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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 521574 times)
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wobblywalrus
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« Reply #2835 on: July 29, 2017, 01:51:13 PM »

It takes effort and time to properly regrind cams I am told.  Sometimes, based on the prices charged for regrinds, it is suspect if some of these hot cams are properly done. 

How long does it take to polish a set of cams using the light spring method?  I was thinking a trip to the local and back for a pint or two and a hot pastrami sandwich is good enough...


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wobblywalrus
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« Reply #2836 on: July 30, 2017, 01:02:27 AM »

Most of the afternoon was spent bopping around town.  The cams were pulled this evening.  The lobe tips and buckets polished up great.  Tomorrow's task is to put in the valve spring shims and the inner springs.
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wobblywalrus
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« Reply #2837 on: August 01, 2017, 12:11:47 AM »

The engine is back together with a full valve spring set.  The dyno session is scheduled for Sunday.  The operator is doing it on his day off.  That is a big favor.

Usually I run in FIM twin cylinder partially streamlined naturally aspirated class.  There was so much to do that I let the deadline pass for the FIM application.  I was not going to run this year.  Gretchen wants to go to Bonneville and Rose does, too.  That is motivation so I put in some serious effort to get the old warhorse ready.

The entry this year is for the bike trials running in 1000 cc MPS-AF on a 211 mph record.  The AMA does not allow standard OEM frames in the altered class so I cannot run in APS-AF with the tail.  An equivalent gasoline to the blends sold on the salt could not be found for a reasonable price here in Oregon.  The gasoline will be Sunoco GT260 Plus, a high octane unleaded.  This puts me into the fuel class.  There is no chance for a record this year.  There is a 150 mph medal at the speed trials and that will be a nice thing to take home.  This should be a good year. 
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RidgeRunner
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« Reply #2838 on: August 01, 2017, 06:40:07 AM »

     Records sure are nice but they are not everything.  It's all about doing the best you can with what you have when you can and achieving personal goals.  Those that matter will recognize your efforts and stout runs towards your goals under the conditions, for others no amount of explaining will ever have them understand.

     Having family with you to share the experience is priceless. My wife and grand daughter had been to Loring with me as spectators, had a good time but never really got into it all.  At the Maine Event last month we were all part of an entry and they now understand thanks to the staff, other entrants, and the extended LSR family.  They are excited and looking forward to going back for the Harvest Meet in Sept.  Like you, that is keeping my motivation factor high as the car gets improvements.

     All the best for a safe, fun, and fast meet for you and your family. 

                   Ed
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wobblywalrus
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« Reply #2839 on: August 02, 2017, 12:56:26 AM »

Thanks for the encouragement, Ed.  I will take the time to explain to Rose about what's going on.   

It is in the 80's here and too hot to sleep.  This is a cold climate and hardly anyone, including us, has a swamp cooler or AC.  The bike is ready to go to the dyno.  It seemed perfectly logical to splash some race gas in the tank and go for a ride.  A warm night, almost deserted streets, and a hot bike.  Suddenly I felt 45 years younger.   
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wobblywalrus
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« Reply #2840 on: August 06, 2017, 09:48:27 AM »

The porting, carbs, air filters, valve sizes, and cam profiles are the best they can be.  The only things left to do are the cam timing, pistons, and exhaust tuning.

The pistons say 13:1 compression ratio on the box and this is with the standard size combustion chambers.  Mine are a bit bigger due to installing 2mm larger intake valves and deshrouding the chamber walls around the valve margins.  The actual compression ratio is in the high 11's.

The valve head to piston clearance was checked with the new cams while rotating the engine.  The valve pockets are far too wide and deep for the setup I have.  This is to be expected.  Most folks that tune these bikes use 5 or 6mm larger valves and cams with up to 0.45 inches more lift than I am using.  The compression ratio can be raised considerably by custom made pistons to work with the cams I have.  This is a project for this winter.

Optimal cam timing varies with compression ratio.  Once I have the new pistons I can see what comp ratio I have and use the 'puter program to optimize the timing.  This is a project for this winter.

The exhaust will be done today on the dyno.  I leave to go to Portland in about half an hour to do this.  The goal today is to see if my conservative approach to cam lift and valve size will get close to the power I need.  The other objective is to figger out the best exhaust end treatment.

 
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Koncretekid
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« Reply #2841 on: August 06, 2017, 04:50:00 PM »

Bo,

I know zilch about your "modern" Triumph motor, but can you leave the base gaskets out for higher compression?  This will back up the valve timing a bit, but that's not necessarily bad (later openings and closings). Just a thought, as I don't think you can ever get too much compression at Bonneville.

See you in three weeks.  You are lucky your family members want to come and I look forward to meeting Rose, and seeing Gretchen again.

Tom
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We get too soon oldt, and too late schmart!
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wobblywalrus
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« Reply #2842 on: August 07, 2017, 08:57:26 AM »

The deck clearance is at its minimum now.  The piston would hit the head if the gasket was removed.  We will look for you on the salt.

The dyno room had ventilation problems.  The poison gas alarm sounded in the morning a few times.  Trial and error testing, lots of fans, cardboard, and duct tape made it sorta work.  The operator ran the bike and got the readings.  He left the room to detox.  I went in and changed the jets, etc, then I went outside. Going home, I felt light-headed and slightly goofy.  A couple of pints and the Sunday steak dinner at the local cured the problem.  Now I am back to as normal as I can get.  The session went well and the jetting, exhaust setup, and spark curve is all at its best.
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wobblywalrus
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« Reply #2843 on: August 07, 2017, 08:37:40 PM »

Exhaust end treatment is a goal of the dyno session.  The muffler curve is the baseline.

The muff is removed and the blooey pipe is tried first.  It is a constant diameter pipe that connects the collector to the muffler.  Horsepower levels off at 80 then it starts to climb at 8,000 rpm.  It is up to 18 horsepower down on the muffler.  This is a bad setup.  No further development of it.

Second is the collector with nothing attached.  It makes more power than the muffler at midrange.  Further development is considered and discussed.  Fresh air dilutes the exhaust gas around the O2 sensor and the mixture readings are inaccurate.  We want the mixture input.  This, and the awful noise, make us not do anything more.

The megga is tried last.  Note the erratic power output and bad performance.  This is the setup to recommend to the competition, for sure.  The muffler is reinstalled and further testing uses it.


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RansomT
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« Reply #2844 on: August 07, 2017, 08:54:12 PM »

Well, this makes me just scratch my head.  Wonder if your header pipes are a size too big and you are loosing scavenge velocity (that the muffler slows down so the pulse can catch up) ?
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wobblywalrus
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« Reply #2845 on: August 08, 2017, 12:19:11 AM »

You might be right.  This is not the first time that this is observed with this engine.  It was seen with some small diameter headers, too.  They worked far better with slightly restrictive mufflers.  My feeling is that Cosworth engines flow well at low lifts and there is a potential to over scavenge during valve overlap.  The added restriction from a muffler reduces this.  This is my theory and someone smarter than me might know the real answer.

Carbs are superior to EFi for this type of racing 'cause they do not rely on electronics, the inlet tract is cleaner without the butterfly valve, the settings stay at where I want them to be, and WW understands them.  This is how I set up the jetting.

1) The jetting was changed during the dyno runs and #145 and #147.5 produced the best power.  #147.5 is the richest jet that makes the best HP.  It is selected.

2)  Dyno printouts show the temperature to average at 88.4 degrees during the three dyno pulls.  The dyno elevation is 189 feet

3)  Run records show the average temperature to be 72.1 degrees at an elevation of 4,213 feet at B'Ville

4)  The -16.3 degree temp change and +4,024 foot elevation change are set on the slide rule.  a #140 jet will be used for the flats.



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Koncretekid
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« Reply #2846 on: August 08, 2017, 06:26:48 AM »

Those are impressive looking results, Bo.  I played around on a dyno with my bike this spring, 72 dyno pulls, 4 different intake lengths, 4 different exhaust lengths, numerous timing and jetting changes, tappet change with different radius, etc, etc, and all runs were within 5 hp, and only about 1-2 more than I have been running.  Time for some drastic changes for me if I want to go faster!
Tom
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We get too soon oldt, and too late schmart!
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wobblywalrus
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« Reply #2847 on: August 08, 2017, 09:14:46 AM »

That BSA is making good power considering it is a single cylinder pushrod engine on gasoline.  Methanol was what Burt Munroe used.  Maybe that is the way to go.

The exhaust system was designed using Dynomation and a ten-point approximation of what the cams might be.  The cams were ground and digital models were made by Kibblewhite.  The digital profiles were entered into the Dynomation program.  It is like looking at two completely different cams.  The entire virtual design needs to be redone using the digital profiles.  Do not waste time using these computer programs with ten-point approximations.

A second exhaust system will be designed and built this winter based on the digital profiles.  I might go back to using PipeMax.  The new setup will use a muffler 'cause I have a lifetime of tuning with mufflers and this is the first time I have used open pipes.  I use the muffler as a performance enhancement and feel at a disadvantage without one.  Odd, but true.
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wobblywalrus
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« Reply #2848 on: August 08, 2017, 10:50:11 PM »

Today the fuel line covers were attached, the carbs rejected, and I put the carbs back on the bike.  "Fap!" as Major Hoople says.  The flippin carbs only open 3/4 of the way.  The way I adjusted them was like I did with the Keihins.  These rascals require a different method.  Another dyno appointment is requested.  There might be more power in that motor.   
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« Reply #2849 on: August 09, 2017, 06:36:50 AM »

Maybe the dyno results will make sense this time....and thank goodness you found the carb problem.
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