cracked pistons!!!!

[REDS HOT AIR]

Originally posted by Steve Wood
No repair center has ever seen one from anyone other than you!

yea only mine have had problems acording to them ....must be a lot of me's running around.

 

[Steve Wood]

yeah, and those me's sure send in a lot of turbos....shaking my head.

 

[Intercooler]

Here is the ZZ4 forged unit!

http://home.att.net/~jesse.adkins/ZZ41.JPG
http://home.att.net/~jesse.adkins/ZZ42.JPG
http://home.att.net/~jesse.adkins/ZZ43.JPG
http://home.att.net/~jesse.adkins/ZZ44.JPG


As you can see the ring is melted and kicked out towards the cylinder wall with chunks of the piston top missing. Also this piston come out of #7 at the rear but due to debris it also messed up the top of #5 rendering it unusable. If you look at the photo of #7 cylinder (rear) you can see the markings where the ring was blown out and riding up and down the cylinder leaving a slight groove. The history of the engine is that this is the second rebuild in less than a year. The first time it had factory Hypers in it and the #7 cylinder leaned out causing a too tight ring gap from GM to butt (was .010" compared to the others being .014"). It didn't take out the ring but a chunk of piston in the gland dislodged and caused a loss in power and idle. The block was honed oversize for correct clearance to use the present Federal Mogul forged units. This time ring gap was over .020" and he leaned it out again with detonation as can be seen in the upper part of the rod bearing where copper is coming through. Bad part is that he got these before the change to the new Federal Mogul line with Teflon coated skirts and now this type can't be found. Guess what he will be doing? He has to spring for a brand new set of the new ones now. Goes to show though that keeping the motor and fueling in check is the key, not piston material type!

 

[Steve Wood]

Re: Here is the ZZ4 forged unit!

Goes to show though that keeping the motor and fueling in check is the key, not piston material type! [/B]

Of course it also shows that if one had bought a piston made for the application, there might have been a margin for error instead of an expensive rebuild.

Even if we were perfect tuners, there is a chance we might buy a tank of bad gas, have an injector that gets a little trash in it, run a bit low on the tank, etc.

Caveat Emptor.

 

[Intercooler]

But I thought the forged Federal Moguls are good pistons It held up. It held up as long as the Hyper before it. Well almost.

 

[OneQuikSix]

To each his own...

 

[gnsrule]

Im not an expert on melting pistons thank god , But those look more like they reached there HP limit more so than being melted. If they were melted, wouldnt they be more burn'd looking ?? Reminds me of an artical Hot Rod or Popular Hot Rodding did not too long ago. They took a cast motor and hit it w/ a 125 hp shot of NOS. They did it in incriments, and when they hit the 400 hp level, thats when the top ring was forced down and eventually broke.

 

[Intercooler]

Did you see the ring in the picture? Melted! This motor wasn't a high horser and I seriously doubt a ZZ4 block would be maxed with these pistons with anything less than 700 HP. No nitrous involved. Did you see the bearing and how pounded it looks?

 

[Steve Wood]

Obviously, the manufacturer does not know how good they are. FM suggests them for claimer motors or mild supercharged applications.

I am sure that I must be wrong in thinking we exert a bit more than moderate. Wonder why FM suggests forged units for severe duty? I guess they don't know their product line very well.

 

[Intercooler]

I can't venture to guess because I am not on the FM board or sales team. I did ask them at their both when I went to the Matco Tools Nationals in Englishtown. What you say is correct, severe duty. He also said Hypers will work fine into the realm of most of us (low 11's to a high 10) except maybe Steve because he is the fastest I can't win this arguement or so it seems so I just presented to you the same motor failing with both. Same piston both times. Almost the same results both times. If you are an occasional racer with more street than track then Hypers are worth a look. If you race two times a week and hard at that then go forged. I am not knocking either one because I have had both and with good luck out of both. I could have very easily bought Speed-Pro or J&E forged units again but for the street I prefer a tighter fit piston setup. What the hell was GM doing in their research dept. using cast pistons in our factory motors, Hypers in the Typhoons and Syclones and what was the Toyota Supra team doing putting Hypers in their motors. Beats me

 

[Steve Wood]

Me, too...maybe you should try some Supra pistons next.