Milwaukee Midget

[RidgeRunner]

     FWIW.  At Speedweek in '71 I listened in on an oldtimer offering his thoughts on air and fuel flow for max performance to those of us waiting in line.  Concluding he repeated emphatically "NEVER SACRIFICE FLOW VELOCITY FOR FLOW VOLUME!"  Being of the age to know it all I had serious doubts as to the validity of his information and logic until the rider he was with proceeded to rip off a 150+ run on a 500 Kawi Mach 111 in a drag style frame with no streamlining.  A run I thought was VERY stout for the bike at the time.  A lesson quickly learned and never forgotten.

           Ed

[Milwaukee Midget]

Well, I admit that you can:  "Just bang 'em together and get 'em out the door."

In fact, I know several engine professionals who do just that.   Some of their clients are happy, some are not.    They respond by saying:  "You can't please all of the people all of the time."

There are, however, alternate choices, depending on the results you want, and how much of a "deep thinker" you might want to be.

As I have mentioned a time or two previously:    "It's complicated."   "Both ways work."   "More or less."   "Eventually."    Decide for yourself whether I put those comments in this order for a specific reason . . . . . . . . . .

"Ya pays yo money, and ya makes yo choice". . . . . . . . .

 
Nolongeraboy

A destroked Rover K?  Most people would have tried to run H/GT. 

I don't think there's ever been a question that I'm in full support complicated! 

[jacksoni]

Chris ( and Mark)- part of my suggestions come from not being familiar with the cam architecture on the K head. I ran into the "disposable head" problem when trying to get mine fixed. Repairs doable (have you considered if bearing inserts of appropriate size might be available? - another can of worms. Finding a good head better/cheaper than fixing the damaged one which is appropriately being used for experimentation to see what is best for the good one. But unless you can find why the spare flow numbers are way off the good head, how will you know if changes will transfer without screwing something up?) but not reasonable.  Onwards and upwards. Looking forward to flow results with the different valves.

 I think the statement to never give up velocity for flow volume (though some would likely debate) shows an understanding above what is commonly believed. Both are important but......."It's complicated" 

[fordboy628]

    FWIW.  At Speedweek in '71 I listened in on an oldtimer offering his thoughts on air and fuel flow for max performance to those of us waiting in line.  Concluding he repeated emphatically "NEVER SACRIFICE FLOW VELOCITY FOR FLOW VOLUME!"  Being of the age to know it all I had serious doubts as to the validity of his information and logic until the rider he was with proceeded to rip off a 150+ run on a 500 Kawi Mach 111 in a drag style frame with no streamlining.  A run I thought was VERY stout for the bike at the time.  A lesson quickly learned and never forgotten.

           Ed

Ed,

I agree, in a very generalized way.    Having seen many samples of engines with ports "too small" for the displacement/rpm, and the result is: ultra high flow velocity.

What I want to do is to have the ports sized to provide the flow required and also have a "good" velocity.

In very general terms, too small ports and the resultant ultra high velocity typically limits top end bhp.

 
Fordboy

[fordboy628]

    FWIW.  At Speedweek in '71 I listened in on an oldtimer offering his thoughts on air and fuel flow for max performance to those of us waiting in line.  Concluding he repeated emphatically "NEVER SACRIFICE FLOW VELOCITY FOR FLOW VOLUME!"  Being of the age to know it all I had serious doubts as to the validity of his information and logic until the rider he was with proceeded to rip off a 150+ run on a 500 Kawi Mach 111 in a drag style frame with no streamlining.  A run I thought was VERY stout for the bike at the time.  A lesson quickly learned and never forgotten.

           Ed

Ed,

I agree, in a very generalized way.    Having seen many samples of engines with ports "too small" for the displacement/rpm, and the result is: ultra high flow velocity.

What I want to do is to have the ports sized to provide the flow required and also have a "good" velocity.

In very general terms, too small ports and the resultant ultra high velocity typically limits top end bhp.

 
Fordboy

OK, here is an example from today:

302 SBC for F/5000 road racing,  4x 48IDA Webers (42mm chokes), headers, etc . . . . .  using 190cfm Brodix straight plug heads, modest cam, low compression . . . . . .

403 bhp peak, @ 6400 rpm  falling to 340 bhp @ 7000 rpm.

Obviously the modest cam and the low compression ratio don't help.   But this engine needs 220 cfm to 240 cfm intake flow to produce 480/500 bhp at ~ 7500/8000 rpm.

A decent 45 DCOE with a 40/41mm choke will flow ~269cfm, per barrel.   Doesn't make much sense to bolt those carbs onto an inlet port that flows 190cfm.   

 
Fordboy

[RidgeRunner]

Fordboy, Jack,

     I agree, too much of less can be just as unproductive as too much of more.  It's all how well various combinations of systems work together in various applications and it can get VERY complicated.  I was just trying to mitigate the commonly held "more is ALWAYS better" approach in things mechanical.  I wasn't engineered to be able to make valid conclusions in other worlds.......

     The referenced discussion was concerning N/A gasoline powered motorcycles in general and in particular the differences between traditional round slide carbs and the flat slide carbs that were starting to be more commonly used at that time.  The actual mixing of gas and air as well as how well and long they stayed mixed with resulting power gains or losses was discussed.  IIRC he was basing some of his thoughts on things he had learned while working for a company that manufactured "pumper" or diaphragm carbs for small gas engines.

      Using blowers, turbos, different types of fuel injection systems, or fuels other than straight gasoline will all add, modify, or subtract factors in the big equation.  As a quick side note I'm expecting direct injection to simplify things a bit after the initial learning curve and parts become more available.  While relatively new to common gas powered use it has been used successfully in the diesel world since at least the '30's.

    Biggest lesson I learned that day many years ago was to always keep my eyes, ears, and mind open to learn at any time regardless any false doubts from first impressions.  Hope I never lose that ability and can keep on learning.   

    Looking forward to more threads on the build diaries and info dumps from both of you and the others.   

                       Ed

     

[fordboy628]

    Biggest lesson I learned that day many years ago was to always keep my eyes, ears, and mind open to learn at any time regardless any false doubts from first impressions.  Hope I never lose that ability and can keep on learning.   

                       Ed
     

And that friends, is the best ability to cultivate.

Let's see,  "data" Vs "common knowledge" . . . . . . . . .   I think everybody can figure out where I stand on that issue.    Yes, data gathering is time, material, and monetarily expensive, that's why most people do not do it.   As shown by my example in reply #5614, even a well known left coast engine "guru" can make poor component selections that dismally affect engine output.

 
Fordboy

[jacksoni]

Not that I know anything but I was surprised to see your "left coast engine guru" put a head that small on any kind of race engine. Where did he find them? Geeezzzzz

'Nuff said- now back to our regular programming (ie Rover K)

[Milwaukee Midget]

Going COMPLETELY off topic with this, other than the fact that by applying a combination of old and new technologies, a creative mind and talented machinist/electronics engineer can produce a remarkable piece of engineering . . .

https://www.youtube.com/watch?v=3gwZ2lHtG0Y

The craftsmanship is beyond reproach.

[Rex Schimmer]

Obviously the designers of the Turbo Entabulator also!!

Rex

[Seldom Seen Slim]

Thanks, Chris.  It's not often that I'll watch an entire five-minute diversion, but that was cool.

[fordboy628]

Going COMPLETELY off topic . . . .
 

Ahhhh . . . . .   isn't that what we do?

Just sayin' . . . . .

 
Fordboy

[fordboy628]

midget,

OK, had a pretty good day @ T & T and finished up the Rover flow testing/development on cylinder head #2.    Got some pretty good results with modest modifications, AND, the flow achieved slightly exceeds what is required to produce 135 bhp even estimating a 10% inlet tract flow loss and a 10% header flow loss.   I also achieved the flow balance % I was looking for, hopefully simplifying the cam selection.

Full data dump soon, say over the weekend.   Just to whet your appetite, a .026" increase in exhaust throat diameter + port/seat matching by hand, nets ~ 13 cfm!!

Just for yuks, I think I'll "waste some time" modeling bhp vs flow for the A in its' final form.    And then compare that to the proposed K specification.   

"I love it when a plan comes together."

 
HannibalSmithboy

[fordboy628]

Going COMPLETELY off topic with this, other than the fact that by applying a combination of old and new technologies, a creative mind and talented machinist/electronics engineer can produce a remarkable piece of engineering . . .

https://www.youtube.com/watch?v=3gwZ2lHtG0Y

The craftsmanship is beyond reproach.

And Mrs. Fordboy thinks I'm weird . . . . . .


I may have to give up fly tying and fishing to concentrate on a small precision lathe and milling machine.

If these sorts of "gear geeks" had been around "back in the day", I would still be playing bass . . . . . . . .  or maybe be dead . . . . . . . .   

The craftsmanship is absolutely "stunning".

Do you think we can get him to port the head for the K?     Just askin' . . . . .

 
MissmyEB2DCboy

(BTW, the Gibson EB2DC was WAY ahead of its' time.)

[Podunk]

I saw Rottler cnc mills at PRI and Chicago Tool Show that had right angle heads that could line bore main bearing bores. Is there enough room in this cylinder head to do the camshaft bores? Are camshafts going to be one offs? If so bearing diameters could be made to suit.