OMG! DIY Cylinder Honing
12-10-2010, 03:19 PM
#17
Rennlist Member
Interesting discussion! Good thing I never used the Harbor Freight Cylinder Hone.
I found the whole pdf for Reconditioning of Aluminum Engine Blocks
So it looks like we need the KS Exposing Stones and KS Silicon Exposing Paste. I wonder if we can get this stuff and glue the stones onto a cheap cylinder hone? This would be great for a refresh when we rebuilding an engine.
I found the whole pdf for Reconditioning of Aluminum Engine Blocks
So it looks like we need the KS Exposing Stones and KS Silicon Exposing Paste. I wonder if we can get this stuff and glue the stones onto a cheap cylinder hone? This would be great for a refresh when we rebuilding an engine.
Last edited by kobayashi; 12-10-2010 at 07:07 PM.
12-10-2010, 07:10 PM
#19
Rennlist Member
Put in an inquiry with Motor Services International for purchasing the Exposing Stones and paste. We'll see if they get back to me and ultimately how much the stones are. Will post when I find out more.
12-10-2010, 07:55 PM
#20
Rennlist Member
12-10-2010, 08:04 PM
#21
12-10-2010, 08:05 PM
#22
Drifting
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Also, what is everyone going to do about the increased piston/cylinder wall clearance?
12-10-2010, 08:52 PM
#23
I'm not sure on the next part but,
I am not sure that honing the block is necessary when doing what you are doing OP. If there is significant damage then some might decide to bore the cylinder walls and get oversized pistons and only then should you have to hone. I don't think honing the cylinder walls of our engine or any engine is something you do unless you are boring the cylinder walls out because you will increase the piston/cylinder wall clearance by honing.
12-10-2010, 09:08 PM
#24
If it still meets the factory tolerances then I would think you're good to go. I'm not sure how much of an increase to expect but it certainly would need to be carefully assessed.
12-10-2010, 09:30 PM
#25
Hey Man
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It's been awhile but there used to be a lister here from Colorado that would loan out his Sunnen hones for free and only ask that the stones and pastes were replaced if they got overused. I almost took him up on it but the kit was in use someplace else.
12-11-2010, 12:07 AM
#26
RL Community Team
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Sounds like a really cool guy!
It was my understanding that usually honing does not increase the bore enough to warrant new pistons, but of course it always needs to be measured and confirmed.
It was my understanding that usually honing does not increase the bore enough to warrant new pistons, but of course it always needs to be measured and confirmed.
12-11-2010, 09:19 AM
#27
Burning Brakes
I have had this process done twice on blocks and it cost me around $500.
It is critical to measure the pistons and cylinders for proper gap. Proper gap does not necessarily mean the factory tolerances, and can be fine tuned by a good engine bulder for the best performance. If the gap is too big often the pistons get coated or aftermarket pistons are ordered. I have watched the process and I would not want to try it myself. Keeping the hone straight and true is not easy without the right equipment.
It is critical to measure the pistons and cylinders for proper gap. Proper gap does not necessarily mean the factory tolerances, and can be fine tuned by a good engine bulder for the best performance. If the gap is too big often the pistons get coated or aftermarket pistons are ordered. I have watched the process and I would not want to try it myself. Keeping the hone straight and true is not easy without the right equipment.
12-11-2010, 10:38 AM
#28
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yes a dial bore gauge is critical to measure taper
And I'm saying it right now, the factory piston to wall clearance for the cast pistons is less than .001"....you'll probably double it by honing and using the old piston again
And I'm saying it right now, the factory piston to wall clearance for the cast pistons is less than .001"....you'll probably double it by honing and using the old piston again
12-11-2010, 02:00 PM
#29
Race Car
That is a valid concern 944CS. However, the above posted info from Kobayashi say that, done properly, the cylinder walls should not increase more than a micron. I haven't done the math, but would this push it out of spec?
12-11-2010, 06:23 PM
#30
Rennlist Member
I think it's important to keep clear the distinction between honing and lapping w.r.t. Alusil cylinders. As I understand it, the honing process is intended to set the dimensions of the bore and remove any geometric anomalies (taper, ovality, etc.). It also prepares the faces of the silicon crystals, which become the surface on which the rings ride. The lapping process, which occurs after final honing, removes a small amount of aluminum from around the silicon crystals, leaving them sitting proud of the surface and making valleys between them in which oil can accumulate. It's the lapping process that uses felt pads and the Sunnen AN-30 abrasive paste.
The KS document I linked above suggests that up to 0.1mm is removed during the honing process. Because of the large amount of material being removed a torque plate is recommended. Lapping, on the other hand, removes a minuscule 1um, and thus there's no recommendation for a torque plate. Note however that this means lapping cannot be used to correct major cylinder wall problems (scratches, taper, ring ridge etc.). If you have any of those problems you will need to hone the cylinders to correct them.
In all the threads I've read, I have never encountered a DIYer that honed their own cylinders--all the threads are about lapping, including HondaDustR's and the mammoth 911 Re-ring Alusils? thread. In all cases the DIYers started out with dimensionally correct cylinders (or at least they assumed they were dimensionally correct) and performed the lapping in order to prepare the cylinder walls for new rings.
[ BEWARE: I'm an not a machinist, and the above information is based solely on the reading I have done on the topic (which anyone else can to do too). Experts in the field are welcome (even encouraged) to slap me down! ]
The KS document I linked above suggests that up to 0.1mm is removed during the honing process. Because of the large amount of material being removed a torque plate is recommended. Lapping, on the other hand, removes a minuscule 1um, and thus there's no recommendation for a torque plate. Note however that this means lapping cannot be used to correct major cylinder wall problems (scratches, taper, ring ridge etc.). If you have any of those problems you will need to hone the cylinders to correct them.
In all the threads I've read, I have never encountered a DIYer that honed their own cylinders--all the threads are about lapping, including HondaDustR's and the mammoth 911 Re-ring Alusils? thread. In all cases the DIYers started out with dimensionally correct cylinders (or at least they assumed they were dimensionally correct) and performed the lapping in order to prepare the cylinder walls for new rings.
[ BEWARE: I'm an not a machinist, and the above information is based solely on the reading I have done on the topic (which anyone else can to do too). Experts in the field are welcome (even encouraged) to slap me down! ]