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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 520367 times)
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wobblywalrus
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« Reply #2565 on: September 28, 2016, 02:03:53 AM »

Jack, it was a tendency to get into speed wobbles on the salt flats that earned me that nickname.  The walrus part of it is sorta obvious when looking at my sleek and hydrodynamic shaped figure.
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« Reply #2566 on: September 28, 2016, 09:52:04 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...

Wobbly, give Dema Elgin a call at Super Lobes. I think his cam shop is still in Redwood City, CA. He has what you need.

John
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wobblywalrus
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« Reply #2567 on: September 29, 2016, 09:24:37 PM »

The least cost alternative is to find an off-the-shelf cam set.  Calls have been made to folks I know in the UK, AUS, and here in the US.   What I am asking for is cam card data so I can enter it into the program and see how the cam works.  The next step if a ready-made pair cannot be found is to call Dema.

Lots and lots of early morning and late night hours are spent banging away at the computer.  What I am doing is varying something like valve size, compression, etc and looking at trends.  One thing that is notable is the best cam for the engine is not radical.  Basic optimum specs are .380 to .400 lift with no advantage to the higher lift, 107.8 to 108.8 lobe center angle depending on lift, 103 to 103.5 intake centerline depending on lift, 271 to 272 intake duration at .006 lift (seat to seat), and 283 to 284 exhaust duration at .006.  These are mild enough specs that a long lasting and low maintenance valve train is possible.  Also, these lobes will fit on the standard tappet buckets.  Life is good.     
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wobblywalrus
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« Reply #2568 on: September 30, 2016, 09:33:22 AM »

Some sort of a plan is coming together.  These Cosworth style four valve heads, professionally ported, flow real good. It does not take  huge valves to provide all of the flow the engine can use.  This is good 'cause fitting bigger valves requires enlarging the combustion chamber around them and the compression drops dramatically.  The program says the valves and ports I have are basically OK, with 1mm larger exhaust valves helping a very small amount.  The cams that are needed to make all of this happen are fairly mild so valve train durability is easy to get.  That is one big worry I had.

Now, it seems there are no major obstacles to moving the rev limit up 1,000 rpm to ten grand except the pistons.  An e-mail will be sent to Arias asking them about this.  They made the pistons and should be able to give some good advice.  The program says there are some big advantages to increasing the peak HP rpm from 8,500 to 9,500. 

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wobblywalrus
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« Reply #2569 on: October 01, 2016, 09:51:08 AM »

There are three models in Dynomation with different input requirements as per cam information.  The relatively simple filling-and-emptying model uses a 10 point cam description including opening and closing degrees at .006 lift, opening and closing degrees at .050 lift, and lift.  That is five points per lobe and ten points when both lobes are considered.

A lot of details on the intake and exhaust systems are not used in the simple F and E model.  I simply entered the type which was a stepped header and the model assumes I have optimized the design of a header of this description.

The F and E program optimizes the lobe center angle, intake and exhaust cam timing, and durations for a given lift.  So, I futzed around using different lifts and found those in the .380 to .400 range work good.  Also, the program figured out the optimum cam timing.

The next stage is wave analysis when the detailed intake and exhaust system info is input and the serious work starts.  Lobe profiles are needed for this.  So, the task is to find a person willing to share their profile with a complete stranger so they figure out whether or not they will buy the cam.  Also, that person needs to be willing to grind the profile on the cam.  This is sorta like being a horny dachshund in a cage full of great danes.  Rejection City.

There are three options i am looking at.  First preference is to look at the cams used in the mile racers like I saw at Sacramento.  The big carbs were purchased from that tuner and he is a nice guy and easy to work with.  Second is to work with a custom cam grinder like Dema if mile bike cams will not work.  Cost might be an issue.  Third is to order two OEM Triumph intake cams for a 790cc model, grind the welds off that hold the gears to the shafts, realign the shafts on the gears, and use them.  That third option is what I will investigate this weekend.  It is always good to have a Plan A, Plan B, and Plan C.
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wobblywalrus
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« Reply #2570 on: October 01, 2016, 02:36:59 PM »

There is a Plan D.  Two sets of race cams were made by the same company.  One was bought in 2009 at I used it since then.  The other is a new set I that I used the exhaust cam from for development purposes.  The old set has profiles that are ground to spec.  The intake and exhaust lobe centerline angles are 9 and 12 degrees out of spec.

Note how the gear is tack welded to the shaft on the new cam and not on the old.  Methinks the camshafts slipped in the gears after almost 200 dyno pulls and years of racing.  This is why I could not get more than 87 HP out of the engine despite all sorts of work.

Ten point lobe descriptions are put into Dynomation for those old lobes.  The optimize option is used to determine the best durations and timing for those aged rascals.  The recommended durations are more than these cams have so they are not optimal in that respect.  The lobes were put in the optimal settings based on lobe center angle and intake centerline angle.  The virtual crank HP is 114.98 at 9,000 rpm.  That is right up near the best I have found after days of dinking around with various combinations of lift, etc.

The plan is to ask web cam to move those gears around to the settings I want and to tack them in place.       


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wobblywalrus
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« Reply #2571 on: October 04, 2016, 02:26:33 PM »

There are a lot of things that can be changed on an engine and it is hard figure out the right combination.  This is how I use Dynomation to figure out some basic stuff, like optimum valve size and cam lift.  The filling-emptying model is used and it assumes these are optimized:  ignition timing, exhaust system using a stepped header, intake system tuned length, and gasoline selection.

The descriptive data is entered for the engine.  The "Cam Timing" option is selected with optimization of the area under the horsepower curve between 5,000 and 9,000 rpm.  As many things as possible will be optimized so the two variables I am interested in comparing will be segregated from all of the other stuff that could be changed. 



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wobblywalrus
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« Reply #2572 on: October 04, 2016, 02:32:35 PM »

The program is run.  The output screen shows the combinations of duration, lobe center angle, and lobe centerlines for the cam with the lift value I entered.  The bars on the graph are in horsepower-rpmx1,000.  This reflects the area under the curve.  The first cam timing combo looks good so I select it.


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« Reply #2573 on: October 04, 2016, 02:36:35 PM »

This is the data screen.  The lifts are the values I originally entered.  The cam timing values such as durations, lobe centerline angle, and lobe centerlines are changed to reflect the optimum settings. 


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wobblywalrus
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« Reply #2574 on: October 04, 2016, 02:40:32 PM »

This one of the engine data output screens and the horsepower is listed in the orange column.  This combo gives about 92 crank HP at 8,500 with typical Bonneville salt flats atmospheric conditions.


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wobblywalrus
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« Reply #2575 on: October 04, 2016, 03:00:07 PM »

This scratchy set of shop notes shows nine combinations of valve diameters and cam lifts.  The flow test results from the 26mm intake valves in the bike were extrapolated to get flows for the bigger valves.  The drop in compression from the head work to install bigger valves is considered, too.

This chart shows several things.  First, there is nothing to be gained by installing 2mm larger exhaust valves.  This would require new seats and is quite expensive.  I was going to do this before I got the program.  There are some small increases from installing 1mm larger exhaust valves.  This can be done using the existing seats.  This I will do.

The area under the power curve between 5,500 and 9,500 was optimized.  Cams with optimum timing all give HP peaks at 8,500 rpm.  The ignition modules are all programmed for a 9,000 rpm rev limit.  They can be left alone.  Nothing is gained by reprogramming them.

There are very slight power increases to be had by increasing lift.  This is not enough to warrant it.  The cams can have lift between .380 and .400 which provides the gentlest valve action.

The program has paid for itself by preventing me from making previously planned changes that would have done nothing.     


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wobblywalrus
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« Reply #2576 on: October 04, 2016, 04:31:16 PM »

The old cams I have been using are slipped in their timing gears.  Their gross lift is 0.388 and their duration at .050 is 244.  These lobes were entered into Dynomation and the timing optimized.  Their best is 92.53 hp at 8,500 rpm.  Not bad and only a HP less then the optimized cams on the previous worksheet.

Next, I called web cam to get the gears reinstalled at the settings I want and to have them tack welded.  They suggested that I buy a set of adjustable cam gears so I can adjust the cams to exactly what they should be and this will compensate for wear in the timing chain, etc.  It made sense from a financial outlay viewpoint to do this so I ordered a pair.

The old cams make make 92.88 hp at 9,500 rpm with the big 28mm valves.  This will require reprogramming the ignition modules and having new seats installed along with bigger valves for only a fraction of a horsepower increase.  Again, this will be big financial outlay for not much gain and not worth the trouble.

The plan is to send the head and cams to Kibblewhite so they can install 1mm larger exhaust valves and get a tad more flow from the exhaust ports and get the old cam profiles digitized.  This can be used to design the intake tuned length and the stepped header.
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« Reply #2577 on: October 05, 2016, 05:10:24 AM »

The old cams I have been using are slipped in their timing gears.  Their gross lift is 0.388 and their duration at .050 is 244.  These lobes were entered into Dynomation and the timing optimized.  Their best is 92.53 hp at 8,500 rpm.  Not bad and only a HP less then the optimized cams on the previous worksheet.

Next, I called web cam to get the gears reinstalled at the settings I want and to have them tack welded.  They suggested that I buy a set of adjustable cam gears so I can adjust the cams to exactly what they should be and this will compensate for wear in the timing chain, etc.  It made sense from a financial outlay viewpoint to do this so I ordered a pair.

The old cams make make 92.88 hp at 9,500 rpm with the big 28mm valves.  This will require reprogramming the ignition modules and having new seats installed along with bigger valves for only a fraction of a horsepower increase.  Again, this will be big financial outlay for not much gain and not worth the trouble.

The plan is to send the head and cams to Kibblewhite so they can install 1mm larger exhaust valves and get a tad more flow from the exhaust ports and get the old cam profiles digitized.  This can be used to design the intake tuned length and the stepped header.

Bo,

You will not regret making this purchase.    Adjustability is the way to go.   There is nothing more frustrating than not being able to adjust something the way you want to or NEED TO . . . . .

 cheers
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« Reply #2578 on: October 07, 2016, 11:59:55 PM »

The big brown truck brought the cam gears.  I made the mistake of opening the box and looking at the gears during dinner.  Oldest daughter, Heidi, picks up the invoice and says "Those dinky parts cost HOW much?!"  The explanation I had didn't sound very convincing to Rose.  I will never make that error again.


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Seldom Seen Slim
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« Reply #2579 on: October 08, 2016, 07:59:37 AM »

That, Bo, was a major screw-up!!!!  Normally I know we don't hassle one another (on this Forum) for making dumb mistakes, but this takes the cake and all racers need to see what happens when --

When we don't ask the vendor to put BOTH invoices in the box, the "Mrs." version being right on top.  You know -- the version that says: "WebCam Adjustable Cam Gears - $12.44 plus shipping of $2.76".

The "real" invoice will likely include a surcharge for the Mrs. copy, but what the heck -- it's worth it! cheers cheers
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