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Torque to turn over new build
#1

I've got the crank, rear main seal, and rods and pistons/rings installed in the block. I'm using a 2.5L crank. I'm measuring about 2 ftlb minimum and about 10 ftlb maximum. Does that seem like what I should expect?
This is with a new Folvo piston and ring package from Stinger.
Thanks
1967 MGB roadster 2.3 turbo T5 7.5 PIMP FMIC 22psi
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#2

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Is that breakaway torque or sustained/rotating torque that you're reading, Dennis? You'd need an old-school "beam"-style wrench to read either one and - while the breakaway torque will obviously be greater - I haven't got a clue what they should be, lol.

If the (oiled) crank spun easily after the main caps were torqued and all other components were then installed with the proper clearances (piston-to-wall, ring end gaps, rod bearings & side clearance, pins, AND none of the oil-ring expander ends were overlapped ~ then........it is what it is!  <shrug>  Wink
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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#3

I'm using a beam wrench, and the readings are sustained. They vary from the lowest at TDC and BDC and higher midway between. Most of the friction is the ring package. Just trying to get a sense of whether I need to check the assemblies. An odd result is that the peak readings are not the same 180 degrees apart.
Tearing this thing down after full assembly will be enough of a pain that I'm trying to doublecheck.
1967 MGB roadster 2.3 turbo T5 7.5 PIMP FMIC 22psi
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#4

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It IS odd that the peak readings aren't the same 180° apart, Dennis......almost as tho some cyls have more friction when the pistons are ascending, than when they're descending! Were the cyls machine-honed with the obligatory cross-hatch?

A friend of mine used to compete in NHRA Stock Class with a 2.3 N/A Pinto station wagon, and he always used the lowest-tension ring set he could find. Then ~ when assembling 'em ~ he would use a fish scale to draw the pistons horizontally thru their bores and then progressively crush the oil-ring expander until he reached some ridiculously-low value on the weight scale, lol.  <shrug>

When building a turbo engine, however, low ring tension - especially on the oil rings - is NOT what you want. Instead, you're far better off with standard-tension rings that fit snugly/properly and seal well. Any improvement that you think might be had by sacrificing sealing &/or heat transfer in order to gain a few horsepower from reduced friction is pure folly AND counterproductive.
Placerville, California
(former)  '78 2.3T Courier w/blow-thru Autolite 2bbl carb ~ (current)  '87 2.3T Ranger w/PiMP’d EFI
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