So I got my set of forged PSD rods in today, and immediately compared the N/A rod, IDIT rod, and PSD rod all side by side.






Obviously the N/A rod is puny compared to either, and though it doesnt look like much in the pic, its substantial when your holding it in your hands. Now how the PSD rod compares to the turbo rod is a bit different, but is still a substantial upgrade (more so than I originally thought) over the IDIT rod. If you are looking at the IDIT and PSD rod with the naked eye, the beams look just about equal, but a pair of calipers shows it ~.020" thicker than the IDIT rod (N/A to IDIT being ~.040"). That doesnt sound like much, but in terms of cross section, thats a bunch of area. Also, the top of the rod is wider for more wrist pin support. Its not enough to need to be narrowed, but its slightly more than the IDIT, which means extra support. Finally, the bottom of the PSD rod, like we have known for awhile, is a little over 1/8" wider than the IDIT rod. There is plenty of meat to narrow it that much with no issues, and the PSD rod has the benefit of 7/16" rod bolts instead of 3/8.

One little tidbit I figured out as well, is the PSD rod bearing is .076" wider than the IDI bearing, but fits right into place on the IDI rod like it was made for it. Using PSD rod bearings in an IDI gives you ~12% more bearing area on the journal... Obviously a ton in terms of low end torque production.







I am sending my rods out tomorrow to a machinist who is going to set up his CNC to cut these to IDI specs for the bronco engine. That will make it easy for future repeatably and a solid readily available alternative to IDIT rods to use with IDIT pistons.

 

My question is this: even with as far as you have pushed the rotating assembly of the IDI or IDIT has there been a failure of a rod or part of it's construction?

 

https://www.ford-trucks.com/forums/1...l#post15704998




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So everything get's PSD rod bearings from here on out it sounds, wonder about the mains.

 

Will the PSD rods work instead of NA rods for the 6.9 guys? Just curious if the can work there as well with those pistons?

 

Good info. Will the PSD crank work in the IDI engine?

 

6.9 pistons have 28mm wrist pins, not 33mm. You would have to bush the small end of the rod as Justin did for his Smogie 6.9 build, or else try to have custom pistons made ($$$). Not really worth it for a 6.9 engine since the head fasteners are the first limiting factor.

 

I'm not sure I understand this correctly... If you can use PSD rod bearings in an IDI, why do you need to modify the PSD rods at all? Will they fit, or are we talking about the top, bottom or...?

Also, what sort of PSD rods are these? I'm thinking forged aluminum rods(not the PM ones). Stock or aftermarket? How much did they cost you, or did you pull them from a motor that was lying around?

 

Agreed, even with Robert doing +625 Material ARP 6.9L Head Stud Fasteners for the 1978 Bronco Build Im not seeing a Turbo lower doing much good. even Robert is considering taking that 6.9L and just going mild on it, throwing it into one of the other Dentside Truck Projects and maybe going with the spare 7.3L we have in the shop from the Centurion and building it up in much the same way to build for power and Compounds for the bronco.... time will only tell.

 

Myself I don't know, but this question was asked on another post, and Justin's response was "They are a little over an 1/8" wider per rod." I'm curious to the answer myself, but I'm guessing the rod just may be that bit too wide on the big end.

I'm no expert on using PSD bearings on an IDI but if memory serves correctly, the PSD bearings actually have slightly more surface area, and while they fit in IDIT rods, they are just a bit wider, but still fit within the IDI Connecting Rods... someone please correct me if I am wrong.

 

The PSD rods are ~.130" wider than the IDI rods at the journal end. So you have to narrow them to use on the IDI crank.

While the rods are .130" wider, the bearing is only .076" wider than the IDI bearing. However, the IDI bearing is overly narrow. I snapped one of the old PSD rod bearings into the IDI rod, and it clears the chamfer on the radius side, and nearly comes flush on the other side. There is no reason it wouldnt work.

 

I knew about the difference with the wrist pins. You did answer my question really well though. What would be a disadvantage to adding a bushing there?

 

Justin mentioned before that 350hp is pretty safe on stock NA rods. That's nothing to sniff at on an idi. As much as he has put into it, I wouldn't be scared to push it to that point whether or not its in the Bronco or a Dent. Another thing to think about, is that if you keep the torque down a bit and aim for more top end power, it might help with longevity of the rods. One way to do that, would be to go am even bigger turbo than a S366. Just some food for thought.

 

don't know how i missed that!

 

Does this mean we only need to take .054(.027 per side) off the PSD rods to make them work? If the bearing is that wide, they should fit, right?
(really, I'd probably take another .010 off just for clearance, but...)

 

Justin you may also want to look at other rods, if you are good enough friends with your machinist to barrow his parts book. My friend has 900hp 460 with rods out of a 250 in line 6 motor. My book says that the 460 journals are close enough to work, but wont tell me length or wrist pin.