xssive

iTrader: (123)

I am guessing this would work correct?

xssive

iTrader: (123)

Ttt...

C4VetteLS1

2 thousandths?? I dont think that would be a problem

Redline-Motorsports

iTrader: (3)

Who's pistons are they?? .002" is too tight IMO..

Diamond usually fits theres .004" to .006". JE is usually .005"-.006". Is the motor NA? Usually with a FI or NO2 motor you will run a larger piston to wall clearance.

xssive

iTrader: (123)

They are Lunati's pistons. This is going to be a NA motor. So the Diamond pistons that are listed for a 3.905" bore are actually undersized by a few thousandths?

strokedls1

iTrader: (1)

Pistons physical diameter is 4-5 thousandths smaller than the bore measured at the skirt of the piston. 2 thousandths small should be fine.

xssive

iTrader: (123)

Lunati lists the bore as 3.903" and they state that they have .004" clearance built into their pistons. That would be a combined .006" correct? Is that too much?

xssive

iTrader: (123)

Ttt...

Reckless

iTrader: (9)

Have the pistons mic'd for circumphrance (sp?). You should shoot for .004-.005 piston to wall clearance with a forged piston.

xssive

iTrader: (123)

Thats the thing. I dont want to order them unless I know they are within range....

Redline-Motorsports

iTrader: (3)

Make sure you measure the piston skirt approx. 1.25" below the oil ring groove and 90 degrees from the wrist pin. All piston manufactures note there pistons by the "finished" bore size. If you asked for a piston for a 4.125" bore they would make the appropriate allowances. For example this piston would be 4.120" and would allow a .005" clearance.

Heres your situation;

I assume that you have a stock bore LS1. That bore is 3.898". Lunati's pistons that you are referring to, are for a stock bore motor that is "finished honed" to a new bore size of 3.903". That is a .005" increase in bore. This will allow you to have a new clean and true cylinder wall and is the max you can increase the bore on a stock LS1 sleeve.

Buy the pistons and bring them to your machine shop. They will know what to do!

kossuth

iTrader: (12)

If you are assembling the motor yourself then I would talk to a few people that have built LS motors before like MTI or Thunder or somebody. I have done a few tractor engines and SBCs as a general guideline .003 - .007 is acceptable but that is dependant upon the type of pistons you use. If you are using the stock pistons I would try to stay around .003 definately below .005 Like was said with Forged parts you have alittle more room to work with because of thermal expansion ect ect.

xssive

iTrader: (123)

I am having AP engineering build me a block. They give a finished bore size of 3.905".

Paul F

iTrader: (2)

Then you need 3.905 pistons NOT 3.903.

JS

iTrader: (4)

What about this scenario..
Say u hone a stock block to remove the glaze. using a deck plate.

Then use a stock piston and file fit ring.
Will u run into any kind of ring seal problem as long as u check piston to wall?