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Author Topic: RPM limits?  (Read 5110 times)

SimonNOS

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RPM limits?
« on: May 18, 2005, 06:52:01 PM »
Can anyone give me an idea of what the rpm limit on a +5mm stroker is, when used with +3mm pistons and crower rods?

Does it make a difference whether the crank is welded or one made from fresh billet?

What about Crower Titanium rods, how much higher would these allow me to rev?
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Offline gazza414

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« Reply #1 on: May 18, 2005, 07:15:26 PM »
Its a fatigue issue  -- how many revs for how many cycles .

As far as weld up or a new forging or machined from bar stock --- no clear answer due to so many manufacturing variables and in house proceedures / specifications.  There are many good stories and a few horror ones too. IMO alot has to do with how the motor was built rather than put togther..... and possible oil starvation at certain points in its life.

Lighter rods are fine but they will still stretch and fail also - depends on section modulus ,and where the weight of the rod is concerntrated, material they are machined from, machining process , surface finish.

oh yer and rod bolts may pose as the weak point / link in the design.

You can do some calcs as to loadings on the rod for different rpm / stroke/ rod length and piston masses and just see what loads expressed in g are exerted .
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Offline TRNorBRN6001

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RPM limits?
« Reply #2 on: May 19, 2005, 09:23:58 AM »
1507, Nice. 8) From an idiots point of view, I think your motor should be able to run up to stock RPM without any problems. I believe Carrillo H rods might work just fine, they have the shorties also. For some reason a lot of people don't like the shorties (maybe rob torque and put stress on crank?). All H-beams use the SPS multi-phase bolts which Carrillo says should not go bad for the life time of the bolt, if installed correctly. I think if you take care of fuel, oil, and cooling issues you should be in good shape.

I think Weld-up should be fine but if you got unlimited funds go for the nice shiney Billet.

In the end I guess it all depends on what you want to do with the bike.

Keep us up to date on your build. Maybe MH or JC will post.
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Offline Steve S

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RPM limits?
« Reply #3 on: May 19, 2005, 11:46:33 AM »
For the reasons mentioned above, I have no idea. I do know, though, that at 10800 RPM the stroker has maximum pistons speeds 8.7% higher than than a stock stroke with speeds approaching 8,000 ft/min.....again max.
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Offline DarkFalcon

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RPM limits?
« Reply #4 on: May 19, 2005, 02:18:00 PM »
Interesting topic. No hard answer here but I suspect oil films and bearings will go first and then the big pieces of metal.
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Offline Jay

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RPM limits?
« Reply #5 on: May 20, 2005, 10:43:50 AM »
Besides stroking cranks, we repair them too. We see everything. We have repaired the high dollar billet strokers that come in with a damaged journal. I think it has to do with assembly and installation. The billets from England have really good nitride on them, like our weld ups. They only fail because of lack of oil. In that case, it doesn't matter how much you paid for it, it won't live without proper lubrication.

Jay
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Offline TRNorBRN6001

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RPM limits?
« Reply #6 on: May 20, 2005, 10:57:48 AM »
I think APE even spins those cranks up to 14,000 RPM. Sure hate to be there if one of them flew off :shock:  :shock:

Where in the land of tea and crumpets do you all get those lovely billet strokers, P3? That exchange rate sure is kind of ugly right now. Might have to get one before APE raises the prices. :lol:  :lol:
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Offline mike45

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RPM limits?
« Reply #7 on: May 20, 2005, 03:30:23 PM »
Any way to use a wider bearing on those strokers? I assume a high volume pump is mandatory.
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Offline TRNorBRN6001

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RPM limits?
« Reply #8 on: May 20, 2005, 04:59:38 PM »
I think the 8 1/2mm Billet stroker APE has is the one that uses the
larger Rod journals (Honda Size :? ) Those oil pump gears APE has would be nice and cheap to feed one of the 8 1/2 or 5mm strokers, might even spin a little extra coolant through too. :)  :D  :D
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Offline gazza414

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RPM limits?
« Reply #9 on: May 20, 2005, 09:17:45 PM »
Quote
mike45 Posted: 20 May 2005 20:30    Post subject:  

--------------------------------------------------------------------------------
 
Any way to use a wider bearing on those strokers? I assume a high volume pump is mandatory.
 



Then the issue becomes Rod big end design.
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Offline DaveO

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RPM limits?
« Reply #10 on: May 20, 2005, 10:47:39 PM »
The english 8.5's use blackbird brgs....wider surface area....

Someone said 8000 fpm on a stroker....better check your math again...

I know of a certain 5mm than spins regularly over 11k(real) rpms and has survived well....and is overdue for new brgs and springs....

Cross my fingers it will make another round at Maxton.....

Gazza,

Is yours a 5mm also???

Dave
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Offline FASBUS

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RPM limits?
« Reply #11 on: May 20, 2005, 11:05:08 PM »
I know of a certain 5mm than spins regularly over 11k(real) rpms and has survived well....and is overdue for new brgs and springs....

 ditto.....I have dealt with many more fueling & valve spring(not carpenter)
fatigue...Than any bearing issues.   MAKE SURE YOU KEEP YOUR OIL LEVEL FULL!
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Offline DarkFalcon

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RPM limits?
« Reply #12 on: May 21, 2005, 06:09:38 AM »
Quote from: DaveO
The english 8.5's use blackbird brgs....wider surface area....

Someone said 8000 fpm on a stroker....better check your math again...

I know of a certain 5mm than spins regularly over 11k(real) rpms and has survived well....and is overdue for new brgs and springs....


Dave


Dave

Max piston speed is over 8,000 ft/min right around 75 degress ATDC. This is not average speed which, of course, is lower and around 4900 ft/min.
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Offline TRNorBRN6001

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RPM limits?
« Reply #13 on: May 21, 2005, 08:25:57 AM »
Hope to see ya pull 222+mph, make them Nos boys cry. :lol:  :lol:  :lol:


What kind of torque #'s are you pulling and where is peak?
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Offline DaveO

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RPM limits?
« Reply #14 on: May 21, 2005, 10:25:11 AM »
Quote from: DarkFalcon
Quote from: DaveO
The english 8.5's use blackbird brgs....wider surface area....

Someone said 8000 fpm on a stroker....better check your math again...

I know of a certain 5mm than spins regularly over 11k(real) rpms and has survived well....and is overdue for new brgs and springs....


Dave


Dave

Max piston speed is over 8,000 ft/min right around 75 degress ATDC. This is not average speed which, of course, is lower and around 4900 ft/min.



Dark,

Apparently I am wrong...I thought I had calculated them just under 5K fps...Please PM me and enlighten me on the 8K..Thanx


Steve,

My bad..sorry..I learn something everyday.

Dave
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Offline DaveO

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RPM limits?
« Reply #15 on: May 21, 2005, 10:28:50 AM »
TRN,

222 on nutz?!?! Gonna need a good tail wind for that....and diff gearing. It's geared for 221 right now.

Dave
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Offline DarkFalcon

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RPM limits?
« Reply #16 on: May 21, 2005, 10:51:31 AM »
Dave
PM sent. Please confirm as I have had probs lately.
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Offline Jay

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RPM limits?
« Reply #17 on: May 21, 2005, 06:34:25 PM »
Quote from: TRNorBRN6001
I think APE even spins those cranks up to 14,000 RPM. Sure hate to be there if one of them flew off :shock:  :shock:

Where in the land of tea and crumpets do you all get those lovely billet strokers, P3? That exchange rate sure is kind of ugly right now. Might have to get one before APE raises the prices. :lol:  :lol:


We don't spin them that fast. We balance for that RPM. It is a mathamatical calcuation that the computer in the balancer does.

It will tell us that on a particular crank weighing XX lbs, to run it at 14,000RPM, the tolerances in "inch ounces" must be down to a certain level. We will then balance it way better than that.

You probably have seen a balance sheet from one of our cranks. It will say "balanced for 14,000 RPM" then it will say the tolerance for that crank at that RPM will be something like .06 inch ounces. Then it will say down at the bottom that the actual balance for that crank came in at .01 or .02 inch ounces. ( which comes out to less than a quarter of a gram)

The lighter the crank and the higher the RPM use, the lower the tolerance number. Those little15 lb 600 cranks that will turn 16,000 RPM, will have a target number of only .03.

Jay
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Offline TRNorBRN6001

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RPM limits?
« Reply #18 on: May 23, 2005, 08:56:41 AM »
Dave O, I know you still have a couple tricks in the bag, with good weather you will make those Nos babies cry 8) . Maybe you can get one of those new Dynojet extended RPM plug in things for USB and put it on top of your allready extended ECU :)  :D  :D . That would get that 1507 reving up :lol:  :lol: . Good Luck at Maxton.

Jay, thanks for the enlightenment. Would still hate to get clucked in the head by one of those free spinners :lol:  :lol: .
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Offline GSXRTURBO1

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RPM limits?
« Reply #19 on: May 24, 2005, 09:47:27 AM »
I always thought 4500 fps (or is it fpm) was the generally accepted max piston speed...?
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