3.4 Progress

[ghnat]

Bummer! I am sorry to hear that. At least you know what the problem is. That cyl prob sounds bad. Might I inquire as to who did the replating? Just in case it is the same company I plan on using.

So what are you going to do about the cyls?

[niner11]

Sorry to hear the news. Joe was the one that explained to me I had several broken head studs. Bad news but he gave me options before doing a total rebuild.

Chuck

[JeremyD]

Yes, fortunate to have Joe to rely on - As far as the cylinders - I bought them used.

[84CAB]

man that stinks. i have been wondering why the dyno numbers hadn't been posted. let us know how things go when she's back on the street.

[Purkinjefibre]

Hi Jeremy, sorry to hear about your engine troubles. Glad to hear that your engine building skills held up!
I am building a 3.2 with 98s. You say you got your 98s used, but do you know who made them.

I have cylinder anxiety

Brett

[89911]

Jeremy, sorry to hear this. I thought my mechanic was nuts for making me spend the money for the Mahle 3.4's. I guess I don't feel so bad. Hope it comes out ok for you. If its any consolation, my car's in storage until March and I'm sure you will be on the road before that.

[JeremyD]

Thanks - The JE pistons were actually incredibly accurate - less than 1/2 a gram difference. diameter was impossible for me to measure a difference. Really the cylinders are the suspect. Reputable shop. I half a$$ed measured the piston clearance - with a feeler guage - But you would think you shouldn't have to have these types of issues. I swear - they looked brand new from the factory.

I'm not going to divulge who did them send me a PM if you are interested and I'll let you know.

[jpahemi]

How much money was saved by using used cylinders and new JE's vs. a set of new 98 mm Mahle P&C's?
j.p.

[Jgordon]

Jeremy, Sorry to hear about this. Is the cylinder guy making it right, or was he under the same impressions you were?

[JeremyD]

JE and replate - $2000 new Mahle motorsport 3.4's = 4-5k

[Porschephd]

Couple of questions should be asked here. How did you initially measure the cylinders? Meaning did you stick the ring in the top or bottom, line them up at the edge and call it a day? If so then you could have not know if any issue would come up. To accurately gap just the rung you must run it down into the cylinder. The 3.4 replates come from 3.2 cores. The ends of the cylinder tend to taper out, not in. So ideally you want to eventually push the ring down at least to the first rind groove of the piston. Normally you can flip a piston upside down and gently push the ring down the cylinder and measure from there. Not doing so will not allow for an accurate measurement. If the cylinder was too tight in this area then the rind could have caused damage to the cylinder and the new plating. It probably would have not broken now since this is a NA motor. In time it would have.

Also regardless of new, used or replated you should always check the bore. Even on new Mahle stuff this should be done. There are four measurements that should be take to accurately measure the bore of the cylinder. I have seen new stuff from Mahle for the 996TT all over the place. I have seen 3.4 turbo Ps and Cs with inconsistent plating and marks. There are only 2 platers in the US that do these. While most of the time all of these outfits are on their game, human error can still become an issue and therefore should always be checked. One needs to build an engine, not just assemble it. Knowing how to check these things will prevent failure and allow for another 120K miles.

Last set of questions, the flame ring has clearly been jeopardized. In a NA there is not enough pressure to blow past those unless they were just not matted to the head properly, or the head was not cut correctly or the ring wasn’t. This will and can cause issues if the ring holds the head up from seating properly into the cylinder. As you continue to crank down on the headstuds you will put pressure on one side of the cylinder. Put that cylinder through a couple of heat cycles and you have a real mess. Also the torque sequence used was what? There is only one way to ensure that the cylinders with the rings lay down and torque perfectly.

These issues are the things that I preach to people. Check and double check and know what and how you are looking for. Anyone can assemble a motor, building an engine is not the same thing and requires some key elements to cementing a correct built.

[89911]

Jeremy, I have these for sale on Ebay. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=8018823299&rd=1&sspagename=STRK%3AMESE%3AIT&rd=1

Why don't you grab them? I could make you a sweet deal

[JeremyD]

I have a set of 3.4 mahles that are going in there.

Stephen brings up a good point. Check everything. I was limited in my measuring capabilities as I think that most home builders would be - will be the first to admit that. I checked ring gaps at the top of the cylinder. Certain measurements I did once - many I did 3-4 times (like the cam timing) I would expect that there would be a quality check before cylinders leave a replater - being the the measurement would be so critical.

Either way - lots of gotchas on these engines -

[Porschephd]

Without question they should be checked before they leave. Unfortunately humans make errors. The other issue could have been that the rings were too tight and caused the cylinders to become damaged. Most will not tell you where to measure. This doesn’t help. The ring never sits at the top edge of the cylinder and as I mentioned, most by design taper out a bit. So the measurement would be skewed.

Tons of gotchas. Even for those of us that do it daily.

[JeremyD]

Here are some measurements taken from one of the cylinders. clearly off on the flame rings.



I contemplated even updating this thread, but figured many could learn from it.