Drag Car front and rear spoiler adviceNeed a little advice on front and rear air foil - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-25-2011, 02:35 PM
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Drag Car front and rear spoiler adviceNeed a little advice on front and rear air foil

Need a little advice on front and rear air foils. I have a 1980 Monza Drag car. The car weighs 2300 lbs with driver, full tank of fuel (5gal) and all equipment. The tranny is race glide with a 4500 stall, the rear is spool with 4.1, slicks are 11 X 30 Goodyear, fronts are 25" Goodyear drag tires, rear suspension is 4 link, the front tires weigh 1176 with the left being 7 lbs heaver, the rear weighs 1173 with the right weighting 9 lbs heaver with driver and equip in car. The car has a 4 degree rake and is level side to side. The bottoms of the rockers sit 6.5 off the ground. Adjustable QA1 coil over shocks at all four corners. The engine is 703 lbs ft of torque with 100 shot @ 5200. Here is the problem! The car goes dead strait until about the 660 then the front of the car starts to lift and if you stay in it at about 130 140 mph or about the 880 it starts to wander and loose traction. I feel the car will run 160 + and low 9s if I can solve the windage problems. see pics
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Old 03-25-2011, 02:50 PM
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Do you have a specific question?? Certainly seems like you could use a chin spoiler to keep airflow from going under the car, and a rear spoiler with side plates to add downforce and directional stability.

I've got a friend with a '79 Z28 built pretty much the same with a similar rake, car is very close to yours in weight(mostly f'glass) and he had the same problems until he added a rear spoiler. Bad enough to scare him on the top end. He hasn't done the front chin spoiler, but his car is just barely above the legal minimum 3" height at the front and doesn't seem to have a bad lift problem on the front...but it also has the Z28 front ground effects shape on the lower nose.

He did mention that making aluminum inner fender panels for the engine bay helped a bunch, keeps air from climbing in the open wheelwells. He had trouble with the carb metering before he added the inner front panels also, too much air buffeting under the hood.
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Old 03-25-2011, 02:56 PM
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I figured I needed front and rear spoilers. How do I figure the length and angle? Is there someone that makes custom spoilers? Is it all trial and error? Is there a web site that might educate me on how to get the best results?
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Old 03-25-2011, 03:17 PM
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Most of the race chassis company's offer spoiler kits...Alston, S&W, Chassis Engineering, Quarter-Max, Jerry Bickel, Competition Engineering, ChassisWorks, Haas and I'm sure a bunch more.

A companies Tech would likely help you with angles, I don't really know. most rears I see have very little angle, only a couple degrees.

You might look around at www.yellowbullet.com, lots of racers there, or at www.DragRaceResults.com in the Bracket Talk forum.
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Old 03-25-2011, 03:23 PM
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Thank you
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Old 03-25-2011, 03:32 PM
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Why the two different user names ?
Oh and i like that monza.

Cole
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Old 03-25-2011, 03:39 PM
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Hey, you got it up and running I thought the car looked familiar but the Username fooled me. Sounds like it moves pretty good

I took a quick look around YellowBullet...LOTS of info there. Most said angle of zero to maybe 3...the main purpose of the spoiler was to help feed the air off the car far enough back so that the leaving air didn't create lift off the short rear section of the body, so a lot of angle wasn't what you want. Several suggestions were for a zero angle, witha 1/4-3/4" wickerbill on the trailing edge,and just adjust the angle on the wickerbill to get the results you need.

Lots lots LOTS of pictures over there at YellowBullet, everyone likes to show off their cool stuff
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Old 03-28-2011, 09:13 AM
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Why the two diff user names

One is my son and the other is me. We are working together.

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Old 03-28-2011, 09:19 AM
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We got it running!

Yes we indured the recession. Money was the problem for awhile. The car is a little more than we were building for, but it is a little easier to slow it down for awhile than pay the money to speed a slug up. I will post some pics of the car at the drags this summer.

QF
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Old 03-28-2011, 02:03 PM
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Originally Posted by Quarter Flash
One is my son and the other is me. We are working together.

Now that is awesome keep on working together.


Cole
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Old 03-31-2011, 10:28 PM
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Much as I don't care for the new prostock cars they do address this problem. They like the wrap around thing on the rear and overall low look. I ran a Monza alcohol funny car in the Jurassic age. We used a couple chin spoilers. The first was the sharp pointy scoop style and the last one was the wrap around sports car style. This is more efficient as the air is directed around the car rather than over it.

You can easily add the Funnycar rear spoiler which is just a flat plate at about 30-45 deg angle. Pick a number say about 3-4 inches high. It causes some drag but better to have some drag and get down the track safely than crash the car. The early Z-28's had these too.

Also popular now is the out turned edge at the bottom of the rocker panels. This prevents the airflow from turning under the car. I had a book on race car aerodynamics that tested this one. There were some really neat windtunnel shots of this one and the typical drag race spoilers. It is limited in most racing sanctions so it is pretty effective.
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Old 04-01-2011, 09:23 AM
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Thank You for all the good advice. It will be helpful..

Bob
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