Milwaukee Midget

[Milwaukee Midget]

I thought it was a Pentacostal thing
G

In a 'Life of Brian" sort of way, yeah . . .

[grumm441]

More in a 5 port head kind of way
G

[fordboy628]

More in a 5 port head kind of way
G

Ahhh yes.     Back to the reality of the 5 port BMC cylinder head . . . . . . .

Okay, for those of you building BMC's, some real world graphs, and, the corresponding numerical data.

I've posted the graph and descriptions one at a time again so viewers can use their screen zoom function to enlarge the images without jumbling the captions.   Once you have an enlarged image, you can use any screen capture method to download/print the information.


This is the graph of Midget's cylinder head flow, all 4 cylinders, both intake and exhaust.    Cylinder head flow only, using a radius inlet adaptor and an exhaust pipe stub.  Contact me via PM if you want the details on my adaptors.    You MUST use some adaptor(s) in your flow testing to obtain consistent and valid results.    My retests are typically within .3%.    You will notice that one intake port and one exhaust port are each significantly better than the other 3 ports . . . . . . . .



The flow data for the graph above, all cylinders.



This is a graph of Midget's cylinder head, averaged flow, versus some other good flowing heads.    Midget's head has very good low-lift and mid-lift flow numbers.   All heads were tested using the same intake and exhaust flow adaptors, for consistent results.    These are all big valve type, all out race heads.    I do have some flow results for heads with smaller (mid-size) valves.     If there is enough interest, I can post those numbers as well.    At this point in time, I DO NOT have any test results for small valve/small bore heads.     If you want one of those types of heads tested, send me a PM.



This is the data for the second graph using average flow values of each cylinder head.

This is data that I've posted before, in a different format.    Previously, I did not include the data numbers, so now these can be used to evaluate other cylinder heads being tested by others in differing locations.    If you are going to test and do a comparison, try to test @ 28" of test pressure.    That is the value I test with, and then there will be NO correction factor for test pressure.    Your test results at a different test pressure can be corrected to 28" or you can factor my test results lower.    I personally think that it is best to test at the same pressure . . . . . .  as you still have any differences in the flow benches to account for . . . . . . .
 
Flowmonkey

[Graham in Aus]

Fordy Flow Monkey Boy 

Great data!  BUT! it must be even more valuable when you have the heads sat right in front of you to visualise where the various improvements are coming from! 

So, Chris needs the inlets 'a la' Swiftune 1A and exhaust per Longman 1 ?

Are the Swiftune heads relatively new, is the 1a an earlier version than the 5? suggesting improvement / development on their part.....?

How is the overall exhaust flow compared to the Inlet? Is the exhaust restrictive, or easily within required capacity?

Sorry for the simple questions, I'm new to this flowbench interpretation lark! 

Thank you again for sharing!!  maybe that should be "Generous Boy" 

[fordboy628]

Fordy Flow Monkey Boy 

Great data!  BUT! it must be even more valuable when you have the heads sat right in front of you to visualise where the various improvements are coming from! 
Sometimes it's helpful, but most of the time the differences are very subtle and not so obvious.

So, Chris needs the inlets 'a la' Swiftune 1A and exhaust per Longman 1 ?    Not necessarily.   Although I am always a proponent of more low-lift/mid-lift flow, big high-lift flow numbers are not always required with smaller displacements.    When you have a smaller displacement engine, a head that flows more will usually have less flow velocity, and that is usually not a good choice.    It would depend on the rpm range that the engine is being designed for.    An engine designed to be used at very high rpm's is going to have a proportionally larger "flow demand".     It is the inability of the inlet tract to fulfill "flow demand" that causes volumetric efficiency losses at higher rpm's.    The torque peak is always the peak of bmep and flow efficiency.    Higher bhp values past the torque peak are a result of the power formula [bhp = tq*rpm/5252] in spite of the dropping efficiency.    And when the efficiency drops steeply enough, bhp falls as well.   I'm sure that a head with those flow numbers could be made to work well with say a 1275/1310/1380cc displacement engine.    I think Chris' head is a good "flow match" for the displacement and the rpm range being used.    And the cam choice is a huge factor here as well, and we aren't even talking about cams.    Remember, "It's complicated".

Are the Swiftune heads relatively new, is the 1a an earlier version than the 5? suggesting improvement / development on their part.....?    My client tells me both heads were purchased and delivered at the same time.    2007, I think was the year they received them.    So recent, but not the very latest.    And certainly not the "new Swiftune" special casting.    It is in fact the limitations of the "sculpted top" 12G940 casting which prompted Swiftune to go to the trouble and expense of the new "special" casting.

This is kind of a touchy subject, BUT, my opinion is that both Swiftune heads were virtually identical when delivered.    And then, somebody suggested that the head(s) could be "improved", by the addition of MED 6mm stem diameter valves and guides.    This was done by a Chicagoland specialty race shop familiar with vintage BMC engines, but without a flow bench/adaptors for BMC's.     The "improved" head promptly "lost" 8bhp on the shop's dyno.     No plausible explanation ever ensued, UNTIL the heads were flowed and the results compared.     Loss of overall intake flow, especially low-lift and mid-lift, is going to cost you horsepower output.    Period.   End of story.

Swiftune 1A is as delivered by Swiftune.     Swiftune5 is the "improved" head and the resultant flow.   Not what I would call development.   Go back to the previous postings of flow graphs.    Swiftune51 is the retest of Swiftune5 with the Swiftune 9/32 stem valves and guides re-installed.    Notice that the low-lift/mid-lift flow is restored to almost the values of Swiftune1A, but the high-lift flow is now less.    Probably due to the valves being "sunken" into the chambers.     IMHO.    If you are going to pay someone, a shop, whatever, for "improvement", you ought to get documentation of the "before" and the "after", SHOWING THE IMPROVEMENT!    Again, IMHO.

How is the overall exhaust flow compared to the Inlet? Is the exhaust restrictive, or easily within required capacity?     I've only graphed some early results for Chris' head, way back in the build diary.    There is "some disagreement" among "engine professionals" about what is required in terms of exhaust flow as a percentage of intake flow.    My own opinion is that the percentage required is dependent on the engine style, number(s) of valves/cylinder, rpm range, application (re: drag/sprint/endure/etc), normally aspirated Vs. supercharged, etc, etc.     "It's Complicated".     My opinion is that for N/A, small displacement, 2 valve/cyl, non crossflow engines like Chris' BMC, I want to see exhaust flow % be between 74% to about 82% of intake flow, to be able to use a SINGLE PATTERN CAM.    Less exhaust flow percentage would require a dual pattern cam with more "lobe area" on the exhaust.     More exhaust flow percentage would require a dual pattern cam with less "lobe area" on the exhaust.    IMHO.

Blown engines require MORE exhaust flow percentage, 90/95%, or more, depending on the boost ratio.     4 valve per cylinder N/A engines require about 85/90%.    Unless the flow percentage is WAY OUT OF WHACK, a good engine engineer can "usually" come up with a special camshaft to "band aid" the situation, BUT, this presumes that the cylinder head flow is "appropriate" for the displacement and intended rpm range of the engine, and therefore the "flow demand" required.    This is a perfect example of why you have to be careful with the parts selection process early on in your build.    You could be stuck with an expensive part that might not be a good choice for your intended purpose.

Sorry for the simple questions, I'm new to this flowbench interpretation lark!      No problem, they are all good questions.

Thank you again for sharing!!  maybe that should be "Generous Boy"       Nah!   I've worked hard and long to create a reputation for being "difficult".    Don't wanna blow it now.

Graham,

Made some comments in your text, sorry.   Still a slow and crappy typist!!
 
Flowmonkey

[Milwaukee Midget]

More in a 5 port head kind of way
G

Ahhh . . .  yes . . . well played.

Another Australian poker player I would be wise to avoid anteing up against.

[grumm441]

More in a 5 port head kind of way
G

Ahhh . . .  yes . . . well played.

Another Australian poker player I would be wise to avoid anteing up against.

I was thinking maybe I should've posted that one on the stupid joke friday thread
G

[Graham in Aus]

Thanks for your explanations F/Boy, the more I think I'm getting to grips, the more factors I realise I've forgotten!

You quote says it all really......

ITS COMPLICATED! 

[Milwaukee Midget]

Fordboy -

For your books -

Piston pop-up -

1  .007
2  .008
3  .008
4  .007

[Milwaukee Midget]

A caution - I have been told by a good friend with a Mac that there may be an issue with the following movie clips.  They are links to my photobucket account. 

Looks like I got lucky.
  
Last November I bought a belt drive cam set-up for the Midget.  The price was stupid-righteous – cheap enough that if it didn’t work, I could either resell it or modify it.

Looks like all I’ll have to do is bolt it on.

My concern about it was that when my block was align-honed, it shortened up the distance between the crank and the cam.  This became apparent when Fordboy whipped up the belt drive for the water pump.  It fit tightly on a stock, unhoned block, but ran a little loose on the Grenade -
Click on this pic – it’s a movie –






My fears were unabated when I was forced to Mickey Mouse a Triumph spring tensioner under the stock chain cover – something that Jack Gifford cautioned me about – and after disassembly, I discovered it’s not likely it would have made another ½ dozen passes.  The stud was quite loose –





But given the size of the pulleys, it appears that I don’t have to fear slipping a tooth on the cam drive with the new Gilmer assembly – again, click on the movie –






Again, the big advantage of this set-up is the access cover to the cam, which will allow us to adjust the cam timing very quickly while on the dyno.  At what dyno time costs, turning a 2 hour tear-down into a 10 minute operation pays for itself before lunch.

[jacksoni]

Although I'd think the cam drive (my Jesel belt is tight but there is slight stretch/movement if you go forward and back on the crank before the cam moves. I understand up to 4* is common) needs to be tight as you show, it is my understanding that accessory gilmer belts do not need to be and even should not be super tight. A little slack is correct. Lacking a tester, I have seen people say you should be able to twist the belt between 45-90 degrees with your fingers. I did a little looking but didn't find a mfg (Gates for instance) say how to set without a tester of some sort. I expect many different opinions on this. But your water pump looked about right.

[Stainless1]

MM, contact our LSR Gates rep for Gates Belt info and tensioning... Jon Amo 

[fordboy628]

pigmy,

I own a Burroughs Tool, belt tension checker for gilmer (square tooth) drive belts.    It is specifically for the 1" wide cam drive belts for Cosworth "BD" series engines.    I'm not sure if the length of free run (part of the belt that is unengaged from the cog teeth) is sufficient to use that tool.    I'll post a photo with a ruler next to the tool so you can see what I'm talking about.

Mini Maven is talking about a Monday/Tuesday search and rescue mission to West Allis, Beerphalia to inspect all things Hillman and Impish.    Does this work for you?   The engine appears to be a Coventry Climax FWMA, in about 3/4 scale . . . . . . .  manufactured by Rootes.    Unlikely that any parts interchange.

 
Fordboy

[Andy Cooke]

If that imp engine is your thing the chap to talk to over here is probably Ben Boult http://www.corley-conversions.co.uk/. 

Andy

[Milwaukee Midget]

Okay - the die has been cast -

http://www.ebay.com/itm/251443838396?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

On its way.

Double over head cams - let's see if we can make some power.

Should be on the salt in 2016.

Chris