Milwaukee Midget

[Milwaukee Midget]

Ugly day in Beerhaven.  Kate’s been down with a nasty cold/flu thing, which she refers to as “the Ick”.  I remained unaffected until last night, but as I had taken today off of work, and intended to get something done on the Pom Rod, sleeping in until 10:30 and waking with a headache and a stuffed up head was not how I intended to start my Friday.

A fist full of Ibuprofen, a couple of Irish coffees and a bowl of Matzo Ball soup put me close enough to rights to finish off the undercarriage . . .





It turned out to be a combination of steel replacement and welding with fiberglass overlay that finished off the rear of the floor.  It’s solid, and while not SOP, it is the best I could muster with my skill set and facilities.  The valence will require additional sanding and a bit of filler, and I’m okay with it . . .



I’ve recently received a new impetus to get the Bugeye running as soon as possible.

Through a Google search and a snail mail correspondence, I was able to contact the father of the fellow who owned this car before Podunk bought it.  The man who owned it has passed away, but his father, mother and sisters all live in suburban Chicago, and they were delighted to hear that the car is still around.  So I intend to stick to my push of having this thing roadworthy by March.  The gentleman is 90 years old and a WWII Navy Vet, and while he’s apparently still in good health, he IS 90 years old.  I want to take him for a ride in it, and let him take it for a spin, if he feels up to it.

Tomorrow, I’ll be working on the rear end.  The car came with a C-Clip replacement kit, which I’m going to install.  I hope to have it rightside up by Sunday.

2.62 rear end and a 5 speed with a 20% overdrive top.  Should be economical.

Also, Mark called today.  He’s making headway on his computer.  Once the head is flowed, we can start looking at component selection for the Midget – which has been sitting far too long.

[Podunk]

Lookin' good.

[Milwaukee Midget]

Terry, you probably never saw these, but I received these pictures from Dave's father.  I digitized them this morning from a Word file, so the resolution isn't great, but this is what the Bugeye looked like in 1977 -





Apparently, he wasn't afraid of turning wrenches on it -

[RidgeRunner]

     I can't think of a better reason for you to get the car roadworthy by March than your respect for, and appreciation of the efforts of, a member of "The Greatest Generation".

     All the best for a successful completion of this worthy goal.

                           Ed

[fordboy628]

Fordboy,
A few questions about the Holiday Gift treatise..
1)  What is your definition of “flow demand”?
2)  On what basis is a new BMEP determined due to a proposed change in compression ratio?
3)  Despite a fairly thorough examination of the SuperFlow website, the “well published formula” for horsepower remained undiscovered.  Could you please provide more guidance?
4)  It has been my understanding that flow bench data is generated at a fixed pressure differential.  If that is the case, how do you generate realistic inlet cycle flow rates vs. valve position for varying cylinder pressures?  Are flow coefficients found for each valve position?  Seems like there would be a circular dependence between cylinder pressure during the cycle and the flow rate.  Is this resolved using an iterative process?

IO,

My apologies for taking so long to respond to your request.   It has been so long since I thought much about this that I went back to review how I wrote my spreadsheet analysis program.

I also think that it is important to note that there is some polite "disagreement" among engineers and engine builders about certain theories and their practical application.    These are some of theories and practical applications I've been using for some years now.   The Milwaukee Midget is just one successful application.   And as I have stated many times before:   "Information, in and of itself, is neither 'good' or 'bad'."    My experience is: That once you start making information based decisions, you will also want to stop guessing about any engine related decisions . . . .      JMHO.

What is your definition of “flow demand”?
I started with theoretical air capacity.   Air Capacity in cfm = Displacement in cu. in * RPM / 3,456    This is going to vary with rpm, peak torque Vs. peak bhp for instance.  Also needing to be considered are Volumetric Efficiency and piston position.   Piston position in the cycle of the intake stroke is a defining characteristic for airflow need (demand).   Flow demand/piston demand then, is a function of rpm, build geometry, air capacity and efficiency, and is calculated as the displacement in cubic inches (or whatever) * efficiency ratio (Volumetric efficiency) relative to crankshaft motion in degrees.

Piston motion, ie displacement, velocity and acceleration is not uniform, and it is not symmetrical to 90 ATDC.   This is due to "the cosine effect" of the geometry.    The crankshaft's rotation displaces the con-rod big end laterally during operation, effectively shortening and lengthening the con-rod, thereby altering uniform piston motion.    For V-8s of typical geometry, @ 90 ATDC the piston will have traveled more than half the stroke.  Way more, like 5 to 8% or so.   Radical geometry combinations can drastically impact piston motion.   So since the piston travel is not uniform, peak flow demand usually occurs between 70 to 80 ATDC.    The peak demand is closer to TDC with shorter rods.   A longer rod has the opposite effect, and peak demand is delayed by some amount of crankshaft degrees.   The geometric effect can vary based on the difference in length.   Depending on the flow characteristics of the inlet tract and the motion of the valve train, a savvy builder might want to alter/take advantage of the flow/piston demand.


On what basis is a new BMEP determined due to a proposed change in compression ratio?
When I do a spreadsheet analysis of an existing engine, I always calculate existing bmep to evaluate the existing level of development.    If the bmep is low, I will typically create a range of cells to re-calculate potential improvement based on either change in compression ratio or change in absolute pressure if the engine is a blower engine.    I use a linear equation to calculate potential increases.   This, of course, presumes a lot, such as adequate airflow is available and V/E remains constant, etc.    It is simply a starting point to estimate what might be accomplished.    I extrapolate on a linear basis rather than an exponential one because my experience has been that peak combustion pressure, measured in the cylinder of a running engine, is a relatively linear function of static compression ratio.


Despite a fairly thorough examination of the SuperFlow website, the “well published formula” for horsepower remained undiscovered.  Could you please provide more guidance?
BHP = observed cfm * power coefficient * number of cylinders

Power coefficient                  flow in inches of water
       0.43                                                  10
       0.35                                                  15
       0.27                                                  25
       0.26                                                  28

This formula also makes a lot of assumptions, namely:
1)  Airflow should be through the complete inlet tract,
2)  Airflow should be the average of all cylinders,
3)  Engine development/efficiency in other areas must match airflow development.

This tidbit used to come in the SuperFlow written manual supplied with each flow bench.   And I suspect Harold Bettes is responsible for compiling the info & distilling it into something useful . . . . .


It has been my understanding that flow bench data is generated at a fixed pressure differential.
Yes.  By far the majority of flow data is/has been accumulated this way.   Much is now being done with computer controlled valve opening/closing devices.

If that is the case, how do you generate realistic inlet cycle flow rates vs. valve position for varying cylinder pressures?  Are flow coefficients found for each valve position?
Yes.  OEM's and big budget Pro race teams devote all sorts of resources to finding the answers.   The data is crunched by complicated specialty software.

Seems like there would be a circular dependence between cylinder pressure during the cycle and the flow rate.  Is this resolved using an iterative process?
Yes.    The latest and greatest simulation programs are multi-variable.    The timing of the flow "events" is also critical, and much effort is done to determine this based off simulation work.   A lot of effort and dollars are expended here.

I apologize for the brevity of some of my answers, but I am getting really close to voiding the contract of my day job, something I do not wish to do.
 
Fordboy

[Tman]

I picked up a girl in the bar that way 23 years ago. She was bartending with my best friend. I still blame him! I could never understand the modern stock car wraps. The graphic designer side of me hates that blur of color! I think you could do well chasing one of those local micro-breweries. A fuel sponshorship if you will!

[Milwaukee Midget]

Chris,

I'm new here but have been lurking for a long time. Should you need any help in sourcing stuff from the UK for a K series then give me a shout as I'm on the right island on this side of the pond.

I should in all honesty, mention that it was reading your stuff on Faceache that gave me an idea to build something to run on the salty stuff and it is Midget based but luckily in another class.

Cheers,

Ian

Ian -

So you're looking to do a turbine Sprite! 

I know NOTHING of turbines or how they're classed for Bonneville, but I WANT TO SEE THIS HAPPEN.  Keep us posted.

One other thing - Your handle inspired me, and I ran with it for a small decal I intend to put on my 215 Buick Frogeye, which has got a bit of a rat-rod vibe going on.

With your permission, I'm thinking of putting this on the deck, just opposite the fuel cap.

If I may introduce to you - Frankensprite -

[fordboy628]

If I may introduce to you - Frankensprite -

Uh-oh . . . . . .

Why am I getting the feeling that Frankensprite is destined for serious "salination"?

(If only on the side streets and back alleys of Beerhaven . . . . .)

 
F/B

[Milwaukee Midget]

Uh-oh . . . . . .

Why am I getting the feeling that Frankensprite is destined for serious "salination"?

(If only on the side streets and back alleys of Beerhaven . . . . .)

 
F/B

It won't be seeing the street until we get past the snow and we've had a solid rain to rinse the salt away.

But speaking of salt - I did get a friendly retweet from our good friends at OSH -

https://twitter.com/MilwaukeeMidget/status/554848564770533376

[fordboy628]

Uh-oh . . . . . .

Why am I getting the feeling that Frankensprite is destined for serious "salination"?

(If only on the side streets and back alleys of Beerhaven . . . . .)

 
F/B

It won't be seeing the street until we get past the snow and we've had a solid rain to rinse the salt away.

But speaking of salt - I did get a friendly retweet from our good friends at OSH -

https://twitter.com/MilwaukeeMidget/status/554848564770533376

midget,

THAT has got to be your best post, EVER! ! ! !   Congrats!

 
Fordboy

[fordboy628]

This post was prompted by an adamant idiot, although he thinks he is an engine development "genius". (geniass? ?)  BTW, not a guy from this board/community.

It is also a duplicate from my thread, How do I make my engine better, Racing Engines 101.    What can I say, more guys read the midge . . . . .


Validation of your DATA . . . . .

Everyone,

Please excuse my rant . . . . .

I get sent dyno data/flow bench data for analysis, on a regular basis.    Some of the data is "useable", some is not.   Dynos & flow benches can vary, BUT, there is a "reasonable" amount of variance that should be accepted.   As with ANY pieces of "scientific testing equiptment", there needs to be maintenance and calibration for continued accuracy and repeatability.

Think about that for a moment . . . .


One of the things that can be done to validate data is "cross-checking".   What I am saying is:

If you have dyno data and flow bench data, these pieces of data can be "correlated", to determine relative accuracy for both sets of data.

I do this on a regular basis for data that I generate, and for data that I analyze.
(This is aimed at normally aspirated engines, but the formulas can be modified for blown engines.)

This is what you can do:

A)   Don't just flow test the bare cylinder head(s).  (You test all the ports, right?   )   Test the entire inlet tract.
2)   Convert from airflow to "potential" bhp using the following formula:

BHP = observed cfm * power coefficient * number of cylinders

Power coefficient                  flow in inches of water
       0.430                                                10
       0.350                                                15
       0.272                                                25
       0.257                                                28

Airflow should be through the complete inlet tract, AND, should be the average of all cylinders.
There is a more complete conversion chart in Harold Bettes' book listed below.    BUT, be aware that flow testing at very low test depressions can be misleading.


d)   IF YOUR ENGINE IS WELL DEVELOPED AS YOUR AIRFLOW, dyno test results should "reasonably" agree with the "potential" calculations.
      1)   If the numbers agree, great.    The dyno and flow bench you are using are reasonably well calibrated and accurate.

      2)   If the dyno numbers are lower than predicted by the airflow:
            a)   Most likely, more development is necessary to "capture" the airflow potential.   OR   
            b)   Perhaps something is out of calibration.   This is easy to check, and there is no excuse to avoid it.

      3)   If the dyno numbers are significantly higher than predicted by the airflow:
            a)   Something is wrong, somewhere.   Either the flow bench or the dyno is inaccurate and need to be tested for accuracy.   You should test both for repeatability as well.
            b)   If your "back calculation" check from C/bhp results in airflow numbers far in excess of what is "normal" for your valve size(s), then something is royally screwed up.


Two books that every racer should have (and have read), explain these processes better than I can are:

1)    "Engine Airflow" by Harold Bettes
2)    "Dyno Testing and Tuning" by Harold Bettes & Bill Hancock

These books may prompt you to begin to digest some of the more technical collegiate texts from my reading list.

 
Fordboy

[Milwaukee Midget]

The January issue of MG Enthusiast is still not available at Barnes and Noble, at least not in Milwaukee, but the February issue has hit the stands in Great Britain.

And Mr. Goldsworthy, the editor, has been very gracious in his description - although I think "epic proportions" might be a bit of hyperbole.

http://mgenthusiast.com/blog/1248-eds-blog-february-2015-issue

I need to start refocusing on 2016.  I don't want to be scrambling 18 months from now.

[Finallygotit]

Chris, you're an international superstar!    

[fordboy628]

The January issue of MG Enthusiast is still not available at Barnes and Noble, at least not in Milwaukee, but the February issue has hit the stands in Great Britain.

And Mr. Goldsworthy, the editor, has been very gracious in his description - although I think "epic proportions" might be a bit of hyperbole.

http://mgenthusiast.com/blog/1248-eds-blog-february-2015-issue

I need to start refocusing on 2016.  I don't want to be scrambling 18 months from now.

midget,

No hard copies at any of the Barnes & Noble stores here south of the cheddar curtain . . . . .

But B&N will gladly sell you an electronic copy . . . . and the nook device to read it . . . .

Kindly pick me up 2 copies of each month if you can, and let me know how much I owe you.   (One copy is for the Mini-Maven, currently recovering.)

Careful, any more International fame, and you are a target for ISIS . . . . . .   

Not sure how much speed the Prophet allows for MG Midgets . . . . . . but like fast women, your car is probably too fast . . . . . . .
 
charliehebdoboy

[WOODY@DDLLC]

The January issue of MG Enthusiast is still not available at Barnes and Noble, at least not in Milwaukee, but the February issue has hit the stands in Great Britain.

And Mr. Goldsworthy, the editor, has been very gracious in his description - although I think "epic proportions" might be a bit of hyperbole.

http://mgenthusiast.com/blog/1248-eds-blog-february-2015-issue

I need to start refocusing on 2016.  I don't want to be scrambling 18 months from now.

Chris, he was probably referring to your ability to get in and out of the car!