Drag racer needing a little help on aero.

[cold85]

I know this is not a drag racing forum but I thought this would be the best place to ask for some aero pointers. I race a radial tire class that only runs 1/8 mile. I know that i need some help in the aero department. My only problem is the car is not like a bracket car in that trying to figure consistancy to changes is going to be hard to judge.
Here are some pics of the car

[cold85]

you can notice on the first pic that we did put lexan in between the bumper and lower grill to stop air and we also had it behind the grill but i am thinking it needs to be in front.

[Dynoroom]

Tell us why "you know" you need aero help. Does the car move around on the top end? Are the MPH #'s down from other cars with similar et's? Why can't you compair et's from pass to pass, I thought the whole idea was to make it go as fast as you can?
Give us some info.

[cold85]

Tell us why "you know" you need aero help. Does the car move around on the top end? Are the MPH #'s down from other cars with similar et's? Why can't you compair et's from pass to pass, I thought the whole idea was to make it go as fast as you can?
Give us some info.

car does not move around but my mph is down from other shop cars that make the same power.
That is the idea but we race on small radial tires so making back to back clean passes with the same power levels each time is hard due to changing tracks.

[maguromic]

What are the class rules on what is allowed, or is it anything goes?  Tony

[racefanwfo]

are any changes in aero going to make that much of a differance in 660 feet.

[SPARKY]

#1  stop blowing the exhasust out the side---put it under the car and point it straight back down the track!!!!!

The exhaust blowing out the sides is just like a 6'x4"x4" sticking out the side of the car.  Not to mention the thrust gained from from pointing it straight BACK down the track!!

I would bet you are also having to crank in a slight strg. correction to the left keep it on track.

[donpearsall]

How fast does the car go now? With such a short distance you probably do not need aerodynamic improvements but more power to the wheels. Usually with stock looking cars like you have that are very draggy from the factory there is not much you can do unless you run way over 125 mph. Give us some details about your engine, gearing, top speed now, desired top speed, etc.

Welcome to the forum!
Don

[cold85]

What are the class rules on what is allowed, or is it anything goes?  Tony

must retain stock appereance but i think small changes like adding a front splitter or lexan here and there is okay

[cold85]

How fast does the car go now? With such a short distance you probably do not need aerodynamic improvements but more power to the wheels. Usually with stock looking cars like you have that are very draggy from the factory there is not much you can do unless you run way over 125 mph. Give us some details about your engine, gearing, top speed now, desired top speed, etc.

Welcome to the forum!
Don

changing the gearing now is not an option due to the small tire we race on. I run around 145-147 in the 1/8

[jimmy six]

May not help you but if you need 2-3 MPH on a liner we have shiny paint and a slick wax job. Primer and flat paint are wind resistance......Good luck

[donpearsall]

I see that there is a lot of plumbing and other stuff sticking out in the wind on the bottom of the car. That causes as much or more turbulence as the grill and windshield. Is there a way to enclose that with a sheet metal pan? Even a front splitter NASCAR style may help. But like I said, at 145 mph, there is not that much more speed to be made with aero improvements. You need more torque and HP.
Don

[hotrod]

Put a 2-3 inch air dam on the front to block airflow to all the under body plumbing and change the ride height at speed through the traps so the car is raked slightly forward (just 1- 1.5 inch nose down) that will force most of the airflow over around the car not under it where all that hardware creates turbulence.


At 140+ mph it takes you about 65 hp to push through the air just due to air drag so you are not going to gain huge improvements but it will help you run someone down on the big end and in the traps.

Larry

[dw230]

How many inches long is the "big end" in 660ft. Larry?

DW

[hotrod]

That would be 330 ft  

The change will be very small at those speeds and the short duration of the run, but Aerodrag begins to influence trap speeds and ET once you get over about 60-70 mph, and he will be going faster than that for about 2/3'ds of the run if he is trapping at 140+

If it takes 20 hp for him to go 60 mph (which would not be unusual for that older body style) it would take 8x that hp to go 120 or about 160 hp, and about 180 hp just to over come air drag at 145 mph.

Larry