Hi Guys,

Getting ready to run another mile shootout with the Cuda. Just curious, at what MPH does the recessed grill start to really become an issue for aero drag and top speed on these?

Its almost an arbitrary number, but aero becomes measurable in a tunnel around 40 mph in auto set-ups. In your case any improvement in grille area would start to be effective over 80mph. imo..

And remember with hp automotive, "everything effects everything else"

BTW, what is the max speed likely here?

Would I be somewhat correct in thinking you spend 50% of the run gaining the last 20% of speed?

Are there various classes?
If so, is there a limit for how fast each class is allowed to go?

Sounds like you’ve done it before. Same car? How fast?

I did the 1/2 mile last year. Got up to 138 and felt some lift on the front. Would like to make 145 or so. That would put me in the top 3 for the non boosted class from last year in the 1/2.

Street - NA no nitrous
Super Street - Boost or Nitrous

Thinking about stepping up to the full mile this year... wondering if a plastic face across the grill would be worth it.

I’d like to try a 1/2 or mile run myself....... I don’t think there are any events like that very close to me though.

This event is part of a three day road race event here in the Nebraska Sandhills. Two open road races, car show, and a shootout event. Lots of fun.

You are probably correct. the first 125mph or so is pretty easy.

Closing off the upper grille should be worth a few MPH; the more flush, the better.
You'll have plenty of air for cooling coming in through the valance.
If you can do it, another hood with some venting to let trapped air escape will also help.
I'd also remove the side mirrors, and probably lower the nose a bit; 5-degrees down has been shown to have benefits.

Does that lower air dam help that car? From my personal experience years ago, I got my 70 cuda up to around 137, still climbing, and a straight road, it felt like it was trying to climb over the air under it, is what it seamed like to me. I lifted.

I use to live near El Mirage dry lake, I was thinking of running my 1970 T/A out there and went to watch and see if I could learn somethings(speed tricks ) while watching. One of the old timer who had been in the SCTA and BNI 200 MPH club made a statement that registered pretty deeply with me back then and it was most people can bring a car out here and run 125.0 MPH, some can run 150 MPH but to get that same 150 MPH car to run 175 MPH takes twice as much HP or you need to reduce the aerodynamic drag by 3 to 5 %
I'm not sure how accurate that statement is as I never ran any of my cars there due to rules and lack of desire as there is no money awarded to set a record and it costs you time and money to join a club and race out there
I owned and flew a 1960 Piper Comanche that would pick up around 13 KPH by sliding the pilots seat back 4 or 5 inches to change the center of gravity which required retrimming the rear stabillator (a flying elevator) to get it to fly straight and level. That airplane would go from 148 KPH to 162 KPH by using the trim and reducing the RPM on the prop from 2400 RPM down to 2300 RPM
My current S/P 1970 Cuda bracket racer runs 147.6 MPH in the 1/4 mile, 115.+ MPH in the 1/8 mile with 4.56 gears and 32.0 (103.0 inch circumference) inch tall drag slicks on the back My message is that car only gains 22 MPH in the last 1/8 mile

Lowering the car as much as possible, especially the front, will help you more than any one thing. Your air dam in the front should nearly touch the ground. wrapping the air dam around the sides and continuing with side skirts will also help. Also keep in mind that the stuff has to be strong, there's a LOT of air pressure pushing against the air dam when at speed. .02

Years ago when I used to go to the dragstrip a lot more there was a guy here who had a purple 70 Challenger with a fiberglass hood and I would watch that car cross the finish line at 130 or so and the middle part of his hood was bowed up really far from all the air being built up in front of the grill with no place to go.

Another guy from Utah used to come here a couple times a year with a green 70 Challenger and that car ran 9 something . He put a clear plastic cover in front of the grill to keep the air out. You could do something like that and just put a few holes in it for some airflow maybe???

Thanks for the input all. I may try and fab up a piece of plexiglass or something for the front this year. I would like to lower the car a 1-2 inches...The current driveline is the limiting factor ( angles get out of whack).






It does help on the track. Feels more planted. I didn't have it on for the run last year though.

There is something called cooling drag, where the drag that it takes to cool the engine comes into play. You only need what the engine requires to cool it, the rest is drag. You might find some formulas in the aviation community.

That is a nice looking car.

Look Here https://www.youtube.com/watch?v=pXpJdx4f8Hk

Maybe foam insert for grill, tape hood, tape hood to fender, tape windshield molding.

Agree with this, maybe copy the sq inches of opening a daytona uses, seal the radiator to the core support, seal all holes in core support, and inner fenders to get air thru the radiator only, and not out around tires and under fenders and , seal the lower support to the k- frame to get the air out further back, figure out a way to get some out of inner fenderwell areas with air dams up front. Anything to get air out and lower opening square inches will help. I dont kbow if removing the seal at rear of hood would help or hurt. Less opening, lower car, seal some holes. Figure out some way to extend front valence rear edges furter back and seal to keep air from getting under fenders. I have a cuda and a superbird, cuda feels front light at 100, the superbirds never feel that way, they spent a lot of time on cooling drag, or at least getting it thru the radiator and not everywhere else on the sbirds and daytonas. The air is boxed to only go thru the radiator, and exits after the k-frame on a wingcar. If you can't lower the car maybe fab up a bellypan starting at firewall, end at rear springs, to smooth out the bottom, should reduce lift.

The wheel well idea brings to mind a question I always had about the Accords I've owned.
Now these are not super speedway cars, but mileage is very important to the manufacturers
today.

When changing oil or other maintenance I can still do at my age,!! I've noticed the small air-dams
in front of all 4 wheel housings. now these are only about an inch or two deep and extend
the full width of the well, but I can see where they must consider it important even for the speeds these sedans normally see.

Joe

You would think it creates a low pressure area behind the housing, letting the air escape. I also notice how flat the bottoms of these new car are compared to older stuff. I am pretty impressed with how smooth some new stuff is underneath, even the plain jane cars.

Read through this report;
http://publications.lib.chalmers.se/records/fulltext/244208/244208.pdf

Back in my race car days, we often use mesh screen for block offs since it would allow some air through but the majority of it piled up and rolled off the car. At least that's the theory I recall reading somewhere.