First start of powerful Idi build...

[icanfixall]

88ford... Sorry to say this for the umteenth time but all pistons in the 7.3 idi engine have the same dome thickness be it turbo or not. I can only suspect the 6.9 engine is the same. 100 or 110 off the piston tops is a mute subject once you go past what the engineers told me is acceptable at Mahle. Will it run... Yes.. Will it last hauling a load up a grade of down the truck pull path..... Its a shame to see something like this run without coling or even the turbo connected to the intake for such a long time. If this engine lasts I bet ca nobody will ever try this again to test the waters...

 

[88 Ford]

What about pistons from other manufacturers? And ya I'm definitely glad there are so many powerful builds going on right now! Diesel Dog Catcher even started to rebuild Barney's engine now too. It'll be cool to see what that engine does too.

 

[88 Ford]

Gary, here is what Justin told me about his pistons compared to the Mahles.

"What Gary has to say about the shaving limits of the Mahle pistons is likely correct. What he doesn't seem to know though is that the factory Mahle pistons are oldschool and out classed by the current available replacements.

I have had both the 6.9 and 7.3 n/a and Turbo pistons in my hands. All 3 use aluminum ring lands, and the turbo piston has an anodized coating on top it seemed.

Take my pistons for instance. They are Keith-Black Silv-o-lites. They are likely a better casting/grade aluminum but I cannot prove this. On top of that, and this is huge... they use steel ring lands, this alleviates the issues that Mahle told Gary about.

So, I have KB's with steel ring lands and potentially nicer casting. They are cryo treated, and I also have a tri-coated piston.

Ceramic top, the sides/skirts/bottoms are impregnated (not just coated) with heat dispersant, and moly oil shedder on bottom.

Rings, I have the "new" style Hastings rings. These are significantly different than the rings that were on my Mahle pistons, and according to Hastings themselves are superior to what was offered for these engines previously. Both compression ring material/shape, and the oil ring.

All in all, while Gary is likely correct about the Mahle pistons, there are better pistons, and superior options available with todays technology.

My pistons are shaved .080. As long as Ken followed the same steps I did, which I THINK he did, since he asked me about my pistons.... .100 will not phase those pistons."

That is kinda why I hope that guys engine will be alright. Who knows til he runs the thing for a bit...

 

[88 Ford]

Also here are some pics of his pistons...

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[riotwarrior]

Wow, is about all I can say....I mean to run an engine for over 7 minutes no coolant, on a fresh engine the amount of friction during a break in is phenominal and that adds up to heat.

The oil would thin measurably due to the increase in heat it has to handle as the only coolant, and likely was vaporizing on underside of pistons.

Sure there was NO load ok that makes it alright I guess..NOT, without the coolant there to help remove heat, those pistons and cyl walls got a huge heat soak and then that leads to ring failure due to the rings loosing tension and becoming soft like butter no longer capable of sealing.

Just plain ridiculous IMHO...but what do I know after all I ain't a mechanic or machinist and never worked in a speed shop when young and and and....ok so maybe I don't know anything...but it's still an opinion!

 

[RLDSL]

Seems to me he spent a whole lot of money on something that's likely to fold by the time he gets it all put together at the rate he's treating the thing

 

[Black dawg]

While I would never do what he did, I have seen stock car motors overheat and loose all coolant (no steam left and glowing) and finish 10 laps on a 1/4 mile track. One particular guy did this race after race pretty much all season. Motor lasted 9 races this way till it broke the crank. mobil 1 5w 50 was not changed all season either.


If this sbc motor could live through this at full power I would hope that the idi motor could live through 10 minutes basically idling.

 

[icanfixall]

The oem pistons in all the early 7.3 idi engines were of the type that didn't have the steel lands between the piston rings and the aluminum piston. The later pistons do have this steel. I would askbefore milling any piston what the dome thickness is before doing anything. Kieth Black has a great reputation for making a great product but knowing what we are talking about will help us much more than guessing. So.. What was the dome thickness before and after milling said amount off the piston..

 

[hesutton]

I have had both the 6.9 and 7.3 n/a and Turbo pistons in my hands. All 3 use aluminum ring lands, and the turbo piston has an anodized coating on top it seemed.

The oem pistons in all the early 7.3 idi engines were of the type that didn't have the steel lands between the piston rings and the aluminum piston. The later pistons do have this steel.

The stock 6.9 Mahle's I pulled from my '86 have steel lands on the top ring. Not sure about the others. Will look this weekend and see. Not sure why the 7.3's wouldn't. Easy to see in the photo below. Seems there is some confusion on the issue.

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ON EDIT: Forgot to mention, my new Mahle's are the same. Also have a stock 7.3 piston in my garage. I'll look at it tonight and see if there is a steel ring land.

Heath

 

[hesutton]

Also, per the info gained from Ron's teardown of Barney's 6.9. Heat transfer certainly is a bigger concern when material is removed from the crown (and those were ceramic coated). Lots of questions to be answered.

Heath

 

[hesutton]

When I got home last night I did check one of my old stock 7.3 IDI pistons when I rebuilt the 7.3 in my F250. That stock piston also has a steel ring land for the top ring. Not sure why there is confusion about Mahle pistons not having them, but they do. Just passing it along.

Heath

 

[88 Ford]

I'll talk to Justin and see if he knows what the thickness is on the Keith Blacks. Also thanks for the info Heath.

 

[hesutton]

Also thanks for the info Heath.

Eh? No big deal.

Heath