Author Topic: Milwaukee Midget  (Read 3255078 times)

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Offline jacksoni

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Re: Milwaukee Midget
« Reply #4740 on: January 24, 2015, 10:07:56 AM »
Fordboy- in one of your excellent posts here you mentioned the effect of rod ratio on flow demand and position of that max. Along with this was the comment that a 4 valve head with better low lift flow than the average 2 valve would, generally speaking, work better with a shorter rod (lower rod ratio) to take advantage of the low lift flow since location of peak demand was somewhat sooner in the cycle. Since you and Midget will need to destroke the K motor to fit the class how are you planning to help mitigate this issue or take advantage of it. You can't just shorten the rods or you get a seriously top heavy piston (longer compression height) which has it's own disadvantages. I am particularly interested as I find myself with a short block with similar issues and am going from a very good 2 valve head to a very good 4 valve head that does indeed have better low lift flow, but similar high lift flow to the 2 valve.  I'm not sure there is anything I can do but am curious what possibilities  there may be. The 4 valve head was designed for the displacement I am running but the bore and stroke are a bit different than what it was designed for. Less of a mismatch than the 2 valve head was. Thoughts?

Jack
Jack Iliff
 G/BGS-250.235 1987
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  G/FAlt- 193.934 2021 (196.033 best)
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Offline fordboy628

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Re: Milwaukee Midget
« Reply #4741 on: January 25, 2015, 08:50:43 AM »
Fordboy- in one of your excellent posts here you mentioned the effect of rod ratio on flow demand and position of that max. Along with this was the comment that a 4 valve head with better low lift flow than the average 2 valve would, generally speaking, work better with a shorter rod (lower rod ratio) to take advantage of the low lift flow since location of peak demand was somewhat sooner in the cycle. Since you and Midget will need to destroke the K motor to fit the class how are you planning to help mitigate this issue or take advantage of it. You can't just shorten the rods or you get a seriously top heavy piston (longer compression height) which has it's own disadvantages. I am particularly interested as I find myself with a short block with similar issues and am going from a very good 2 valve head to a very good 4 valve head that does indeed have better low lift flow, but similar high lift flow to the 2 valve.  I'm not sure there is anything I can do but am curious what possibilities  there may be. The 4 valve head was designed for the displacement I am running but the bore and stroke are a bit different than what it was designed for. Less of a mismatch than the 2 valve head was. Thoughts?

Jack

Jack,

I'm working on flow bench adaptors and some simulations for the 'K', whilst juggling some other projects, AND, most importantly, some home improvements regally decreed by the "Mighty Queen".    If you catch my drift . . . .

One of the issues I have not rambled about is the "match" or "balance" between "flow demand" and "flow capacity".

"Flow demand" is the minimum the engine needs.    "Flow capacity" is the induction tract's ability to fulfill this "need".    Current ideas about the definition of "flow capacity" revolve around the inlet tract flow numbers combined with the valve train's "ability" to provide the "flow" required Vs crankshaft position.    I'm not sure how clear that is conceptually, so I'm going to post up the graphs I generate for this project as we go along, so readers can gain a better understanding of what is going on.

Also of importance to note is that for normally aspirated engines, the ability to "fulfill" "flow demand" early enough in the cycle, might be unlikely with a given "build geometry" and "valve train".    That puts the engine in "catch up mode".     And it is also why the "intake ramming" portion (BDC to intake valve close) of the intake cycle becomes so critically important.   This is where comparatively "small" changes to either the "build geometry" and/or the "valve train" can pay off.   It is also important to note that when I say "valve train", I mean everything from the cam to the valve, and, probably including the cam drive method as well.

The point being is that if you have the opportunity to choose some of these dimensions/parts/etc, it is important to choose "wisely".    I don't think you can know any of this without spending some time doing the number crunching and analysis.   My own personal opinion is that I would rather know the numbers, (even if they are "poor") than just rely on chance/dumb luck.    I want every opportunity to influence/improve the results of my efforts.

You are correct though, when you say that there are situations where you can't do very much.    But I am of the opinion that it is always a "compromise" anyway, so I want to pick the "best" compromise based on several factors, say planned rpm range, "realistic" part loadings, airflow capability, etc, etc.     Somebody said, "It's complicated", I agree.    I think you are going to have to make some hard choices with your build and you should run the numbers so you can make the best choices.

The 'K' is going to have some of the same problems you are encountering.    Namely:
1)   We have to destroke.   Reducing bore isn't really a good choice for this build.   You might be in a different situation.
2)   F1 type rod/stroke ratio.     We are stuck with the block deck height, for various reasons.
3)   Flow capacity perhaps "too large".    This remains to be verified by flow testing.

My initial thoughts are:
1)   That since the stock compression height is very short, we can shorten the rod a "bit" without making the piston too heavy.
2)   Flow capacity can be altered appropriately with high intensity camshafts.

My thinking on this is subject to change without notice, based on the measurements & analysis . . . . . .

One final comment:  If you utilize a low duration cam/valve train to reduce "flow capacity" and/or increase velocity, you probably can't fulfill "flow demand" on a timely basis.   In other words:   You screwed yourself . . . . . .     This is why it's important to do the math and pick "the best compromise".
 :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 fordboy628

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Re: Milwaukee Midget
« Reply #4742 on: January 25, 2015, 11:11:01 AM »

I am particularly interested as I find myself with a short block with similar issues and am going from a very good 2 valve head to a very good 4 valve head that does indeed have better low lift flow, but similar high lift flow to the 2 valve.  I'm not sure there is anything I can do but am curious what possibilities  there may be. The 4 valve head was designed for the displacement I am running but the bore and stroke are a bit different than what it was designed for.   Less of a mismatch than the 2 valve head was. Thoughts?

Jack

What are the differences, specifically?     I tend to be more concerned about total displacement as a factor, UNLESS, the bore, stroke, rod/stroke ratio are significantly different.   Ie: greater than 4/5% different.

And, for anybody who thinks 4/5% is not significant, would you give up 4/5% of your airflow or displacement? ?    Most guys work pretty hard for 4/5% . . . .
 :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 fordboy628

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Re: Milwaukee Midget
« Reply #4743 on: January 25, 2015, 11:34:35 AM »

Despite a fairly thorough examination of the SuperFlow website, the “well published formula” for horsepower remained undiscovered.  Could you please provide more guidance?


IO,

Finally got around to making the time to do a "deep dive" into the SuperFlow site.

http://www.superflow.com/support/supportDocuments/flowbench_applications.pdf

This is in .pdf format so anyone who wishes to view these pages will need the appropriate version of Adobe Reader.

The aforementioned formula is listed here, as well as some handy others.    There are also some tidbits about flow bench use, adaptors and other flow measurement tools.

More information on these and other formulas are contained in "Engine Airflow" by Harold Bettes.    The SuperFlow information is no doubt the result of Harold's long tenure with that company.

Other airflow formulas (I'm not sure how much duplication there might be) can be found in "Performance Automotive Engine Math" by John Baechtel.

Of course there are many other reference books as well.    Enthusiasts looking for some answers from these books need to be able to perform some engineering level math.    A good engineering calculator is handy.
 :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 #4744 on: January 25, 2015, 01:45:04 PM »

I am particularly interested as I find myself with a short block with similar issues and am going from a very good 2 valve head to a very good 4 valve head that does indeed have better low lift flow, but similar high lift flow to the 2 valve.  I'm not sure there is anything I can do but am curious what possibilities  there may be. The 4 valve head was designed for the displacement I am running but the bore and stroke are a bit different than what it was designed for.   Less of a mismatch than the 2 valve head was. Thoughts?

Jack


What are the differences, specifically?     I tend to be more concerned about total displacement as a factor, UNLESS, the bore, stroke, rod/stroke ratio are significantly different.   Ie: greater than 4/5% different.

And, for anybody who thinks 4/5% is not significant, would you give up 4/5% of your airflow or displacement? ?    Most guys work pretty hard for 4/5% . . . .
 :cheers:
Fordboy
My engine is bore 3.883, stroke 2.58, 122 CI, 6.25 rod for 2.44 R/S. The original engine (some difficulty finding numbers as being a race engine such stuff is not generally published) had bore 3.66 (I have a piston so pretty sure of that), stroke 2.9,for same displacement, rod length about 155mm (6.11in) for 2.1 R/S ratio. So bore is 6%, stroke 12% and RR 16%= "significantly"  :-o

At this point, peak piston demand is at about 78.3* (rod at 90* to crank throw) and is 307 CFM (according to some software I have). Head flows 345+ at that point>

Compression height on the piston is 1.480 and I don't want to make it more, which would require new rods, change the piston order already placed and increase weight of the piston to boot.
« Last Edit: January 25, 2015, 01:48:11 PM by jacksoni »
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 Frankenhealey

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Re: Milwaukee Midget
« Reply #4745 on: January 26, 2015, 05:54:09 AM »
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!  :-o

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 -






Chris,

Sorry I didn't bookmark your thread so missed this. 'Frankensprite' is a great name but when anyone asks always pronounce it as 'Fronkenspreet' as in Mel Brooks' Young Frankenstein movie. Always confuses people when I pronounce my handle as 'Fronkenhailey' but they finally get if they're film buffs and if not just think I may be Seouth Affrikkan :evil:

Actually it's not a Sprite but a SpridJET as getting a Sprite as a base car is waaaay too expensive. The turbine package fits nicely in the passenger side (note : hi-tech cardboard mock-up)



And you can see how seriously the rest of the team are taking it



My big problem is how to fit an SCTA mandated rollcage into something like this and still be able to see over the dash :-P



Also have you considered a fastback hardtop like this



The guy that sent it to me reckons that on a standard Midget it improved the top speed from 95 to about 100.

 :cheers:
1954 Chevy Healey V8
1956 Bedford RHLZ Racecar Transporter
1971 SpridJET (hopefully coming soon to a Salt Flat near you)
Hare and Tortoise Racing - Scuderia Astuto Piano - Ecurie Albion Perfide - Rennabteilung Sturm und Drang

Offline tortoise

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Re: Milwaukee Midget
« Reply #4746 on: January 26, 2015, 02:28:08 PM »
Also have you considered a fastback hardtop like this



The guy that sent it to me reckons that on a standard Midget it improved the top speed from 95 to about 100.

 :cheers:

Just the thing for your project, but I think not class legal for Chris's.
« Last Edit: January 26, 2015, 03:04:53 PM by tortoise »

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4747 on: January 26, 2015, 04:25:53 PM »
Also have you considered a fastback hardtop like this



The guy that sent it to me reckons that on a standard Midget it improved the top speed from 95 to about 100.

 :cheers:

Just the thing for your project, but I think not class legal for Chris's.

Yeah, none of the aftermarket body parts are legal in GT.    Has to be stuff supplied by the manufacturer.
 :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 fordboy628

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Re: Milwaukee Midget
« Reply #4748 on: January 26, 2015, 04:31:30 PM »

My engine is bore 3.883, stroke 2.58, 122 CI, 6.25 rod for 2.44 R/S. The original engine (some difficulty finding numbers as being a race engine such stuff is not generally published) had bore 3.66 (I have a piston so pretty sure of that), stroke 2.9,for same displacement, rod length about 155mm (6.11in) for 2.1 R/S ratio. So bore is 6%, stroke 12% and RR 16%= "significantly"  :-o

At this point, peak piston demand is at about 78.3* (rod at 90* to crank throw) and is 307 CFM (according to some software I have). Head flows 345+ at that point>

Compression height on the piston is 1.480 and I don't want to make it more, which would require new rods, change the piston order already placed and increase weight of the piston to boot.


Jack,

Which software are you using for your calculations?

Just curious.
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 #4749 on: January 26, 2015, 05:37:48 PM »

My engine is bore 3.883, stroke 2.58, 122 CI, 6.25 rod for 2.44 R/S. The original engine (some difficulty finding numbers as being a race engine such stuff is not generally published) had bore 3.66 (I have a piston so pretty sure of that), stroke 2.9,for same displacement, rod length about 155mm (6.11in) for 2.1 R/S ratio. So bore is 6%, stroke 12% and RR 16%= "significantly"  :-o

At this point, peak piston demand is at about 78.3* (rod at 90* to crank throw) and is 307 CFM (according to some software I have). Head flows 345+ at that point>

Compression height on the piston is 1.480 and I don't want to make it more, which would require new rods, change the piston order already placed and increase weight of the piston to boot.


Jack,

Which software are you using for your calculations?

Just curious.
Fordboy
Pipemax for the demand, and the visual engine function of EA Pro to get valve lift at crank angle plus the flow chart to match.
« Last Edit: January 26, 2015, 07:16:06 PM by jacksoni »
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 Milwaukee Midget

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Re: Milwaukee Midget
« Reply #4750 on: January 27, 2015, 12:04:14 AM »
Okay, I got the rear end mocked up on the Pom Rod -



There's something about a chrome cover on a 10 bolt that just screams "hot rod".  About 3/4" of clearance on the inside, but any pretence of keeping things subtle are 86ed if I keep the gumballs . . .

Anybody got a set of Vega GT or Chevy Monza wheels they'd like to trade?

"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4751 on: January 27, 2015, 07:48:01 AM »
Okay, I got the rear end mocked up on the Pom Rod -



There's something about a chrome cover on a 10 bolt that just screams "hot rod".  About 3/4" of clearance on the inside, but any pretence of keeping things subtle are 86ed if I keep the gumballs . . .

Anybody got a set of Vega GT or Chevy Monza wheels they'd like to trade?


Now that's what the Nascar guys call a "tiaar" ! !    :wink:

Don't think subtle is going to keep it hooked up . . . . . . .
 :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 #4752 on: January 27, 2015, 10:02:49 AM »

Don't think subtle is going to keep it hooked up . . . . . . .
 :cheers:
Fordboy

This looks like more grip than the chassis can handle. 

I'm thinking a set of 155 80R13 whitewalls will get the job done, probably ride nicer, maintain a stock look and give me better gas mileage.

"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline fordboy628

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Re: Milwaukee Midget
« Reply #4753 on: January 27, 2015, 11:41:39 AM »
Well, well, well . . . . .   Better late to the table than never, I guess.


http://www.mossmotoring.com/worlds-fastest-midget/


 :cheers: :cheers: :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 fordboy628

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Re: Milwaukee Midget
« Reply #4754 on: January 27, 2015, 11:43:30 AM »
Well, well, well . . . . .   Better late to the table than never, I guess.


http://www.mossmotoring.com/worlds-fastest-midget/


 :cheers: :cheers: :cheers:
Fordboy

OOPS,  I almost forgot!

Congrats! !

F/B
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