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| Full circle v/s counterweighted cranks http://woodsbuggy.com/phpBB3/viewtopic.php?f=3&t=8374 |
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| Author: | Buckmaster [ Sun Jan 03, 2010 9:22 pm ] |
| Post subject: | Full circle v/s counterweighted cranks |
Which one is prefered and what are the advantages and disadvantages of each one? |
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| Author: | Buckmaster [ Tue Jan 05, 2010 7:54 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Damn did i put up a boring subject or what.What happen to all the expert engine builders on here,there is usually more than one.I need to know if a full circle crank is better crank to run in a woodsbuggy compared to a counterweighted crank? |
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| Author: | Firebug [ Tue Jan 05, 2010 8:00 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Subaru eg33 has 7 mains,,,,oops,,,, |
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| Author: | dunebuggynut [ Tue Jan 05, 2010 8:17 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
I know what the difference is between em but Ive never run a full circle, only counterweight. I would think a full circle would be best in a stock case as it would cause less stepping of the mains. An aftermarket block would not care due to the increased strength. Again this is an opinion rather than experience. |
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| Author: | hyde [ Tue Jan 05, 2010 9:24 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Buckmaster wrote: Damn did i put up a boring subject or what.What happen to all the expert engine builders on here,there is usually more than one.I need to know if a full circle crank is better crank to run in a woodsbuggy compared to a counterweighted crank? What i have read counterweighted is best but on welded crank full circle ads strength on big strokers like 88 & 90 mm |
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| Author: | Buckmaster [ Tue Jan 05, 2010 9:48 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Well i can get my hands on a nice welded 84mm full circle crank for the same price as a counterweighted.I can see what you mean by the rotating mass on the mains,but would'nt it be more of an equal weight distribution with the full circle or just simply more weight being slung around? |
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| Author: | ironhorse [ Tue Jan 05, 2010 10:23 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
i have built many engins with both ,both are good but the full circle provides better balance to allow your more to return to idle from a qiuck burst of gas. and the torque from the heavier full circle gives you a little bit more for long hills just my $.02 worth |
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| Author: | hillaholic [ Wed Jan 06, 2010 2:55 am ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
here is a post about them http://www.thesamba.com/vw/forum/viewto ... rcle+crank |
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| Author: | Buckmaster [ Wed Jan 06, 2010 7:09 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
hillaholic wrote: Looks like the full circle is an old school type crank and counterweighted is the way to go.Thanks for the info Hillaholic. |
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| Author: | turboblue [ Fri Jan 08, 2010 12:56 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Cranks need to be full circle when the stroke gets around 88 or 90mm. The journal overlaps start getting pretty wide and a crank that big will start flexing w/o being full circle. Not necessary on any stroke under 88 IMHO. Waste of money and the crank will unnecessarily heavy. If the balance is an issue on either, the crank wasn't right to begin with. Full circle and welded counterweighted cranks should both be balanced from the vendor. Having them checked is a good idea though....... 
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| Author: | ironhorse [ Fri Jan 08, 2010 3:09 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
turboblue wrote: Cranks need to be full circle when the stroke gets around 88 or 90mm. The journal overlaps start getting pretty wide and a crank that big will start flexing w/o being full circle. Not necessary on any stroke under 88 IMHO. Waste of money and the crank will unnecessarily heavy. If the balance is an issue on either, the crank wasn't right to begin with. Full circle and welded counterweighted cranks should both be balanced from the vendor. Having them checked is a good idea though....... the balance of both cranks is not a questionn its just that the full circle is better for higher rpms |
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| Author: | turboblue [ Sat Jan 09, 2010 4:11 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
ironhorse wrote: turboblue wrote: Cranks need to be full circle when the stroke gets around 88 or 90mm. The journal overlaps start getting pretty wide and a crank that big will start flexing w/o being full circle. Not necessary on any stroke under 88 IMHO. Waste of money and the crank will unnecessarily heavy. If the balance is an issue on either, the crank wasn't right to begin with. Full circle and welded counterweighted cranks should both be balanced from the vendor. Having them checked is a good idea though....... the balance of both cranks is not a questionn its just that the full circle is better for higher rpms We regularly spin welded counterweighted cranks to 8500 + with no issues. I still say adding all that weight to a 86 or less stroke crank is not necessary. If we needed that added weight why do most all people run lightened flywheels? |
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| Author: | Buckmaster [ Sat Jan 09, 2010 5:04 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Not to switch subjects to much but what do you guys think about a crank that has been turned 30 thousands on both the main and rod journals?Is this to much and will it last as long as a new crank if built properly?Also what is the limit on turning cranks? |
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| Author: | ironhorse [ Sun Jan 10, 2010 12:05 am ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
if turned properly it will be fine for the woods in my opion i dont like to use turned cranks unless i know who turned them and i would say .60 is all i would turn a crank because 1 thats as big as bearings you can get and 2 you are getting down into the mains on the crank to far some say the metals are weaker i dont know about all that so thats my too cents anyone eles |
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| Author: | turboblue [ Mon Jan 11, 2010 11:47 am ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
ironhorse wrote: if turned properly it will be fine for the woods in my opion i dont like to use turned cranks unless i know who turned them and i would say .60 is all i would turn a crank because 1 thats as big as bearings you can get and 2 you are getting down into the mains on the crank to far some say the metals are weaker i dont know about all that so thats my too cents anyone eles What is this .60 dimension/ If it is a metric measurement, that is .0236" in inches and no such bearing exists. If you meant .060" inches undersized, I've never seen one of those bearings either. I keep them to .040" inches undersized for the mains and rods but very few.,...... Buck I've used a few .030" under cranks without issue. Just have to remember down the road if you ever have to rebuild it, you are pretty much done on reusing that crank if it needs turned. What stroke are you looking for? |
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| Author: | Buckmaster [ Mon Jan 11, 2010 7:56 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Ive got a 90mm full circle lightweight that is 30 and 30,plus i have a 84mm that is 20 on the mains and standard on the rods.The thing is,ive seen some smaller motors run better than bigger motors,of course when built right and with a good set of heads.So i im not sure if i should go ahead and go big and hope that it last for a long time or just build a 2332 with everything ive got.Cant i have the 90mm welded backup and turned back to standard or is that just a myth? |
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| Author: | ridenrace6 [ Tue Jan 12, 2010 1:37 am ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
does a full circle require any more clearancing than a counterweighted or vice versa or does the "type" of crank have any bearing on clearance issues? |
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| Author: | turboblue [ Tue Jan 12, 2010 12:28 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
Buckmaster wrote: Ive got a 90mm full circle lightweight that is 30 and 30,plus i have a 84mm that is 20 on the mains and standard on the rods.The thing is,ive seen some smaller motors run better than bigger motors,of course when built right and with a good set of heads.So i im not sure if i should go ahead and go big and hope that it last for a long time or just build a 2332 with everything ive got.Cant i have the 90mm welded backup and turned back to standard or is that just a myth? Never had the mains welded up. Not sure I'd want to. Rod journals are done all the time, that's how they are built up to machine for the stroke. .030 on the rods tell me that 90mm stroke crank has been around for a while. They come from the vendor standard on the rods. For just a 7% increase in size, I'd probably put together the 84. |
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| Author: | perrib [ Wed Feb 17, 2010 10:28 pm ] |
| Post subject: | Re: Full circle v/s counterweighted cranks |
I have a DeMello full circle race weight crank in my 2180 after 19 years of hard use the case line bore is still ok. Bob at Demello Cranks claims when he was developing the full circle crank, Loyyd Mosher (Little Giant Killer) found the heavier crank made more HP. As far as the .030 over rod journals you can always change to Buick journal rods and turn the rods journal smalller. Welding up the mains is going to cost close to a new welded crank. You could weld them up to go to all type 2 mains. DPR cranks also have a good reputaion. Both will grind a crank to your specs if you want to run more than stock clearance. |
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