Newb. Question..Benefits of Boring??

[sleeping95gsx]

I just recently picked up a 6 bolt bottom end. The guy who I picked it up off of said his friend had it in his dsm, and used an old timing belt; so when he turned the car on and shut it off, the belt broke and bent some valves. The valves slightly touched #1 and #3 (I believe that's which ones they are) pistons on the exhaust side. So now I'm breaking the block down and rebuilding.

QUESTION: Im going to be using some newer pistons (probably slightly used), and the cylinder walls do not seemed to be scarred or anything, but should i get the block bored out anyway? What's the benefit of boring the block? And if the decision comes to getting it bored..what bore size should I go with? Any help would be appreciated. Thanks

 

[cyclonekid77]

I would take the block to a machine shop and have them measure it and see if its within spec. If it is they can just hone it to put the cross hatch back into the walls. Boring on our engines doesnt take the overall displacement up very much. Its more to just restore the cylinder walls for your new pistons and rings. Are your newer pistons made for the stock bore? If not you will have to get the cylinders bored for the pistons.

 

[shortyskater]

If you bore the block you can run some bigger pistons or even a stroker kit and produce more power. I would bore it out/send it to a machine shop just incase. If your going to rebuild it you might as well do everything right the first time. But if your on a budget, at least get it resurfaced and cleaned up a bit.

 

[knochgoon24]

You bore the block to clean it up for the new piston. This is usually done when the cylinders walls are in poor shape (scarred, oval, etc.). You usually bore it in steps, starting at .020 over and increasing from there each time it gets done.

A good machinist will take your pistons when he bores the block and match each one to a cylinder. Then, after the bore and hone, each piston will precisely fit.

If you bore the block you can run some bigger pistons or even a stroker kit and produce more power. I would bore it out/send it to a machine shop just incase. If your going to rebuild it you might as well do everything right the first time. But if your on a budget, at least get it resurfaced and cleaned up a bit.

A bore is not required for a stroker kit. The increase in displacement is negligible.

 

[Defiant]

^ +1. On a four-cylinder, the displacement "gains" from boring are going to be minimal. You bore them to fit the pistons, or to clean out scratches and true the cylinders.

 

[sleeping95gsx]

I believe im going to go with the stock bore size for the pistons. Ill take the block to a machine shop after Im finished taking it apart and see what they say. Now the decision is Ross or Wiseco pistons? Haha thanks for the help guys

 

[shortyskater]

Wiseco

 

[98gsxtuner]

^+1 on the weisco

 

[sleeping95gsx]

Wiseco it is. I appreciate the fast replies and help. Thanks again!