Opinions on new piston rings in old cylinders
03-06-2007, 01:14 PM
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Opinions on new piston rings in old cylinders
I'm refreshing a race engine with some top end work, new rod bearings etc. The cylinders are in great shape with no scratches or marks.
I don't have the time or feel it is necessary to do a full rebuild of the bottom end at this time. Would it be worth it to put new piston rings in without doing any type of honing to the cylinder walls? Would the rings seat OK?
I don't have the time or feel it is necessary to do a full rebuild of the bottom end at this time. Would it be worth it to put new piston rings in without doing any type of honing to the cylinder walls? Would the rings seat OK?
03-06-2007, 09:22 PM
#4
Drifting
With the material these blocks are made out of, you're more likely to end up worse off if you do hone the block than otherwise. You can't just hone these blocks without damaging them, you need to do some funky dozen-step process with numerous hazardous chemicals.
If you need to do anything to the cylinders, you're best bet is really to just cut out the cylinders and have sleeves done (~$3k), or the cheaper option is to find a different block.
That said....just replace the rings as it's you're only choice.
If you need to do anything to the cylinders, you're best bet is really to just cut out the cylinders and have sleeves done (~$3k), or the cheaper option is to find a different block.
That said....just replace the rings as it's you're only choice.
03-07-2007, 12:29 AM
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Thanks guys. My concern is just seating the new rings with an old cylinder but that doesn't seem to be a big deal. I mic'd the cylinders and they are standard size. They are in excellent shape. I am doing the rod bearings as well.
03-07-2007, 12:59 AM
#7
Three Wheelin'
New piston rings installed in alumasil blocks works great! Oil consumption (bad) WILL go down as well as COMPRESSION #'s which is (good) WILL go up! Even if your cylinder walls are scored in spots they still help bring compression up!
So in case you get other input just ignore it as many have no idea what they are speaking about!
I myself still learn something new about the 924/944/968 model line on a daily basis!
So in case you get other input just ignore it as many have no idea what they are speaking about!
I myself still learn something new about the 924/944/968 model line on a daily basis!
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03-07-2007, 10:56 AM
#8
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Originally Posted by special tool
The engine that made 543 at the wheels in my sig. had new rings put in untouched bores. 
Check the ring gap and do the rod bearings, too.
Check the ring gap and do the rod bearings, too.
This, being quantifiable data from a trusted source, is probably the most positive indication I've seen to date that re-ringing good condition bores on these Alusil blocks without honing/lapping is OK.
I struggled with the same questions too, as I plan to re-assemble my motor with new rings in the excellent condition, but un-touched bores.
Two other sources I have confidence in that I contacted were Marc Thomas (Devek) who emphatically said if the bores are good, just put in new rings. The other gentleman is Brent Cross (Whaletail Canada) who I had do the head work etc. He was even more emphatic (and he can do the Sunnen procedure if he needs to, so his motivation to say leave it alone was not because he could not do the work).
Still, Special Tool's data point is the best news.
03-07-2007, 11:14 AM
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Originally Posted by Scootin159
If you need to do anything to the cylinders, you're best bet is really to just cut out the cylinders and have sleeves done (~$3k), or the cheaper option is to find a different block
03-07-2007, 12:10 PM
#10
Drifting
Originally Posted by chris luckett
This is a joke, right?
The only other solution I've heard of is sleeving the block. I have one block in my garage that's damaged (~1 mm deep gouge in one bore), and got a quote from Chris White to have the block sleeved. I don't remember the exact figure, but it seems to me it was in the $3k neighborhood (when you figure in pistons, etc.).
03-07-2007, 12:50 PM
#12
Addic
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Originally Posted by Scootin159
About what part? My understanding (correct me if I'm wrong) is that there's no way to 'repair' the bores on these blocks, at least not through conventional means, and that the non-conventional means are cost-prohibitive.
The only other solution I've heard of is sleeving the block. I have one block in my garage that's damaged (~1 mm deep gouge in one bore), and got a quote from Chris White to have the block sleeved. I don't remember the exact figure, but it seems to me it was in the $3k neighborhood (when you figure in pistons, etc.).
The only other solution I've heard of is sleeving the block. I have one block in my garage that's damaged (~1 mm deep gouge in one bore), and got a quote from Chris White to have the block sleeved. I don't remember the exact figure, but it seems to me it was in the $3k neighborhood (when you figure in pistons, etc.).
block repair
03-07-2007, 01:27 PM
#13
Drifting
Originally Posted by wizkid918
928 motorsport can take care of you
block repair
block repair
03-07-2007, 07:30 PM
#14
Addic
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only if they bore it more than original.
i had talked with them about repairing a deep score for a potential 951, and they will weld the block, bore to original size and re-coat the cylinder that needs it, or you can go oversized
i had talked with them about repairing a deep score for a potential 951, and they will weld the block, bore to original size and re-coat the cylinder that needs it, or you can go oversized
03-07-2007, 07:30 PM
#15
Sunnen has a special process to hone the bores on these (and similar) motors. IF you hone them, have that done.
That said, anytime you re-ring a motor you run the risk of the rings not seating. If the rings are not worn and measure in spec, I would reuse them. If the cylinders have any glaze, you need to remove the glaze or the new rings probably will not seat.
Can new rings be used in untouched bores? Sure, there is evidence of that in this thread. Is there a risk that the rings will not seat and you will be doing it all again? Yes.
That is the choice facing anyone who is building/repairing a motor and not replacing all of the parts (that would be most of us who rebuild motors). There is always a chance that the new parts and old parts might not like each other so to speak.
Cheers
That said, anytime you re-ring a motor you run the risk of the rings not seating. If the rings are not worn and measure in spec, I would reuse them. If the cylinders have any glaze, you need to remove the glaze or the new rings probably will not seat.
Can new rings be used in untouched bores? Sure, there is evidence of that in this thread. Is there a risk that the rings will not seat and you will be doing it all again? Yes.
That is the choice facing anyone who is building/repairing a motor and not replacing all of the parts (that would be most of us who rebuild motors). There is always a chance that the new parts and old parts might not like each other so to speak.
Cheers