BSA B50 -500 APG Build

[MattGuzzetta]

Tom, we had a cylinder head temp and an oil temp gauge to keep tabs on the motor.  We ran the bike from San Diego to Daytona Speedway during motorcycle speedweek in 1984.  I will send you particulars of the vehicle tonight as I am at work today. 
This pic shows the exhaust outlet
This pic shows the NACA duct
I will send more info tonight, enjoy!

Matt Guzzetta

[Koncretekid]

Will this work?

The following photos show a mocked up cardboard shroud surrounding the sides and the back of the cylinder.  In the left side photo, you will see a 2" round duct coming thru the fairing, which I now think won't be enough air.  But you will also see an oblong hole around the fork tube which is larger, although in back of the wheel & fender.  In the right side photo you will see a 3" cardboard tube exiting the shroud which would protrude thru the side of the fairing like the exhaust.  My idea is that the air passing the end of this 3" duct cut off square to the pipe should create a vacuum to pull available cooling air coming thru the openings at the front.

     Do I need to increase the size of the 2" entry duct and connect it directly to the front of the new shroud, or will the vacuum created by the exit on the right side pull enough air?
     Should I at lease add a section of 2" tube with a diverging opening to aim directly at the motor?

[MattGuzzetta]

Hello Tom!
You are on the gas, great!  Here is a link to a company that sells the sheet pattern wax that will make the contour fitting shield much easier to make:  http://www.bccproducts.com/kindt-collins-waxes.html  The cost is not much compared to what  the material does.  You can form the wax (1/8" thickness would be good) right on the fins and when you glass over the material (sandwich some medium mat with cloth on both sides, then saturate and piece the material on the wax.) you will have a close fitting shield that forces the air into contact with the fins like they do in airplanes, it really scrubs the heat from the metal. 
We used 4" dryer hose to start with and that could work with your setup, we use butterfly valves in the intake to get the heat where we wanted it.  We never had to have the valves wide open, so a 4 inch intake might work on your bike. You can see the levers to operate the butterfly valves in the photos of the motor.   I would bring the cooling air into the exaust side  and just come out the back with another tube that you can dump on the side or back of the bike if there is a low pressure area back there.  I would definately use a cylinder head temp gauge, we used one that with a sensor that worked as a washer under the spark plug, a go kart part if memory serves this old brain.
I will see if I have more photos that can describe the air inlet better.  You might be able to pick up the intake air through the fork tube clearance holes as that should be a high pressure area.
Til then, keep up the thinking and mock ups! 

Matt Guzzetta

[Koncretekid]

Matt,
Your photos and advice have been a great help.  Never try to re-design the wheel!  The fact that yours worked, presumably in slow as will as fast conditions, is the best information I have received.  

I have fabricated up an aluminum shroud, as I don't have time to get the pattern wax and make a fiberglass one.  You said "close fitting, so that is what I have.  It actually contacts the fins - - will that be a problem?  For the exit duct, I rolled up a piece of aluminum and pop riveted it to the shroud, exiting the left rear quarter and out thru the fairing.  I'm not sure what shape it should take at this point.

For an inlet, I've pretty well given up on the idea of using my 1-3/4" inlet as being too small.  In one photo, you will see what I believe I can do.  I'm holding a short piece of 3" diameter steel tube on the right side of the shroud, just below a 2-1/4" shop vac wand extension which I will try to use to supply cool air to the carburetor (more fabrication required).  I need a NACA duct to install in the right side of the fairing.  I see used ones for sale on Ebay at very cheap prices (new ones as well), but nobody wants to ship them to Canada.  Summit Racing won't take questions, so I can't find out about shipping to Canada, and M/R racing want $28 shipping!  If anybody out there has one with a 3" round duct at approximately 90 degrees, I'll buy it from you, and pay the actual shipping to Canada!

[Koncretekid]

Photo of right side with proposed inlet.

[saltwheels262]

not being an expert, I do have a few views --
    might that shroud hold more heat than it dissipates ? ( acting as a heatsink ).

     do you think you could get more cooling with the tube directed at the top of the cylinder and head ?   with the air flow then exiting the fairing on its own. or through a dedicated opening .

  
      I have run both an aero shroud and a flat plate the length of my down tubes. at the salt and loring . the rocker boxes on the 120" never got so hot that I could not hold my hand on them after a run. even the 1 time the bike was ridden back to the pits in maine.
    

franey

[Koncretekid]

Bill,
Remember that I now have full partially streamlined body with no opening behind the front wheel except at the fork tubes.  When the CanAm 125 was run in this configuration, the motor seized up on the return run as it crossed the end of the timing section.  That may be OK for Bombardier (who were promoting their new bikes), but not for me.  I agree that the shroud would not help, but hurt, if it does not get enough air flow.  If you look at any stationary air cooled motor, there's usually a shroud plus a fan.  I'm thinking I could probably just wing it at Loring, but would be in trouble at Bonneville.  I have ordered a temperature gauge with a sensor under the spark plug.  I can remove the entire shroud with the exit tube in about 10 minutes, if necessary.  I'll have to keep the inlet port removable.  Time will tell.
Tom

[Nortonist 592]

The shroud will work providing there is adequate air flow.  The shroud and decent airflow will keep your engine cooler than you know.  Airflow is vital.

[wobblywalrus]

Any way that you can put a bell shape on the air intake will help a lot.

A lot of our cross-country and enduro races in Oregon and Washington are very muddy.  Sometimes the entire front of the engine is covered with caked mud.  It is amazing how well these air cooled engines work in less than optimal conditions.   

[MattGuzzetta]

I like what you are doing with the aluminum, that will be faster than making from fiberglass.  Look at the intake size on a 4 or 6 cylinder airplane motor.  These are large displacement motors running at a big load all the time, no coasting!  I worked at BSA at the research establishment at Umberslade Hall and the scientific guys there always referred to motorcycle motors as oil cooled motors, so the oil tank size can also be a big help.  Keeping the shroud close and even touching is a good thing as it forces the air to "scrub" the heat from the fins instead of the air bouncing off due to no direction.  I would try to get the air entrance  as close to the exhaust area as possible as that is the hot spot on the head.  The fuel being evaporated on the intake side keeps that side a bit cooler that you might think.  It appears that there should be a high pressure area around the fork tube that you could use to put the intake for the duct which should be able to ensure good flow.  You can check the temp to be sure to keep the head cool.  You might want to check the temp on an open bike to see how much cooling you get without any shrouding. I would direct the air out of the shroud to keep the heat out of the shell.  We use to close the butterfly valves to bring the engine to operating temp and it took about 30 miles of 55-60 mph on the road to get the oil and cylinder warm.   If you can exit the air in a controlled manner you can be pretty efficient at cooling. 




A side shot of the bike showing the size of the NACA duct


A front view of the original front air intake used in the first year we ran the bike.


This view shows the dryer hose we used for air direction on the first version of the
bike.  We went to the NACA duct to cut the internal friction of the 3 or so feet of
dryer hose.

This is a shot of Don Vesco riding the bike at El Mirage after we ran the bike the
first year. The thing ran 82 mph with about 10 hp.

I hope this is more help to you!

Matt Guzzetta

[Koncretekid]

Bo,
I am now planning to just enlarge my original 2" diameter inlet to 3", and have it project out thru the front an inch with the front squared off, like a pitot tube. Some previous suggestions indicated that it might even be better if this tube projected out in front of the wheel, but that seems like it would really mess up the streamlining.  I'll probably use something like ABS pipe with a thick wall that I can round out the entrance, bell shaped a bit.

Matt,
I'm still unclear on what your outlet looked like on the outside of the fairing.  I don't see one at all on the left side of your bike, yet I would think the outlet and it's shape would be potentially as important as the inlet in creating a partial vacuum.  My outlet is 4", but I think I'll only go to 3" on the inlet, as the incoming air velocity will be greater than the hotter, slowed down exit.  Does this make sense?  I'll be using more of a pitot tube shape as I've read that these are more efficient than the NACA duct, especially at the front.

82 mph with 10 hp!  Did crosswinds affect the "dustbin" front fairing?

Tom

[Old Scrambler]

Tom......I like what your doing and the professional advice seems to make sense.......on the outlet I would think a baloney-cut at a slightly greater angle than the fairing would keep a small lip on the leading edge to create more vacuum..........Just my thought........not professional......or experienced......but I read a lot

[MattGuzzetta]

Tom,
I tried to download some photos last night to answer your question about the cooling exhaust but the computer was not cooperating!    Tonight, the uploading is working
We did not have an outlet through the body of the shell, I made a shaped exhaust duct that started out round and ended at the edge of the shell just ahead of my knee on the left hand side. I do not have a good pic of that section, but these pics should give you some indication of what we did.  The idea of coming out the side at an angle can work as there should be air rushing by enough to possible add some suction to that area.  If nothing else, it should allow the air to exit with little or no back pressure.  Here are a couple of pics of the butterfly valve (you shouldn't need it) and a small  view of the end of the exit area.


This is a view of the intake segment that connects to the NACA supplied plenum that is actually part of the shell. This also shows one of the 2 butterfly valves we installed to help keeping the motor in the correct temp range...we were after mileage, not ultimate speed. We did run the bike at El Mirage with the cooling system and it worked well on the high speed runs.


This photo shows the cooling exhaust segment with the butterfly valve lever on the top.  It kind of shows the unit directing the flow to the edge of the shell.



This photo shows a bit of the "fan" end of the segment that dumped the air along the edge of the shell at the rider's leg cutout. If the cooling outlet is dumping thru or at the edge of the shell, you should be good.  Just watch the temp gauge and compare it to riding the bike without a fairing.  It should be an interesting experiment. 

We did a shield wrap on a Yoshimura road racing Suzuki and the only part we were able to use was the segment that shielded the carbs and that was actually a good thing as it kept the carbs cool.  They gave us the wrong cylinders to build the shell on and weren't able to use the front section, bummer.

I hope this is of some help.  It should be really interesting to see how well it works.  The more you can direct the air into the fins, the better the cooling. 

Kepp up the good work!
Matt Guzzetta

[Rex Schimmer]

Tom,
I am attaching a sketch of how you can use your engine exhaust to extract the air from you engine shroud. Porsche used this same idea to pull cooling air through the intercooler on their small 1.4 liter turbo 911 back in the mid 70s and it works very well and it is free and it works when ever the engine is running and does not increase your aero drag. This idea is also used by many experimental aircraft builders to move air through their aircooled engines and reduce aero drag.
Rex

[Stan Back]

Now, even I understand.