Bill,

You're probably right but if I'm going to keep this car for another 10 years I thought now would be the time to do all this work. As I said, it started with an intake R&R project, then I thought it would make sense to pull the engine and do the head gaskets, which I'm glad I'm doing now as I would like to add a supercharger this summer and want to have it in top shape.

Plus the fact that I've always wanted to do this and I find it a lot of fun! I figure at the end of the day the engine will be like new.

I'm not driving the car right now so I'm in no hurry to get it finished but I have a self imposed deadline of the end of April so I can get it on the track. Besides, since I've been on this site I've seen a lot of guys spending a lot of time and money doing some strange things to their cars so I didn't think my project was that big a deal!

 

an ounce of prevention is worth a pound of cure Bill

Brendan, how about you post up some pics of the 951 rings compaired to the 928/944 rings.

I have all the rings to rering a 928 engine, but if the 951 rings really are going to be better for boost (and lack of blowby) then I may see about selling these and picking up 951 rings.

 

I was just putting some piston assemblies together tonight and tried to take some pics of the rings. Difficult to get the light right. I'll post some pics tomorrow.

 

https://rennlist.com/forums/showthre...t=ring+end+gap

 

In this case, I would have left well enough alone. Rings are very rarely an issue with these cars, even supercharged, and you need to be real good with rod bearings to get the right new ones installed correctly with the right clearances. I think there's more opportunity to screw things up than improve anything. While he's in there, he might as well pull the crank and have it drilled. At least that could make a difference in those long sweepers at high RPM!

 

All the Porsche rod bearings I got are the yellow versions. The parts counter said thats been true for a while. The glycos seem about the same (for alot less money) but for a refresh on a newer engine, I think the Porsche rod bearings are the best bet. They seem a bit looser, but not a huge difference when cold.

Would the difference increase or decrease when heated? Heat makes something expand, so I guess the clearance would get even tighter. In that case, going on the lose side for a high output engine seems like a good plan.

 

Now that I've taken all the pistons out I've started removing the carbon deposits. I'm using a Dremel with a steel brush to start, then an abrasive finishing pad and then a polishning compound.

I've done the tops of the pistons which look awesome and started on the sides. In the second pic I've polished the area above the first ring land but below it looks like the aluminum has oxidized? just wanted to confirm that it's not some sort of special coating that shouldn't be removed. I'm pretty sure the whole piston should be polished to it's original metal finish.

Any comments?

Top View

Piston #1.jpg

Side View

Piston side #1.jpg

 

Bill,
Could you elaberate a little on the rod bearing issue; "right new ones installed correctly with the right clearances".

Could someone advise me of the correct part number?

Also I have read many post where it does not seem during installation they are using plastigage to check the clearances. I know the WSM does read to check and states the tollerances. What if you check the clearance with the new bearings and it is out of range. What do you do??

Sorry for all the questions, but its my 1st time and don't want to miss the opportunity to change the bearings while the engine is out if I need to.

Thanks

 

Absolutely not. Don't polish any further, and on the next piston, just polish the tops. The coating is a ferrous coating that is a sacrificial lamb in the name of preventing galling from aluminum on aluminum. Do not take that skirt coating off!

 

Brent,

Great job on the pistons, they look great. Sorry I can't help you with your questions, but they sure look good.

PS: Keep the pic's coming...

 

Brent,

I think Brendan is right, I read that somewhere but just was not sure enough to advise you. I am trying to find where I read about that coating.

 

Brent,

There is some discussion about the coating in the following thread. Hope this helps.

https://rennlist.com/forums/showthre...iston+cleaning

 

Thx Brendan, I had a hunch that there might be a special coating but wasn't sure. Luckily I only did a little section on one piston above the first ring.

The tops come up pretty nice after I let them soak in some piston cleaner for a few hours. The carbon comes right off and polishes up like new.

 

Justin???!!!!

 

Ba-hahaha!
Nice...

On another note, what you could do (I've heard the 951 guys have good luck with these guys) is send the pistons off to swaintech (.com) and have them put the PC-9 on the skirts and TBC on the top. Its basically a ceramic coating setup. Keeps your pistons cooler when you're cramming forced air down its throat and the skirt coating would be a great addition, and I hear its safe to use in our blocks too and won't really mess with clearance either. $38/piston for this. I'm going to do it for my 928 and my 951.
They also have a really cool coating for BEARINGS that sound like it will extend their life. Something like $41 to do a set I think...