Commando Crankshaft Porn

comnoz said:

pouchy750 said:

What VW engines are these special cranks taken out of?

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The cranks were made from 1/2 of a 1.6 liter Volkswagon Rabbit diesel crank.

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What did you use for main bearings ?
The center main would be easy to use the VW bearing, but what about the ends ?

Is the stock oiling system adequate ?
Thanks.
Ian

Ian,
I used the VW bearings on the ends also. I made a steel bushing with the VW ID and the Norton OD and made a special tool to press the bearing inserts in from the side. I removed the tang from one shell and cut a relief in the bushing for the other tang.

I used a custom built oil pump in the stock position for pressure and another pump in the mag area for scavenge. Jim

The light bulb just came on. :idea: :mrgreen:

Excellent, thank you.

I picked up a Yamaha XS650 crank, 74mm stroke, to see if I could narrow it up;
but the VW crank sounds almost bulletproof, and the stroke might be longer.

I have a spare NOS xs650 crank sitting on the shelf that will someday be a 277 rephase. I do not like thinking abot pressing all those pieces back together!

Unkl Ian said:

The light bulb just came on. :idea: :mrgreen:

Excellent, thank you.

I picked up a Yamaha XS650 crank, 74mm stroke, to see if I could narrow it up;
but the VW crank sounds almost bulletproof, and the stroke might be longer.

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The VW cranks were available in two different strokes. Short stroke for the 1.5 and a longer stroke for the 1.6. There is enough metal on the 1.6 liter crank to offset grind it to 89mm stroke with the stock Norton journal size. Jim

Jim: Rods were my next question. :lol:

Would the VW rods be an option ?
Probably with better bolts.

Have you looked at the 1900 crank?
95.5mm stroke. :mrgreen:

Unkl Ian said:

Jim: Rods were my next question. :lol:

Would the VW rods be an option ?
Probably with better bolts.

Have you looked at the 1900 crank?
95.5mm stroke. :mrgreen:

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The cranks I used were from the diesel motors. The rods were huge and heavy with very large wrist pins so they were not considered.

I used Carrillo rods for a Norton in .450 inch over length with short pistons. Going to the Norton rod journal size allowed me to offset grind the considerably larger VW rod journals up to stock 89mm stroke which was necessary in the class I was racing. I believe the 1.6 diesel stroke was originally 86mm.

Never looked into the 1.9 liter motor. Jim

comnoz said:

quote:
I have a third crank that was cylinders 2 and 3 from a Mercedes 6 cylinder but it is in a motor. Jim

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Was this to get a 270 degree firing order,

or some other consideration ?

Ian

Youd have to assume it was 120 / 240 .

Bear with me , A Vincent was 50 Deg V ,
A odd fire Jota was flat plane , 360/180

So , if ' we ' could get a crank thatd rework to 100 Deg interval , we'd have a Vincent inirtial set up .

Bearing In Mind , the THEORY for the so called ' 270 ' Crank , was based on piston inertia , in that if
one piston is at full speed ( mid stroke ) it throws the other over its area of changeing direction , SO
the speed of rotation Throughout the entire 360 degrees of rotation is more consistant, deg / sec .
(or part thereoff )

SO , the original set up was a ' tangentally dispossed ' Crank , WHERE , with one piston at say T.D.C.
( or is it bottom D.C. ? ) the other is about mid stroke , WITH the Crank Throw tangental to the ROD .

Vis . , the offset cylinder is at maximum leverage . in one place . but like most things , it depends on
HOW you look at it .( the angle was defined by the mid stroke bit , & the rod length / stroke )

If you look at it like a Vincent , its 50 / 100 Deg . ( crank / cam ) 45 / 90 & 60 / 120 worth a look too .

though comeing to ultimate conclusions would require more than one type of each as peculiarities of one
design could engender false conclusions , that were only particular to that type .

Basically the Jota (crank) is a four with a cylinder ' lost ', the 100 Deg. would be akin to a T 150 crank with
one cylinder absent . The idea being to get the forces overlapping to give one long lope to the motion . :mrgreen:

Unkl Ian said:

comnoz said:

quote:
I have a third crank that was cylinders 2 and 3 from a Mercedes 6 cylinder but it is in a motor. Jim

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Was this to get a 270 degree firing order,

or some other consideration ?

Ian

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It was 120/240. Power was good but high frequency vibration was annoying with isolastics. It felt just like a 270 degree crank from the saddle.

Also tried cylinders 1 and 2 from a 4 cylinder for a 180 crank. It was un-ridable.. The higher you revved it the larger the handgrips would get.
I ended up back at 360 degrees. Jim

Jim: Did you consider any other 4 cyl cranks, besides the diesel VW ?

Unkl Ian said:

Jim: Did you consider any other 4 cyl cranks, besides the diesel VW ?

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In looking for a crank to use I found the VW and Mercedes cranks were small bore and long stroke so the cylinder centerline was close enough that it could be lined up with the Norton cylinder centers. Engines with a larger bore will have too much spacing for the throws.
I also liked the Mercedes and VW diesel crank because of the quality of the forging.

I am sure there are other cranks that would work. I recall a fellow in Canada using a crank from some French car many years ago. Don't recall what it was. Jim

Jim,

IIRC, that was an Alfa Romeo crankshaft.

Ken

OK while subject is heating up again, what can one do to find safe crank rpm limit if everything else has more tolerance than the jump rope crank? Only thing I can think up is a soft bolt run up to flywheel rim, then backed out a bit then examined as rpms crept up on to know rev limiter setting.

TC ran Hog Slayer to 8000 shifts and got 160 runs w/o opening engines up. Don't know his crank or bearing technology but would be a contender to place here.

I'm thinking of makng some cranks with bolt on counter weights on the cheeks to re-distribute the weight toward the outside in order to reduce flexing. The center flywheel may also have bolt on weights for machining reasons and for keeping the weight down (but not too light). Other than the bolt on weights it would be one piece. The plan being providing a strong crank able to withstand racing & large displacement motors as well as failure free extended use on street bikes. Would take a lot of investment on my part and right now its only an idea but I'd like to know how much interest there is out there. Cost would be typical for after market cranks.

Jim S

jseng1 said:

I'm thinking of makng some cranks with bolt on counter weights on the cheeks to re-distribute the weight toward the outside in order to reduce flexing. The center flywheel may also have bolt on weights for machining reasons and for keeping the weight down (but not too light). Other than the bolt on weights it would be one piece. The plan being providing a strong crank able to withstand racing & large displacement motors as well as failure free extended use on street bikes. Would take a lot of investment on my part and right now its only an idea but I'd like to know how much interest there is out there. Cost would be typical for after market cranks.

Jim S

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Look at page two of this thread or explore http://www.britishclassicbikes.de/ they make exactly what you are thinking of.

Jean

Jim, that's the ancient accepted way of 360' crank racers and is exactly how Ms Peel's deal is done. I've two concerns, one the crank end flex and two the power pulse traction effects on tire edge as dampened via the isolastic drive train.
As ya know and see in this prono show most place expensive heavy metal in checks which I found is more dense and less expensive than depleted uranium I've looked into. DPU, is very common in equipment and aircraft and boats but covered up so unseen or detectable w/o sensitive meters.

In Peels deal her rpm anti-histamine remedies are one piece welded nitrided, [ugh, re-straightened] crank, your light weight wonder rods/pistons and Drouin blower. When there is forced pressure always seen pushing on top of pistons then it helps shove piston over TDC crank jerk hump and no suction is seen that resists piston jerk down like natural inspired intakes. Last thing you want to do to shut down OVER rev'd engine is snap throttle shut vs WOT with kill button held. How much above is worth in rpm tolerance who knows so I seek some non destructive way to approach it at times.

One thing I've not seen in Nortons yet is make case bores to offset crank from piston throws, which is said to both lower piston drag and ease the jerk down acceleration G's a bit more.

Here's some uplifting data that may relate to our love pets power potential.

However, it is astonishing that the Cup BMEP (remember, flat-tappet cam, pushrod / rocker arm, two-valves-per-cylinder, single carburetor) is only 0.3% less than the Formula One figure at peak torque, and only 4.1 % less than Formula One at peak power.

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Way more of interest to see here
http://www.epi-eng.com/piston_engine_te ... _to_f1.htm

In addition the crankshaft axis has been offset 14 mm, relative to the cylinder-bore axis, so the crankshaft does not sit directly under the cylinder. This minimizes friction from the side thrust of the pistons against the cylinder walls, just after top-dead-center, as each piston begins its descent on the firing stroke. Honda claims this reduces internal friction by as much as three percent.

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Lightweight aluminium-alloy pistons are used in the IMA engine. The pistons have a minimal skirt area and the surface of the skirt has been shot peened with small ceramic balls to give a micro-dimple surface. This improves the retention of oil film between the piston and cylinder and another 1.5 to 2 per cent reduction in internal friction.

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yes i did the math and the numbers you gave me pan out but i guess it still doesnt help too much because i know some guys are running actual max piston velocity of 45 m/s. that is 86mm stroke at 10000. and there was talk that someone was running 94mm stroke at 9800 which is about 48 m/s. but all of the oem guys seem to stick in the range you had of 38 m/s. its the privateer guys that are going nuts.

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http://www.eng-tips.com/viewthread.cfm?qid=85349

One reason for longer rod ratios in high rpm engines is to reduce the max acceleration at TDC (there are also benefits from being near TDC for longer and better rod angularity during the combustion stroke.)
I found some interesting piston kinematic spreadsheets on this page (and page 2.)

http://e30m3performance.com/tech_articles

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Offset bores to crank throws is old hat we might want to catch up too.

http://www.fireballroberts.com/smokey_yunick1.htm

Turning the pistons around is an old moon shiner trick according to Smokey Yunick. Smokey went as far as producing "math" that
calculated the maximum distance to offset the wrist pin to produce the maximum amount of HP gain. In the article, he mentions that with "modern" technology, the car companies didn't offset the wristpin anymore. He said in the old days, you could just install the piston "backwards" and get more HP. He felt that piston makers should offer offset pistons for race car. He did say said if you bought enough you should be able to get your
piston maker to do this. He indicated that every winston cup team did this.

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http://www.hotrodders.com/forum/anyone- ... 28686.html

Didn't the Hudson Hornets have really long connecting rods? What was the rod ratio on those things? Did they offset the crank to simulate a shorter rod on the power stroke or a rod that was even longer yet?

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http://speedtalk.com/forum/viewtopic.ph ... 3fe666f5a3



http://members.iinet.net.au/~tduell/rep10.pdf

Here's a site that claims True Hp reports for many cycles and looking for reports to fill in the blanks on old-new, big-small cycles. Worth a scan through for those trying to keep score on impossible to compare shaft vs chassis dyno tests or any conversion method to explain their differences.

http://www.factorypro.com/dyno/true1.html
Today, about 75% of the entire world's hp values are a mess of dynojet "hp" and dynojet dyno clones' rough approximations of dynojet horsepower , some brake dyno mfgr's "dynojet channel" that's "+/- 10% of a dj number" , some dynos that out exaggerate the dj numbers and imply that they know what the transmission hp and crank hp is, and even other dynos with the most expensive brochure that read whatever the user wants them to read, True, Real, SF and DJ..... or make up your own inflation factor (sigh...)

mightve been covered hear , but ' Welding Journal Throws ' .

Is the steel the crank ends utilise suitable for redimensioning , as per 50s V-8 strokeing tecnology .
Which type welding rods , any heat treatment required .

Being Awkward , will they fit in the Crankcases .

How much clearance to case from rod end retainers ( rod nut , bolt end ) .
1 or 3 m.m. envisaged , but whats visual clearance stock for bolt in . ?

Here's a pic of a 90deg nourish weslake cranshaft from a 750 regular (not short stroke) engine.
It's a pratice for posting pictures so I thought I'd stuff it in here.
Rods Carillo, pistons Omega.