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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 521470 times)
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Interested Observer
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« Reply #2550 on: September 21, 2016, 07:21:14 AM »

Wobbly, a couple comments--

The intake port looks more oval than elliptical, may have more area.

Have you acquired weightless buckets and shims for the valves?

Race springs likely have a higher spring rate as well as increased seating force.  Higher load/stress at or near max lift.
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« Reply #2551 on: September 21, 2016, 09:01:11 AM »

The fellows in AUS also remove the counterbalancers and shave the crank bobweights.  In my thoughts now are the triumph streamliner team that are tying to do far too much, too soon, with little experience and getting no results except problems.  The bike has been in impound at the speed trials five years in a row and has held or holds seven records.  None of them are exceptionally fast but the incremental development method is serving me well.  It is best for me to stay at 9,000 rpm till I get that sorted, reliability wise.  Ten grand has a nice sound to it and is very tempting.

The buckets and shims are in the listed weights.  I forgot to mention them.  The standard Triumph bucket has a shim on the top which is 25mm dia and the race shim is 10mm dia and it sits underneath the bucket in a circular hole on the top of a titanium valve spring retainer.  That is how the race system saves weight.  The little ports that feed each valve are the ones I measured.  They are elliptical.  That big port is upstream from the bifurcation and it is oval.  The smallest port areas on this engine are downstream from the split.  The springs do have a higher rate.  I will need to consider that.       
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« Reply #2552 on: September 23, 2016, 07:39:54 PM »

The valve diameter is based on the outside diameter.  The intake valves are 2 mm larger than standard and the exhausts are the standard size.  The combustion chamber was enlarged to accommodate the larger valve seats and a minimal amount of metal was removed from around the valves to reduce shrouding.  This small change dropped the compression ratio considerably.  The pistons provide 13:1 compression with the standard combustion chamber.  The measured compression is 11.7:1 with the bigger intake valves.  The head provides plenty of flow so the valves will not be enlarged to get more.  The mach number will be checked and the valve size increased on that basis, if needed.

A piston is in the second picture.  The piston crown edge touches the bore side when the engine is cold and before the piston is fully expanded from combustion heat.  The ceramic coating was truncated on the crown top away from the bore edge.  This reduces the chance of the hard coating rubbing against the cylinder walls.  Two alloys can be used for these pistons.  High silicon 4032 which is long wearing and best for lower stressed street bike use is one alloy.  No silicon 2618 is more suited for race motors with high physical and thermal stresses.  These are the 2618 option.  It is a relatively soft alloy.  The coating is intended to protect the skirt from wear until the rings scrub down the fresh honing and smooth the cylinder walls.     


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* 2017 Builld 006.JPG (191.07 KB, 967x768 - viewed 54 times.)
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wobblywalrus
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« Reply #2553 on: September 23, 2016, 07:47:12 PM »

The gudeon pin offset is needed for the short block data.  It is used in the internal friction calculations.  A pin offset towards the piston thrust face makes the rod more "straight-up-and-down" during the compression stroke.  This reduces the pressure on the piston thrust face and consequently the friction loss.  The pins on these are offset just over 1mm toward the thrust face.

An easy way to figure out pin offset is to measure the distance between one piston face and the back of the opposite side of the pin, then turn the piston around 180 degrees and repeat the procedure.  Subtract the little measurement from the big one and divide the result by two.  This is the pin offset. 


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wobblywalrus
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« Reply #2554 on: September 24, 2016, 09:46:25 AM »

The big brown truck stopped by a few days ago and the delivery guy gave Rose a package. In it is the Dynomation 5 program.  It was ordered from Audie Technologies, it cost $518 and there are two compact disks and a security key.  This gives the program some portability and durability.  I can move it from computer to computer and if the computer pukes up its hard drive, I do not lose the program.  The program is windows based.  My preference is Windows 7 for PC use.  Fortunately the thing will work with it.

The program is one of the two disks.  The other is the entire Comp Cams lobe profile library with over 1700 grinds.   This is what sold me on the program and its use.  All of the other cam grinders I know about do not provide this level of detail about their products.  Unfortunately for them, this profile data is what I need to make an intelligent choice, so Comp Cams grinds will be looked at.

The tech support fellow is giving me good service.  Several questions about how to measure things for input data were answered quickly and I was told what I needed to know.

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« Reply #2555 on: September 24, 2016, 11:30:28 PM »

The engine data is entered and I went through the on-line Comp Cams catalog for lobe grinds.  There are three for an overhead cam engine with direct acting lifters and 1.1 inch wide buckets.  #9013 has 0.410 lift and 226 duration at .050, #9014 has 0.420 lift at 232 duration at .050, and #9015 has 0.430 lift at 238 duration at 0.050.

The cam timing optimization options were used in the filling-emptying model.  The best combination is a moderate lift #9014 lobe for intake and a higher lift #9015 for exhaust with a 110 degree lobe centerline.  This equates to 107 crank HP or 96 rear wheel HP.

The need for a higher lift exhaust cam makes me think the exhaust valves may be too small.  Tomorrow evening the wave action model will be used to look at mach numbers.

The intake flow data I entered was for the head, manifold, carb, and air cleaner at 28 inches.  Then, I also calculated and entered the carb restriction based on 10 inches.  A call was made to tech support.  I thought I was entering the carb loss twice.  They said I was and the flow data should be for the head and manifold, only.  Fortunately I have that and it will be entered later this evening.

The program has a feature to look for optimum cam timing for any fixed lift value.  I wanted to figure out optimum lift.  The tech support guy says that is too hard to program.  Flow and HP tend to get better with more lift and there is no way to set a realistic ceiling.  He said to look at the physical limits of the valve train, durability, and affordability to figure out maximize lift, then to optimize the cam timing for that lift.         
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« Reply #2556 on: September 25, 2016, 10:28:16 AM »

This morning I fixed the flow data.  Flow with the head and manifold at 28 inches is used.  The carb restriction is added separately.  Also, higher lift and longer duration intake cams were modeled.  None made much of a difference in power.  The power I am maximizing is the area under the horsepower curve between 5,000 and 9,000 rpm.  There are four choices to maximize, peak torque, peak power, greatest area under torque curve and greatest area under the HP curve.  The cam combination that worked yesterday is retained for today.

It looks like the barrier to more HP is in the exhaust side of things.  The system I was modeling and is on the bike is large headers with mufflers and no cats.  This morning the entry was changed to large dia stepped headers and open exhaust.  There was a big jump in power, 10 hp at the flywheel, so I need to do this change.  The program will give me the optimized dimensions for this exhaust type.
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« Reply #2557 on: September 26, 2016, 11:05:44 PM »

Oops, I started to select cam profiles without considering the minimum base circle radius.  This is the radius of the cam opposite of the lobe tip.  It needs to be correct in order to obtain the correct tappet clearance.  There is a limited range of clearance adjustment shims.

The first step is to lay the head on a surface plate, which is a piece of plate glass in this shop, and to measure the height of the cam journal when it is sitting in the head.  It is 5.464 inches.

The next step is to measure the height of the base circle opposite from the cam lobe.  It is 5.560 inches. 


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« Reply #2558 on: September 26, 2016, 11:15:07 PM »

Now the cam journal diameter is measured.  It is 0.904 inches.  The height of the cam centerline is the height of the top of the journal minus half its diameter.  This is 5.464 - (0.904 / 2) = 5.012 inches

The base circle minimum radius is the height of the base circle minus the height of the cam centerline.  This is 5.560 - 5.012 = 0.548.  Base circle radii are nominally described to the nearest 0.010 inch, so the minimum base circle radius is 0.450.

There is another minimum base circle radius I can use.  It is based on the height of the button in the follower cap.


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« Reply #2559 on: September 26, 2016, 11:20:38 PM »

This is measuring the button.  There are two button heights, 0.098 and 0.135.  Mine are the larger ones.  Use of the smaller ones allows a bigger base circle, as follows:  0.450 + (0.135 - 0.098) = 0.487 inches.  A cam with a 0.490 inch minimum base circle radius can be used if the followers have shorter buttons. 


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« Reply #2560 on: September 27, 2016, 12:01:03 AM »

Ack!  The cam profile selection for a 0.450 minimum base circle dia is exactly zero.  There is only one cam profile for a minimum base circle dia of 0.500 with reasonable lift.  That base circle dia is within the shim range if I use buckets with smaller buttons.  It is Comp Cams 6807, minimum BCR = 0.500, minimum tappet bucket dia = 1.000, duration at 0.010 = 286, and duration at .050 = 250.  It is for a flippin' Volkswagen.  Who knows, it might work.  That will be tonight's project.
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« Reply #2561 on: September 27, 2016, 06:52:31 AM »

Quote
The base circle minimum radius is the height of the base circle minus the height of the cam centerline.  This is 5.560 - 5.012 = 0.548.  Base circle radii are nominally described to the nearest 0.010 inch, so the minimum base circle radius is 0.450.

Shouldn't that be 0.550 ?
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« Reply #2562 on: September 27, 2016, 07:49:17 AM »

Hey - somebody else is awake enough to read the numbers carefully.  I thought i saw something funny -- but didn't question it.  I showered first -- and by then you'd seen it.

But - is it an error or is it Oregon Cam-Speak? rolleyes
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« Reply #2563 on: September 27, 2016, 11:06:59 PM »

This is really great for you'll to see my mistake.  I guess I cannot use that VW lobe.  It looked pretty good in the engine simulation.  The selection of lobes for a .548 base circle is even slimmer, there are a couple of ones at .540 and .544 for a flathead Ford...
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« Reply #2564 on: September 27, 2016, 11:53:58 PM »

Hey Wobbly- if you don't mind a personal question- how'd you come by that moniker?
The most famous context of that word (at least to me) was the "wobbly web" wheel designed by Colin Chapman in 1957. I think it was a brilliant design. (Google it).
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