Pre-Power Stroke Diesel (7.3L IDI & 6.9L) Diesel Topics Only

Interesting article on the IDI's. Got some questions for you guys.

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Old 08-18-2016, 06:05 PM
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Interesting article on the IDI's. Got some questions for you guys.

I found this article and thought it was pretty cool. It gives a history on the 6.9/7.3.
Ford Diesel Truck - Diesel Tech - Diesel Power Magazine

As I was reading a few questions came to mind. I was hoping that you guys would be able to help me understand a bit more.

In 1984, the 6.9L engine's compression was increased from 20.7:1 to 21.5:1, raising torque to 338 lb-ft at the same low 1,400 rpm. Horsepower did not increase. (from 170hp

From 1988 to 1992, 7.3L engines made roughly 180 hp at 3,300 rpm and 345 lb-ft at 1,400 rpm.
Only a 10Hp and a 7lbs torque increase. Maybe its just me, but this seems like a very little difference. I thought the 6.9 and 7.3 had about 50hp difference and 50lbs torque.

From what Im understanding, a turbo charged 6.9 gives out much better performance than a 7.3IDI.

However, the article says that "7.3L 190 hp at 3,300 rpm and 388 lb-ft at 1,400 rpm" Thats a significant increase in torque, but not so much on Horsepower.

What I don't understand is how a turbo PSI affects HP and Torque. Is there a formula? Wouldn't more PSI mean more torque and HP?

Unfortunately the article didn't say anything about 'a 6.9 performance when a turbo is added on. So im left wondering what my 6.9 8psi turbo is pushing in hp and pulling in torque


"It is not uncommon for a 6.9L or 7.3L outfitted with a turbo, intercooler, freer flowing exhaust, and a little fuel pump work to make 325 flywheel hp"

Here is where I am lost. How can I tell if the truck that I just purchased has an intercooler? If it does not, what is its function?

"freer flowing exhaust". I remember the ad of my truck said it had a down pipe connected directly to the turbo. I think thats a freer flowing exhaust right? It was a 3" diameter.

As for fuel pump work. Since I had bad luck already with the electric fuel pump that it came with, and my mechanic is currently switching it back to a mechanical pump, how would I increase fuel delivery on a mechanical pump? If possible, I would like to avoid electric. That means id have to switch back and i dont think thats a good idea. That 325hp sounds reeeeallly nice.

Year: 1993-1994
HP: 185 hp at 3,300 rpm190 hp at 3,300 turbo
Torque: 360 lb-ft at 1,400 rpm


Woohooo! Looks like my work Van skipped the early 180hp and 345 torque version of the 7.3. I wasn't gonna buy a turbo for it anyway, but now I can give a reason other than "i just don't wanna spend the $ into that truck".
 
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Old 08-18-2016, 06:18 PM
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Originally Posted by Resendiz
What I don't understand is how a turbo PSI affects HP and Torque. Is there a formula? Wouldn't more PSI mean more torque and HP?

Here is where I am lost. How can I tell if the truck that I just purchased has an intercooler? If it does not, what is its function?
Boost (PSI) increases the air density in the combustion chamber allowing more fuel to be burnt more efficiently, thus more power.

When you compress air, it builds heat, hot air is less dense. An intercooler is a radiator looking thing that cools the charged (compressed) air down, thus increasing density.

-Enjoy
fh : )_~
 
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Old 08-18-2016, 08:18 PM
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Originally Posted by Festus Hagen
Boost (PSI) increases the air density in the combustion chamber allowing more fuel to be burnt more efficiently, thus more power.

When you compress air, it builds heat, hot air is less dense. An intercooler is a radiator looking thing that cools the charged (compressed) air down, thus increasing density.

-Enjoy
fh : )_~
Its a radiator looking thing next to the turbo? I dont see one
 
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Old 08-18-2016, 09:02 PM
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You likely don't have one ... They are typically in front of the radiator.

None of the IDI trucks came from the factory with an intercooler, those of us that have them have done a custom install.

-Enjoy
fh : )_~
 
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Old 08-18-2016, 09:42 PM
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This is an Intercooler.
And this is the thread about the truck's conversion:
https://www.ford-trucks.com/forums/7...onversion.html
 
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Old 08-18-2016, 10:07 PM
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Originally Posted by Resendiz

"It is not uncommon for a 6.9L or 7.3L outfitted with a turbo, intercooler, freer flowing exhaust, and a little fuel pump work to make 325 flywheel hp"

Here is where I am lost. How can I tell if the truck that I just purchased has an intercooler? If it does not, what is its function?
You don't have one. You'd know it if it had one.
Originally Posted by Resendiz

"freer flowing exhaust". I remember the ad of my truck said it had a down pipe connected directly to the turbo. I think thats a freer flowing exhaust right? It was a 3" diameter.
Do you have your truck? Or is this something you plan to buy? Why are you referencing the "ad" for your truck? Why not just go outside and look at your exhaust. "freer flowing exhaust" doesn't mean your down-pipe. it means getting rid of the stock muffler and putting something like 3.5 or 4 inch exhaust with a hi-flow muffler on it.
Originally Posted by Resendiz
As for fuel pump work. Since I had bad luck already with the electric fuel pump that it came with, and my mechanic is currently switching it back to a mechanical pump, how would I increase fuel delivery on a mechanical pump? If possible, I would like to avoid electric. That means id have to switch back and i dont think thats a good idea.
For your concerns, the fuel pump ain't gunna matter. Unless you are running an R&D IDI Performance IP with 110cc, you won't need anything more than stock or an e-pump. What brand is your e-pump? Frankly, if I were you, I'd stick with the e-pump. I went epump on both my fuel systems and I'll never go back. So much easier, simpler, and less of a mess to deal with than the stock lift pump. (some guys like the mech pump for RPM reasons tho, I'll let them pitch it for you.)
Originally Posted by Resendiz

That 325hp sounds reeeeallly nice.
Don't get your hopes up.
Originally Posted by Resendiz
Year: 1993-1994
HP: 185 hp at 3,300 rpm190 hp at 3,300 turbo
Torque: 360 lb-ft at 1,400 rpm


Woohooo! Looks like my work Van skipped the early 180hp and 345 torque version of the 7.3. I wasn't gonna buy a turbo for it anyway, but now I can give a reason other than "i just don't wanna spend the $ into that truck".


On this forum, you have posted a few recent posts that have me inferring that you desire massive HP. What are you trying to accomplish? Hauling? Work truck? Towing? Racing? Why do you need so much horse?

Look, the formula is pretty simple. You take a typical IDI engine, install studs, install a turbo, add an innercooler, pull off as many belts as you can, get better exhaust, upgrade the IP, upgrade the diesel filter system, and get a set of new injectors. Then time it. That's about it. And even if you do all that, you probably won't exceed 350HP. If you got the money, then just do it already. But what concerns me about your original post are the words "my mechanic." If you ain't doing this work yourself (especially something as simple as reinstalling a mech lift pump), then maybe you are dabbling with an engine that you should just buy new. The cost of the IDI performance parts PLUS the cost of having a mechanic do the work will never stay cheaper than just buying a 2017 truck.
 
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Old 08-18-2016, 10:16 PM
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Originally Posted by awhtx
This is an Intercooler.
And this is the thread about the truck's conversion:
https://www.ford-trucks.com/forums/7...onversion.html
I definitely don't have one of those, but will get one. Thanks for the link!
 
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Old 08-18-2016, 10:33 PM
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Originally Posted by genscripter
You don't have one. You'd know it if it had one.

Do you have your truck? Or is this something you plan to buy? Why are you referencing the "ad" for your truck? Why not just go outside and look at your exhaust. "freer flowing exhaust" doesn't mean your down-pipe. it means getting rid of the stock muffler and putting something like 3.5 or 4 inch exhaust with a hi-flow muffler on it.

For your concerns, the fuel pump ain't gunna matter. Unless you are running an R&D IDI Performance IP with 110cc, you won't need anything more than stock or an e-pump. What brand is your e-pump? Frankly, if I were you, I'd stick with the e-pump. I went epump on both my fuel systems and I'll never go back. So much easier, simpler, and less of a mess to deal with than the stock lift pump. (some guys like the mech pump for RPM reasons tho, I'll let them pitch it for you.)

Don't get your hopes up.




On this forum, you have posted a few recent posts that have me inferring that you desire massive HP. What are you trying to accomplish? Hauling? Work truck? Towing? Racing? Why do you need so much horse?

Look, the formula is pretty simple. You take a typical IDI engine, install studs, install a turbo, add an innercooler, pull off as many belts as you can, get better exhaust, upgrade the IP, upgrade the diesel filter system, and get a set of new injectors. Then time it. That's about it. And even if you do all that, you probably won't exceed 350HP. If you got the money, then just do it already. But what concerns me about your original post are the words "my mechanic." If you ain't doing this work yourself (especially something as simple as reinstalling a mech lift pump), then maybe you are dabbling with an engine that you should just buy new. The cost of the IDI performance parts PLUS the cost of having a mechanic do the work will never stay cheaper than just buying a 2017 truck.
I bought the truck about 3 weeks ago. the electrical pump caused me to stall and die twice. So i sent it to the mechanic to have it removed. Maybe E pumps are better, but the very little experience with one, has made me feel like i cant count on it. I saw 2 other E pumps in the bed of the truck so I assumed he was having to replace them repeatedly. Maybe a bad brand im sure.

I am getting info and messing around with this truck for 2 reasons. I like old looking trucks and I can spend what I want since its so cheap. Over time im sure It will add up, but right now im just glad i have a personal vehicle again (its been years). I have had 6 IDI's now. 4 Uhauls (7.3) and 2 6.9 pick ups, my avatar and my f350 now. This is the only engine that I know, and I don't know much. These engines have been with me through thick and thin, call me crazy. I feel a bond with this engine. Ive replaced fuel lines, air filters, belts, batteries, minor suspension work, glow plugs, fuel pumps, gaskets, thermostats, radiators, relays, rebuilt 3 engines (paid for) and done very little work. I don't want to learn any other engine since I don't have time. My mechanic does/will do what I can't/wont be able to. He works on big rigs. I feel like im wasting his time working on small things like this, but when its beyond my knowledge, ill just hire him.

I don't have much knowledge on 6.9 performance enhancing, most were just uhaul work trucks. So im finding out all i can so that when im ready to put $ down, I know exactly what im getting into. I may definitely be spending more on this truck than Its worth and will never see a return on the investments, but thats now why im doing this. It's just gonna be a fun project.

EDIT: Also, to answer your question, I plan to use it to tow my future RV that im planning for on Christmas and just have as a bad *** truck.
 
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Old 08-18-2016, 10:40 PM
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400 torque and 250-275 horsepower would be high hopes. To be honest, I'm fine with the truck as is. Anything extra is just a bonus.
 
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Old 08-19-2016, 11:58 AM
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ahhhh. I was totally confused, cuz I thought I remembered your name from prior posts, but then you were posting all these HP questions about a new truck. So my mind went sideways and thought you were a noob or someone else. My bad. Disregard my latest comments, except about hte e-pump and R&D.

Nice about the RV. Once I finally swap out my leaking 7.3 for my spare 6.9, and replace the short block for the 7.3, I'm gunna start shopping around for airstreams here in Socal and Arizona. Gotta find some snow bird that kicked off so I can get a deal on a zero-rust trailer. Are you going 5th-wheel or trailer style? Or are you converting your U-haul to be a custom RV?
 
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Old 08-19-2016, 04:32 PM
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400 torque and 250-275 hp is readily done with the addition of a turbo, free flowing exhaust, free flowing intake, and tuned up injector pump.
i prefer no muffler. for intake i run a 6637 rite into the turbo. pump is tuned for very slight haze at full throttle, and timing is bumped 2 degrees if i remember correctly. this gives me best power and fuel economy.
 
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Old 08-19-2016, 05:53 PM
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Originally Posted by genscripter
ahhhh. I was totally confused, cuz I thought I remembered your name from prior posts, but then you were posting all these HP questions about a new truck. So my mind went sideways and thought you were a noob or someone else. My bad. Disregard my latest comments, except about hte e-pump and R&D.

Nice about the RV. Once I finally swap out my leaking 7.3 for my spare 6.9, and replace the short block for the 7.3, I'm gunna start shopping around for airstreams here in Socal and Arizona. Gotta find some snow bird that kicked off so I can get a deal on a zero-rust trailer. Are you going 5th-wheel or trailer style? Or are you converting your U-haul to be a custom RV?
I thought about an airstream, but they are pricey and they dont expand. But, man do they look nice.
Looking for a 5th wheel, I figured since I have a dually might as well. My uhaul is for work only, no conversion.
 
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Old 08-19-2016, 07:25 PM
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Remember that flywheel HP is always higher than wheel HP.
250 wheel HP is going to be somewhere over 300 flywheel HP, due to losses in the drive train.
To put it another way, wheel HP numbers are smaller for the same actual driving power.

250 HP at the wheels isn't too hard to get; you can get somewhere near that with just a Banks Sidewinder kit(10-ish PSI boost) and cranking your pump up. You might even be able to get away without studs; some around here have done that for years.
The reason that the stock engines(especially the stock factory turbo engine) don't have much extra HP compared to the older versions is simple: Emissions and/or not wanting to undermine the Powerstroke. They literally did not turn the IP up, so you end up running really lean and not using the extra air. Add as much fuel as you have air, and you'll get a bunch more HP and torque easily.

And if you can get a /lot/ of air and fuel in there, you can get a /lot/ of HP and torque, until you hit the 450WHP/1000Wheel torque range and you just break connecting rods...
But there's a lot of ground between a NA motor making 100-120 HP at the wheels(180 at the crank) and 450 at the wheels.
 
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Old 08-19-2016, 09:43 PM
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Originally Posted by Resendiz
I found this article and thought it was pretty cool. It gives a history on the 6.9/7.3.
Ford Diesel Truck - Diesel Tech - Diesel Power Magazine

As I was reading a few questions came to mind. I was hoping that you guys would be able to help me understand a bit more.

In 1984, the 6.9L engine's compression was increased from 20.7:1 to 21.5:1, raising torque to 338 lb-ft at the same low 1,400 rpm. Horsepower did not increase. (from 170hp

From 1988 to 1992, 7.3L engines made roughly 180 hp at 3,300 rpm and 345 lb-ft at 1,400 rpm.
Only a 10Hp and a 7lbs torque increase. Maybe its just me, but this seems like a very little difference. I thought the 6.9 and 7.3 had about 50hp difference and 50lbs torque.

>> nope they just cut .4 liters of displacement off of the cylinder walls .. not any change in stroke or big change in pump or anything .. it seems like a poor way to get 10hp to me .. because the thinner walls invite bites from the 'block worms' .. though there were some real improvements also .. better rocker arms ( easily swapped out of a 7.3 donor into a 6.9 as i have done ) and bigger head studs ( just gotta live with that .. and the resultant lower turbo capability with a 6.9// limited to 10-15 psi safely .. some have gone higher .. i cannot say i have a NA )

From what Im understanding, a turbo charged 6.9 gives out much better performance than a 7.3IDI.

However, the article says that "7.3L 190 hp at 3,300 rpm and 388 lb-ft at 1,400 rpm" Thats a significant increase in torque, but not so much on Horsepower.

What I don't understand is how a turbo PSI affects HP and Torque. Is there a formula? Wouldn't more PSI mean more torque and HP?

Unfortunately the article didn't say anything about 'a 6.9 performance when a turbo is added on. So im left wondering what my 6.9 8psi turbo is pushing in hp and pulling in torque

>> yep u can do a turbo .. but like i say thhere is a limiting factor of 7/16 head studs on a 6.9 the 7.3 is 1/2 inch .. other then boost potential there is no real appreciable difference in the motors ..

"It is not uncommon for a 6.9L or 7.3L outfitted with a turbo, intercooler, freer flowing exhaust, and a little fuel pump work to make 325 flywheel hp"

>> yep like Tom said .. open intake / exhause / no rest muffler .. ect .. add a turbo if u like .. that's about it .. also r&d has some performance pumps and injectors .. though you know i'm sure from having owned several other .. that a high speed truck is unlikely .. they are fast enough for a truck .. for me NA is plenty fast enough .. it's only a little slow off the line .. it just gives onlookers a few more moments to gape in awe at the awesomeness of a ford they wish they had ..

Here is where I am lost. How can I tell if the truck that I just purchased has an intercooler? If it does not, what is its function?

"freer flowing exhaust". I remember the ad of my truck said it had a down pipe connected directly to the turbo. I think thats a freer flowing exhaust right? It was a 3" diameter.

>>3" is ideal .. the intercooler is an 'air radiator' that cools and densifies air coming from that hot impeller that was next to the exhaust and spinning wheel .. these make heat and that drops the performance gain to a degree .. the intercooler re-densifies / cools that air .. and as a great bonus .. if your wheel somehow shreads or you get some debris in it .. the pieces go into your intercooler instead of your engin e .. it's a rare occurance .. but it can / does happen from time to time ..

As for fuel pump work. Since I had bad luck already with the electric fuel pump that it came with, and my mechanic is currently switching it back to a mechanical pump, how would I increase fuel delivery on a mechanical pump? If possible, I would like to avoid electric. That means id have to switch back and i dont think thats a good idea. That 325hp sounds reeeeallly nice.

>> everyone has a n opinion about fuel pumps .. i like mechanical everything .. fuel pump especially .. they just work for 20 years then they break .. so just remember it will need replacing but probably not for awhile .. that's my opinion .. your milage may vary .

>>probably not gonna get 325 .. but hey .. maybe . . it's all about tq not hp anyway .. is it gonna outpace a new bmw .. on a good day ?/ never ..

>>but you can pull over the bmw owners' house with a chain .

Year: 1993-1994
HP: 185 hp at 3,300 rpm190 hp at 3,300 turbo
Torque: 360 lb-ft at 1,400 rpm


Woohooo! Looks like my work Van skipped the early 180hp and 345 torque version of the 7.3. I wasn't gonna buy a turbo for it anyway, but now I can give a reason other than "i just don't wanna spend the $ into that truck".
i'm just gonna type a little bit more because it said

'the message you typed was too short .. please lengthen to 10 characters'
 
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Old 08-20-2016, 08:19 AM
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on the electric fuel pump: most people put the mr gasket or similar E-pump on and then badmouth the e-pump conversion when the cheap pump dies.

the problem is the use of a cheap pump.
if doing an electric fuel pump conversion on a diesel, you need a pump designed for extended diesel use, like the facet dura-lift pump designed for use in refrigerated trailers.
i have a dura-lift 40285 on my 88 for the past 300,000 miles.
if it ever dies i will replace it with the 40222 pump, because this one has a 9-11 psi rating instead of the 4-7 psi of the 40385
 


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