if you want to lower your compression then just have your stock pistons machined down .040 that will drop it a few. if you live in a cold area then you are going to have to use spray either to fire it up. the drop in compression will make it a lot harder to start no matter how good your glow plugs are. if you tried to get down to 18:1 that the psd is, you'll never fire it. you would need either, glow plugs, block heater and a intake heater.

 

hahaha..... we all want 350hp, but its not gonna happen. twin turbo isnt needed at all, you can WAY overboost with a single turbo. these arent high hp engines, and 350 is HIGH. the money it will take to get that out of a idi, you can build 3 psd's. believe me, im workin on a 6.9 build already. best ip and injectors alone will run you 2k. expect a build to cost around 7k for that power

 

what is the most we can push on these engines without breaking the bank???? i just want it to pull like crazy i pulled about 10,000 LBS of logs 45 miles and on flat ground it was ok uphill..... forget about it dogged down like crazy was screamin in 4th gear but was still loosing speed

 

be happy with 225hp or so. thats with a turbo, cold air intake, intercooler and free flowing exhaust.

 

350 horse out of an idi?i honestly dont think you can build a "dependable idi thats pushing that HP.for what its gonna cost you to get 350 hp you can buy a psd or even an older cummins and sink a little cash in it and make over 350hp all for what it would cost you to build an undependable idi.the idi was not built to go fast it was built to work and last forever.im not trying to persuade you to bu another truck im just letting you know what you will be getting into by even attempting to build up an idi.im waiting on a "certain person"to chime in on this.he has probably the most modified idi on here

 

First question about propane PSI.
That depends on what size orfice you run.

As for wanting 350 HP, you have to think for a minute, that is almost double the HP of a stock NA IDI engine.

In the day, all three of the turbo manufacturers claimed up to a 50% power increase.
So that takes a stock 185 HP engine up to 277 HP, if the fuel system and supporting mods are done and the boost is kept at a safe level for the engine.

There were a couple pistons on that page that would work.
But that brings up the next BIG question.

This engine is new to you?
Do you know if it has had SCA's added to the coolant and been kept at proper levels from day one?

Stock bore on a 7.3 is 4.110".
Cavitation is a very real thing.
The pistons on those pages ran from 4.110" to 4.150" for the bore size.
So they ran from stock to .040 over.

In my opinion you may get away with .010 or maybe even .020 over on your cylinder size if you know for sure the engine has had SCA's from day one.
If you overbore an engine without knowing that, you are asking for trouble.
You bore into a cavitation hole, you now have an expensive and heavy boat anchor.

I bought a reman 7.3 turbo from a national rebuilder.
I blew three of them up in 14 months.
They were bored 20 over, 4.130" bore.
They sent me a fourth engine under warranty, I tore it down while it was still bolted to the shipping pallet, then refused to install it since I saw the same problems in it as I had in the other three after they blew.

After a couple months haggling, I got a buyout on the engine.
I took that money, bought a salvage yard 6.9 and built my own engine.

If I had know then what I know now, I would have done things a little different.

First, I would not have milled the pistons, that costs fuel mileage and a bit on bottom end torque untill the turbo starts to spool.
Second, I would have kept the boost under 20 PSI, going higher brings out problems with blown intake/valley pan gaskets and blown exhaust manifold gaskets as well as leaking exhaust system joints between the exhaust manifolds and turbo.

Remember the IDI engine was never designed to run boost, let alone high boost.
That and the high base compression ratio makes high boost hard to make reliable.
6.9 at 22.5 to 1
7.3 at 21.5 to 1

Now lets look at a Stroke engine, 18 to 1 compression ratio.
Put 30 PSI of boost to it, 54.73 to 1 effective compression ratio.

If you put 21 PSI of boost to a 6.9 the effective compression ratio is 54.64 to 1.
If you put 22.5 PSI to a 7.3 the ratio would be 54.4 to 1.

Now let me tell you that very few 94 to 97 Strokes are running 30 PSI of boost.

If you add up the rebuild and parts you need there, then the machine work required, head studs, twin turbo's, intercooler and an IP and injectors that can support your other mods do you know how much money you are looking at?

I will through out a number, 10,000 dollars.
And that has you doing a lot of the work yourself if you have the tools and place to do it.

I did all of the tear down and assembly on my engine, I have 4500 in it for parts and machine work, with no intercooler or twin turbo setup.

 

and thats the guy i was waiting on.lol

 

what kind of torque can i expect if i stay in the 12lb range? i just want a strong puller i don't want to dog and a grade with only 10,000 lbs behind me.... not when knowing i can take a 6.7 and pull up the same hill gaining speed.... i know its probably comparing apples to oranges but i love my idi its the first heavy duty iv'e ever personally owned.... im never going to get rid of it but i was looking into building this one up or just buying a new truck and having both once im out of school and finish the basic officer course after ROTC ill be farming and moving alot of very heavy equipment

 

Ahhh, the old, slow, steady workhorses, wasted on the young...... LOL

Want to go fast? Buy a newer truck. Want to have cheap, reliable transportation that is easy to maintain in the driveway? Keep your IDI.

 

I totally agree grey, and I'm only 26.


well, as far as the idi tq vs 6.7l..... Spend the 50k on the 6.7l because you aren't gaining any speed on a grade with 10k behund you unless it's under 5% and that's with a tail wind. I understand wanting power, hell we all do. But it will never be the 6.7, it will never be the 6.4 or the 6.0 nor the 7.3psd. BUT you can fee good as you wave goodluck to them on the other side of that hill as they just broke down AGAIN and you will have another 100k miles under your belt

 

thats not what im getting at.... im saying that load weighed 10,000 LBS and i dropped from 60 to 45 in a very short distance..... what if that weighed the 24,000 LBS we pulled with the stroker 50 miles to the scrapyard...... wouldn't have gotten anywhere.... its not about going fast its about having the power to safely move the load

 

Who cares about the power to safely MOVE the load? I want the power to STOP it. Anyone pulling 24K with a pickup is looking for trouble. It's not a semi, it's a pickup!!

For me to legally pull 24K I have to have a commercial truck (and driver's) license, annual safety on truck and trailer, paperwork done daily, and not be overloaded on any combination of vehicle, trailer, axles, tires, etc.

I am licensed for just short of 20K gross combined weight with my dually, but maximum legal tow weight is 10K pounds. I still have to have a pile of paper to be legal, and a bunch of other things, including a fire extinguisher, flares, triangles, and a first aid kit. I also have to do a circle check each day and document it.

I pulled across the scales with my dually with a net of 7980 pounds Friday. Hauling what is called 'modified B', which is a sand gravel mix, with stone up to 2". My gross weight with that load is pushing 8 tons. Even with that, I will not haul that kind of weight into the city or high traffic areas, just too many chances of things going wrong. I have new drums, shoes, lines, booster, master cylinder, front rotors, calipers and pads all less than three years old at any time when I haul these kinds of weights. The brake maintenance alone costs me about 5-600 a year.

If you watch a semi, they slow down hauling up hills too, it's part of basic gravity and physics.

 

I know it's not on topic, but DAMN do you learn a lot about these trucks reading some of these threads...

Just throwing it out there, 23, and love my idi.

 

Funny how most of us have to learn the hard way. I myself overbuilt many an engine in my youth and broke many a drive train part because of it. Too much muscle under the pedal only leads to the temptation to use it... and if you use it at the wrong time stuff breaks.

 

Pulling 24K with any IDI will have the gross up around 31K, a full 5000 pounds over what you can pull with a non CDL drivers license.

As for the pulling 10,000 pounds gaining speed on a 5% grade like the 6.7 does, the 50,000 dollar truck is exactly what it is all about.
Remember a 10,000 pound load, plus the weight of the truck, you are looking at around 18,000 pounds gross.
18,000 pounds is nothing to sneeze at with a 16 year old one ton truck.

375 HP and 735 foot pounds of torque just won't happen with an IDI engine.
If it does, every time you mash the skinny pedal, you can count on some serious drive line repairs.

I know my engine is strong, but not that strong.
I just took some spagetti looking drive shaft, a broken transfer case that I split in half and a bunch of broken axles in for scrap a while back.



I've seen that way to many times.

Makes you feel a little funny when you use a vice to press the U joint caps in the yoke.
Six months later you pull the snap rings out and the caps fall out from gravity alone.

My max gross weight is usually under 20,000 pounds, which is what I am licensed for, and they cost me enough every year I have no desire to go higher.
Also my commercial insurance to cover 20,000 pounds is considerably more than what normal pickup insurance costs.
That said, I have also exceeded that every once in a while by a couple thousand pounds.

Busted for over 26,000 pounds, I would never take that chance, it gets to expensive.

The 99 and up trucks did get a rather good upgrade to the driveshaft.

So bottom line, if you want to gross 20K pounds and run up an 8% grade at 70 MPH, go on down to the local Ford dealer and sign up for 1000 dollar a month truck payments for the next 6 years.
Don't forget those large insurance payments that go with the truck payments.

I myself, can go a lot slower and leave that cash in my pocket.