have a cold one guys!!
What does IDI mean?
Senior User
Joined: May 2008
Posts: 198
Likes: 0
From: I live in Tennessee
It means the fuel is injected in a precombustion chamber with a glow plug in it. The fire gets sprayed out into the cylinder kinda. The next generation trucks used the DI direct injection powerstroke. That one squirts the fuel dead center of the cyilinder and it has mexican top hat pistons for improved fuel swirl and mixture. The fuel squirts right on top of the piston and gets curled around in the cylinder becuase of the shape of the piston. The IDI has a regular flat piston. More abrevieations you could hear for the IDI is IP means injection pump, GP glow plugs, FSS fuel shutoff solenoid, VRV vacuum regulator valve(regulates vacuum to the modulator valve in an automatic truck)
Junior User
Joined: Aug 2009
Posts: 60
Likes: 0
What I haven't been able to figure out yet is why the direct inject systems didn't get better fuel mileage than the IDI's. Direct inject is much more efficient than indirect that one could easily assume you'd get better fuel mileage. This has always been the strike against Cat. engines as they weren't direct inject like the Detroits, and they got much poorer fuel economy. I'm surprised the 7.3 direct injects don't get upwards of 10-20 percent better fuel mileage than the old IDI's.
Cargo Master
Joined: Feb 2008
Posts: 3,409
Likes: 1
From: back in SE Iowa
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Senior User
Joined: Mar 2012
Posts: 317
Likes: 1
From: Back in the sticks of VA
Electronically controlled- 4 speed-with OverDrive. It's the replacement for the mechanical C6 auto 3 speed. For manual transmissions, the T19 is the older 4 speed non-overdrive tranny made by Borg Warner. It has the non synchronized granny gear. This tranny was last used in 1986. The other manual tranny is the ZF5. (4 speed with overdrive) There where two ZF5s. One was the earlier ZF5-42. The other was the identical but slightly beefier ZF5-47. The ZF5 ran from 87 all the way into the Powerstroke era. The ZF5 is the most common swap in IDIs. The replacement for the ZF5 was the ZF6. (5 speed with overdrive) Rarely swapped into an IDI, the ZF6 was used on the Super duty pickups until 2008.
Lead Driver
Joined: Apr 2008
Posts: 6,945
Likes: 13
DI only about 10% more efficient than IDI (so ive read) and in my experience not only does our IDI get better mpg than the DI 7.3, it also makes more power per CC of fuel. So im lost on the whole less efficient thing too. I know when IDI was introduced it was the "new" diesel tech. ran quieter, better mileage, better power and less emissions.
Senior User
Joined: Mar 2012
Posts: 317
Likes: 1
From: Back in the sticks of VA
I know a guy who has a 2000 Stroker and gets 20 MPG. My bro gets around 12MPG with his 99 Stroker. Funny how I get better fuel mileage and my truck is older. 
Got to love IDI. Very simple to work on and the parts are relatively inexpensive.
Got to love IDI. Very simple to work on and the parts are relatively inexpensive.
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
That is the major part, as thermodynamics in general shows that with higher compression is higher efficiency. Look up Carnot Cycle, that is the ultimate ideal efficient cycle that all power cycles are compared to. By theory, higher compression will net better return, however in the real world, there of course is mechanical limits to what compression can truly be run.
Laughing Gas
Joined: Mar 2011
Posts: 1,229
Likes: 1
The T-19 is actually synchronized in all four forward gears. It was the T-18 that was nonsynchro'd on first.