Cylinder out-of-round...
09-13-2019, 11:18 AM
#1
Rainman
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Thread Starter
Cylinder out-of-round...
Looking for thoughts and experiences here.
We know alusil can't be bored/honed/paste-lapped properly by just anyone - takes certain equipment and technique to do it right. Rare to find a shop that can do it without shipping the block out.
And if you do have a shop, oversize pistons (Wossner) are $650.00 minimum a set.
I have a 1987 944S block with something around 120,000 miles that ran great before being pulled. Pistons, rods, crank are all very good shape and in spec.
However the smooth, clean bores (group 1) measure out of round by ~0.038mm, almost twice the "wear spec" from the WSM.
Really didn't want to spend all that much money over a standard rebuild on this but now I have a dilemma.
Purely a street engine, will be driven a few times a month as a toy. Plan was eventually to try some boost on this build (944S rods are being swapped for worked 951 rods).
1) Just put new rings in and hope for the best. Might use some more oil than normal or be a little low on compression but it should still run OK.
2) Find someone semi-local who can prep the alusil bores for the next oversize and get pistons (~$1000 or more all-in)
3) Sleeve the block back to standard, and find rings that will work. My local machine shop quoted almost $1000 parts+labor to do the sleeving.
Has anybody run into this situation, and just ring'd it and hit the road? Or will that lead to grief and certain death?
We know alusil can't be bored/honed/paste-lapped properly by just anyone - takes certain equipment and technique to do it right. Rare to find a shop that can do it without shipping the block out.
And if you do have a shop, oversize pistons (Wossner) are $650.00 minimum a set.
I have a 1987 944S block with something around 120,000 miles that ran great before being pulled. Pistons, rods, crank are all very good shape and in spec.
However the smooth, clean bores (group 1) measure out of round by ~0.038mm, almost twice the "wear spec" from the WSM.
Really didn't want to spend all that much money over a standard rebuild on this but now I have a dilemma.
Purely a street engine, will be driven a few times a month as a toy. Plan was eventually to try some boost on this build (944S rods are being swapped for worked 951 rods).
1) Just put new rings in and hope for the best. Might use some more oil than normal or be a little low on compression but it should still run OK.
2) Find someone semi-local who can prep the alusil bores for the next oversize and get pistons (~$1000 or more all-in)
3) Sleeve the block back to standard, and find rings that will work. My local machine shop quoted almost $1000 parts+labor to do the sleeving.
Has anybody run into this situation, and just ring'd it and hit the road? Or will that lead to grief and certain death?
09-13-2019, 12:22 PM
#3
Burning Brakes
Join Date: Sep 2017
Location: Formerly the DPRK, now seeking political asylum in Oregon
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Ditto!
That's ~.0015", I measured a brand new LS7 block (torque plate honed from the factory), found the cylinders oval by .0005"
If it wasn't an all-out motor, I might be tempted to run it...
I'll bet most back yard rebuilds have cylinders wayyyyyy worse than that, and no one can ever tell.
That's ~.0015", I measured a brand new LS7 block (torque plate honed from the factory), found the cylinders oval by .0005"
If it wasn't an all-out motor, I might be tempted to run it...
I'll bet most back yard rebuilds have cylinders wayyyyyy worse than that, and no one can ever tell.
09-13-2019, 12:23 PM
#4
Rennlist Member
09-13-2019, 12:29 PM
#5
Rennlist Member
Looking for thoughts and experiences here.
We know alusil can't be bored/honed/paste-lapped properly by just anyone - takes certain equipment and technique to do it right. Rare to find a shop that can do it without shipping the block out.
And if you do have a shop, oversize pistons (Wossner) are $650.00 minimum a set.
I have a 1987 944S block with something around 120,000 miles that ran great before being pulled. Pistons, rods, crank are all very good shape and in spec.
However the smooth, clean bores (group 1) measure out of round by ~0.038mm, almost twice the "wear spec" from the WSM.
Really didn't want to spend all that much money over a standard rebuild on this but now I have a dilemma.
Purely a street engine, will be driven a few times a month as a toy. Plan was eventually to try some boost on this build (944S rods are being swapped for worked 951 rods).
1) Just put new rings in and hope for the best. Might use some more oil than normal or be a little low on compression but it should still run OK.
2) Find someone semi-local who can prep the alusil bores for the next oversize and get pistons (~$1000 or more all-in)
3) Sleeve the block back to standard, and find rings that will work. My local machine shop quoted almost $1000 parts+labor to do the sleeving.
Has anybody run into this situation, and just ring'd it and hit the road? Or will that lead to grief and certain death?
We know alusil can't be bored/honed/paste-lapped properly by just anyone - takes certain equipment and technique to do it right. Rare to find a shop that can do it without shipping the block out.
And if you do have a shop, oversize pistons (Wossner) are $650.00 minimum a set.
I have a 1987 944S block with something around 120,000 miles that ran great before being pulled. Pistons, rods, crank are all very good shape and in spec.
However the smooth, clean bores (group 1) measure out of round by ~0.038mm, almost twice the "wear spec" from the WSM.
Really didn't want to spend all that much money over a standard rebuild on this but now I have a dilemma.
Purely a street engine, will be driven a few times a month as a toy. Plan was eventually to try some boost on this build (944S rods are being swapped for worked 951 rods).
1) Just put new rings in and hope for the best. Might use some more oil than normal or be a little low on compression but it should still run OK.
2) Find someone semi-local who can prep the alusil bores for the next oversize and get pistons (~$1000 or more all-in)
3) Sleeve the block back to standard, and find rings that will work. My local machine shop quoted almost $1000 parts+labor to do the sleeving.
Has anybody run into this situation, and just ring'd it and hit the road? Or will that lead to grief and certain death?
09-13-2019, 12:43 PM
#6
Rainman
Rennlist Member
Rennlist Member
Thread Starter
I had the girdle on and "snug" but not torqued to spec, the block castings were just screwed together to get it all cleaned at once.
But there's a definite ridge at the top worn into the alusil from the rings cutting below that.
Funny thing is the curse of alusil for all its wonder...0.0015" or so is still within tolerance if this were a typical iron block.
Last edited by V2Rocket; 09-13-2019 at 01:03 PM.
09-13-2019, 01:57 PM
#7
Three Wheelin'
NO
Coming from a background in building 350 chevy engines we ALWAYS used a torque plate when we honed an engine. When I built my 44 engine I talked with several engine builders and they said, not needed. I called BS My engine was apart so I decided to see for myself... I carefully measured the bores and made notes. Then I installed the head with a head gasket and measured the bores in the same relative spots. (measured from underneath with no rotating assembly in) The results proved that torqueing the head on had no effect on the roundness of the bores.. any deviation in the numbers was so miniscule that making / purchasing a torque plate would have been a total wasted of money.
As for the issue in this thread.. Well, what risk are you taking? If it doesn't work and the engine smokes Then you are out all the labor and gaskets... Sure its a gamble and nobody can say for sure if it will work or not.. Only you can answer the question if it is worth it or not.. I just did a block (alu-sil) and the tooling from sunned cost about 600 bucks and I did it myself using a friend of mines sunnen CK-10 honing machine.. I have enough material to do like 20 blocks... So, I have three other engines I will build and the stuff has paid for itself..
Coming from a background in building 350 chevy engines we ALWAYS used a torque plate when we honed an engine. When I built my 44 engine I talked with several engine builders and they said, not needed. I called BS My engine was apart so I decided to see for myself... I carefully measured the bores and made notes. Then I installed the head with a head gasket and measured the bores in the same relative spots. (measured from underneath with no rotating assembly in) The results proved that torqueing the head on had no effect on the roundness of the bores.. any deviation in the numbers was so miniscule that making / purchasing a torque plate would have been a total wasted of money.
As for the issue in this thread.. Well, what risk are you taking? If it doesn't work and the engine smokes Then you are out all the labor and gaskets... Sure its a gamble and nobody can say for sure if it will work or not.. Only you can answer the question if it is worth it or not.. I just did a block (alu-sil) and the tooling from sunned cost about 600 bucks and I did it myself using a friend of mines sunnen CK-10 honing machine.. I have enough material to do like 20 blocks... So, I have three other engines I will build and the stuff has paid for itself..
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09-14-2019, 10:23 AM
#8
Race Car
Option 4) you shoulda took the low CR 16V Wossner set and fresh block bored/honed/decked/ported precisely for these pistons.
I even knew someone who woulda carried them up to you, freight free, in the trunk of his personal car.
Needless to say, I done been and gone.....
T
I even knew someone who woulda carried them up to you, freight free, in the trunk of his personal car.
Needless to say, I done been and gone.....
T
09-14-2019, 10:56 AM
#9
Rainman
Rennlist Member
Rennlist Member
Thread Starter
Option 4) you shoulda took the low CR 16V Wossner set and fresh block bored/honed/decked/ported precisely for these pistons.
I even knew someone who woulda carried them up to you, freight free, in the trunk of his personal car.
Needless to say, I done been and gone.....
T
I even knew someone who woulda carried them up to you, freight free, in the trunk of his personal car.
Needless to say, I done been and gone.....
T
I guess i was waiting for you to say you made it to town
i was on church/5th st 3 days last week, lol.Maybe I'll have to roadtrip your way, or make the UPS guy earn his wage hustling the 60lb block around.
09-14-2019, 06:03 PM
#10
Race Car
I was all over up and down 3rd, 4th and 5th, all the way from Union down to Korean's.
My hotel was basically on 4th and Church, 1 hotel down off the corner.
It's a bout a 5 hr drive to Hot Springs, I could be easily coaxed to bring the stuff at least that far, since I'm 99% sure headed back out in a couple weeks (Columbus day weekend).
You should come hang out, your wife would love the spas.
http://quapawbaths.com/
Cool town, a lot to do, bars everywhere, good good food.
I walked a 3/4 acre lot just south of town, already flat enough to build on.
On a ridge on a peninsula jutting out into Lake Hamilton.
Not lakefront, but lake view.
$10,400.
A lot that size where I live is $40k.
T