Reliable to bore out & replate cylinders
 

I'm planning to rebuild a 993 based hot rod motor and want to reliably increase the displacement. Here's my question - can stock 993 cylinders be reliably bored out from 100 mm to 101 mm or slightly larger..

I've researched threads online where some have concluded that boring to 102 would be too much and would likely go out of round quickly. So, Inquiring to see if stock cylinders can be reliably bored to a safer measurement like 100.7, 101 or 101.3 mm to increase displacement to 3.7. I realize that I'll need custom pistons.

I've used them many times for a lot of tricks

Automotive Cylinder Services | Millennium Technologies

Automotive Cylinder Services | Millennium Technologies

+1

L&N engineering will get it done for the same price as millennium. They ship out to millennium to have them done. But they also take all the critical measurements to match them correctly with your pistons and spec out the correct finish. Glad I did mine that way found out they needed cryotreated due to being out of round from detonation. So l&N sent them out to get them cryotreated then they were bored and plated to match the individual pistons.

Good tip on going through L&N. I was aware of Millenium but not sure how much stock 3.6 cylinders can be reliably bored out before getting too thin.

Any thoughts on that issue? I'd like to bore from 100 to 101.3 or even 102. Maybe a call to L&N is in order.

Honestly it’s prob not worth the effort to bore and replays them if you need custom pistons then too. Id just get 102 cylinders and matched pistons.

I sent my 3.6 cylinders out to LN a couple years ago and had them replayed for my rebuild. I matched them with a set of FSR JE pistons. LN supplied everything and I bought new rods from R&R.

We actually stopped reconditioning factory cylinders late last year. Too many compromises. Porosity issues are just one problem. We also never would do oversizes on cylinders that had sealing ring grooves. They get too thin and blow out at the tops.

If you do choose to recondition your original cylinders, my rule of thumb has been the cylinders need to be in spec. Seems counter-intuitive, but at least that way you know they haven't been abused or overheated. If overheated, they won't stay round after they are put back into service.

What's the going price nowadays for a straightforward strip and replate per cylinder?

I have 2 that need done. 98mm.

About $200 a hole including resurfacing the deck (if it doesn't have a sealing ring groove).

Ok, thank you

You might also talk to EBS in Reno, NV . . . https://www.ebsracing.com/
They did our 964 cylinders out to 102 and we use JE 12.5 CR pistons in a race engine.
We did a refresh after 2 years of racing and cylinders still had cross hatch - put in new
rings and bearings and has been good for another 2 years . . .

Regards,

Thanks Roy. I know Jon at EBS and willl get his thoughts. I’d like to save on not buying new cylinders if possible.