Looking for Advice on a 7.3 IDI Turbo Build

I have a '87 F350, Crew Cab, Long Bed, 6.9, ZF-5, RWD. It's a non-running project truck. The plan is to make it a capable towing vehicle with 4 wheel drive. It has 4.10 gears and I'd like to run 35's or so. I have sourced a Dana 60 (1990 version, kingpin 4.10), ZF5 4x4 trans (1995 S47), and a 1994 IDI turbo that likely needs to be rebuilt.

My plan is a mild-ish rebuild. I don't need/want anything crazy, but I'd like to have over 500 ft/lbs of torque, if that's possible.

Plan is to rebuild the short block; I'm thinking it's likely standard bore and in need of a slight overbore. How much of an overbore can a 7.3 IDI handle? Any recommendations on pistons?

I'll add head studs, and plan to replace the cam with something a bit more aggressive. I believe a few companies offer cam profiles for an IDI turbo. Anyone have any recommendations on cam?

On the heads, what do I need besides a valve job and upgraded springs? I forget which springs everyone seems to use, but sounds like a no-brainer to me to swap mine out.

Obviously, I'll get some new injectors (R&D IDI?), and perhaps a new and upgraded injection pump (R&D IDI?).

I'm guessing the turbo will need a rebuild/refresh, along with a new downpipe. I'll certainly be adding a boost gauge and pyrometer.

What am I forgetting here? Also, any idea how much torque I should have?

Truck is near Fredericksburg, VA area (between Richmond and Washington DC on I-95). If anyone has any recommendations on a local machine shop, that would be great, too.

bulletpruf said:

My plan is a mild-ish rebuild. I don't need/want anything crazy, but I'd like to have over 500 ft/lbs of torque, if that's possible.

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That should be easily possible. It takes a little more work if you're talking about wheel torque VS. flywheel torque, but still not terribly difficult to get there.

bulletpruf said:

How much of an overbore can a 7.3 IDI handle? Any recommendations on pistons?

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People often go to .030" over. DO NOT go farther than that. The cylinder walls in a 7.3 are relatively thin so the less over bore, then better. I used to work in a shop that remanned these engines back in the late 90's and early 2000's. Our machine shop wouldn't go over a .020" over bore. There is only one choice of pistons for this engine. The pistons that a Factory Turbo engine takes. The wrist pin in the rods/pistons is much larger on these engines so "regular" pistons won't work. As for brands, I'm not sure so I won't make any recommendations.

bulletpruf said:

Anyone have any recommendations on cam?

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Since you're planning to go with R&D, I would use his cam too.

bulletpruf said:

On the heads, what do I need besides a valve job and upgraded springs? I forget which springs everyone seems to use, but sounds like a no-brainer to me to swap mine out.

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I ALWAYS recommend having bronze liners put in the exhaust guides. The common valve springs are Comp 910 springs.

bulletpruf said:

I'm guessing the turbo will need a rebuild/refresh, along with a new downpipe.

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After all of the work that you're going to put into this engine, a stock Factory Turbo will probably be the limiting factor. You may want to look into an upgraded drop in turbo for more air flow.
Since you're planning to use Justin at R&D, I would get him on the phone. He would be the one to double check with on all of these questions. I would probably also use all of his products. Sometimes it just seems to work out better if you buy all of your performance parts from one place. Justin can probably supply most, if not all of the other upgraded parts too. Things like pistons, valve springs, etc.

You should research the difference tween Russ and Justin before picking cams!
Also timelines for delivery!

One thing I didn’t see you mention was an intercooler. That’s pretty much mandatory with any larger than stock IP. Also when I was doing my IDIT build a few months ago, standard and .030” over were the only pistons available, and I only saw Mahle.

224-3512HA.020 is the mahle pistons I found a few months ago that are .020 over, that was hard to find. Total seal piston rings S2884-20 are also what I went with but may be overkill, be sure the top ring is keystone with the set you get. Also the powerstroke rod bearings fit and have more surface area.

Clb said:

You should research the difference tween Russ and Justin before picking cams!
Also timelines for delivery!

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Ok, Justin is R&D IDI, right? What about Russ? Thanks

bulletpruf said:

Ok, Justin is R&D IDI, right? What about Russ? Thanks

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Yes for justin and russ is @typ4, this is russ'es site.

Russ repair

1mouse3 said:

russ is @typ4,

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That's his screen name on here.

Stickies man stickies...
Hall of shame
Tech pages
Carry on

What your asking is very doable. I even have a dyno vid of me making exactly that. 226/501.
Stock turbo injection pump, 3" downpipe, ww2 in turbo, hypermax intercooler. 7 psi boost. Egts were very manageable and had good power.

What I would recommend is not a ww2 but a turbo to either one of russrepair.com upgrades or a idiperformance.com stage 1 drop in turbo.
It would pair wonderfully with a 90cc, and definitely intercool it.
I personally prefer the r&d cam because it suits itself to higher rpm power. Which is where I use my turbo and engine all the time. High rpm.
Russ cam is more low end power. What you want for that is up to you.

You will have an issue finding head studs, valley pan and pistons. Can be found but difficult. Definitely stud the heads at minimum, valve springs are always a great upgrade.
Also highly recommend total seal rings.

But a good turbo, intercooler and fresh fuel system will wake the truck up tremendously. AND make good power to boot.

I'm running almost all of justins parts on my truck.
Stage 1 turbo, injectors, stage 3 fuel system, heads, cold air intake, downpipe and many other things

03wr250f said:

What your asking is very doable. I even have a dyno vid of me making exactly that. 226/501.
Stock turbo injection pump, 3" downpipe, ww2 in turbo, hypermax intercooler. 7 psi boost. Egts were very manageable and had good power.

What I would recommend is not a ww2 but a turbo to either one of russrepair.com upgrades or a idiperformance.com stage 1 drop in turbo.
It would pair wonderfully with a 90cc, and definitely intercool it.
I personally prefer the r&d cam because it suits itself to higher rpm power. Which is where I use my turbo and engine all the time. High rpm.
Russ cam is more low end power. What you want for that is up to you.

You will have an issue finding head studs, valley pan and pistons. Can be found but difficult. Definitely stud the heads at minimum, valve springs are always a great upgrade.
Also highly recommend total seal rings.

But a good turbo, intercooler and fresh fuel system will wake the truck up tremendously. AND make good power to boot.

I'm running almost all of justins parts on my truck.
Stage 1 turbo, injectors, stage 3 fuel system, heads, cold air intake, downpipe and many other things

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You must have a lot more power now with the stage 1 turbo and stage 3(130 IP?) fuel system and cam, eh? I'm curious what your numbers are now, sounds like a great setup. What kind of boost are you seeing?

As for the OP, lots of good advice above. A hotter IP is mandatory for the power numbers you want, and no matter what don't skip the charge air cooler. 250hp/500tq is around the max for these stock turbos(sure they can be pushed further but I wouldn't, and are becoming a major restriction at these power levels), so a drop-in is the answer.

Just make sure your brakes work well after all this work so you can stop the beast after all the WOT runs!

The_Josh_Bear said:

As for the OP, lots of good advice above. A hotter IP is mandatory for the power numbers you want, and no matter what don't skip the charge air cooler. 250hp/500tq is around the max for these stock turbos(sure they can be pushed further but I wouldn't, and are becoming a major restriction at these power levels), so a drop-in is the answer.

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Are you talking 500 ft/lbs at the crank or to the wheels? If it's to the wheels, that sounds good.

On the drop-in turbo, that's interesting. Price doesn't seem to be outrageous for the Stage 1 at $1,200 - https://idiperformance.com/shop/turbochargers-and-turbo-parts/rd-stage-1-factory-drop-in-turbo/. I should be able to offset that a bit with selling my OEM turbo.

Sorry @The_Josh_Bear I realize my statement was a bit misleading
I had a sleeved block, Decompression pistons, total seal rings, coated pistons, stage 1 cam and balanced rotating assembly motor. It was n/a and I blew it up.
When it blew up it destroyed the cam as well.
So I know how r&d's cam works and runs in a engine(disclaimer if putting in a aftermarket camshaft always degreee it with a degree wheel
) don't skip this step

I'm currently running a mostly stock Factory turbo motor. Studs and valve springs is about all that's done to it.
I have a stock turbo cal ip maxed out with a stage 3 fuel system (lift pump @9psi)

In 4th gear I max about 18 psi on fuel and 20 psi on m3th
On 285/75-16 tires I made 272, and 276 whp on fuel
286 on water m3th
556 ft lbs at 2769 rpm
642 ft lbs at 2340 rpm

In 5th gear I make around 25 psi on m3th
So yes a good bit more power than when I dynod 5 years ago

Do you need to do a sonic test of the 7.3 cylinders before boring? Just wondering how you address the possibility that there was some damage due to cavitation at some point.

Disassembled the engine this weekend.

It had a sticker on the valve cover indicating that it had been dyno tested and made 200 hp at 3,000 rpm. Pretty sure that was from when it was remanufactured.

Some knucklehead broke off a flexplate bolt in the crank flange and didn't bother to fix it.

Bores appear to be standard, but some cylinders have some light scratches.

Looks like some of the pistons are cracked on the top; I'll have to clean them up and verify.

Turbo is an OEM Garrett.

Had hoped to do rings and bearings and hone it and call it good, but now I'm thinking it needs to go to the machine shop.