Got my block bored .020 over and the guy says it was perfect, exactly what the Wiseco sheet says to size the bores too (3.661), I take it home which is 1hr away but later that night when its like over 15+ degrees cooler and the bores are about 1 thousandths too small to be at the size wiseco wants. I've bugged him enough since I'm A.D.D. with other people working on my stuff since I thought it was his fault but could it be smaller since I checked it when it was cooler out? For the hell of it I warmed up the cylinder with a cheapy heat gun (nowhere near accurate of a test but still) and it grew 1 thousandths, maybe a little more but was hard to tell since it wasnt exactly evenly heated throughout.

I have read it somewhere already, What is the ideal temp to measure all the clearances at so I can tell it is where it should be and get this thing assembled?
And yes I'm uber picky

 

If you sized at Weisco's specs then you are already f'd. Have it re-bord to a clearance of 0.0045 to 0.0050. If I recall Wiseco's usually call for 0.0030 to 0.0035 which is way too tight for a motor making significant power.

 

3-3.5 thou is really tight for a turbo motor. IIRC, my 2.4l DSM motor I had at 5-5.5 at room temp.

As for what temp, you must understand that you have both the piston and block expanding as the engine heats up and on top of that, you have a highly non-uniform heat distribution in the combustion chamber. You can assume that the block and piston expand at different rates with the piston expanding much more. So the more power and heat you plan on making the greater PTW clearance you'll need to start with.

 

What temp did you take your measurements at and what clearances did you get?

 

It can always be honed out a couple more thousandths no need to bore. What I don't get is Wiseco makes the HD pistons FOR High Hp turbo motors with high boost/method/nitrous so who says there clearances will be too tight since they know the material they use and expansion rate etc?not saying I always trust the engineers but since that's what its specd out for why go bigger since its made for the purpose? Plus it has a skirt coating which is supposedly worth about half a thousandths thats already into the equation

Wreckleford ill measure again after work and post it up

 

Its just generally known that wiseco's specs are too tight for PTW clearance

 

agreed, .0045 to .0050 is about what you need for clearances

 

Really depends on power goals, but generally in the 4.5 region is a decent blanket statement.

 

clearances are normally measured at room temp (70F), but that also means the parts are up to that temperature.. not like taken out of a freezer and measured in a 70 deg room lol
That's an extreme case, but its also like if you do machine work the coolant from machining can drop surface temps down pretty low.

 

I rechecked everything and everything was at a stable 65ish degrees, it was like .003 ptw clearance, so I'm going to get it honed out another thousandths which will make it .004 and if or when the skirt coating wears off it will be .0045.....Sound good?

 

How much power are you planning on making? .0045 is generally good for cars running 40+ psi and 700whp. Don't necessarily need that much clearance for something making less, .0040 is good if your running a black probably.

 

If it wasnīt bored using a torque plate the cyls will expand around 0,015mm once head is torqued down. Thatīs the number I got when I unbolted the torque plate from my block.

 

The blocks are cone shaped if you don't use a torque plate to hone then measure it with one or the head bolted on.

 

*may expand , also was it honed with the Mains.
What did you use to measure the bores in the first place ?

 

A bore gauge?!

When the block came back to me the main girdle was untouched so I guess they machined the bores with it. I measured the bores with the torque plate bolted and found out perfect .040" over cyls. After unbolting the torque plate I measured them again and found them 0.015mm smaller.

The stock clearance is 0.03mm.