Author Topic: Milwaukee Midget  (Read 3255247 times)

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Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #4890 on: March 24, 2015, 05:18:34 PM »
midget,

Whilst perusing the DLRA site for news, I just happened to notice that I/GT is an open record at Lake Gairdner . . . . . .

Could this be a "bucket list" item?

Transport over on a raft, "Kon-Tiki" style?

 :cheers:
F/B

I thought I shared that with you.

Before I'm done, I intend to go for the trifecta -

Bonneville, Gairdner and Pendine Sands.

I want to run this thing where Eyston ran "The Magic Midget", then I'll retire it.

He ran 120 at Pendine in his Midget - I want to run just a little faster in mine.  :wink:

I suppose I had better get back to those sponsorship proposals . . .
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Elmo Rodge

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Re: Milwaukee Midget
« Reply #4891 on: March 24, 2015, 06:35:34 PM »
Don't forget El Mirage.  :wink: Nothing wrong with a little "One-upsmanship".  :-D Wayno

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #4892 on: March 24, 2015, 07:58:35 PM »
Don't forget El Mirage.  :wink: Nothing wrong with a little "One-upsmanship".  :-D Wayno

107.655 is the record at Elmo.

My best pass at Bonneville in the one was 121.079.

Gee, I'd have to find a club member to drive it.   :roll:  :wink:
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Elmo Rodge

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Re: Milwaukee Midget
« Reply #4893 on: March 24, 2015, 08:43:27 PM »
I know a Miler Mental Midget.  :-)  :cheers: Wayno

Offline Stan Back

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Re: Milwaukee Midget
« Reply #4894 on: March 24, 2015, 09:35:11 PM »
I'm a roadster driver -- even if it has a top.

I haven't spun for years!
I haven't driven for a couple, too.
(Since the spin.)

Stan
Past (Only) Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club" -- 19 Years of Bonneville and/or El Mirage Street Roadster Records

Offline Jack Gifford

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Re: Milwaukee Midget
« Reply #4895 on: March 25, 2015, 02:58:11 AM »
... That piston would be very heavy though, compromising the plan to use a narrow, low tension ring package...

Rod/stroke ratio is going to be very high... Piston dwell at and around TDC, is going to create piston to valve clearance issues...
These two statements surprise me. I don't see piston weight limiting narrowness of rings. My hemi pistons are monstrously heavy but Diamond recommended 1.2mm top rings and 1.5mm 2nd rings; if it weren't to be supercharged, they would have gone with 1.0mm top rings.

For 'reasonable & possible' changes to R/S ratio (for instance, +/- 0.5" on rod length), piston-to-valve clearance differences @ about 12 degrees from TDC (where clearance is usually minimal) is negligible. Unless I screwed up the "geometry exercise", it would be on the order of a thousandth or two.  Please show the math that supports your "dwell" concern.
M/T Pontiac hemi guru
F/BFL 1-mile Loring record 2020

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4896 on: March 25, 2015, 07:16:02 AM »
... That piston would be very heavy though, compromising the plan to use a narrow, low tension ring package...

Rod/stroke ratio is going to be very high... Piston dwell at and around TDC, is going to create piston to valve clearance issues...
These two statements surprise me. I don't see piston weight limiting narrowness of rings. My hemi pistons are monstrously heavy but Diamond recommended 1.2mm top rings and 1.5mm 2nd rings; if it weren't to be supercharged, they would have gone with 1.0mm top rings.

For 'reasonable & possible' changes to R/S ratio (for instance, +/- 0.5" on rod length), piston-to-valve clearance differences @ about 12 degrees from TDC (where clearance is usually minimal) is negligible. Unless I screwed up the "geometry exercise", it would be on the order of a thousandth or two.  Please show the math that supports your "dwell" concern.

Hi Jack,

What I'm concerned about on the piston is that with a "tall" compression height, the mass becomes very concentrated at the top (dome) of the piston.   Combined with short, slipper, low drag skirts, the piston tends to "rock over" at TDC, which tends to compromise the dynamic ring seal.    I'm not sure just how much of a problem it might turn out to be, I just want to avoid it if I can.

I'll try to get to the rod geometry later in the day.   If anybody recalls, the BMC engine has this problem because of the very high rod/stroke ratio.   It appears that the Rover R/S is going to be higher.    It can be overcome, but the piston needs to be designed to be able to accommodate deeper valve notches.
 :cheers:
Fordboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline jacksoni

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Re: Milwaukee Midget
« Reply #4897 on: March 25, 2015, 08:51:56 AM »

For 'reasonable & possible' changes to R/S ratio (for instance, +/- 0.5" on rod length), piston-to-valve clearance differences @ about 12 degrees from TDC (where clearance is usually minimal) is negligible. Unless I screwed up the "geometry exercise", it would be on the order of a thousandth or two.  Please show the math that supports your "dwell" concern.
[/quote]
Indeed the position of 10-12* before and after TDC are often quoted as the spot of closest P-V approach ( and I have seen a good engine building book suggest checking at 10*-only-) you have to check. My engine with high R/S ratio, big valve, high lift cam had closest P-V at 20 degrees. I checked at every 5 until I was sure where that occurred. If you rely on one "generally accepted" spot, I humbly suggest Mr Piston and Mr Valve may become closely acquainted. :cheers: :cry:

Though there are effects of rod ratio on airflow, as FB has pointed out, piston design and ring package and seal are also a factor to be considered and may be more important. Everything becomes a compromise. When putting my engine together a 6.2"rod on a 2.58' stroke (2.44 RR) gave a 1.450" Compression height on the piston. It was suggested to me that this was more than Ideal and a longer rod- rod ratio be damned- would give a better piston/ring package. Along the lines of what FB is saying here.
Jack Iliff
 G/BGS-250.235 1987
 G/GC- 193.550 2021
  G/FAlt- 193.934 2021 (196.033 best)
 G/GMS-182.144 2019

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4898 on: March 25, 2015, 09:21:27 AM »

I don't see piston weight limiting narrowness of rings. My hemi pistons are monstrously heavy but Diamond recommended


Every piston I have ever seen from Diamond has been "monstrously" heavy.    I am currently trying to get one of my vintage clients to change from Diamond to JE.

On a 3.220 bore, the weight difference is 62 grams!!    A Wiseco or CP would be even lighter . . . . .

The Diamonds are cheap though . . . . . .
 :cheers:
Fordboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #4899 on: March 25, 2015, 09:39:40 AM »
Okay, all this raises the question - how "heavy" is heavy?

Now I realize we're looking for RPM considerably higher than what Jack is looking at, but relative to the stresses on the rods and rod bolts, and keeping in mind that due to the short stroke, we'll have a VERY stiff crank with considerable journal overlap, and 5 main bearings this time (a huge improvement), at what point does "heavy" become "too heavy?"

I'm also thinking a longer piston would help minimize piston rock.

We're talking about an engine - despite its inadequacies - that is is capable of 300 hp in a 2 liter configuration.

Let me see if I can find the weight of the J&Es I used in the Grenade.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #4900 on: March 25, 2015, 09:43:28 AM »
Found it  - Grenade weights for comparison.

Pistons - 256 grams
Rods - 422 grams.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Stainless1

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Re: Milwaukee Midget
« Reply #4901 on: March 25, 2015, 09:57:10 AM »
When considering custom pistons and rods, I would suggest checking with Wossner USA.  John Noonan is very LSR racer friendly guy since he is one.  :-D
These days you can specify a crown thickness so pistons don't have to be lightened after production.  CnC is a wonderful thing
The worm can is now open  :cheers:
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4902 on: March 25, 2015, 10:04:48 AM »

For 'reasonable & possible' changes to R/S ratio (for instance, +/- 0.5" on rod length), piston-to-valve clearance differences @ about 12 degrees from TDC (where clearance is usually minimal) is negligible. Unless I screwed up the "geometry exercise", it would be on the order of a thousandth or two.  Please show the math that supports your "dwell" concern.


Hi Jack,

It is not the piston position itself at a particular crankshaft angle that is my big concern.    As R/S increases, dwell time around TDC is expanded, ie, it takes more crankshaft angle in degrees to begin moving the piston away from TDC.   This, itself isn't "bad".    Coupled with a "high velocity" valve train, problems occur.     I want to use a cam that will give something like .0052"/.0055" lift increase, per degree.    And I want to design in some "freedom" to advance/retard the cams a bit, on the dyno.



Indeed the position of 10-12* before and after TDC are often quoted as the spot of closest P-V approach ( and I have seen a good engine building book suggest checking at 10*-only-) you have to check. My engine with high R/S ratio, big valve, high lift cam had closest P-V at 20 degrees. I checked at every 5 until I was sure where that occurred. If you rely on one "generally accepted" spot, I humbly suggest Mr Piston and Mr Valve may become closely acquainted. :cheers: :cry:


If the point of closest V/P clr is altered by 4/6 degrees, the valve notches have to be .022"/.033" deeper for the cam(s) I'd like to run.    I want this built in.     I don't want to take the engine off the dyno to machine pistons or change pistons, just to be able to change cam timing.

On "monstrously heavy" pistons, machining an extra .030" out of the valve clearance notch is probably of no concern.    On the MM's BMC, we had to compromise on the cam, because the lightweight piston would not tolerate .020" of valve clearance machining.    The dome was already very thin, .180" or so.   Why?   Because it had been designed for minimum weight to begin with . . . . . .      I do not want to be in this position again . . . . . . .

On larger displacement engines, there is typically "room" or material, to alter (or "massage") the parts.    On very small displacement engines, (61 cubic inches) there is much less leeway for "errors".    I'd rather spend the time calculating out what is needed, than have a manufacturer send me what they "think" I need.    It is always "a crapshoot".

And if mistakes are made, compression ratio suffers . . . . . . .

I'll get to the math on this for you later.
 :cheers:
Mark
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4903 on: March 25, 2015, 10:07:42 AM »
When considering custom pistons and rods, I would suggest checking with Wossner USA.  John Noonan is very LSR racer friendly guy since he is one.  :-D
These days you can specify a crown thickness so pistons don't have to be lightened after production.  CnC is a wonderful thing
The worm can is now open  :cheers:

Stainless,

You read my mind on the piston lightening.     Designing the piston to satisfy all the design parameters will not be difficult, just time consuming & finicky.
 :cheers:
Fordboy
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #4904 on: March 25, 2015, 10:07:52 AM »
When considering custom pistons and rods, I would suggest checking with Wossner USA.  John Noonan is very LSR racer friendly guy since he is one.  :-D
These days you can specify a crown thickness so pistons don't have to be lightened after production.  CnC is a wonderful thing
The worm can is now open  :cheers:

Spoke with John at the PRI show, and what's good about Wossner is that they have an MG/Rover 75 mm piston in their catalog that they market in Europe, so at least we have a starting point to get them cut!
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll: