Track Roadster Cd or Coefficient of Drag

I'll get them to ya when I get a chance. I did the aero for STP.
Yep if it wasn't for cars I would have missed out on a lot of learning.


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Thank you!!!

 

For STP

Aero HP = CD * FA * (MPH Cubed) / 146600
Drag LBs CD * FA * (MPH Squared) / 391



http://www.wallaceracing.com/Frontal-Area HP-Calculator.php

http://phors.locost7.info/phors06.htm

 

Excellent. Thanks again. I've been on the wallace racing site before, but not that second link. Lots of good info on there.

 

Thus my remark in the beginning of too many variables.Now that we know you are shooting for economy and aero,combined with daily driver capabilities,and old time look we are starting to narrow it down.Buick 215 rover aluminum might hit your requirements staying hamb friendly

 

ROD1, you're right. I should have stated my purpose initially to eliminate some of the guesswork. You are also spot on regarding my intentions of this project. Nothing of this idea is set in stone, and I'm open to ideas, but I'm leaning heavily towards a traditional skin with modern organs. If I do go this route, whatever is modern will be hidden to the best of my abilities. Long story short, I'm tired of sitting in class listening to people talk about how terrible and inefficient American cars are. If I do in fact take on this project, I want to be sure I succeed, and hence my request for help with the aero of an early track roadster. Thanks again for your input.

 

Different thinking here

One wants to PUNCH a hole thru the air, the hole has to be big enough that the waves are deflected from the remainining surface area. with a small frontal area the waves wrap around the remaining surface area creating drag.
Take the roadster pictured and drive it into a large sheet of plastic. and imagine the plastic conforming to the roadsters shape. Everyware the plastic touches becomes drag. Now turn the roadster around and back it into the plastic and see that the plastic will not come in any further then the widest part of the body. Measure the contact area of both senerios--which has less contact (drag)area.
For free flowing aerodynamics, the perfect shape is that of a raindrop- fat front ,skinny tail

 

Good*****ogy. I will agree that a teardrop shape with more surface area in front as opposed to the rear of the vehicle is ideal. The key is making that look good. After cruising through the Bonneville thread yesterday, many ideas were stored into the memory banks! I'm almost more pumped on this new project than the current one haha. Must....Finish....Project...

 

Remember these are reasonably accurate "back of the envelope to make quick and close approximations.

I checked my calcs against wallace and we get the same results based on a standard air density.

Increasing Temps or Humidity make the air less dense as does altitude, (See how many argue the humidity ).

The Buick 215 might be a close engine. You will want to make the chamber as small as possible, run 10.5 or more, run a late intake closing but low overlap cam. Have fun!! Maybe make it deactivate some 4 cylinders, or play with VVT.

Sounds fun, wish you were closer.

 

A VVT Buick with cylinder deactivation would be pretty neat for sure! I'm not sure I'd be the one to pull that off, though! I'll have to sit down and start planning this thing. I think getting some dimensions off my T bucket, modeling them, then reshaping the nose, windshield, etc in the modeling program and simulating wind tunnel testing is my best bet for the body.

 

These guys built a universal Deactivation system in 79. The problem was it raised NOX so wasn't adapted.

Might want to search them out.

Inventor
Ted Brock
1440 Hill Street
El Cajon, CA 92020
Patent is Attachment A
Manufacturer of the Device:
Ambac Fluid Power
511 Glenn Avenue
Wheeling, Illinois 60090
Mathy Machine
429 Vernon Way
El Cajon, CA 92020
Manufacturing Organization Principals:
Dennis Duncan - Ambac Fluid. Power
Jay Mathy - Mathy Machine
Marketing Organization/Applicant:
ACDS Inc.
1440 Hill Street
El Cajon, CA 92020

http://epa.gov/otaq/consumer/devices/511817.pdf

 

I'll have to check them out after work. I wonder why NOx went up? Did they just eliminate fuel/spark to those cylinders, but the valves continued to function regardless? I wonder if heat transfer from deactivated cylinders caused temps to spike and NOx to rise?

 

Just off the top of my head: for reduced drag on open tires, should not cycle fenders be mounted over the top half of the tire rather than behind? After all, the very top of the tire is moving forward at two times the vehicle velocity! I'm thinking a scaled down wind tunnel would reveal some interesting phenomenon. During the test the tire would have to be rotating at several predetermined RPM corresponding to various wind tunnel air flows.

 

I spent about a half hour browsing the .pdf file. Very interesting. Essentially, if I wanted to replicate their product, I could just pull valve covers, remove half the push rods and start testing. Quite simple really. I still don't quite understand how emissions went up, though. Also, from an efficiency stand point, I think I'd be better off looking at smaller engines rather than cylinder deactivation. Looks like (at least from their testing) the results weren't anything ground breaking. Interesting article though, so thank you for sharing.

 

A scaled down wind tunnel is an excellent idea, and one I was considering ideas for. My thoughts were that I could model a given body shape, have it 3D printed in the lab at school, test shape, and revise. I don't think a scaled down wind tunnel would be an easy task, though. To get accurate results I'm guessing it would need a lot of fancy measuring equipment, and I'm guessing all of my available cash will be getting thrown at tuition and the car itself The ability to simulate wind tunnel testing in SolidWorks is most definitely an option, though.
Your comment on fenders is also related to ideas I've been considering. Initially, I was thinking: "Why bother with fenders at all?" After reading the HRM article on the Thacker & Shine roadster and how something like 40% of an open wheeled car's drag is due to the tires and exposed suspension, I had to reconsider. If I do in fact put fenders on this thing, they will be streamliner-esque and incorporate to the track nose in order to hide suspension pieces. Essentially, the idea has evolved from a roadster with a track nose and belly pan to a roadster with a complete aero kit lol. How feasible is this? Who knows. I guess there's only one way to find out!

 

The illustration, One Wrench by Tim Conder comes to mind.

 

Here is an excellent link loosely fitting the requirements of my idea! It's a Model T that someone way back when put an aero body on and yielded great results:
http://ecomodder.com/forum/showthread.php/aeromodding-1930s-38-mpg-70-mph-model-t-92.html

 

I just looked up a photo of that. Yes; that is a very close visual to what I had in mind! Thanks for sharing.

 

I think it could be done with the 215 with stacked gearing, overdrive ,with an efficient rear, like Like the s10 2wd.has possibilities.A complete long block was 317lbs. 200 hp was do-able in 1961.The dual path******* was the downfall.

 

Tim;

Re: the front wheels. You could use wheel pants like on some small homebuilt aircraft. Dragsters of the 70s'-60's used these. A similar style was also used on the Barris-built(altered) chopped Model A coupe (aka: Dobie Gillis). Can't remember whose car it really was right now, but Chrisman Coupe sticks in my mind as the original builder. Fairly narrow, low-rolling resistance & hi-pressure tires are where it's at for mpg.

Windshield should have a 2-dimension curve to it. Doesn't have to be a lot. Flat glass is horrible for aero.

As for fuel & engine mods, I'd look to a decent ignition system. Look at Krupas' FireStorm plug system. For fuel, I'd look at a vaporizing method, using piezio-electric discs. I have the schematic from one of the patent-holders (who was the tech genius behind it). I'd share if you were to actually use it. Also on the fuel side, I'd look at a system that helps w/the burn, (& lies to the computer - if you use one) using hydrogen (water gas) & I know of a system that works well. Everything would have to be hand built, except the waterfuel deal. BTW: I sell none of this, it's just an interest of mine. &, I'd suggest a turbo for a couple of reasons. Getting it to work together might be a challenge. .

In school in the 70's ->80's, we built a couple of hi-mileage cars, starting w/a vw bug, that used a 2cyl ac engine. Named the 50:50, for 50mpg @ 50mph, which it did, using the oem carb & points, although everything was modified. & vw bugs aren't "aero". . Circa '73 (gas-"shortage/wars").

In the mid->late 70's, I drew up some partial plans to do just what you're doing, except I wanted to do a daily driver. The deal was a low-slung T, track-nosed, open-wheeled, turtle-decked critter, using an acvw 2-cyl that was front-mounted & (I was looking to use alcohol, or maybe what eventually became E-85, along w/EFI) rear-wheel drive (probable transaxle in the rear), although I considered a standard 5spOD + conventional rearend. I was shooting for 100mpg project. Very light weight, nimble, & I thought it'd be reasonable cost. Getting out of school, not having access to the machine shop, not to mention a small bank-roll, + the technology of the day compared to what is now available, = the rather permanent set-aside of this project. . ;( .

I had forgotten all about it, 'till I came on this thread. Thanks for starting it, brings back good memories. .

If you want any particulars, drop me a PM w/a ph#.

Good luck w/your project. You'll do well.

Marcus...

 

I've always like the front fenders on Prowlers, they fit very close to the tire. But they are about 2K each NOS these days. Anyone ever repop them? Gary

 

Marcus,
I think you've paid a visit inside my head! I'm right there with you in almost every point of your post (except fuel vaporization and ignition bits; I'm not familiar with what you've mentioned). I'll definitely shoot you a PM with phone # to chat sometime (when I can feasibly start this project).

First of all, is this the coupe you're referring to?



I found the above photo when I was searching for information on the Chrisman coupe:





Second of all, your remark, "Windshield should have a 2-dimension curve to it". Do you mean a curve from bottom of windshield to top or from side to side? Or does it matter? I wonder if I could just find a curved windshield at a wrecking yard and have it cut down?

Third, I really dig your track roadster ideas. My current project for school is a "flex fuel roadster", which I will temporarily run on e85, e98, methanol, and regular gasoline to compare/contrast results. Here's the car:



Here's some modifications to the carburetors. Screw in air bleeds, blue accelerator pump cups, stainless steel needles, and Holley jet conversion:





In the future, I think a home brewed ethanol operation would be feasible after reading what they've done with algae. Which is another reason why I was considering a small turbo diesel for the new project as apparently you can get biodiesel from algae, too (depending on the strain).

Fourth, excellent job achieving 50mpg from a bug. That's some serious bragging rights! Very nice to have met you, Marcus! We have very similar ideas!

 

Not sure on repopping the Prowler fenders. I was curious what kind of Cd that car had, so I looked it up. Care to guess? 0.49 is what I was able to find. That's not too good, but not too bad considering some people are saying a stock T roadster is somewhere around 0.7 haha. Here's what I found for ultimate inspiration the other day:



I drew a couple quick sketches to see if my brain could produce a visual concept. They're not the best, and proportions are all out of whack, but you get the idea. Here's one for a track T roadster with turtledeck and "wheel pants" as I guess they're called:



And here's one for an aero coupe type thing. I was thinking maybe a 40's pickup cab that was extended to a point in the rear, or maybe a Model A or T tudor could be a donor. I dunno. I'd have to really sit down and think about how to get this off the paper and into real life:

 

^The above drawing, in my eyes, appears to be the size of like a fleetline or some similar late 40's fastback. My intentions were to have this be about the same size as a Model T. I dunno. I think that sketch needs some refining.

 

I hear you about the fenders, but they just look so cool. How about one of these, less the front fenders? Kinda swoopy. Gary

http://www.decorides.com/foosebt.htm

 

How about a very areo front wing like an F-1 car. Move the air where you need it to go

 

That's a good idea, but how would I make it look like it belonged on the car?

 

WOW. That one at the top of the page is pure****. I love it. It's a little steep on price for a poor college student, though! I love the style, though. That's almost exactly what I had in mind. I'm not wild about the grilles they're using, but the body is amazing. I wonder if I could just buy fenders off them...

 

rod1, I didn't see your comment until just now. I really would like to try something like this (actually I have a 4.3L Chevy V8 from the '94-'96 Caprices -the "baby" LT1- that is along the same lines and concept), but I don't think that, given all the options out there, these would be the best choices. The only thing I'm worried about using something like a Buick 215 is parts availability/retrofit costs. I think by the time I had that thing all tricked out I could have purchased several low mile OT small turbo diesel engines that would require zero modifications. I know it is not traditional, and a small cubic inch aluminum V8 would be completely rad, but I just don't see guaranteed results from this idea. It would be a "best case scenario" to achieve my goals with this, and I would need to know all the tricks****ociated with the Buick, which I do not.

 

There probably is no more than a handful of engines that have lasted as long and been the heart of as many cars as this engine.Rover bought the rights to this engine from GM and used it up until just a few years ago.The 3.5 version in their range rover is direct bolt on near everything. These tanks weigh in at 5000 lbs,aero as a brick and get 12 -15.They have powered the Triumph Tr8, the Tvr Griffiths,Morgans,MG v8s .Mickey Thompson took the Pontiac version and qualified like 8th in the 62 Indy.Personal history: we built a 34 Vicky for a customer in the 80s. Bored030,mild port, edelbrock 4 barrel, 350-?500cfm .D and D adapter to turbo 350. 3200 stall , 8 inch 3.20-3.50 gear.Tri Y style header. To the customers specs.We were skeptical. Got 24 -28 mpg.Ran like a dream Sounded way bigger.Now if you brought more gears to the table,a more efficient rear axle,better fuel management...Besides, Trying to stay traditional.lol