nosecone. If anything, that would increase lift.... If the air that gets through the radiator under pressure exits under the engine - that too would increase "lift".... No win situation???

In reality though, I can't imagine the angle of the radiator having any noticeable effect on the aerodynamics. The nosecone must act like a parachute when it catches that massive volume of air at speed.

Double Venom · #11 (**permalink**) 09-21-2002, 06:03 AM

DV's (series1)

:
Start to get light (noticeable) at 158 with no head wind. A front spoiler helped trememdously but due to an serious crash (R&G) no further or accurate testing was done.

DV II's during initial testing, with the naca duct on the nose and the reversed hood scoop showed no noticeable lift at speed. But once again, due to unforseen circumstances, (not with the car!) all testing was stopped for this season.

The DV's are based from a Classic Roadster's kit. The radiator maintains it's vertical , upright posisition.

Just another 2-cents input.

DV

ac andy · #12 (**permalink**) 09-22-2002, 12:18 AM

750hp,
i wonder if spanky meant having the radiator angled with the top forward and the bottom further back?

750hp · #13 (**permalink**) 09-22-2002, 04:42 AM

Quote:

Originally posted by ac andy
750hp,
i wonder if spanky meant having the radiator angled with the top forward and the bottom further back?

....if there was a corresponding vent fitted to the bonnet (hood!?!) that allowed the hot air to escape over the car maybe??? If no extra vents, then we're back to square one again aren't we?

Spanky.... where are you???

coyled · #14 (**permalink**) 09-22-2002, 11:03 AM

I really don't feel mine lifting at high speeds, like 8,000 rpm in 4th at road america, around 165 mph. I am running 3 inches of clearance at the front frame rails and 5 1/4 in back. Maybe the rake helps. scott

Excaliber · #15 (**permalink**) 09-22-2002, 11:14 AM

Coyled,
WOW,,,thats a BIG rake. Does the car get "tail happy" being that high in the rear? I noitced mine did when I put TO much rake on it.

Ernie

coyled · #16 (**permalink**) 09-22-2002, 01:08 PM

No high speed wiggles, pretty stable actually. There is a bump on the front straight at willow springs that I am not crazy about but the chassis just stays straight. I am running 1/16 toe in out back.Scott

Spanky · #17 (**permalink**) 09-22-2002, 07:35 PM

Okay you guys,

The shroud design that I saw installed was angled back at the top and a sweet bit of metal work at that. Now the parachute effect was the problem they started with and although the angle would produce an apparent increase of the "ballooning" effect, there was a compensating channeling of the air underhood (bonnet) and if memory serves it was channeled to aid brake cooling as well. The underhood was not visible to me at the time so I can only remember the theory and hand gestures of the mechanic. There was no mention of a heating problem and again as I remember it, the air was moved through the underhood area even faster than before the modification.

I wasn't alone at this meeting so maybe someone may have a better discription of the arrangement. If not, I'll try to get more information from the shop.

Spanky.

Back in Black · #18 (**permalink**) 09-22-2002, 10:26 PM

I have the same setup in my soon-to-be-delivered West Coast, so I am curious...does it really grab? How many miles do you have on it?

My motor will have about +~630 horses, so I wanted the very best..hope the centerforce dual friction is a goodie!

Ed Csoltko · #19 (**permalink**) 09-23-2002, 09:14 AM

All you snakes that go over 100mph are crazy! Sorry, no offense to anyone. Going over 100mph in a 2,000 pound car seems crazy to me. I may be an old snake (62), but I like to enjoy my retirement for a while. I enjoy my FFR going 40-80 mph in the winding Texas Hill Country roads. Stop by some streams, park, have some coffee, and enjoy mother nature in the early mornings or evenings. (My FFR looks pretty nice parked along a river bed.) All I have to say is: drive safe, slow down, and enjoy life.

rdorman · #20 (**permalink**) 09-23-2002, 09:49 AM

I remember reading some where the the amount of lift in the front of a stock 427 body style was about 80 pounds at 80 miles and hour. Remember that the progression is geometric. So at 160 that is 320 pounds of lift.