Stroker cranks pros and cons - Honda TRX Forums: Honda TRX 450R Forum

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Old 07-03-2007, 10:02 PM   #1 (permalink)
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Well this is a spin off thread for since I now have to replace a Brand new but F'd crank due to a brand new but F'd crank bearing that ruined the crank and a brand new but now F'd right crank case.

Oh well shat happens and Kam is more than just a great sponsor. Without a shadow of a doubt he is totally stand up. I wont go into details but I can say that he is making things right IMO and neither he nor I are getting the short end of the stick, and THAT is the most important thing here.

So..now onto the thread topic.

My delima and one I would like EDUCATED input on.
Do I use another OEM Honda crank with an OEM length Hot Rod rod (longrod) stroked by Crankworks that is lightened,welded, and balanced.

OR
Do I use a "short rod" 3 mil stroker from Hotrods.

I doubt the Hotrods get all the "trick" work in them that Kam has done to his re-worked stockers.

Please discuss and give me the benefits and down falls of each.

And yes the reworked stocker is more expensive..by a few hundred dollars.
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Old 07-04-2007, 06:32 AM   #2 (permalink)
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Im not an engineer but this is my take on the subject....

Anytime you can get a quality company like Hotrods that you can buy their crank right off the shelf, use it with any darn piston you want and not have to wait for ANYONE, thats a serious plus.

The difference in the rod length is probably neglagable in the real world. Sure, the longer rod is nice however i think if all your parts are of good quality (like no bad factory main bearings) and it is properly assembled with all the specs being in check, i think your good to go.

The only thing is you will not have a truely balanced piston to crank like Brindley said is important in his post. In my mind though, i just dont understand how people can account for the counter balancer in this equation and what that does to the balancing effect of the engine. I think it quite possibly could be a waste of money and time but im not going to gaurantee that. Lots of good minds on here....it will be interesting to see some points of view.
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Old 07-04-2007, 05:57 PM   #3 (permalink)
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In another post a while back, I was talking about the differences in side loading that seemed to always pop up when discussing a short rod stroker. I know Mix was against it in the past, and I had an open mind since that's what I do best - analyze shtuff. I ran the numbers and it turns out there isn't that much difference at all in the side loading between these two setups, so that part of the equation goes away. Now, there is the issue of piston availability and I think the HotRods stroker has an advantage in options - although you still have to check to clearances when dropping the piston into the cylinder, so there may be piston mods needed. I am quite sure as this crank gets installed in more builds, there will be more info and pistons that do not need mods. Cost - well, there's obviously an advantage to HotRods here. Balancing - who says you can't have the HotRods crank balanced if you want? Is it worth it? I can't say. You would think that a well balanced motor would obviously not vibrate any more than stock - possibly less - but my 477 wasn't balanced and I didn't have any vibe problems. I don't expect any from my 511 either. Bearings - I don't know what lower rod bearing they use for the HotRods crank - but I haven't heard of any issues with any of them, so I can only assume they are fine. I understand the stock rod stroker uses a stock rod bearing. I have seen more issues with the stock rods breaking, but not so much about the rod bearings actually failing.

There can also be some differences in the actual rotating mass of these new cranks. Maybe they rev slower, maybe not.

The way I look at it, there isn't a "wrong" way to build the bottom end. I am obviously banking on the HotRods crank wirking out for me. The last thing I need is to have a problem build.
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Old 07-05-2007, 09:55 AM   #4 (permalink)
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longer rods will definately transmit less pressure to side loading froces on the cylinder walls.....

and in general...due to dwell time differences...longer rods will make a bit more torque too.....

so...everything be equal and available... i would always check the " long rod " option box on my check list...


BUT...

the availability of the Hot Rods cranks.... combined with the great pricing... is a big plus for the short rod strokers they now offer
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Old 07-05-2007, 10:31 AM   #5 (permalink)
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I not sure but I think the difference between the cranks you are interested in is very minor amount. the hotrod crank caculates out at 1.62 and the stock crank with custom piston is 1.64 stroke to rod ratio.
There really isnt enough there to worry about. You would have to base your decision on price and durability. Hotrod has proved itself with other cranks they make and its cheaper route. I personally like the idea of balanced and welded crank. I think the balancing helps keep down vibration and reduce some harmonics, which is present in all engine even if you dont feel it.
As John mentioned there are other factors like piston dwell, sidel oading, ect ect. Longer rod will have more piston dwell at TDC which can increase peak torque but also is more prone to detonation.
The shorter rod had more dwell at BDC, more side loading ect ect. Usually you will have more mid range torque and less chance of detonation.

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Old 07-05-2007, 11:05 AM   #6 (permalink)
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All I do is stroker big cc TRXs so I would say if $ is tight use a HOT RODS! If $ is not a problem you are better of sending a piston to crank works and have them build you something thats balanced for your piston! I have had great luck and sucess with Kevin and those guys great group of people at crank works!
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Old 07-05-2007, 11:08 AM   #7 (permalink)
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Quote:
......
The shorter rod had more dwell at BDC, more side loading ect ect. Usually you will have more mid range torque and less chance of detonation.[/b]

TDC and BDC dwell have to be the same for a given rod length. The short rod will accelerate to TDC and BDC faster as well as accelerate away from TDC and BDC faster than a longer rod.

I still think we're splitting hairs here.


Now - what about the change in piston rock force when you move the piston pin up when using the longer rod? With the long rod, you take a stock pin location and move it toward the piston crown, therefore increasing the leverage the rod has to force the top of the piston into the cylinder wall. With these slipper pistons, I would expect piston life to actually decrease with modified pin locations.


Anyone? Anyone?
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Old 07-05-2007, 01:39 PM   #8 (permalink)
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I think the real Q is why we didn't saw a REAL FAST with big hp/tq gain Nmotion or MP HUGE CC short rod stroker engines.

The only proven engine i saw is KBR/Venom 501..Still much smaller cc with 3mill stroker only

I mean why do u think Hotrod 3mill short rod will outform Falicon 6mill or 7mill short rod?

Hey J&J .. do u use short , stock length or longer rod?

Personnally we saw a muchmore power/tq with longer rod stroker YFZ engines.

I'm waiting for KBR/Venom 533cc new engine setup
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Old 07-05-2007, 01:47 PM   #9 (permalink)
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FWIW the Hot rod crank is quite a bit heavier than a stocker even with a hot rod on it.
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Old 07-05-2007, 02:42 PM   #10 (permalink)
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Quote:
FWIW the Hot rod crank is quite a bit heavier than a stocker even with a hot rod on it.[/b]
I actually am happy to hear that. Mine revved too quick as a 477. I was hoping to slow the revs down with the stroker. I will have to weigh mine versus the stock crank when I get it....
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06 TRX511ER - SOLD
Venom Porting and Head Mods with +1 KW Valves all around
Venom 100mm 14.25:1 Piston
Venom Modded ESR Intake
Venom Modded 43mm FCR with Rat Stack
Venom Exhaust
Hot Rods +3 Stroker
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Old 07-05-2007, 03:31 PM   #11 (permalink)
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Quote:
Quote:
......
The shorter rod had more dwell at BDC, more side loading ect ect. Usually you will have more mid range torque and less chance of detonation.[/b]

TDC and BDC dwell have to be the same for a given rod length. The short rod will accelerate to TDC and BDC faster as well as accelerate away from TDC and BDC faster than a longer rod.

I still think we're splitting hairs here.


Now - what about the change in piston rock force when you move the piston pin up when using the longer rod? With the long rod, you take a stock pin location and move it toward the piston crown, therefore increasing the leverage the rod has to force the top of the piston into the cylinder wall. With these slipper pistons, I would expect piston life to actually decrease with modified pin locations.


Anyone? Anyone?
[/b]
I agree with a short rod you will achieve a right angle sooner and the piston will be higher in the bore when its at 90 degrees. Thats why you will have higher cylinder pressure with a short rod at 90 degree rod angle.....which can help midrange torque.


Piston will have less piston rock/less stress with pin at higher location.
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Old 07-05-2007, 03:49 PM   #12 (permalink)
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It seems to me that most of the reported crank failures involve the right center case bearing. Maybe on some it's the main bearing that goes first causing the case bearings to go as well, not sure...

With that in mind, would'nt a balanced crank with less vibration and harmonics help preserve bearing life? I would also think that the heavier the crank the more important the balancing becomes.

Are the new 3mil hotrod cranks balanced? Or is that something only acheived by customization?

I do not have the engine knoweledge that you guys do so please excuse my ignorence. But I am also installing one of these new hotrod +3's and am very interested in learning as much as I can about this topic.

Thanks for the great info! Learning alot from you guys...
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Old 07-05-2007, 03:58 PM   #13 (permalink)
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According to my scales there is a 1 oz difference in the OEM crank and a Hot Rod crank.
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Old 07-05-2007, 04:00 PM   #14 (permalink)
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My lady prefers my Long rod over the short rod!
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Old 07-05-2007, 04:39 PM   #15 (permalink)
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well i've heard of guys adding weight to the cranks to improve hole shots! so this may be a good thing.
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