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| Crankshaft strength.... https://www.ausmini.com/forums/viewtopic.php?f=2&t=191 |
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| Author: | MiniK [ Wed Mar 31, 2004 12:39 pm ] |
| Post subject: | Crankshaft strength.... |
has anyone heard of mini cranks splitting, in particular the 1100 cranks? i want to know the strengths of these things, or would it pay me to shot peen it etc if i planned on turbocharging my engine:) I dont want to spend money on the block to have the crank split and punch a hole in the side of it 
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| Author: | drmini in aust [ Wed Mar 31, 2004 3:07 pm ] |
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I put 8 cracks in a NEW 1100 crank in 20,000 miles..... but I did rev it past 9000 lots of times.... not a good idea. 
And, I snapped the back off an old 1100 one, and the front off an 850 one ... 
I'd find a standard one, or a NEW one if possible, grind the pins if needed, balance it, then get it shot peened, or tuftrided. and DON'T rev it too hard! Really, a 1275 with large journal crank is better- it has bigger bearings. 
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| Author: | MiniK [ Wed Mar 31, 2004 3:45 pm ] |
| Post subject: | |
thats what im worried about, although i dont want mine revving that high anyway. I want to keep boost to low revs if i possibly can to avoid such damage 
Were the blocks you snapped those cranks in all throwaways kev? |
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| Author: | drmini in aust [ Wed Mar 31, 2004 4:54 pm ] |
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Only the 9000 rpm one, which was 1220cc with Imp 68.0mm pistons.. A circlip came out of an Imp piston and the gudgeon pin scored the bore 5/8" wide... ouch! 
Usually on the small bores IF they go, they only crack the crank at one end or the other. Block is usually OK. I drove the 850 5 miles home!... 
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| Author: | min13k [ Wed Mar 31, 2004 6:48 pm ] |
| Post subject: | |
hey kev i can sell ya a 998 with a gundgin polish on the bore
makka |
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| Author: | MiniK [ Thu Apr 01, 2004 9:14 am ] |
| Post subject: | |
drmini in aust wrote: Only the 9000 rpm one, which was 1220cc with Imp 68.0mm pistons..
A circlip came out of an Imp piston and the gudgeon pin scored the bore 5/8" wide... ouch! Usually on the small bores IF they go, they only crack the crank at one end or the other. Block is usually OK. I drove the 850 5 miles home!... ouch alright..lol 
well it looks likr if i go ahead with it, ill get it strengthened, or look out for one in better condition and get that strengthened like you said! |
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| Author: | Tombo [ Thu Apr 16, 2009 12:29 am ] |
| Post subject: | |
My 1100 natural aspiration is good for 7000 and on its 2nd rebuild showed no crank cracks  No shot peening etc.
Still good for 7000. Top khana engine. |
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| Author: | drmini in aust [ Thu Apr 16, 2009 7:49 am ] |
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Tombo wrote: My 1100 natural aspiration is good for 7000 and on its 2nd rebuild showed no crank cracks
No shot peening etc.Still good for 7000. Top khana engine. Geez Tombo, you really dredged this one up from the past.. 
Yep, a well built and balanced 1100 (we can get 1188cc easy now with GR's +.100" pistons) is fine to 7000. With good torque too. 68mm Imp pistons are too hard to find now (and exxy) for GOOD (ie UK) ones. If you are going to rev it, I'd try and get a 1098 crank that is still at standard size or -.010". Crack test then regrind it if needed, making the corner radii as big as possible. Then balance it. |
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