145+mph

tc_sj · #1 (**permalink**) 11-05-2009, 10:23 PM

My company rent a run-way at Alameda Naval base for flight test simulation, since the run-way was too long & smooth, I decide to take the car out for fun/fast high speed run.

I have tried at least 6 times, but never able to reach 150MPH, top speed I can get around 145+, may be there it a limiter on my car.
May be I am chicken-out!!!

FYI
Myth Buster used this run way for their test-TV show.

Tan

Got the Bug · #2 (**permalink**) 11-05-2009, 10:26 PM

Quote:

Originally Posted by tc_sj

My company rent a run-way at Alameda Naval base for flight test simulation, since the run-way was too long & smooth, I decide to take the car out for fun/fast high speed run.

I have tried at least 6 times, but never able to reach 150MPH, top speed I can get around 145+, may be there it a limiter on my car.

Myth Buster used this tun way for all of their test & show.

Tan

That's cool Tan! Did the car feel pretty stable at that speed? Any lifting in the front?

tc_sj · #3 (**permalink**) 11-05-2009, 10:38 PM

Doug

The car feel very stable, and straight at the speed posted, I do not feel any lifting in the front, however there was a bit swerving on either 1st or 2nd gear if I push her to hard.

Tan

PANAVIA · #4 (**permalink**) 11-06-2009, 01:53 AM

Tan - I think you are hitting an "air=wall" Aero-Dynamic issue at 145. --

145 is very respectable with a car that blows a .45-54 CD ratio.

( who has the drag coefficient numbers on the 427 bodies >? )

tc_sj · #5 (**permalink**) 11-06-2009, 09:25 AM

Steve

I failed physic test @ college, therefore I could not figure this out

I recalled my old Corvette can reach higher MPH then my Cobra.
Like what I said, I possible chicken out!!!

Tan

Quote:

Originally Posted by PANAVIA

Tan - I think you are hitting an "air=wall" Aero-Dynamic issue at 145. --

145 is very respectable with a car that blows a .45-54 CD ratio.

( who has the drag coefficient numbers on the 427 bodies >? )

zrayr · #6 (**permalink**) 11-06-2009, 11:33 AM

Quote:

Originally Posted by tc_sj

Steve

I failed physic test @ college, therefore I could not figure this out

I recalled my old Corvette can reach higher MPH then my Cobra.
Like what I said, I possible chicken out!!!

Tan

your old Corvette likely had an optimistic speedo.

Z. Ray

tc_sj · #7 (**permalink**) 11-06-2009, 11:56 AM

The old Corvette has digital speedo meter, so likely more accurate then the analog on the Cobra. I may have passed the 150MPH threshold,but due to analog reading so it's hard to judge with large scale incremental.

Quote:

Originally Posted by zrayr

your old Corvette likely had an optimistic speedo.

Z. Ray

PANAVIA · #8 (**permalink**) 11-06-2009, 12:01 PM

Remember -- in the end ; everything tastes like chicken.

I found something close to what i was looking for. -

http://www.mayfco.com/cobra.htm

scroll down to the charts.

He is using .42 Cd for his calculations which I think is optimistic. -- I think the open cobra is more like a .54-.60 Cd range.

I need to figure out how to figure that out.

--Steve
Rocket Scientist

Gunner · #9 (**permalink**) 11-06-2009, 12:33 PM

Quote:

Originally Posted by PANAVIA

He is using .42 Cd for his calculations which I think is optimistic. -- I think the open cobra is more like a .54-.60 Cd range.

I need to figure out how to figure that out.

It's pretty hairy math. You have to begin by measuring/calculating the square footage of the frontal area. This is the easy part. One technique is to take a photo, from the furthest possible distance to flatten perspective and the longest lens available to bring the image close, with measuring references in the pic. Print large, outline the car surface, and measure measure measure.

Calculating or even estimating the Cd from there would be... entertaining.

The short way to do it is see if anyone's ever thrown a Cobra into a wind tunnel, or find a similar car that's been tunnel-tested.

.42 doesn't sound too far off, IME. He says "published figure" but doesn't cite the source.

Dwight · #10 (**permalink**) 11-06-2009, 12:54 PM

Tan
Do you know your horsepower?

Dwight

RedBarchetta · #11 (**permalink**) 11-06-2009, 04:43 PM

145...150...Doesn't matter...You were still haulin' ass!

Tommy · #12 (**permalink**) 11-06-2009, 05:00 PM

For comparison, my fastest speed on the front straight at Roebling Road racetrack was about 140 MPH. I exited the turn before the straight at about 100 MPH, accelerated full bore along the roughly 2,000 foot straight before hitting the brakes to slow to about 80 for Turn 1. My car accelerated strongly to near 140, but it felt like it would have taken a lot more straight away to reach 150. Keep in mind that at 140 MPH, you're traveling more than 200 feet per second. If it took 5 seconds to gain another 10 MPH, you'd cover more than 1,000 feet in that time, and your braking point would have to be moved back even farther because of your higher speed.

Dangerous Doug · #13 (**permalink**) 11-06-2009, 05:01 PM

I've hit over 140 on a closed course with my ERA 289 FIA. 302 with a TKO-600, 0.82 OD.

It was still pulling at 140, but I was running out of runway. I think I can hit 150-155.

Yes, it was very stabile, even under heavy braking. Thrilling, to say the least.

DD

Got the Bug · #14 (**permalink**) 11-06-2009, 05:07 PM

Quote:

Originally Posted by Dangerous Doug

I've hit over 140 on a closed course with my ERA 289 FIA. 302 with a TKO-600, 0.82 OD.

It was still pulling at 140, but I was running out of runway. I think I can hit 150-155.

Yes, it was very stabile, even under heavy braking. Thrilling, to say the least.

DD

Would that "closed course" happen to be Hwy 17 in Scotts Valley with no other cars around?

Got the Bug · #15 (**permalink**) 11-06-2009, 05:11 PM

Quote:

Originally Posted by Dwight

Tan
Do you know your horsepower?

Dwight

I'm pretty sure Tan has a CHP 427 Street Fighter, which is just under 500 hp.

RodKnock · #16 (**permalink**) 11-06-2009, 05:13 PM

Quote:

Originally Posted by Got the Bug

Would that "closed course" happen to be Hwy 17 in Scotts Valley with no other cars around?

That would be scary.

tc_sj · #17 (**permalink**) 11-06-2009, 06:22 PM

The PO said 515HP, that 's all I know

Quote:

Originally Posted by Got the Bug

I'm pretty sure Tan has a CHP 427 Street Fighter, which is just under 500 hp.

twobjshelbys · #18 (**permalink**) 11-06-2009, 08:26 PM

Quote:

Originally Posted by Got the Bug

Would that "closed course" happen to be Hwy 17 in Scotts Valley with no other cars around?

That would be among the roads I'd like to rent for 4 hours. #1 on my list is Big Thompson Canyon from Loveland to Estes Park.

Dangerous Doug · #19 (**permalink**) 11-06-2009, 08:45 PM

Let's just leave it at "closed course".

DD

RICK LAKE · #20 (**permalink**) 11-07-2009, 04:38 AM

tc_sj There are a couple of easy things to do if you are looking for a couple more mph.
#1 remove the windshield and go with either a comp shield or full face helmet
#2 tape up any seams along the hood.
#3 enclose the passenger side of the car and tape down the tonno cover
#4 air pressure in the tires max, put nitrogen in them also for high speed runs.
#5 As you said check the rev limiter in the car, may need to add 500 rpm.
#6 EXHAUST, the biggest killer of power. Race pipes are needed.
#7 drop the nose of the car about 1" for wedge to help push through the air.
#8 Fill in the radiator openning with aluminum or wood to stop the air from getting under the car and lifting at high speeds. Same with front ducts in nose.

These 8 things should get you into the 150 club with what you have.
Unless you have a full certified rollcage, fire suit, and other safety equipment in the car, You should be happy with the 145.

I have been to 135mph and was happy with this. Have been to 158 mph in 1/4 mile and it was not alot of fun when things don't go just right. Front end lift off from the wind coming at you from the end of the track. Did need to change shorts after run. No damage but what a ride.

Rick L.