max rev's?

Ohhhhh, dirt oval, now that's a horse of a different gait! With the blown power plant you know how much the rear really rules the roost! hobot

Matt Spencer said:

WHILE WHERE HERE , its a lot more stressful Throttle Shut at whatever revs . Destressing , the rod will part company .

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What's the thinking behind this? Why is something more likely to break if the throttle is closed at high revs?

hobot said:

If this ever happens again I hope to have presence of mind to hold WOT and just use kill switch

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And what's the thinking behind this? If the failure isn't triggered by the sudden cessation of the combustion process, as would happen when you hit the kill switch, what is it triggered by?

Gary

Youngs Modulous of Elasticity . :roll:

its more the nerd whistling along ,seeing the city limit sign , and dropping it in 2nd , at 80 mph , WITH the throttle SHUT .

not the same thing as ' catching it on the throttle ' at all .

Will elaborate if I dig some figures out . Essentially , rods dont jump ship for No Reason . Theres mathematics involved .
Seems a good many observe rpm MAX ads advisary . DNE on a aeroplane means the wings fall off . Seldom Repeated . :lol:

Id be getting worried with stock rods regulartrly run to 7.000 , at about 50.000 miles . The old V2 = E squared helps .
That Said , the old Bonne with the presumably originall skinny rods installed with 118.000 on the clock SINCE a 65 rebuild
regularrly ran 7.500 , often 8.000 , and floated the valves by 8.500 horifieingly if it threw out of gear .
Had a new 72 crank , new 8 stud head , valves , springs and the like fitted though .
Farm Boy After me , we fitted unit primary , and bored to .060 .
One couldnt describe him as cautious with it .
He hit ssecond at 60 once , coming into a red light . Green , hitting the throttle , it stood up at those revs , for 100 yards .
Splitting the lanes . :lol: :shock:
He traded it in on a T150 with oversize pipes , and averaged 85 mph for a 60 mile journey , 1/3 of it on twisty gravle .
I think he respected Max. rpm's though .

Steam cleaning the pre unit after the overhaul got it rusting in parts . No real leaks , no kero in the steam cleaner , and lime on the back roads in winter .

SO , the engines not a exhaust brake , at redline or beyond . Its the city slickers chargeing into blind bends at 80 mph
and throwing it into second ' as its faster ' that ventilate the cases . Ive Found .Anything with excess clearances down
below ( a fresh top end on a lossening bottom end ) the unrestricted slack starts hammering .
Trying to find a way out ? woopsie .

The Bonneville , youd catch it on the throttle and push it into the corner rolling in the power , to avoid it going knock kneed .

Commando , with the tourque ( not a stock one ) and haveing a disc on the front ( had a firm grip from the forestry work )
I wouldve considered hooking up a lower gear at 4.000 to be looking to goe into orbit . Possible on a Race Track , NOT on the road , unless ' All Clear ' , and broad and fairly smooth out ahead . Being a shrimp .

Start calculateing the pilots trajectory in a sudden high side at 90 kph .when the thrust from the machine is of three times the riders weight ,with the 31 in seat hight as radius about the ' catapult ' fulcum .We wont do That , Again . :shock:

http://en.wikipedia.org/wiki/Hiduminium

Heres some drivle . What we're looking for though , is Strength in COMPRESSION Vs Strength in TENSION .

Throttle SHUT ( on the downshift ) its alledged the FORCE generated against a Vacume is in excess of that
in Compession by the old 180 Lb odd per Sq. in ( and theres half a dozen odd piton area .) b m e p .

Tecnically I think ' tensile force ' is what we wish to evaluate .

And what's the thinking behind this? If the failure isn't triggered by the sudden cessation of the combustion process, as would happen when you hit the kill switch, what is it triggered by? Gary

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My heart has been broken a few times by loss of a motorcycle, first was the P!! drag bike and then Ms Peel's hopped up Combat over rev event, so I too often reflect in my heart - that If I'd Only Left The Throttle WOT and holding kill button - the lessened vacuum sucking on pistons decent might have lessened the damage enough I could of just put the Drouin on it and already be whipping sports bikes asses way over the ton rather than just up to it. Ms Peel's weak points prior to the stuck throttle was her drive train from main shaft candy cane to 3rd gear teeth fractured off to fanning over the main shaft sprocket teeth to mere ruffles of teeth remains on rear drum.

Since that time I've tossed in bed conceiving a way to hit 11,000 rpm, now we have Schimdts' pistons-rods to take it. One way was to put bearings in case to contact round rim of flywheel but found the surface translation speeds would first heat shock wave pressurize the oil till it exploded like a diesel then the metal surface would deform like a water wave till its splashed in rebounds to explode into dissociated elements of glowing plasma. Then thought well shoot only need support past 8500 or so, so why not put sacrafical bearing blocks in case around the smooth rim of flywheel to take advantage of the plasma pressure waves to hold crank from center jump rope for say a drag strip worth of time, then adjust blocks in for next run and renew when too thin. MIght need a C02 or N2 fire suppression system to flood crankcase too.

Then I found spriographic way to draw a linear line with planetary gears so no surface translation at all with a strong ring of steel around the cases seam and no wobble in rod in piston so no wrist pin needed to lighten oscillation inertial. This could fit in factory shaped cases and would then make the valve train the next limiter.

Otherwise our engines ain't even up to what Harley Big Twins turn when spent on enough. Sobering to realize we are stuck in farting power delivery zone.

Here's another common method to up rpm tolerance. Ain't heard of it applied to Nortons yet but may now. Can't let crank jump rope too much or long stroke pull pistons so fast/hard they come apart.

The piston and its half of the connecting rod stops twice per crankshaft revolution, even though the crankshaft continues to turn. This means the piston and top of the rod also start back up twice. This stopping and starting imposes stresses on all three of the parts, stresses that increase with crankshaft rpm. To reduce these loads, the piston is mounted to the connecting rod slightly offset. This causes the piston to reach top dead center at a different time than the connecting rod, effectively spreading the shock loading over a greater number of crankshaft degrees. In short, the real reason for piston pin offset is that it softens reciprocal loading, permitting lighter more power-efficient parts to be used, and the engines to be capable of higher rpm.

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more
http://www.motorcycleproject.com/motorc ... ffset.html

Matt Spencer said:

Tecnically I think ' tensile force ' is what we wish to evaluate .

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It is not as simple as tensile force or tensile stress.

What needs to be evaluated is the durability; the number and magnitude of load (stress) reversals are factors in determining durability or endurance limit of a material or component.

I recall steel being one (if not the only) material that at or below a certain magnitude of stress reversal will perform for an infinite number of cycles without failure. Most other metals have a finite life even with very low magnitude of stress reversals.

Aluminum rods in dragsters have a very short life and are replaced because of the finite life, there are other reasons aluminum rods are used in dragsters. I am going to go out on a limb here and speculate that for dragster applications, the aluminum rods are less prone to buckling since they have a significantly different slenderness ratio than that of an equivalent steel rod.

The main reason of Al rods in dragsters is the lighter mass to over come and in the more extreme cases to act a shock absorbing springs to take up the essentially compressed to liquid mixture phase and detonation explosion shoving them down. Al rods or Al structures built beefy enough for their application like our factory rods in mostly factory set up engine under 8000 rpm are not prone to this fatigue failure time line. Going by my own and others reports Norton rods in 750's can tolerate 9000 for years if weaker items can take it.
The M.A.P. Al rods with Al caps require some case grinding to get clearance I'm told on factory stroke cranks.



My RGM triple trees are only 1/2 lighter than steel ones and bigger in size too.

The piston and its half of the connecting rod stops twice per crankshaft revolution, even though the crankshaft continues to turn. This means the piston and top of the rod also start back up twice. This stopping and starting imposes stresses on all three of the parts, stresses that increase with crankshaft rpm. To reduce these loads, the piston is mounted to the connecting rod slightly offset. This causes the piston to reach top dead center at a different time than the connecting rod, effectively spreading the shock loading over a greater number of crankshaft degrees. In short, the real reason for piston pin offset is that it softens reciprocal loading, permitting lighter more power-efficient parts to be used, and the engines to be capable of higher rpm.

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The only time the piston ever reaches top dead centre at a different time to the connecting rod is on the revolution immediately following the catastrophic failure.

Gary

hobot said:

Al rods or Al structures built beefy enough for their application like our factory rods in mostly factory set up engine under 8000 rpm are not prone to this fatigue failure time line.

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Not so. Look into the endurance properties of aluminum and steel and compare. Below a certain stress level steel will endure for eternity whereas with Aluminum, there is no lower threshold; it will eventualy fatigue and break. Steel rods do operate above the lower threshold so there is some parity there when compared to aluminum rods.

hobot said:

Going by my own and others reports Norton rods in 750's can tolerate 9000 for years if weaker items can take it.

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9000 what? I do believe the Commadno rods are well designed and very suitable for their intended use and then some. Plenty of race bikes use them without incident. Apparently they do begin to split when used in a high output 1,007cc engine.

hobot said:

The M.A.P. Al rods with Al caps require some case grinding to get clearance I'm told on factory stroke cranks.

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I just purchased a new, never been used Steve Maney 1,007cc race engine with MAP rods and I am having them changed out to JS rods as the MAP rods are not a good application for this motor.

So why are so many going to the JSMotorsport steel rods?

The point of my post is to take exception to the statement about "tensile forces"; that is an incomplete and maybe a bit misdirected view. All materials have an endurance limit but steel is the only material I know of where below a certain stress reversal threshold the endurance is unlimited. I am not saying that steel connecting rods operate below this threshold. I suppose maybe this is why you see steel springs and not aluminum springs.

Again, aluminum rods generally have other physical dimensional properties that a steel rod cannot achieve for the same weight. With a Blown Nitro burning dragster the combustion chamber pressures are significantly greater than for a naturally aspirated gas engine thus connecting rods have other performance criteria to meet (buckling).

hobot said:

My RGM triple trees are only 1/2 lighter than steel ones and bigger in size too.

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The fact that they are bigger in size in some cases is a good design attribute. This is my point with Blown Nitro dragsters where "size does matter" or where overall cross section of a rod is increased and reduces buckling tendencies. It is not simple.

I look up to you racers over powering factory items but I'm sticking to my story that Norton rods are not a weak fatigue item in all but most extreme over size over run engines. Look up the dragster use of Al rods as better springs than steel to protect the rest of the force transmitters. But as you say, Al dragster rods are a consumable item like tires. There is a threshold of Al structures, like Norton rods that the fatigue flex life time is essentially unlimited.

I was going to reuse Peels rods in her 920 blown engine - till Jim's came available and his pistons saved milling out combustion volume, so put Peel's over over rev'd rods in Trixie this last 4th re-build. I did have them shot peaned after cryogentic tempering, just in case that helped them some in density compacting.
They will have an easy life style inside Trixie Combat.

I would take your (race) bike to the dyno & see where it makes power.

I would look at the dyno curve & only rev it to the point where when you change gear at the revs on the downward slope of the curve, it is equals the same torque / power on the upward slope of the curve. Hope that makes sense.

You might also need to look at the gearbox ratios & produce a torque cascade graph. (I think that's what is called). Because the revs at which you change each gear might be different depending on the space of the gear ratios.

Why rev an engine way past where it's making the best horsepower? Unless the finish line is down hill with a back wind!

' For Sale - Carrillo rods , Chev 350 , 7 off ' . :shock: :lol: Ive seen that add a few times .
presumeably all Time Expired .

The Nitro burners if they use alloy its as they are considered kinder on the crank , acting as a shock absorber ( shock load )
(for a season :lol: )
Coustomary to replace the crank Ea season if running steel rods as it wears more with impact loading from steel rods .

Remembering these things often get new bearing shells Ea few runs . :shock:

Was reconed Triumph Alloy 650 Twin rods were lifed at 60 raceing hours ( English Circuit Raceing )

Somebody had an old DC 10 or C 130 Flap bracket to cut bits from , as it failed the Crack Test . Crack was visable .
Was a big triangular webbed thing with Eyes in two or three places .
Sitting at the right window looking at the Flaps in a 777 or 747 as they shudder and jar holding up the 300 ton device
makes you hope they havnt left the split pins out . :wink: and gives an idea of whats up between the piston and the crank .

How much flex is there in a built up crank, at 7500 rpm :?: I read that john Coopers works Rocket 3 rods crank flexed/bent 30 thou at 10000 ,the pistons touched the head ,this was when he rev'ed it flat out to beat Ago.

He reved it to 10.500 to Blow of Curruthers when he realised he didnt have a lap on him , too . .

If the Temps over 30 C , 90 F. in a long race , the old ' heat soak ' and oil thinning , would make the components
dimensionally varied . ( another cam of worms ) and allow clearances to go one sided under duress ( take up the slack )

Alledgedly the Triples ran . 012 clearance , piston to head . Getting annoying , the Last 4 cyl ' Kent ' block weighs
considerably more than the first series ( Ford pushrod / 1000 / 1600 c.c. ) Allowing the Horsepower to be increased
as it has greater dimensional stability .

More annoyingly , a 3 bearing case would fit under a Commando top end ( with a 3 bearing crank ) .
Open bottomed for Mains Acces , one piece casting ( Britten & everything else-ish )
Just run full circle flywheels adjacent to the centre main . Less problematic if theyre all plain bearing.

But , it'd be easier to go the whole Hog and do a Cosworth Rip Off . PRE UNIT , of course . For adaptability . 8) :mrgreen:

The alloy rods have a degree of elasticity , and are thus ' shock absorbing ' , to a extent . Ask T. C.

Matt Spencer said:

' For Sale - Carrillo rods , Chev 350 , 7 off ' . :shock: :lol: Ive seen that add a few times .
presumeably all Time Expired .

The Nitro burners if they use alloy its as they are considered kinder on the crank , acting as a shock absorber ( shock load )
(for a season :lol: )
Coustomary to replace the crank Ea season if running steel rods as it wears more with impact loading from steel rods .

Remembering these things often get new bearing shells Ea few runs . :shock:

Was reconed Triumph Alloy 650 Twin rods were lifed at 60 raceing hours ( English Circuit Raceing )

Somebody had an old DC 10 or C 130 Flap bracket to cut bits from , as it failed the Crack Test . Crack was visable .
Was a big triangular webbed thing with Eyes in two or three places .
Sitting at the right window looking at the Flaps in a 777 or 747 as they shudder and jar holding up the 300 ton device
makes you hope they havnt left the split pins out . :wink: and gives an idea of whats up between the piston and the crank .

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That is some comprehensive anecdotal information there. Thanks for sharing.

Rev it until it blows and back off 500 rpm.

Greg