Hello,
Does anyone know where the sweet spot (top of the torque curve) is from a 1989 7.3L IDI 180HP?
and how much torque that engine has?

the engine is still original.

 

338 @1800 RPMs for a NA 7.3

388 @1400 RPMs for a factory turbo

 

Hello Jayro, these 338, are they N/Mtr? or ft/pound

 

ft/pounds

https://en.wikipedia.org/wiki/Intern..._Harvester_IDI

 

With a N/A IDI, the torque peak is at 1600, not 1800, according to the Ford IDI Turbo coffee table book.

With the turbo model(or any idi with a turbo), those numbers are stock/factory. The engine and turbo can handle *far* more fuel than it was given, and this changes the torque curve - On mine(with lots more fuel available), I find that the torque curve starts out at "stock" levels, then climbs from there all the way to 2800 RPM. So, while the "torque peak" becomes 2800RPM, it's not because you are losing anything at, say, 1400 RPM... it's the extra burnable fuel just boosts the entire mid/high end drastically.

This is also why on a N/A IDI, the torque drops from 1600 - the engine having a harder and harder time sucking enough air in, less fuel can be burned(per rev) so the torque drops.

...Which all goes to show, if you want power on an IDI, stick a turbo on it and crank up the fuel to match.

 

well, I´m not trying to get HP´s, what I want is TORQUE

at this point I´m calculating what I schould do to get bigger wheels on the truck.

Just bolting them on is one thing, but since the Idea is to go traveling, I prefer to go from dually to srw, and then finding a tire that can handle the weight all by himself, is quiet a thing.

so I´m looking at certain speeds what the engine rev´s are, and try to calculate the same thing for the given future tiresize, so that not too much changes in the drivability.

 

If you want torque chage the gear ratio but the trade of is fuel mileage the higher the number more torque les mpg/kmg

 

Ive always been a firm believer in the adage, "gearing is just compensation for lack of power". Case in point, going from 3.55 to 4.10s in a stock NA IDI is a huge difference. In the race car we blew up the center section, was 456 or 488 cant recall. The only one we had laying around was a 3.55, stuck it in and the car only slowed from 10.30s to like 10.60s. Now that i have my 110 and 362, trying to workout what it will cost to regear to 3.55 or 3.31 from 3.73s (was originally 4.11, but swapped in 3.73 SD axles)

With hp comes torque, hard to get one without the other has hp is a mathmatical equation bases off of torque vs. rpm. If you dont have a turbo, get one, if you have one, turn up the fuel. I promise you wont be sorry you did, seat of the pants feels like twice the power, and its even better if heavy.

 

Well, I like to think more like: HP for speed, and torque to move things.
And since I'm not the speedy speedy type, (as in 100Mph over the autobahn), but I like to move things, like tow tractors or heavy trailers.

But then, My thought behind this calculation (and asking here and there to see what the possibilities are), is that if I decide to go with bigger wheels, say 325/85R16, or 12.5R20, my truck has still the same way of accelerating, or tow this heavy trailer uphill, as it does now on it's standard tires 235/85R16.

For the moment the truck doesn't have a turbo, and over here it's very difficult to get Ford truck pieces (other side of the pond).

Also, and this might be stupid to a lot of you,(for me as well, but it's just like that and nothing else) I bought this truck in 2005, and have hardly driven it since, due to registration problems, but in the next year I found a way to get it (officially) registered, and start driving it!!!!
In the meantime I only maintained it, and drove it once a month around the block untill it warmed up, to keep things supple and lubricated.

Before that time I drove the Dodge that I have for 25 years now.
Nothing wrong with that, (W-200) but my F-350 can load more, and tow more, and that will be a pleasure!

I can't wait to start gathering driving experiences with this huge diesel monster!

so I really appriciate all the help you can offer.

Thanks.

 

Bart
I think in your situation gearing would be better, till you can get back over here and get a turbo.

 

Yep, that's what I thought.

About turbo's, mine beeing N/A, what are the thoughts for a turbo install, any preferences? or things what sure NOT to do???

(just for future reference)

 

If you are looking at new it either banks or hypermax

Ford performance by Banks Power

https://www.gohypermax.com/Catalog.a...e-42f0e0da6da8

 

Thing is... in an IDI, torque and HP are very linked(yeah, I know). In a gasser, you can make a lot of HP without a lot of torque, because it can rev higher. So by doing things that increase your rev limit, you can make more HP, without more torque.

In an IDI, you aren't going to increase the RPM that the engine spins at(for several reasons), so the only way to add HP is to add torque.

Also, an IDI is designed to use the entire RPM range effectively - you don't need to worry about running it at 3K RPM against the governor for hours on end - they'll do it just fine.
However, it *will* suck more fuel doing that.

On the other side, yes, you can effectively drive around at 1200RPM, and should be fine doing it as long as you aren't "maxing out" the engine at that RPM, else your EGTs will skyrocket and you'll probably hurt something.


What you want to plan for in gearing, in an IDI, is the ability to:
1. Get off the line quickly. Realistically, the turbo isn't going to do much below 25MPH, unless you are towing an absolutely massive load. This is where you need gearing(low gear, larger final drive ratio) to change that 300ft-lbs of torque into a lot more, so you can get that 16,000lb trailer moving.
2. Accelerating the load. As you get beyond 25, the turbo will end up pushing a lot more power to the wheels, as you can load the engine down. You want to be able to keep the revs in the 2000-2800 range at all times.
3. Cruising at highway speeds, loaded. Because you are pulling a big load with a lot of wind resistance, you need to be able to keep the revs high enough that you get good power(usually 2k+ with a turbo), while keeping them lower for fuel economy.
4. Cruising at highway speeds, unloaded. Here, you want tall gearing. A 'final drive' ratio in top gear of around 2.43 is optimal(zf5+4.10s+GV Overdrive, ZF5 + 3.55s). With stock tires, this puts you at 1600RPM @ 60MPH approximately, and like 2K at 75.
Interestingly, NA, unloaded, 1600@60 is fine, 2K @ 75 is maxing the engine out.
With turbo, 2k@75 will give you enough extra torque to pull a light/unloaded trailer too(towing at 1600/60MPH however, not going to happen.


I'm not sure if this made any sense or helped... but I'm hoping it did.

 

well, I understand the direction of what you are saying, there is only on thing in your story (maybe actually two things) that isn't compatible with my case, that's a ZF5 (mine is a E4OD) and a turbo, snif, snif....

 

There not nuch differance between the specs on the trannies