Milwaukee Midget

[Interested Observer]

Sorry, meant to say that the frontal area, weight, and driveline efficiency were estimates.

[Jack Gifford]

... Total Cd of 0.25 seems to me to be a number more likely for a "lakester"...

Do you have available any lakester values of Cd? Ever since some Hot Rod Magazine author (Don Francisco maybe?) showed a table of "representative" drag coefficients back in about 1954, I've been under the impression that drop-tank lakesters are typically on the order of 0.9 Cd.

[Rob]

There's a good list here that includes the Insight, alas no Midgets, no lakesters

http://ecomodder.com/wiki/index.php/Vehicle_Coefficient_of_Drag_List

I'm unsure of it's accuracy as it gives the Lexus SC400 (Toyota Soarer) a Cd figure of .27 and my prior research found .32 with no front air dam and .30 with it.

We now return you to the usual off tap grog and dairy products.

Well done Chriso, WOS or bust?

[38flattie]

Chris, it was great seeing you again, and watching you run! That thing sounds angry!

You're close to your goal-keep at it, and I think you'll get it!

[Milwaukee Midget]

Thanks, Buddy - yeah - it's surprising. 

Kate put it this way - "It's just this cute little itty bitty thing, and it doesn't look fast or anything, but when he fires it up, it scares the hell out of people". 

Tough luck on that exhaust port. That's repairable and inexpensive, but it's like getting pulled from the game with a hangnail.

Here's a question - on the time slips, there is an adjusted air density.  What is that referenced to?  If I use that number when calculating HP loss, I wind up with a 30% HP reduction with altitude calculated in, whereas if I reference at zero instead of 4200, I'm looking at about a 15.5% reduction - which is more in line with what I would expect.

The calculator I'm using is this one -

http://www.teamsolillinois.com/pics/links/calc_hp_dp.htm

I'm working on calculating the ACTUAL cd with the top on - a number nobody seems to have a solid reference on.

[fordboy628]

Data in attached document for your consideration:
Cd, weight, and driveline efficiency are estimates.  What are actuals?

Cd for Insight of < 0.30 may be realistic, have seen coast-down test results for production class Firebird at Bonneville of about 0.26.

Interested Observer,

Thanks for the jumpstart!!    Will use your format & plug in the actual values.    I'm sure Midget will be willing to do the measurements/posting.

I am aware that Wikipedia, among others, lists the Insight @ 0.25 Cd, and the Firebird number is impressive.    If I refer to some "classic" Cd examples though, the 0.25 for the Insight seems like a bit of "Honda Hype".

For instance, on the same Wikipedia page is a listing for Bucky Fuller's Dymaxion car from 1933.   The Cd listed is 0.25, and the Dymaxion had a teardrop nose with a fully tapered boat tail rear, so something doesn't add up here. 

I'm not saying it's impossible for the Honda to be < 0.30.     Based on reliable information from people I trust, there is some "disagreement" about the numbers.

Besides, what the heck do I know!!    I'm just the engine guy!!

Fordboy

[fordboy628]

... Total Cd of 0.25 seems to me to be a number more likely for a "lakester"...

Do you have available any lakester values of Cd? Ever since some Hot Rod Magazine author (Don Francisco maybe?) showed a table of "representative" drag coefficients back in about 1954, I've been under the impression that drop-tank lakesters are typically on the order of 0.9 Cd.

What I was told, by a guy I trust, was:

Typical values for Cd, based on wind tunnel testing.    Wind tunnels did NOT have a moving ground plane, so numbers in the real world would go UP slightly.

Aerodynamically "dirty" production cars:     Cd's of 0.40 to 0.55
Aerodynamically "clean" production cars:    Cd's of 0.30 to 0.39   (He agreed that a really "good" Bonneville car could be < 0.30, but that it would be one slick ride.)
Lakesters, ( )etc:                                   Cd's of 0.20 to 0.25   (based on the numbers, these have to be enclosed wheel.   The numbers are just too low for open wheel.)
Streamliners, etc                                       Cd's of 0.10 to 0.15

How he defines "lakester", I have no idea.  But if it is open wheel with radius rods, beam axles, etc, your number of 0.90 is probably closer to correct.    Numbers for open wheel F/1 cars are generally accepted to be 0.70 to 1.10, depending on downforce required.    And they still go plenty fast.    Most of the conversation with the aero guy centered around the Midget Vs. other potential competitors in I/GT, with the words Lakester & Streamliner thrown in as examples.

Again, what the heck do I know!!     Still just the engine guy!!

Fordboy

[Rex Schimmer]

Chris,
I am really sorry that I did not get a chance to meet you at the salt this year. I ended up coming down with a bad case of bronchitis and came home on Sunday while I could still drive and have been down with it ever since. So again I really wanted to meet you and see your car, especially you getting into it!

That said I do have a couple of thoughts regarding some aero and other possible improvements on you Midget. Regarding the Cd you pretty much "got what you got" not much allowed in your class that would have much affect on reducing the Cd but you might consider lowering the car as much as possible as this will have the effect of reducing the frontal area. On cars like your Midget the frontal area calculation should include the space under the call also as this is an area of heavily turbulent air and lowering reduces this area. A couple of other thoughts, is it legal in your class to take engine inlet air from the grill area back to the carb? a properly designed air inlet could be worth some HPs: Tranny and diff oils, are you running a light weight oil in both and also under filling them? Sparky is a big proponent of running 30 wt in the diff and has seen good results. Brake drag, do you push back the front pads and adjust the rear shoes so that they are not dragging?  You are at the place where you need to make a number of small improvements that potentially can all add together to get that last 3 MPH you need.

I can certainly say that your engine is extremely impressive, great horse power and fantastic reliability. One other thought, last year there was a MINI that was running a BMW 4 cyliner DOHC head on their engine, could this be applicable to your engine??

Next year for sure!!!

Rex

[Freud]

Going home Sunday may be one reason I didn't see you.

Sorry.

Then again, I don't remember if I looked for you.

I try to avoid sickies.

FREUD

[fordboy628]

BTW,

"LUV" the new avatar!!

Well . . . . .  OK, not as much as I "LUV" Mrs. Fordboy, or as much as I "LUV" beer, or as much as I "LUV" dyno testing, or as much as I "LUV" flow testing, . . . . . . .

Alright, the new avatar is . . . . . . .  whatever . . . . . . . .

Fordboy

[38flattie]

Here's a question - on the time slips, there is an adjusted air density.  What is that referenced to?  If I use that number when calculating HP loss, I wind up with a 30% HP reduction with altitude calculated in, whereas if I reference at zero instead of 4200, I'm looking at about a 15.5% reduction - which is more in line with what I would expect.

Chris, that's density altitude. Cars make more HP at sea level, due to denser air, so you'll often see a 'corrected' HP to sea level, on dyno sheets.

This is the air correction due to temp and humidity.. B'ville is approximately 4200', so the car performs far less efficiently than at sea level. Add high temps, and humidity, and the corrected, or density altitude, may be well over 7000'. Pilots and drag racers use these numbers often, as they can really effect performance!

[Graham in Aus]

Rex is bang on the money with lower viscocity oils and stuff Chris; Patricks bike runs ATF in the gearbox no trouble, you are so close, some small items when all added up might be all you need to get you there...

Ceramic wheel Bearings? Do you have to run front brakes? run more clearance on the rears? or maybe lever the front disc pads back before the run?

I guess I should read up on the GT rules.

I'm sorry now I was so busy with the bike to not have more time to help you with your thought processes during the meet, I could have learned a heap of stuff too!

I know you can get there! 

[hotrod]

Here's a question - on the time slips, there is an adjusted air density.  What is that referenced to? [/quote}

Try this guy's website, lots of in depth discussion about how all that is calculated and some nifty calculators you can use to try some number combinations out to see how it compares to what your car would dyno at when you are tuning at home.

By they way dyno correction factors due to density altitude are bogus with turbocharged cars, because the correction varies with the boost level, so you need to account for the boost level in the calculations. The standard SAE correction at high altitude (like here in Denver) is almost 2x what is should be on a turbocharged car running 1 atmosphere boost (14 psi).

http://wahiduddin.net/calc/calc_cf.htm

http://wahiduddin.net/calc/calc_hp.htm
http://wahiduddin.net/calc/calc_hp_dp.htm
http://wahiduddin.net/calc/calc_hp_abs.htm

etc.

[Milwaukee Midget]

Buddy, Hotrod, thanks - I'm still trying to master the Mr. G calculator Fordboy gifted to me, but I'm starting to see some numbers that make sense, and while I'm not running any boost, the online calculators have been a good reference point.  I think I've got enough raw data to back peddle the numbers and actually come up with a pretty solid cd for further calculations.

I hit the ground running at work this week, but before I die, I'm going to get a whole post on the whole week up here - but some names that I must acknowledge right away are :

Fordboy - His insistence upon testing and his analytical and machining skills got this little turd to the point that it is a competitive car in a class with a record that has sat for 20 years.  Thanks, Mark.

Martin McGlone - When I was in line on Monday, this Englishman came up to me and said, "I/GT, eh?  Do you know what car holds that record?"  I said, "Damned right, some stinkin' little Abarth". 

Martin said, "It's an Abarth Bialbero, and I own it."

Without missing a beat, I said, "I have a picture of your car in my basement taped to my dart board."

Turns out Martin is a racer in England, and races a Sebring Sprite.  He became my #1 fan.  After my last run on Monday, he came up and asked, "How fast did you go?"  I said, "118.069."  His response?  "Not fast enough!  Get back out there!"

Pork Pie - Most people aren't aware of this, but he stopped by and literally coached me and Nick through the whole procedure.  Yeah, we would have eventually have picked up the subtleties of line etiquette and what to look for and to watch, but his early involvement in the week probably added two full runs to our attempts.  Pork Pie, I am in your debt.

Nick Martin - My nephew, my crew chief, my friend.  You brought to this the competitive edge that I lacked.  Nick - you are my Cicero - you made sure my head was in the right place, you quickly picked up the details necessary to send the Midgetmus Maximus into battle, and you directed a shoes-string operation that shouldn't have had a snowball's chance to the point of being competitive to a point of respectability.

Dan Warner - When I first started this project, we corresponded quite a bit, and while I'm sure you and many of those who saw this project from the start were skeptical, I never received a note of discouragement from you - or anybody in SCTA-BNI.  Thanks for making me feel welcome.

Freud - The beat-poet laureate of the salt.  When I grow up, I want to be a kid again - just like Glenn.

Doctor Goggles - "Few understand what I'm trying to do but they vastly outnumber those who understand why."  Half way around the world, and I found the friend who understands that particular gut level, visceral sixth sense, and had the literary know-how to  actually be able to put it into a cogent sentence.  That's a tattoo, there, mate.

My Dad and Mom - Frank and Pat - My Dad for buying Road and Track, Competition Press, Motor Trend - and to my Mom who complained about them but left them lying around the house so that I had access to them.  All the trips to Road America, Brainerd, Mid America, Hawkeye Downs, NEITA.  I love you both. 

Kate - Mrs. Midget - who has sacrificed 4 vacations in the last 5 years to follow me around on this escapade.  The woman who I wake when stumbling into bed at 1:30 in the morning after installing a fire suppression system - who pops out to the garage to make sure the car hasn't fallen off of the jacks and pinned me down - who saw I ate something other than gas station roller dogs and truck stop coffee - the next destination is your choice, be it Ireland or an Indian restaurant - I owe you - and I love you.

Enough for now - desalination continues.  Chip stopped by Tuesday and we stripped the front end off of the Midget - I cleaned up the fenders, grill, hood, etc., and it's all safely stored upstairs in the attic.  The process will continue this weekend - I want to get it down to the point where I can flip it over on its roll cage and give the underside a complete cleaning, a wire brushing and some new paint.

This Brit-tin is very susceptible to corrosion - I've got too much time in it to let it rust.

[Kiwi Paul]

So.....Kate would like to go to Ireland, EH? Happens that my better half is direct from the Emerald Isle, so if you are serious, hints are available.....Of course if New Zealand was the travel plan.....I could get you in sooooo much trouble.... Still researching the Mystery Can.....It`s not Boddingtons....