Team Go Dog, Go! Modified Partial Streamliners

[wobblywalrus]

It starts in elementary school.  The are girl's achievement rewards pinned up on the walls.  Special recognition days for people of color, handicaps, etc.  Nothing for white boys with no big issues.  This continues as the boys go through the entire Oregon education system.  The Disney flicks lionize everyone except white males.  This societal "shunning" does not let the white boys develop normally.  The two daughters did well in school.  Both were honor roll students.  The three sons all struggled, or more realistically, did not apply themselves.  The military built up the son's confidence in them selves and all three boys excelled.

The public schools had class rooms for auto repair, machine tool operation, sheet metal fabrication, drafting, etc. in my time.  Shop class was the only thing I liked in school.  It kept me there and gave me something to be interested in besides drugs.  The local high school turned the auto shop into a day care for student mothers.  The other shop classes were discontinued.

It was difficult for Rose and me.  We knew the local police officers on a first name basis thanks to the boys.  One needed his record expunged so he could enlist.  It was a major effort to get all three graduated from high school.  One big challenge was trying to bolster the boys self confidence without encouraging them to be racial bigots or sexist.  Dealing with children is like jacking up a car.  Raising one wheel higher lowers another one unless all the wheels are supported. 



 



 

[wobblywalrus]

The 2018 engine was modeled in Dynomation 5.  From the user's manual:  "Dynomation-5 incorporates two distinct engine-simulation mathematical models: 1) A Filling-And-Emptying simulation that provides extremely fast mathematical solutions to engine physics, including port- and- induction flow calculations and simplified intake and exhaust-manifold/runner modeling, making the  Filling-And-Emptying model a fast and powerful way to "ballpark" engine design with very good accuracy, and 2) A full Wave-Action simulation that accurately predicts the complex pressure-wave dynamics and particle flow in intake and exhaust ducting.  The Wave-Action model picks up where the Filling-And-Emptying model leaves off and "homes in" on the best port sizes, runner lengths, header-tubing sizes, cam timing, valve motion, and much more, providing unprecedented accuracy for detailed engine analysis."  The next posts show where the modeling was before the bike was ran at the speed trials.

[wobblywalrus]

The dyno data is approximate.  The pull was done and the session was finished with recommendations to raise the needles a notch and drop the main jets one size.  No verification run was made after those changes were made.  The filling/emptying (FE) model results are shown.  The exhaust system was modeled as a generic "Large-Tube Headers, Mufflers WO/Cat."  In reality it is a large tubed step header with collector and muffler and no catalytic converter.  The modeled and actual systems are slightly different.

The F/E model assumes correct mixture and no reversion.  The drop in torque and power between six and seven grand may be due to one or both.  The model curves do not show this and this is expected.  The rev limiter was set at 8,900 rpm and the model was extended to ten grand.

The F/E model has a good match to actual power if reversion or mixture issues are resolved.

[wobblywalrus]

The Wave-Action (W-A) model is next.  It does not model mufflers.  Data for the stepped headers, collector, and a megaphone were entered.  The W-A model is a poor approximation of the dyno data.  This is likely caused by it's inability to model mufflers.     

[wobblywalrus]

The Dynomation 6 user's manual says "In cases where you have sufficient test data for the Wave-Action model, but you would like to test a restrictive exhaust system (which requires the FE sim), you can select the Hybrid-Sim model that runs both simulations and combines the results to emphasize the strengths of each model.  That is what I did using the Dynomation 5 model as shown.  It gives a better match between predicted and actual torque and power.

[wobblywalrus]

The exhaust and intake systems were designed using W-A modeling and a 6-inch long megaphone with a 1.4 degree taper.  This megga looked good in the computer design and the bike ran awful on the dyno.  A muffler was installed and the bike ran great.  This was during the 2017 season, a year before.  So, I knew the W-A model was flakey during the 2018 development.  The F/E model was used for the 2018 tuning.  This shows a comparison of different cam timings using the F/A model.  The intake lobe centers were from 106 to 116 degrees.  The exhaust centers were from 106.5 to 116 degrees.  The 106-116 degree timing was used for the 2018 dyno work and at Bonneville. 

Now the Dynomation 5 model is being updated to Dynomation 6.  Various megga configurations will be tried in an effort to match the W-A predictions to the dyno data.  Then it can be assumed the performance of the megga used for data entry sort of matches the muffler on the bike. 

[wobblywalrus]

Rose is back in town.  She was visiting in the UK, or more specific, Cornwall, England, and Wales.  My computer, dynomation stuff, tech manuals, etc were spread out all over the kitchen table.  "This morning these things will go back into the shed" I said.  My "office" is a nook under the stairs to the loft and it is cramped, dark, there is no room for a printer, and it has no internet.  She says "Gretchen's school desk and bookshelf is not being used.  I cleaned the place up.  Move everything up there."  Gretchen moved out and is in the UK.  Now the "office" is well lit and spacious in an upstairs room. It has internet, too. 

[wobblywalrus]

The Dynomation 5 model was polished up using guidance in the Dynomation 6 user manual.  The inside of the muffler starts out at the 2.5 inch diameter of the downstream collector end.  It expands through a series of tapers and straight sections to a 3-inch diameter immediately upstream from the diffuser and baffle in the muffler.  The length between the two sections is 13.8 inches.  Dynomation wave-action option does not model mufflers.  It does analyze megaphones, so this was entered as a megaphone in the wave-action (W-A) model.

The exhaust system has large diameter tapered headers going into a collector and into the muffler.  One filling/emptying (F/E) model was made that assumes the exhaust system is the "Large Stepped-Tube Headers - Open Exhaust" option.  This is partially appropriate.  Another model assumed the exhaust was "Large-Tube Headers, Mufflers W/O Cat."  This is also applicable.
     
Two hybrid-simulation models were made.  One combined the Large Stepped Tube Headers - Open Exhaust F/E model with the Stepped Header, Collector, Megaphone W/A model.

I smell burning turkey.  This post will be finished later this evening.   

[wobblywalrus]

The other model had the Large-Tube Headers, Mufflers W/O Cat F/E model combined with the Stepped Header, Collector, Megaphone W/A model.  What I am doing is following Dynomation's recommendations as described as per reply 3214.

The results are plotted and they describe two arcs as shown on the attached.  The actual dyno results fit between the curves pretty well.   

[wobblywalrus]

Calculations from a run on Tuesday during the meet show a slip factor of 0.964, or just under 5 percent.  The slip factor is assumed to be between 0 to 5 percent during the 149.6 mph pass on Thursday.  This is 8,392 rpm and 8,705 rpm, respectively.  The rev limiter is set at 8,900 rpm.  The engine was very close to its rpm limit.

The orange power curve band shows the engine should rev higher than it is.  Setting the rev limit at 9,400 rpm should provide 161.5 to 167.5 mph at 5 and 0 percent slip, respectively.  A goal for this year is to send the head to Kibblewhite to make sure the valve train will be able to handle that 500 rpm increase.  Another objective is to have an additional 500 rpm programmed into the ignition module rev limit.  Then the engine needs to be checked to make sure the rod bearings and other critical parts are OK. 

[tauruck]

Bo, have you ever considered moving to South Africa?.
We could really benefit from your research.

You inspire me. You leave no stone unturned. Thanks man.

[RansomT]

The graphs are great!
My only comment is that the dyno results won't truly reflect the computer models unless the AFR is dead on.

[wobblywalrus]

MIke, it has been several days since your post and I was thinking about the time between retirement and the final croak.  It was only today when a reply can be made.  The problem with the final stage in life is it is so unpredictable.  There is a likely chance Rose and I, and our children will be better off if we are nearby and in familiar surroundings.  The next move for me will be to the local old folks home or the boneyard.  That does not mean I will not visit various places.

The Dynomation program should work in South Africa.  It is easy enough to use that the average guy or gal can figure out what they need to do.  There might be a model for a Cleveland in it and it does analyze turbo and supercharger addition.

Ransom, the next dyno session will focus on the AFR, only.  Fight now the Dynomation 6 model is being made.  Then, wave action will be looked at closely.  There might be reversion issues at midrange that cannot be corrected by jetting.       

[wobblywalrus]

Two short lengths of aluminum rod, a 1947 Logan lathe, and a confused old guy are the four actors in this drama.  Is there a reference that shows how to turn an elliptical shaped bell mouth on a lathe?

[Peter Jack]

Bo, you may want to look for articles on metal spinning. That looks like an ideal application.

Pete