If you wanted to rebuild a 7.3 idi, increase it's performance w/o a turbo, what would you do?

At some point I'm probably going to rebuild my 1990 vintage 7.3 idi. It has a little under 190K miles on it. I'm well versed with rebuilding gasoline engines but don't have much experience with non-turbo diesels.

What upgrades are available to increase hp / torque w/o adding a turbo? Different camshafts, head work, exhaust work, change in compression, etc?

Or is it basically the only option is stock Ford / International?

TIA.

Scott

Look up r&d diesel performance..
You're going to get guys saying wes also...

What would I do?



Turbo.

Any particular reason you don't want one?

A cam probably makes the most difference. Headers do too if you can find them. There's debate about it, but I feel like porting the heads added a little bit. Other than that, you're looking at a turbo. Those will add some, but not a big amount.
I've seen people claim that without a turbo they can't keep up with Texas traffic. I have ported heads and headers and I didn't have any trouble keeping up with it. I can't accelerate like they can, but I can run high speeds just fine.

A while back I read through a lengthy discussion on FTE regarding porting the heads and as I recall it was Justin at R&D who was saying that porting didn't add much.

I think if you're running N/A then overall gearing has a big affect on how powerful the truck feels. I recall an old post from Towcat where he talked about how important proper gearing was with an N/A engine. After years of DD with 4.10 and N/A I wouldn't mind going to 4.56 and just dealing with it on the highway. But I also live in the hills so deeper gears are better. I wouldn't want to run 3.55 with an N/A engine. When the N/A 7.3 IDI was used in medium duty applications it seemed a 2-speed rear end was often used as well.

Nero said:

What would I do?



Turbo.

Any particular reason you don't want one?

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I just dropped a grand on a new moose injection pot that’s set up for stock, non-turbo, and I don’t wanna lose that investment. Plus, I’m planning to put a dunk bed on this truck and use it a lot around the farm so there’s not much opportunity to get up to speed or a turbo would make a big difference.

Looks like the primary NA cam option would be the Type 4 / Logger cam from Russ. Anybody have experience with the Stage 1 Premium injectors from CDD?

I can do a port match on the heads and intake manifold when I have the engine apart and also a multi angle valve job.

Years ago when I was involved in Automotive racing there were two schools of thoughts on exhaust porting. For ultra high RPM and turbo engines we wanted to port match the heads to the headers but I’m lower RPM high torque Street motors we wanted the header to be larger than the head ports For anti-reversion benefits. This helped with exhaust scavenging. Any thoughts regarding the subject on a 73 normally aspirated?

My truck has 4:11’s.

What about Engine rebuilding kits? Are any better ones to consider or should I look at sourcing parts individually? Unfortunately I won’t know what the cylinder taper is until I get it apart but I’m figuring that I’ll probably need to do a 20 over bore or so more. I take it that these are not sleeved engines?

Many thanks for the feedback.

Scott

scsmith42 said:

I can do a port match on the heads and intake manifold

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There isn't much to do at all on the intake manifold. It's practically the same size as the holes in the gasket. Same goes for the intake ports in the heads. You could do some polishing in the manifold, but I didn't because I was afraid of not being able to get it clean so I didn't touch it. I just barely touched the ports to match the gasket holes. I did polish them though. No swirl is needed here since only air goes through these ports.
The exhaust ports can take a lot of porting to gasket match them. You do want to use caution though. There's a head bolt hole that protrudes into the exhaust port. You can see it when you look with the heads off. I ruined a head from grinding through into that passage. From my limited experience, Ford heads, both IDI and Windsor series, don't need much to open up the intake ports, just the exhaust ports are restrictive.

scsmith42 said:

Any thoughts regarding the subject on a 73 normally aspirated?

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Again, I have a extremely limited experience here so it's just a guess. These can't ever be a high RPM engine so just keep that in mind. I did gasket match the exhaust ports, but maybe I didn't have to.

scsmith42 said:

What about Engine rebuilding kits? Are any better ones to consider or should I look at sourcing parts individually?

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What I tell people here is to just stick with big name brand parts. From your gas engine days, you remember names like Melling, Clevite, Perfect Circle, etc. I don't know how they are these days since most things don't have much quality, but I feel like you stand a much better chance of getting good parts by using the big names.

scsmith42 said:

I take it that these are not sleeved engines?

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No they aren't.

As far as general rebuilding tips for these engines, Justin At R&D has a YouTube channel called RacinNdrummin. He has a 4 part series where he shares a lot of knowledge while he builds an engine, I learned a lot from it.

Run a compression/leak down test and see how healthy your engine is. You might find that all you need is cylinder heads rebuilt. The bottom ends of these engines are pretty stout, and you’ll get to look at the cylinder bores when you pull the heads off if you are really worried about it. I feel like you only hear about chuffing/valve guide failures, you don’t really hear of anybody genuinely wearing out the rings/bores on these engines like you do on day carbureted big block gasoline engines.

Good luck whichever way you go.

scsmith42 said:

I just dropped a grand on a new moose injection pot that’s set up for stock, non-turbo, and I don’t wanna lose that investment. Plus, I’m planning to put a dunk bed on this truck and use it a lot around the farm so there’s not much opportunity to get up to speed or a turbo would make a big difference.

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Turbo isn't just for speed, it is also for power. If you have your mind set on no turbo, the stock idi is still pretty good as a tractor in its stock form. Turbo bolt on kit is easy and you can find used ones for good prices. To replace injectors or a cam you'll easily be $400 or more into it.

If it's the pump warranty you are concerned with, you can run a turbo without modifying the pump.

Fwiw
And to add to what nero said...
Call moose and ask about warranty and turning up the fuel screw, you might be surprised...

Turbo also helps with elevation, if I remember right, every 1000ft is -3% in power, if your at 5000ft that’s -15% right of the bat, just some food for thought.

Not sure what your hoping for power and your expectation but this is a 45 year old engine technology, they don’t have good power but will run all day forever. I’ve built mine with turbo internals, put a 093 kit, new injectors and ip, bigger down pipe, head studs and cam, all I gained was 10mpg, egts go insane on hills and still struggles going up 7% grades with no load. These aren’t like the new trucks and if your expectations is something like the newer trucks your better off changing platforms now and save your time and money. Just my 2 cents

ifrythings said:

Turbo also helps with elevation, if I remember right, every 1000ft is -3% in power, if your at 5000ft that’s -15% right of the bat, just some food for thought.

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Altitude does sap power, in anything internal combustion.
Same reason why the germans ran nitrous on the fighter planes.
Turbo adds it back by volume.

ifrythings said:

Not sure what your hoping for power and your expectation but this is a 45 year old engine technology, they don’t have good power but will run all day forever.

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Literally a Combine powerplant

ifrythings said:

I’ve built mine with turbo internals, put a 093 kit, new injectors and ip, bigger down pipe, head studs and cam, all I gained was 10mpg,

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Not sure, but this might be a typo...
10-20 mpg seems to be the "quoted " mileage on these...

ifrythings said:

egts go insane on hills and still struggles going up 7% grades with no load.

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Needs an i.c.

ifrythings said:

These aren’t like the new trucks and if your expectations is something like the newer trucks your better off changing platforms now and save your time and money.

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This ALL DAY LONG.

ifrythings said:

Just my 2 cents

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Ditto

Clb said:

Not sure, but this might be a typo...
10-20 mpg seems to be the "quoted " mileage on these...

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The best I ever could get was mid 10mpg in the summer and 8mpg in the winter, drove like a grandpa made no difference, this was with a zf5, 4.10 and 35” tires, tried 3 different IP’s and made no difference, tried timing from 6-12degrees didn’t help either. In the end I found my expectations had changed and I switched platforms. Nothing wrong with the IDI but for me I can get lots more power and better milage with a different truck.