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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 504289 times)
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hoffman900
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« Reply #2880 on: September 07, 2017, 05:04:26 PM »

An advertisement for Dynomation 6 came in last week's mail.  They mention megaphones as end treatment options for headers with collectors.  There is no mention of mufflers.

The dyno work says meggas are not a good setup for this engine and mufflers are.  This is backed up by my experience with earlier versions of this build.  Vannick's software literature says their program can look at other options besides meggas.  Now I have his e-mail and I will order a copy of his program today.  

I disagree about megaphones. They can work very well when built correctly. It looks like your earlier versions had baffles in them? No bueno.

Megaphones with mufflers need to look like this:




Then the muffler slips over the reverse cone lip. This is how the flat track guys do it as well as the sport bike guys (take a look at the inside of the Factory Yamaha Graves exhausts).

Modeling a set up like this works VERY well for filling in the mid range as well as power up high. I'll post more later with examples.
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wobblywalrus
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« Reply #2881 on: September 08, 2017, 12:49:52 AM »

Thanks for posting this.  What do the inside of the mufflers look like?   Do they quiet the bike down?



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hoffman900
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« Reply #2882 on: September 08, 2017, 06:28:46 AM »

Thanks for posting this.  What do the inside of the mufflers look like?   Do they quiet the bike down?





Just straight through, with packing. The id of the muffler slips over the outside of the reverse cone. The annuals between it and the housing is filled with packing. Noise level? Still really loud, but it's also dependent on how much packing / size of the muffler. The cool thing that anyone who has been around exhausts like this is the pulse of air coming out of it. The megaphone slows down the exhaust pulse and reduces its amplitude. In return, it increases pressure. It feels like one of those air guns if you're behind the bike. 

To make exhausts like this really quite you build a 'boom box', which is basically a box that goes over the outlet of some volume and a hole on the opposite end. Like this:


I'll post stuff at the end of the weekend as I'm on my way out the door for a camping trip.
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wobblywalrus
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« Reply #2883 on: September 08, 2017, 08:54:58 AM »

There was twin cylinder Superbike racing in the late 1990's.  The manufacturers made small batches of the bikes for the street so they could homogulate them for racing.  Someone took one of them to the BMST and raised the twin cylinder record to the high 160's.  It was in the high 150's before the meet.  Right now I am rethinking about this hobby.  It is hard for the homebuilder to match factory technology and be in contention for records.     
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wobblywalrus
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« Reply #2884 on: September 09, 2017, 11:47:01 PM »

A switch to FIM 2-cylinder partially streamlined forced induction will allow me to use the tail.  This class is for home builders.  There is no factory built bike that can enter.  None are made.  The plan for this year is to do the listed and make one more attempt at the NA record.  Remake the tail to fit the new FIM regs.  Make some new triple clamps with a few mm less offset.  This will reduce or eliminate the speed wobble during decal.  Figure out the best cam timing using the computer programs.  Get some pistons made with 13:1 static compression based on my combustion chambers.  Design another exhaust system using EngMod4T.  Try three exhausts on the dyno, the old one I used before 2017, the one I used in 2017, and the new one built this year.  Go back to using Sunoco Standard for tuning and its ERC equivalent when on the salt.  Thanks everyone on this website for the help.  Faith at Webcam, Denis Manning, and Mike Perry at Kibblewhite all gave me some good advice this year.  There is hope.

The engine made more torque with the old cams and pipes.  Now, with the new cams and pipes it makes more power.  A big task is to get back the lost torque and retain the new power.  The current lobe center angles are 112 and 111 degrees intake and exhaust, respectively.  That is pretty wide and tightening them up can give more torque.  Torque between 6,000 and 9,000 rpm was calculated using different lobe center angles with Dynomation.  The best torque curve used 108 inlet and 110 exhaust lobe centers according to that program.  Raising the compression from 11.7 to 13 to 1 helped too.  Both changes give 3 to 4 more pounds-feet throughout the 3,000 rpm range.  The EngMod4T program is ordered and I am figuring out how to load it on the computer.  I will recheck these LCA's using that program.   
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wobblywalrus
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« Reply #2885 on: September 18, 2017, 10:19:54 PM »

This time last year I had a 90 horsepower engine and was a lost soul.  I could not figure out how to get more power.  This program was ordered, installed on the PC, and I read this book five or six times.  A virtual model was made of the motor and I started to do computer based hop-up.  One thing I learned was the "garbage in-garbage out" saying really applies.   Actual flow test results, digital cam profiles, and measured compression ratios are essential to get decent results.  I used approximations at first and then had to reanalyse everything over again when I got the better input data.  The predictions were quite different depending on whether or not I used refined input.

The program manual has some guidelines about what to look for in all of the output graphs and tables.  Good references are Vizard's books, Dema Elgin's website articles, and "The Horsepower Chain" by Don Terrill, among others.  A couple of other engine builders gave me advice, too.  It took months of late nights for me to figure out the various concepts.

The results are a 107 hp engine.  This is right where most folks get with these engines powerwise.  The upside of all of this work is that all of this is done with much smaller valves, lower compression, and milder cams than most other tuners folks are using.  That is the beauty of virtual tuning.  It is getting the right combination of parts.

The downside of the program is the exhaust tuning.  Only limited options are available that can be used with wave tuning.  The exhausts I made based on program data did not work at all.  These engines need something other than open-ended pipes or meggas, like mufflers or reverse cones.  The program could not model these with wave action.

Do I recommend the program?  Yes.  It is a good learning tool and an additional 17 HP from an already developed motor is not bad.  The next step is to use another program that models many more exhaust options.   

 


* 2018 Build 001.JPG (315.98 KB, 883x1080 - viewed 26 times.)
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wobblywalrus
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« Reply #2886 on: September 22, 2017, 11:36:17 PM »

The Triumph uses custom made forged pistons in plated cylinders (Nakisil or similar).  The static compression ratio is 13 to 1 based on the original equipment manufacturer combustion chamber volume.  The combustion chambers are larger than this due to bigger valves and seats being installed and relieving the combustion chamber walls around the valve margins for better flow.  The actual static compression ratio is 11.7 to 1.  It would be nice to have some custom pistons made that give 13 to 1 static compression ratio for the larger combustion chambers.

The bores, pistons, and rings are in good condition.  I was thinking of having a set of high compression pistons made, putting the old rings on them, and using them in the old bores without any honing.  Has anyone done this?  Does it work?
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jacksoni
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« Reply #2887 on: September 23, 2017, 07:08:06 AM »

If you are getting new pistons, you have the opportunity to look at the ring package and perhaps (not knowing what you have now) go to a better package. Thinner perhaps ( less friction) or other changes that could improve sealing or control. Unless really unusual $ not too bad and hone is cheap. Take advantage of being sure the freshening is top notch. It's a race motor and you are working hard to get every last HP out of it. Why cheap out now?
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Jack Iliff
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wobblywalrus
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« Reply #2888 on: September 24, 2017, 12:36:35 AM »

Time is the big issue.  A hone and new rings means a bunch of extra tasks like changing to break-in oil, bedding in the rings, changing back to race oil, etc.  Right now I am working a lot of overtime at the job there is not much time to do all of this.  This means I am looking for Mickey Mouse ways to get by with minimal effort for BMST 2018.  I retire in July so I will have lots of time to get the engine right for BMST 2019.  Of course, as a pensioner I will have no money so I will be looking for Mickey Mouse ways to save $. 
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Old Scrambler
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« Reply #2889 on: October 07, 2017, 11:06:24 AM »

Bo...modern parts usually do not require break-in oil..........Do the dyno testing and put in fresh oil for the BIG WHITE DYNO.
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2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2016 AMA Record - 750cc M-CG HONDA CB750 sohc - 130.7 mph
2016 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 137.7 mph
Chasis Builder / Tuner: Dave Murre
wobblywalrus
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« Reply #2890 on: October 07, 2017, 06:59:18 PM »

There is more to this story than what is in the build diary.  The bores are plated with something like nakasil.  The last piston swap was from 10.5 to 1 pistons to 13.5 to 1 pistons (based on the standard size combustion chamber).  The local machinist would not hone or break the glaze for me.  He said the bores were worn enough to make it too risky.  He said if he honed them round there was a chance he could break through the plating and there would be too much skirt clearance.  He also did not want to break the glaze.

So, I broke the glaze myself using hillbilly methods.  The rings seated perfectly.  Lots of cranking compression with the new motor.  Also, very little blow by past the rings based on looking at the oil retained in the breather catch tank.

Another try at backwoods honing for a new set of rings is risky.  Also, having the bores plated and honed for new pistons is risky, too.  Right now I am having very poor luck with work I farm out to others.  Either they screw it up or they do it right and take a long, long, time to do it.

The plan is to have Arias make a new set of pistons and rings with higher compression.  Then, I will put the new pistons in with the old rings and do a cranking compression test.  If it works, that is great.  If not, I will have the bores replated and honed for new rings.

The flight I will be on from Atlanta to Portland will center punch Hurricane Nate.  It will be a tropical storm when we go through it.  Pistons and rings are my least worry now.   
 
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wobblywalrus
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« Reply #2891 on: October 09, 2017, 09:52:29 AM »

We flew through the remnants of Nate.  It was rough.  I was worried that the wings would break off of the plane.

Racing on a pension is something I thought a lot about while in Virginia.  It was good that I got soundly thrashed at the speed trials.  A lot of these 1000cc bikes setting new records in Bolivia and elsewhere are using OEM engines or close to it.  They are water cooled with downdraft or semi-downdraft ports and the bike that has the record this year is a factory designed race bike.  The Triumph is an air cooled twin with old style side draft ports tuned by a backwoods hillbilly.  Its days of being competitive in naturally aspirated gasoline burning form are done.

Then I looked at aero.  The drag coefficient with the tail on is reasonably low.  A fellow racer looked at my helmet and neck when I was in a tuck at the BMST.  I thought my leathers are pushing my helmet forward so I can not see where I am going.  That is not the case.  It looks like I have a short turkey shaped old folk neck and it is my shoulders that are tilting the helmet forward.  There is nothing I can do about this.  My tuck is poor and that is what it is.

Medical expenses for Rose and I during retirement are basically medicare supplemented by a wobbly walrus funded insurance plan.  There are some big coverage gaps in this with major financial impacts if I crash the bike and need long term care or have serious hospital costs.  This makes pushing speeds a lot higher with forced induction or fuel unattractive.  This bike is not a hayabusa or anything designed for going fast.

Fortunately I like to travel.  This gives me some realistic and satisfying goals.  No more record chasing.  The plan is to dink around on the bike during the off-seasons to keep it running and to do modifications I can afford.  Another attempt at 150 mph is planned for the 2018 BMST trials.  A trip to the UK is planned for 2019 or 2020 to run the Yorkshire mile.  I have never done runway racing.  Then, the bike stays in Europe and I will try to run on the frozen lake in Sweden.  All of this will keep me busy for a long time.   
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wobblywalrus
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« Reply #2892 on: October 17, 2017, 12:13:58 AM »

The program described in Post 2872 was purchased.  Evening after evening is spent trying to figure the Dodge thing out.  It is like making passes at a frigid lesbian.  User unfriendly.  Is there another program that analyses exhausts?
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Tofu
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« Reply #2893 on: October 17, 2017, 09:59:12 AM »

Is this of any assistance?

http://www.rddreams.com/neels/Baleno.htm
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wobblywalrus
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« Reply #2894 on: October 18, 2017, 12:19:24 AM »

That is useful info although I am working with a four stroke engine.  Right now I am getting up at 5:00, going to work for long days, getting home, doing chores, and have only an hour or two before midnight to work on the computer modeling.  It looks like I was sent a beta version.  It is non functional and I am in no mood to troubleshoot it.  Other computer analysis programs are being investigated. 
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