Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 813504 times)

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Offline WOODY@DDLLC

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3225 on: December 09, 2018, 10:08:19 AM »
WW, were your ears burning on Friday? Mike Perry and I were talking about you at PRI!  :? :-D

http://www.profblairandassociates.com/pdfs/RET_Bellmouth_Sept.pdf

Tracer attachment for your Logan: https://www.youtube.com/watch?v=DEyvheENhdI

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Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3226 on: December 10, 2018, 09:21:43 AM »
The spinning looks to be the most efficient method.  There are two 5.5 inch diameter by 2 inch long aluminum rods that cost $58 waiting to be mauled and mutilated into stacks so I am "invested into" the cutting from billet procedure.

My old engineering graphics textbook from college shows how to draw an ellipse.  This afternoon I will draw the stack cross-section on graph paper and then draw where each cut will go.

An e-mail was made to Arias that included the job number for the pistons.  I asked them for the maximum average piston speed the slugs can handle before accelerated wear becomes an issue.  They were also asked the maximum acceleration the pistons can have before ring flutter is a problem.  Right now the rev limiter is set at 4,000 feet per minute average piston speed.  That is a limit we used in the 1970's and it might be slow when considering modern materials.

Tractive force calculations show an advantage to using gearing with a high numerical ratio and lots of rpm from the engine.  The elliptical stacks with plenums can be modeled in Dynomation 6.  Use of them shows an increase in power at horsepower peak rpm and more power in the decay portion of the power band beyond the peak.
   

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3227 on: December 10, 2018, 11:42:42 PM »
I was thinking about both of you on Friday.  That tracer idea reminds me of something I did back in hi-school metal shop to make a complex shape.

There is a formula in Harold Bette's book "Engine Airflow."  It empirically equates intake flow to horsepower.  Intake flow tops out at 230 cfm at 28 inches water for the complete system using valves, port, manifold, carb, and air filter.  There are two cylinders.  The "Coefficient for Estimating Horsepower" is 0.257 (See Page 82).  2 x 0.257 x 230 = 118 HP at the flywheel at 60 degrees F, 29.92 inches pressure, and 0 percent humidity.  This corrects out to 117 flywheel HP in the Dynojet Standard atmosphere of 68 degrees F, 29.92 inches pressure, and 0 percent humidity.  A traditional wild guess at drivetrain loss is 10 percent.  117 x 0.9 + 105 HP  This is almost exactly what the dyno read during the tests last summer.

Peak power RPM is also calculated empirically based on a formula in Bette's book.  "Coefficient for RPM" 1196 (See Page 83).  Displacement is 30.35 cubic inches per cylinder.  Air flow is 230 CFM, as in the previous equation.  Peak power RPM is (1196 / 30.35) x 230 = 9,063 RPM.  This is almost exactly what the dyno says.

The preceding formulae predict performance from a fully developed engine.  This is an air cooled twin with side draft ports.  There likely is not a lot more performance to be had - unless intake air flow is boosted.  A successful tuner of these things told me ten years ago I would need to go to a bell mouths on the carbs like I am designing now.  It was something I never had time to do, until now.  He also said the motors needed to be spun up to ten grand.  This was something I could not do until now.  My motor building skills needed to be developed.

It is a long road from dreaming about going fast to actually doing it.           

Offline Interested Observer

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3228 on: December 11, 2018, 08:07:49 AM »
Wobbly,
It might be easier to turn a (wooden) plug mold and then lay up fiberglas bells around it.

Offline tauruck

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3229 on: December 11, 2018, 03:09:41 PM »
What size is the ID on those venturis Bo?.

Offline RansomT

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3230 on: December 11, 2018, 06:54:48 PM »
I was thinking about both of you on Friday.  That tracer idea reminds me of something I did back in hi-school metal shop to make a complex shape.

There is a formula in Harold Bette's book "Engine Airflow."  It empirically equates intake flow to horsepower.  Intake flow tops out at 230 cfm at 28 inches water for the complete system using valves, port, manifold, carb, and air filter.  There are two cylinders.  The "Coefficient for Estimating Horsepower" is 0.257 (See Page 82).  2 x 0.257 x 230 = 118 HP at the flywheel at 60 degrees F, 29.92 inches pressure, and 0 percent humidity.  This corrects out to 117 flywheel HP in the Dynojet Standard atmosphere of 68 degrees F, 29.92 inches pressure, and 0 percent humidity.  A traditional wild guess at drivetrain loss is 10 percent.  117 x 0.9 + 105 HP  This is almost exactly what the dyno read during the tests last summer.

Peak power RPM is also calculated empirically based on a formula in Bette's book.  "Coefficient for RPM" 1196 (See Page 83).  Displacement is 30.35 cubic inches per cylinder.  Air flow is 230 CFM, as in the previous equation.  Peak power RPM is (1196 / 30.35) x 230 = 9,063 RPM.  This is almost exactly what the dyno says.

The preceding formulae predict performance from a fully developed engine.  This is an air cooled twin with side draft ports.  There likely is not a lot more performance to be had - unless intake air flow is boosted.  A successful tuner of these things told me ten years ago I would need to go to a bell mouths on the carbs like I am designing now.  It was something I never had time to do, until now.  He also said the motors needed to be spun up to ten grand.  This was something I could not do until now.  My motor building skills needed to be developed.

It is a long road from dreaming about going fast to actually doing it.           

Motorcycle loss is closer to 7.5%...that figure can be lowered to about 7% with fancy super slick chain lube and ceramic wheel and transmission bearings.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3231 on: December 12, 2018, 10:58:31 AM »
Thanks for the help with this.

IO, thanks for the idea.  It might be a good method and I will remember to consider using it.

Ransom, the old factors I remember from about 45 yeas ago are 10% for a bike, 15% for a 2-wheel drive car, and 20% for a four wheel drive car.  I have no idea how those factors were derived.  My guess is the 10% loss was derived from bikes with primary chains and gearboxes full of heavy oil, like Harleys and British bikes.  This bike has only four straight cut gears between the crank and the countershaft sprocket and all run in synthetic engine oil.  That 7.5 percent drivetrain loss makes sense and I will use it.  The Dynomation 6 program allows manual input of this value.

MIke, the spigots are 55mm OD, 51mm ID, and 8mm long.  The wave-action model will be used to determine optimum spigot length.  The bell diameter will be determined by packaging issues.  There is a big square main frame tube near those bell mouths.  Handling might suffer if chunks of it are sawed out to make room for stacks.  It will take a couple of days for me to figger out the stack length and bell diameter.

The ideal intake and exhaust system tuned length is calculated for an rpm halfway between the peak torque rpm and peak power rpm.  Does this seem to be a good choice?   







 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3232 on: December 12, 2018, 12:53:35 PM »

Offline thecarfarmer

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3233 on: December 12, 2018, 02:13:49 PM »
Wow, I just spent the last few days reading through the last 216 pages...

At various points, I found myself wanting to post a reply "you need to join the Speedtalk forum...", "you don't *need* to buy a mig gun, your oxy torch and Solar flux Will weld SS", and so many others - and remembered that the topic was years old...

But now I've caught up, I'd recommend cutting a few sets of bells out of some inexpensive plastic.  PE oughta be cheap.  Fuel cells are made of it, so gas shouldn't hurt it.  TAP Plastics has stores in PDX and Tigard; is one of those close?

I expect you might find an advantage to being able to tune that intake length to track conditions, changes in cam timing, etc...
We all enter this world in the same way: naked; screaming; soaked in blood. But if you live your life right, that kind of thing doesn't have to stop there.

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Offline tauruck

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3234 on: December 12, 2018, 03:04:01 PM »
Thanks for the help with this.

IO, thanks for the idea.  It might be a good method and I will remember to consider using it.

Ransom, the old factors I remember from about 45 yeas ago are 10% for a bike, 15% for a 2-wheel drive car, and 20% for a four wheel drive car.  I have no idea how those factors were derived.  My guess is the 10% loss was derived from bikes with primary chains and gearboxes full of heavy oil, like Harleys and British bikes.  This bike has only four straight cut gears between the crank and the countershaft sprocket and all run in synthetic engine oil.  That 7.5 percent drivetrain loss makes sense and I will use it.  The Dynomation 6 program allows manual input of this value.

MIke, the spigots are 55mm OD, 51mm ID, and 8mm long.  The wave-action model will be used to determine optimum spigot length.  The bell diameter will be determined by packaging issues.  There is a big square main frame tube near those bell mouths.  Handling might suffer if chunks of it are sawed out to make room for stacks.  It will take a couple of days for me to figger out the stack length and bell diameter.

The ideal intake and exhaust system tuned length is calculated for an rpm halfway between the peak torque rpm and peak power rpm.  Does this seem to be a good choice?   







 


I'll measure mine in the AM and let you know.👍👍👍

Offline tauruck

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3235 on: December 13, 2018, 05:34:37 PM »
Bo I measured my Venturis.

ID is 60mm.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3236 on: December 14, 2018, 12:46:11 AM »
That is a lot of pages to read.  As per trackside tuning, I did it for a few years.  By the time the changes were made and after standing in line to make the run the track changed to something different than the one I anticipated when I changed things.  Now I sorta know what to expect when setting the thing up beforehand.  Trackside changes are limited to correcting things I did wrong in the setup or putting on a different sprocket.  The bike does have sand racing pipes, cams, etc.

The highest piston speed according to Vizard in "How to Build Horsepower" is "A good cast-steel crank and a decent set of rods should be good for a mean piston speed of 4,500 feet per minute."  That equates to just over 10,000 RPM.  The rev limiter will be set for that and it is 1,000 RPM higher than it is now.

The article in reply 3225 is a good one.  It tells about the best bell design and it also gives enough information to make a good compromised design in less than optimum situations.  That big black frame tube in the photo limits the bell length and width from the ideal.  The compromised bell shape is shown in the picture.  The dimensions were entered into the computer model and the bells are calculated give to up to five more HP at high RPM.

 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3237 on: December 14, 2018, 10:22:59 AM »
Municipal water demand is quite variable.  It is very low around midnight and extremely high at other times - such as when lots of toilet are flushed during Super Bowl halftime.  It would be very expensive and impractical for the city to size the water supply pumps for this maximum flow.  Instead, they use smaller pumps to fill a water tower or a tank on a hill with a much lower steady flow.  Demand surges are supplied by the water stored in the tower or tank.

Engine air demand is unsteady, too.  The intake valve is open and passing mixture for only a small part of the engine cycle.  The rest of the time it is shut.  The air filter is mounted directly to the carb now.  This is a lousy setup.  Their is a very small reservoir of air beyond the air intake for the engine to draw from.  It is the inside volume of the filter.  The filter is subject to pulsing flow demands.  These can be quite large.  It is a filter on a 500cc single cylinder engine turning 10,000 rpm, in reality.

A plenum will be made along with the new stack and it will be sized to provide a reservoir of air in front of the filter.  The minimum volume will be the cylinder volume x the maximum volumetric efficiency.  It will store at least one gulp of air between the bell mouth and the filter.  This will reduce peak flow loads on the filter and reduce any restriction the filter might provide during those peaks.  In addition, the two plenums will be connected so the reservoir is larger.

One thing governing the stack size is the need to keep it at least 1/4 inch from and plenum wall.  This will promote more a more even inflow rate around the stack perimeter.  This is a problem with this bike I have known about for a decade.  Right now I am finding the time to fix it. 


 

Offline RansomT

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3238 on: December 14, 2018, 10:26:20 AM »

The highest piston speed according to Vizard in "How to Build Horsepower" is "A good cast-steel crank and a decent set of rods should be good for a mean piston speed of 4,500 feet per minute."  That equates to just over 10,000 RPM.  The rev limiter will be set for that and it is 1,000 RPM higher than it is now.


Just for reference: The newer factory Kawasaki ZX10r has a piston speed at redline of 8050 feet per minute, peak HP occurs in the 7500 feet per minute range.

I've found that there are more issues to be addressed with valve train harmonics/weight than piston speed.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #3239 on: December 16, 2018, 09:54:12 PM »
Those are incredibly high piston speeds.  There is no way I can come close to matching factory technology and performance.  My goal is to go over 150 mph without crashing or breaking the motor.