just offering a possible reason that they found the valves weren't sealing, as we use a vacuum tester that pull smore vacuum than what they were using, and we found all valves were sealing perfectly!

my contention is why didn't GTM measure the diameter of a NORMAL piston to COMPARE to the used pistons to tell the WHOLE story when they were claiming that are piston to wall clearances were excessive?!?!?!? They accused us of sloppy, blatant machining errors, shame on GTM ...

 

I said from the start. Its the blame game. No one will step up. Its just part of the modified car business. When something goes wrong, its always someone elses problem. Ive been down this road, everyone did there own anyalsis and everyone wiped there hands clean. Cut ur losses my friend. Im really sorry to have to say that, but the sooner u move on, the sooner u can heal.

Tuner blames the builder, builder blames the tuner. Blames the tuner who blames the user. funfunfun

 

I am well aware of this pattern, what do you think of our resolution? Don't you think we are handling this fairly? We did a scientific analysis of the components, determined the most logical explanation from the FACTS and we are STILL offerering to rebuild the engine... where is the problem in that?

You don't think we are frustrated? We have been badmouthed and on the defensive when the engine was torn down by a shop that views us as a threat to their competition. We took the attitude of: "if it WAS our mistake, we will fix it"... then we check out the engine to find that the obvious was NEVER stated!!! The pistons collapsed from heat! The rings fatigued from heat! And for the past month, evryone assumed WE made some blatant error?!?!?!?! If we made a mistake, we would own up to it... bottom line, I am still fronting the MONEY to rebuild the engine!

 

Handled your self well and going well beyond what most would do . Good job Todd !!!!!!!!!!!

 

shrunken pistons due to excessive temps (either coolant or egts....maybe both) is what I took from the analysis.

 

ignition timing also leads to excessive EGTs. People will often refer to less ignition timing as conservative, but too little timing can skyrocket EGTs. I have no knowledge of the tuning of this engine, I am only suggesting that it may not have only been a "lean" issue.

 

sounds like cyl. temps killed this motor,and is far from any of gtm's findings.how did gtm miss those rings?like i said in the other thread... "million dollar equipment" does not make gtm better than a builder with passion.sadly for gtm this whole debacle has only exposed their lack of knowledge and lack of professionalism.good luck joe and maybe gtm will give back that crazy diagnosis money they charged since they missed some of the most obvious,basic,amateur,b mechanic indicators that any builder,with any competence would find automatically.

 

very true, my most recent tune on my personal engine, at 17psi, I started with 11degrees timing at peak torque then 14 at redline, egts skyrocketed initially. As I added timing and monitored power gains and any signs of detonation, the power increased and EGT'sdropped significantly.

 

This thread is going to do downhill quick. Just preparing you.

 

Good write up. I would still put you on my short list for a built engine when the time comes.

-Mark

 

It very well can, let's try to keep it objective and not place judgement. I tried very hard to present a professional analysis and not resort to name calling (I leave that to you guys)

 

Very thorough writeup and I think well explained.
Hopefully everyone can find common ground and resolution on this.
Thanks for the info Todd...

 

This is like reverse Blueprinting of a shortblock...so now you know
how much actually goes into the building of a true built motor.
It is alot easier to build one from new than than perform a autopsy
without all the parts. You did a great job as a coroner in finding
what went wrong and did it for yourself as much as for Joe. You
should feel good about the origional build and your offer for a rebuild
is very generous.
Thanks for the pictures showing everything you went through for the
Z community. We all will learn something from this....TUNING!!!!

 

Great write up - hopefully everything will work out...

 

Hello all, I am one of the machinists at the shop that Todd uses. I helped Todd throughout most of the extensive testing we did yesterday on this motor. I would just like to add that Todd is extremely cautious, detailed, and meticulous when building his engines. All of what Todd found and wrote is 100% accurate from what we found. I did the measuring of the pistons and was surprised at first that we had about .006" and up to .0065" piston to wall clearance. As stated, we then got a brand new set of pistons out and measured them and they were .001" to .0015" larger than the used pistons which made me feel better about our machine work that when pistons were original, the piston to wall clearance was right at .005"

Todd, we need to check the spring pressures on the motor to make sure the heat did not contribute to the springs losing their tension as well before you send his motor back. If it was combustion temps. that caused this, the springs will probably be fine. They will be weak if the coolant temps got too high.

 

GTM=owned.

I used to have a lot of respect for them before this fiasco and another private dealing I've witnessed. They may do good work, but the ethics are questionable IMO. They'll tell the customer anything to make a buck.

Joedirt, sorry, I like you, but you just wasted $14k. GTM should have mentioned the poor condition of the piston rings, the apparent "shrinking" of the pistons, the bogus valve seal results, and the signs of detonation before passing the blame on to Todd. Almost makes me sick to see how they pulled the wool over your eyes. They're only intent was to put more money in their pocket and trick the forum into thinking that they're God's gift to the 350Z.

Shame on you, Sam.... Oh, and did you finally get around to sending out my friend's motor after a year of waiting and unnecessary expenses?

 

Definately, I will bring the heads in for complete tear down before they go out anywhere, want to pressure check them as well, just to make sure

Also, I know the pistons can still be used at .006-.0065 piston to wall clearance, straight from the mouth of Arias, but if the customer chooses, at his expense, we can put in a set of NEW pistons to reduce the P-W clearance back to the actual original spec of .005.

 

I was just wondering about that.

 

I can't comment on the findings, but I would suggest locking this thread almost because too many people are going to OT comment and cause flaming...

good luck to Joe, I'd take the offer and sell the engine!

 

they will still be fine at the slightly larger clearance, but they will slap a bit more at start up, and may make a bit of noise at certain rpm's..tough to say, if this motor is rebuilt with these pistons, as I stated earlier, the piston dome will be machined approx. .020" to prevent any possible contact with the heads in a high rpm/ hot/ piston rocking scenario...

thinking back to the original analysis, it was explained to the customer that the boring/honing was too large and the block COULD NOT be re-used..if that isn't the furthest thing from the truth!

I always like slightly larger clearances as it affords for a bit more liberty/ room for error in a freak tuning issue