A few questions about this “IDIT”

IDI_Journeyman

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So I’m working on an engine for a customer of mine that is supposedly a factory turbocharged 7.3 from either 1993 or 1994. The engine came with no turbo, but the guy that sold it said it is a turbo motor with the stronger pistons and whatnot, he had just sold the turbo kit separately.

Personally I believe it’s a turbo motor because of two things. 1 is it still has the factory heat shielding on the back of the heads. And also because the engine number near the timing cover starts with “7.3 T” (pics posted below)

I took the heads off it yesterday for an inspection of the pistons and the valves, and I found that some pistons are “A” pistons and some are “C”. Is this normal?

I also found that 5 out of the 8 pistons have a slight amount of damage at the top where the injector fires. My Theory is that the guy pumped fuel up with no pyro and got the ol girl a little too hot.


So I guess my questions are, do you guys think this is a factory turbo engine? And how bad do those pistons look based off the damage?

Any advice or comments is greatly appreciated.

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Thewespaul

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Thats an IDIT for sure, but its been rebuilt. Some of the pistons have been replaced it looks like. The wear on the pistons is fairly normal, looks like it had some injectors hanging open and it ran for awhile like that, so make sure the injectors are replaced before it is run anymore.
 

Thewespaul

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They’re basically the same pistons, some are just original to the truck, and some were replaced, hard to say which are original and which are newer, but those are all idit pistons. If you’re rebuilding this engine, replace them all and balance the assembly. If they are different sizes, they would have the oversize amount stamped in the piston.
 

IDI_Journeyman

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The crosshatch looks great on all 8 so I don’t think we’re going to be rebuilding the engine. we’re just cleaning up everything and resealing everything from the deck up. However I will be lapping all the valves and putting in new seals, my friend tells me there is no valve stem seal for the intake valves? Is this true?
 

Thewespaul

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Theres probably no seals on there now since the 7.3 style seals fall apart quickly, I would do the 7.3 cooling mod and use 6.9 head gaskets and valve seals. The 6.9 valve seals will allow more lubrication to the valve guides, but will keep your oil cleaner than if you had no seals.
 

icanfixall

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Only real difference in turbo and non turbo engines is the exhaust valave material being Inconel and the piston pins are larger on the turbo pistons. Non turbo blocks serial number ended at 1,116,330. Then from 1,116,331 and up came the turbo blocks.Any non turbo block can be fitted to turbo specs and... A turbo block can be fitted as a non turbo block.At one time we could buy a turbo and non turbo oil cooler bundle. But now its only the turbo bundles available. The cooling system modification is something I discovered over 10 years ago and posted it up on the forum.You bet several members beat me up telling anyone that would listen that 6/9 head gaskets on a 7.3 will not fit. I measured and documented everything possible.Bottom line... They fit... They work... Sadly noting more can be said because owners will do what they are told to do..Like install a cork oil pan gasket...
 

IDIBRONCO

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Bottom line... They fit... They work...
Yes they do fit, barely. When I put them on my 7.3, I had to sweet talk them over the head studs. It was probably just the stud diameter differences. If you were using bolts and putting them in after the head is on, you'd probably never notice a difference. I don't think you'd want to set the gasket on and then install the studs. From reading others' posts, I put anti sieze on the lower part of the studs. I wouldn't want to take a chance on somehow contaminating the gaskets with anti sieze and causing them to fail. That may not even be possible, but I'd rather not take the chance of having to do it a second time.
 

Randy Bush

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Only real difference in turbo and non turbo engines is the exhaust valave material being Inconel and the piston pins are larger on the turbo pistons. Non turbo blocks serial number ended at 1,116,330. Then from 1,116,331 and up came the turbo blocks.Any non turbo block can be fitted to turbo specs and... A turbo block can be fitted as a non turbo block.At one time we could buy a turbo and non turbo oil cooler bundle. But now its only the turbo bundles available. The cooling system modification is something I discovered over 10 years ago and posted it up on the forum.You bet several members beat me up telling anyone that would listen that 6/9 head gaskets on a 7.3 will not fit. I measured and documented everything possible.Bottom line... They fit... They work... Sadly noting more can be said because owners will do what they are told to do..Like install a cork oil pan gasket...
The IDI blocks where reported to be more prone to cavitation on left bank cylinders. something that was not as prone in the IDIT blocks. Also a IDIT is a much stronger block with the main webs .100 thicker , the headgaskets use a heavier fire ring on the gaskets also, not saying though that the 6.9 will not work. Pistons in the IDIT are anodized aluminum alloy with two keystone compression rings along with the larger piston pins does make for a much stronger engine. IMHO
 

IDIBRONCO

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the headgaskets use a heavier fire ring on the gaskets also, not saying though that the 6.9 will not work. Pistons in the IDIT are anodized aluminum alloy
Oh the 6.9 head gaskets hold up JUST FINE. if you don't believe me, just ask Wes! I still can't quite bring myself to completely believe in the anodizing though. They forgot (and still do as far as I know) the outside 1/4" or so of the top of the piston. I just can't see why they do this. I've seen WAY more pistons (anodized and plain aluminum) burn down the sides like these did rather than actually crack. I do know that they can and do, but usually, it takes something extreme like putting gasoline in your engine or maybe running too much nitrous. I can't remember at this time whether or not Wes's pistons were cracked on the tops, but I used that as an example.
 

Thewespaul

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My pistons were not cracked, but the cylinder pressure did push the rings and ring lands hard enough to break off the pistons, but not enough to lift the heads torqued to 150ft lbs, even though they were just cleaned and reassembled, no decking or matching. 6.9 head gaskets are all I use anymore. The idit certainly is a stronger engine especially with the bigger connecting rods that typically eject from the na engines around 400hp.
 
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