Granite 944

I'm going to rebuild my engine from the '85/1. Machine shop says my block is out of spec. and needs rebore. I think I'd rather not sleeve the engine, (not planning on racing it and kinda like the idea of the alumsil matchup as far as durability goes).Oversize pistons are going to be required, and I know I can buy 100.5 Kolbenschmidt piston kit for approx. $430.00. I'm wondering about a few things as below. I haven't done much research into it yet, and was hoping for some thoughts and/or input.

1: Are Mahle and Kolbenschmidt the only choices I have in pistons in this unsleeved block? any aftermarket pistons that will work in this engine with these tight tolerances and alloy makeup?

2: I've heard Mahle is much more expensive and harder to acquire. Is this true?

3: Is there any real difference between Mahle and Kolbenschmidt pistons?

I'm very new to the Porsche, been gathering manuals, TSB's, and trying to learn as much as I can from this board! (GREAT COMMUNITY) TIA

Mike B

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Granite 944:
<strong>Oversize pistons are going to be required, and I know I can buy 100.5 Kolbenschmidt piston kit for approx. $430.00.
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">If you can find a set of four pistons, complete with wrist pins and rings, for $430.00 then buy about 2000 of them cause that would be the best deal on the planet...

Best I could find, if I could find a supplier who had them in stock, was about $1250 US...

I agree with your thinking on going to 1st oversize though...That is what I did...I couldn't find anyone who had sleeved block that had lots of miles on it...I was concerned about longevity...

I believe either Mahle or Kolbenschmidt have the proper composition and coating to be completely compatible with the block...

Best of luck!

Granite 944

I'm sure the $430.00 quote I got was a per cylinder price, but I will double check it. These parts are very expensive, I'd rather do a proper rebuild, but also can't help but think that there are more choices out there for pistons than just the Mahle and Kolbenschmidts. Thanks!

jabbadeznuts

What are the advantages / disadvantages to getting your block sleeved? What does it do?

johne

It allows you to get a bigger bore, thus giving you more displacement thus increasing hp and torque. I believe most people bore to 104 or 105 mm giving yielding a 2.7 L motor. The main problems are the risk of cracking your cylinder walls if you bore to much over and reduced cylinder rigidity possibly causing the cylinders to sway under pressure thus making head gaskets go bye bye I know this sounds like a horrible thing but it just happens if you overdo it there are several racers(not ricers ) out there with sleeved blocks running high boost. The main problem in my book is cost, dang not having infinite money. <img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" />

btw. were did you get the "4x9 fromt" speakers

Danno

" but also can't help but think that there are more choices out there for pistons than just the Mahle and Kolbenschmidts. "

Any iron-coated piston would do. There are plenty of them out there...

Granite 944

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Danno:
Any iron-coated piston would do. There are plenty of them out there... [/QB]</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I'm not up on all the technical aspects of the materials used in these alumsil engines, and the pistons used in them, but I thought the pistons used in an unsleeved engine needed to be a special light alloy (silicon treated?). I guess I don't understand the term "iron coated" as compared to shop manuals description of "cast light alloy". Any suggestions on where I can go to get myself educated on this subject? Maybe I should just start calling around to say maybe,JE Piston company and start asking questions? Any suggestions are greatly appreciated. I'm in no hurry to get engine back together, so I've got the time to learn. Thanks Danno