Bore size

D

Dirtkart90

Member
Hi, I was wondering if anyone can help me, I’m trying to get raptor block bored I wanna go as big as possible was wondering do I need to get a certain steel sleeve then have them bore as big as possible?it has stock steel sleeve right now. Thanks
 
Dirtkart90 said:
Hi, I was wondering if anyone can help me, I’m trying to get raptor block bored I wanna go as big as possible was wondering do I need to get a certain steel sleeve then have them bore as big as possible?it has stock steel sleeve right now. Thanks
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Worry less about bore size and look into availability for the size of piston. That would be the deciding factor. You will most likely need to get an oversized sleeve.
 
Sleeves are available in a number of oversizes. To go to the largest overbore, you would need to move the #7 head bolt out (similar to a Honda flathead.) Without welding and a lot of effort, you can machine an aluminum bore as close as you dare to that bolt thread, then have the aluminum cylinder Nicasil coated.
Stock sleeve can be safely bored to +.080." Any bigger than that and the ribs start pulling (these IC blocks are cast around the sleeve - which has ribs on the OD to hold it in place.) You can sleeve both aluminum and steel sleeve engines to a larger bore size. 2.750" OD is the standard "big bore" sleeve, but you can fit a 2.813" sleeve if you are real good. That will get you to just under +.200" and leave barely enough material that it'll run.

The bigger problem, as mentioned above, is piston availability.
Now, you can get custom pistons made at a cost, but be ready to order 10 of the same size at one time...simply not enough demand any more to do that.


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Carlson Racing Engines
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