The IDI Myth Thread....
..)... I feel its time for a thread that is dedicated to exposing the myths of the IDI engine...I have made a positive effort as far as every interest I have, to blow the conventional wisdom out of the water... Some things have done just that, and some have proven the status quo... I would like to use this thread as both a tool to explain the current status of the IDI, as well as a medium to solve the issues we all agree are problems with the platform.
This is not a forum for contention, but a forum for exploratory ideas only... You can disagree, but keep things civil.... The exchange of Ideas will prevail... That is my goal with this thread... hopefully we can all come to an agreement...
IDI injectors are set to different pop pressures depending on code...
All the codes pop at the same pressure.... I haven't had a set yet that popped consistently different than another...
Also, the nozzles/pintles themselves, are not different, aside from manufacturers...
The IDI block flexes enough to pop freeze plugs out...
No, the IDI block is one of the stoutest I have seen... However the Freeze plugs are the ****tiest I have seen...
Compare a BBC block to an IDI block sometime...
Reality: have been proven to handle 350+hp for extended periods of time meaning thousands of miles
Nope.... 2.81whp/cc is actually pretty damn good, even being a V8 diesel... That's better than most powerstrokes... Nothing there to say IDI is a limiting factor...
can it happen? yes.
does it happen regularly? no
i have seen ONE 7.3 suffer from cavitation in the past 28 years, and that was on a 3 year old truck that was used and abused every day of it's life. in 3 years the truck had 165,000 miles put on it with only 3 oil changes, and still had the factory coolant in it. .
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Fact: It's the same engine! A 7.3 is a bored out 6.9.
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power doesn't come from smoke and mirrors.
myth: advance the engine timing as much as possible beyond 8 BTDC to gain lots of extra clatter because that's where the power and fuel economy is for all idi's regardless of the setup.
the more fuel you provide the engine with,the lower the timing wants to be.
myth: the idi's oil cooler was over engineered and therefore you'll never need to worry about oil temps when adding a turbo to a n/a idi.
the '93 and '94 turbo engines received an oil cooler with more cooling fins.
i had to installed an aux air oil cooler to keep oil temps below 240° (at the pan) on the grades.not only were the 260°+ oil temps no good for the engine,but it transferred the heat to my coolant,bringing down it's efficiency and putting needless stress on my cooling system.
myth: the 7.3l is so legendary that god used it to start the rotation of the earth.
this ones likely true.scientist just haven't proven it yet.
can it happen? yes.
does it happen regularly? no
i have seen ONE 7.3 suffer from cavitation in the past 28 years, and that was on a 3 year old truck that was used and abused every day of it's life. in 3 years the truck had 165,000 miles put on it with only 3 oil changes, and still had the factory coolant in it. .
Both 7.3's I have (Jigblock and my IDIT) had perfect jacket-side cylinders, I saw no evidence of cavitation. I know that my IDIT hasn't been taken care of per the rule book either...
I think cavitation is a freak of nature core shift occurrence, exasperated by a bore job on a crappy block...
I think I posted in my thread recently, but by gasser standards (Yes I know...) Jigblock has plenty of meat for an overbore... It could probably go .020" over and take as much as my IDIT has.
I agree, cavitation is a way overblown issue...
I don't care what sort of BS has been passed down the line... You simply do NOT need to cycle the studs...
My IDIT had 4 steps done on it, and a finish pass, it was even less than the instructions I pass out to my stud customers.... 85,105,125,150... It has arguably put the test on things as far as stock compression goes, and I never had one HG issue, even at 34psi and 180+cc of fuel...
You don't need to tighten/loosen the studs five times, that's uneeded wear and tear on the gasket... The studs don't stretch, they are NOT TTY head bolts....
Tighten them once and forget it...
Myth: get a 6.9 because they don't suffer from cavitation. They are immune.
Fact: 6.9's do cavitate, and pumping toxic waste through your block (instead of clean coolant of the correct type and under the correct pressure) will have the same corrosive and catastrophic results... Eventually.









