custom Mahle pistons are useless.. major vendor fail
 

As a side note: Pelican parts had nothing to do with any of this. everything I've ordered from them has been correct.

After ordering custom Mahle 3-3.2 conversion pistons 10-1 compression for my engine from a respected vendor which was specifically spec'ed to be used with an aggressive camshaft with high lift valves the final result is useless. At the initiation of the process my engine builder (30+year experience with this) spoke with the vendor to explain the engine being built and answer any detail questions to be sure they made the correct part. I had my engine builder do this directly so that nothing was missed in the process. This has been a 3 month process with error after error. After 5 weeks the first set of pistons shows up and it has the incorrect wrist pin diameter. They gave me the turbo writs pin size on a 3.2 conversion piston. So this shop takes the Mahle piston back and puts a rush with Mahle to reproduce a replacement with the correct wrist pin. I explained I had a rally to get to the end of September and this was now pushing my timeframe. We also rediscussed that my engine was using aftermarket aggressive camshafts with high lift valves. Additionally a "fire ring" on the cylinder head was specified. After waiting another 3 weeks the pistons show up from Mahle but with no fire ring. The vendor machines in the fire ring which adds an additional week. The pistons plus cylinders plus rings show up at my engine builder. He does his initial layout and quickly realizes the the valve pockets are of stock high and will not work with my specified from the beginning high lift cams/valves. At this point we are gravely behind schedule and the vendor tells us to at our expense machine the pistons to add the valve relief pockets needed as there is not time to ship back and forth to him for them to do it. My engine builder lays this out with his machine guy, does one piston, that clears the valves so the other 5 are done. That added an additional 4 days we didn't have. In the mail I receive a bill from this vendor charging me the shipping to get the replacement secondset of pistons to me as well as charging for the fire ring machine work. I was flabbergasted they would try to charge me with this. After a few emails back and forth they retracted that bill which I cannot believe they sent in the first place My engine builder then starts to mock up the engine and and while the valves clear fine the layout of the piston (I'm leaving the zone where I have the technical understanding to explain this fully)and how it mates to the cylinder makes for only 9.6:1 compression. The pistons will not hold the compression they were made to. My builder has built hundreds of these engines and gave me a string of technical problems with the pistons. So after explaining to this vendor twice what was needed they failed on multiple accounts completely screwing up my build time frame and costing MANY hours of my engine builders very expensive time. The pistons they made would work in a stock 3.2 motor running stock cams. not the 3-3.2 conversion motor running hot cams that we spec'ed these for. I have now overnight ordered a set of 10.5:1 JE pistons with the necessary valve relief already inplace to be used with the new Mahle cylinders. By having custom Mahle pistons produced for my engine I thought I was including the best of the best parts. The Mahle pistons are useless to me and might as well be paperweights. I have a call out to the vendor who wasn't there Friday. If they do the right thing and refund my money for the piston portion of the charges then I'll move on as lesson learned. If not I will be happy to share the name of the vendor with any in the porsche community who will listen. That is not the shop to use to get the details right on a custom build If they take the pistons back and refund my money then at least they have a moral compass. The lack of attention to detail is shameful. As well I will fight the charge through Amex that has a good track record of protecting the consumer in these situations. I'm not looking for a fight, I just want my money back on the useless pistons so I can pay for the JE ones I had to rush order. Will I make my rally now? We'll see. At best car will make it on transport and my first drive of her will be on the rally. This has been a more stressful process than it needed to be.

This my build (minus pistons): Introducing my Tangerine 73 project - Page 9

Mahle pistons............
 

Sorry to hear about your troubles! I, too, used a set of 100mm Mahle 10.1:1 pistons for my 3.3SS engine build. My Mahle pistons also were bored for the 23mm wrist pins but after talking with my vendor, decided to have my rods re-bushed to take the larger pins. I was concerned about the piston-rod-deck height being correct, but in the end, it all worked out with a deck height of 1.1mm. Admittedly, I'm not running high lift cams (using 964 cams) but everything else worked out quite nicely. The completed engine makes 160 lbs of compression on all 6 cylinders and, after about 500 miles, had very little metal on the drain plug magnets at the last oil change. The vendor that I used was very helpful, swapping out the 23 for the 22 mm pins at no cost. I guess the old saying that "It's better to be lucky than good" is sometimes correct!

Man, I can't even read a wall of text like that. What ever happened to paragraphs? Sorry for your troubles but I don't know what they are...

I'm with Matt. There are reasons for having paragraphs, and they aren't just from fuddy duddies.

I love you guys. Poor guy is spilling his guts about his hardship and you hammer him with grammar issues. Lol
JE is excellent quality. You should feel good about having those slugs in your motor.

I am not sure how all vendors work, but a common practice is to have a written order with specifics IRT piston dimensions, hole spacings, valve relief pockets, rings, etc.

Do you know if your builder received the written specs and reviewed them before completing the order?

I think if this was not done your builder shoulders the responsibility for it going wrong, or if it was done he is still wrong.

x2. They have a sheet you can fill out if you want custom dimension pistons made... they also sell off the shelf Porsche pistons with valve reliefs for the hottest cams. I'd rather have JE than Mahle...

Matt, it all becomes clear after the third pale ale!

May I correct you in that it's not a grammar but a layout issue ;-)

- Manfred

Touché

Just a heads up but no manufacturer is perfect. Last year JE had a production issue that cost about a dozen POC racers in SoCal their engines. I think Jeff at Aase got saddled with rebuilding six or seven because of the problem. Also pretty sure it got documented here if people care to search.

Sorry if my comment was seen as offensive. But on a phone it's pretty impossible to read.

+1 on the engine builder "of 30 years' experience" wearing some of the responsibility. Also he should have been able to identify all the issues with the pistons at once rather than one issue, having the pistons machined, and only then identifying another problem.

Why did the enging builder go with that particular vendor? It sounds like it wasn't the one he normally uses.