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Discussion Starter · #1 ·
Hello fellow IDI owners! I have always gone to the internet and used the resources to help me work on my 7.3 idi turbo. I have never spoke out or engaged in conversation on the forums about the IDI's.
I have had the truck for 6 months now and I've got it modified the way I like it and have some goals for it. I want to eventually get a intercooler set up along with a new IP and injectors. Before I do that, I have been trying to achieve 15 psi of boost and no more. I am just me, but I want to be sure to get 15psi before I dump any money into a intercooler. I have short ram air, deleted the squashed piece of the downpipe, muffler deleted to have the air flow in and out nicely and I have the waste-gate shut completely. My injection pump has been turned all the way up on the fuel screw and the torque screw backed out to where I like it, unloaded i get about ~4-5 psi and ~700 to 800 egt cruising 70mph on the highway, no smoke. But on the cruise nights in my town, i like to do hard 3rd gear pulls. It will blow smoke, take about a second to spool up and I can hit about 10 to 12 psi fairly quick all day long. I know increasing boost without an intercooler will not help me much because of the heating of compressed air. I would believe that the stock turbo is small enough to get more boost, and I have kept aware for leaks on the hot side especially at the y collector, but see no leaks there. I looked for possible obvious leaks on the cold side where the intake hat connects the turbo and the manifold and everything is snug. The hole in the back of the manifold is also tight. I am not trying to be like the powerstrokes and the cummins hitting up to 30 or 40 psi of boost, but I just want to know why this engine has such a difficulty increasing the boost? Is it due to high compression or the stock turbo not made to handle that kind of boost?
Thanks for any response or input!
 

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but I just want to know why this engine has such a difficulty increasing the boost?
Don't know as it has a "difficulty". The mfgrs chose a turbo designed to be compatible with the 7.3 engine. A retired FoMoCo factory engine guy used to be a member here and he stated that with Ford's research and development they found the longevity of an internal engine component was shortened when boost was raised over 10 PSI. In other words, it showed premature failure over the long term. And I could drag out my original ATS turbo installation and info and quote where ATS found with their R&D in engine stands, etc, that you actually lose pulling power and performance by increasing boost over their factory setting. One of the reasons they mention is that the designed in cylinder scavenging effect is destroyed when boost is modified.
These things make a sorry excuse for a dragster anyway. A few guys on another site took their 7.3 turbo IDI's to a drag strip and they turned a blistering 67MPH, even the new gas engine 1/2 ton Ford, Dodges, and Tundras all turn 94+ according to Car & Driver mag.
 

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He didn't say what size exhaust he has, or if it's a 3" down pipe. Increasing the exhaust from 2-1/2" to 3" might get another 1 pound of boost, any increase size over that is useless.. But to achieve 15 PSI boost, you have to being going uphill in WOT.

But he better have an EGT gauge.
 

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Discussion Starter · #4 ·
He didn't say what size exhaust he has, or if it's a 3" down pipe. Increasing the exhaust from 2-1/2" to 3" might get another 1 pound of boost, any increase size over that is useless.. But to achieve 15 PSI boost, you have to being going uphill in WOT.

But he better have an EGT gauge.
I have an EGT gauge for sure. My down pipe and exhaust is 2.5". But I am trying to find out why can't I achieve 15 psi on flat ground and not up on a hill? It will take a good 5 or 10 seconds for it to climb to 13 or 14 psi while on a hill.
 

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I have 3" outlet housing and 3" exhaust. Pulling a hill with the fiver hooked on, go pedal mashed (1225 EGT) I only see about 11.

Max boost will be under heavy load at Max throttle. I limit my RPMs to 2600-2800 when climbing a hill.

It ain't about speed with these mules, it's all about longevity. Forget about 15 psi, be happy that it will start and run every time you turn the key so you can tow your buddies home when they break down.
 

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Max boost will be under heavy load at Max throttle. I limit my RPMs to 2600-2800 when climbing a hill.
Right, maximum boost is strictly dependent on the volume of exhaust gas. Maximum volume is increased on any diesel only when pulling hard at power producing RPM, in this case, 2600-2800. Sounds like he just hot-rods around town not towing a load.
 

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Interesting stuff, my factory IDI turbo is unmodified, I'm happy with it. If I needed more power I'd just go power stroke.
 
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Interesting stuff, my factory IDI turbo is unmodified, I'm happy with it. If I needed more power I'd just go power stroke.

Only reason I did anything was because I towed a big fiver. Factory turbo came with 2 1/2" outlet and smashed downpipe. I was able to get the ATS bigger turbine housing, outlet housing and DP. It does spool faster and my EGTs are lower.
 

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A couple years ago I rode in a dreaded 6.0 liter Powerstroke. The owner was a mechanic and had torn it down completely and modified/changed all the horrible things the 6.0 liters do plus hopped it up. He got on it on a remote open road and that thing was really impressive to put it mildly compared to my IDI. A guy I know has a chipped, etc, Duramax and his dad said the power it puts out is flat scary.

Only reason I did anything was because I towed a big fiver. Factory turbo came with 2 1/2" outlet and smashed downpipe. I was able to get the ATS bigger turbine housing, outlet housing and DP. It does spool faster and my EGTs are lower.
Which only made sense and was a logical improvement IMO since ATS designed the system with the 3" outlet and 3" exhaust with straight through muffler. Word back then from Ford dealers was that Ford derated the power with the smaller exhaust to prevent overheating when towing. Not one of their smarter moves.
 

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Only reason I did anything was because I towed a big fiver. Factory turbo came with 2 1/2" outlet and smashed downpipe. I was able to get the ATS bigger turbine housing, outlet housing and DP. It does spool faster and my EGTs are lower.
Sounds like a good and worth while mod to get existing turbo breathing easier. I tried to get the outlet housing but couldn't find one. I did change out the downpipe to a round one but did not increase the diameter.
 

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I think Chuckster and others said the outlet housing is no longer sold. I guess the only option is find a 093 ATS turbo system at a wrecking yard and buy the outlet and 3" exhaust. As a sidenote, I bought one of the first 093 kits produced, in fact ATS said it was approved, but so new they hadn't received the CARB paperwork from CA. After installing it, I had to phone ATS with a complaint. Just off idle when going slow through a parking lot, or down my pot-holed dirt road the turbo whine was so loud it would get my white trash neighbor's German Shepherds howling when I went by. After the owner of ATS quit laughing, he said yeah, you're right, we're working on a computer designed muffler that will cancel most of it out. He said he'd send me a new one if I would ship the old one back, which I did, quickly.
 

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My Hypermax just barely pushes the needle past 10psi when I'm goofing off on a long up hill. EGTs right around 1100, give or take. Cruising a 70 its about 3-4psi and 600deg. Funny, it will jump 2 psi when the cooling fan kicks in.

A Powerstroke it is not. I've been for beat runs in a high modded(turbo, studs etc) 6.0L. Things that large should not move that fast.
 
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Check out R&D, this guy was able to turn his truck into a 350+Wheeled HP and 740 Wheel ground pounder. Granted, using the stock turbo's that come with the ATS kits, and the factory kits don't produce a whole lot of anything other than smoke, boost and noise if they're the non-waste gated set ups. Anything over an average of 10PSI does in fact shorten life spans, as R&D will tell you, it's fairly easy to blow head gaskets on these trucks at those levels, but once you stud them, ring them and shave the piston tops. It's fairly easy to build power.

If you really sit and think about it. The Banks kit back when new pushed the IDI to Powerstroke level of performance by simply adding a turbo. The 7.3 is, dollar for dollar just as difficult to build power out of as the IDI. Injectors cost 250 bucks a piece for stock replacements...performance replacements are...at best, 500 bucks for a full set? It makes sense when you sit down and think about it. I owned a stroker and it's not all it's not all it's cracked up to be.
 

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What do you want? Diesel engines never were designed to go fast. They were designed to pull. Just plain stock, and with the right gearing behind them these engines will pull a house up a hill, just not very fast. If you want to go fast, get a gasoline engine, and build it to the hilt. The gas engine is the race horse, the diesel engine is the work horse
 

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What do you want? Diesel engines never were designed to go fast. They were designed to pull. Just plain stock, and with the right gearing behind them these engines will pull a house up a hill, just not very fast. If you want to go fast, get a gasoline engine, and build it to the hilt. The gas engine is the race horse, the diesel engine is the work horse
Absolutely, and the component that fails from overboosting over the long term is NOT head gaskets according to Ford's research back in the day.
 

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I agree with you. To a point though. Although there are many people mostly younger kids that are now buying these Cummins powered or diesel powered trucks want to go faster in a quarter mile than the Lamborghini I am not one of those people my point of you is I want more power to be able to tell more efficiently such as not going up a mild grade with a 10000 pound load doing 35 when the speed limit is 60 or 65 because at that point you become not only a hazard but a danger to all other drivers who may or may not be able to tell that you are going much slower than other traffic
 

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I have NO problem going up a hill at 20 MPH pulling my trailer. If I hold traffic until a safe place to pull over, too bad...so sad.

Have I been given the "salute" as I let people go by, but the majority wave and say thank you. I disagree that I am a "hazard", and at least out here most steep long grades have a truck lane.
 

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I would much rather keep with traffic. Not race them but at least not impede the flow. Though I am curious. Anyone ever put a turbo on their truck? Curious not only for the benefits of lower engine temps but also for ease of install since full kits are hard to come by anymore
 

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I have the factory turbo on mine.
I haven't really encountered many rude or impatient people when I pull 18,000 pounds up a hill. I am just like any other OTR truck...getting there the best I can.

Since I never had a non turbo engine, I can't say the turbo lowered temps vs. N/A.
 
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