N/A IDI Turbo Conversion

[david85]

I'm not aware of any diesel engines that came with domed pistons. Anywhere.

The confusion here might be coming from the fact that modern, direct-injected diesels have lower static compression than older, Indirect-injected diesels. Someone who comes from a gasser background might interpret this as domed vs non-domed. But that's not how it works.

IDIs usually have 20-22 Compression Ratio
DIs usually have 16-18 Compression Ratio

Dynamic compression between the two is similar, because direct-injected diesels will usually run higher boost pressure, thus pumping more air for the same engine displacement. This makes it much easier to get more power per CID of engine displacement with direct injected diesels compared to older IDIs.

However, neither style uses a domed piston.

Indirect-injection uses a pre-chamber that is built into the head, while direct injected typically has a circular recess (or 'bucket') machined into the crown of the piston.

The prechamber is where the IDI injects its fuel, before the flame propagates down into the cylinder. This is done to allow pre-mixing of fuel and results in a better burn, lower emissions, and less engine noise.

Direct injection doesn't need a pre-chamber because higher injection pressure allows for adequate fuel adomizing and mixing. The drawback is a more expensive fuel injection system, and a faster burn that results in a louder ignition knock. Modern diesels can actually pulse the injectors at high pressure to maintain good fuel mix while still slowing down the ignition event to control noise.

 

[MIDNIGHT RIDER]

I am going to offer a suggestion that will make whichever turbo system you use or create a whole lot easier to install and make any future endeavors much easier, plus it will give you many more options as to the what and how of whatever project you may embark upon --- before doing anything else, get yourself either a Borgeson or a Flaming River steering shaft and install a simple two- or three-inch body-lift.

A two-inch body-lift will result in seemingly a mile of extra space around just about any project or repair one attempts, especially turbo and exhaust projects.

Any truck will benefit from getting the body up away from the frame.

The steering shaft will allow you to do so safely.


When I first got my 1985 F-350 6.9, many many years ago, it was equipped with a Hypermax turbo kit.
Out of necessity, there was a big hole cut into the firewall behind and above the turbo.
Special bent wrenches had to be heated and bent some more in order to turn the nuts half-a-hex at a time.
The exhaust crossover input tubing just fit between the engine and firewall and had to be made in jointed sections with the clamps oriented just so, else the clamps would reverberate against the firewall.
Working on or around any part of it was a dreaded nightmare.
Then, I installed a two-inch body-lift and my whole world opened up.

Of course, later, I dropped in the 6BT and everything became a lot easier, but that is another story.

 

[Macrobb]

I like the Banks kits. I put my first Banks(wastegated, what they sell now) kit on my '88, and it wasn't too hard. You do need to bend the cab seam for the downpipe, but other than that it's just install and go. No lift needed.
It makes a *ton* of difference, especially once you crank up the fuel for all the new air. You'll about double the HP available.

Also, with a mild banks kit, they are designed to be bolt-up, no studs needed. Yes, it's extra piece of mind, but not needed. Plenty of idis out there with them, no studs or anything else.
Actually, most any 'mild' kit like that will work the same, it's only once you start pushing 20+psi of boost that you *need* studs.

The auto you have is the E4OD, not the AOD. Completely different transmissions.

 

[Dieselcrawler]

The auto you have is the E4OD, not the AOD. Completely different transmissions.

was waiting for someone to catch that

 

[Hydro-idi]

I like the Banks kits. I put my first Banks(wastegated, what they sell now) kit on my '88, and it wasn't too hard. You do need to bend the cab seam for the downpipe, but other than that it's just install and go. No lift needed.
It makes a *ton* of difference, especially once you crank up the fuel for all the new air. You'll about double the HP available.

Also, with a mild banks kit, they are designed to be bolt-up, no studs needed. Yes, it's extra piece of mind, but not needed. Plenty of idis out there with them, no studs or anything else.
Actually, most any 'mild' kit like that will work the same, it's only once you start pushing 20+psi of boost that you *need* studs.

The auto you have is the E4OD, not the AOD. Completely different transmissions.

If you are referring to head studs, this may be true with a 7.3 idi, not a 6.9. Your on borrowed time when you turbo a 6.9 without headstuds. At the very least, headgaskets and bolts should be replaced if your not going to use studs when you turbo engine.
One of the weakest links with these engines was the original headgasket design. Gasket technology has come a long way. Both VR & Felpro make a great headgasket for these engines.

 

[Macrobb]

If you are referring to head studs, this may be true with a 7.3 idi, not a 6.9.

OP has a 7.3, not a 6.9, according to the first post.

Your on borrowed time when you turbo a 6.9 without headstuds. At the very least, headgaskets and bolts should be replaced if your not going to use studs when you turbo engine.

I still wonder exactly how much is from turboing, and how much is just old age?
Considering I've read a number of posts of people with 6.9s pushing 10+ psi through them, without studs.
That seems a little much, but Banks wouldn't have sold a kit without some *severe* warnings if it was a time bomb, at least back in the day.
And they do sell them for the 6.9.

 

[david85]

Turbocharged 6.9s do fine with stock bolts if you stay below 10 psi. If you're really concerned, you can keep the boost under 7 PSI. But comparing a non-turbo to even as little as 5 psi of boost is already a night and day improvement. If all you want is a modest improvement in performance, you really don't need that much.

As far as longevity goes, the engine may actually last longer due to lower EGTs for the same amount of power produced. Studs are still nice though.

 

[Hydro-idi]

Every 6.9 & 7.3 that I have seen that has not been opened up has had weeping headgaskets. That is the #1 problem with these engines imo. Blowing headgaskets.
When I bought my truck, headgaskets seeped coolant & oil for years before I put new gaskets on during turbo installation.
Long story short, if you have a 6.9 and add a turbo with original headgaskets, you are on borrowed time before one lets go. ARP bolts are even better insurance if you can afford them, since stock 6.9 bolts are notorious for breaking even when trying to remove them lol.
It all depends on when you want to do the head pull, not if.....and where you want to do it. In your garage, or 1,000 miles away from your house in the middle of nowhere because you thought truck would be reliable with stock headgaskets & a turbo.

 

[saburai]

As a new guy, from what I've read, it's extremely difficult, if not impossible to do the heads with the engine in the truck, is that correct? If I were able to R&R the heads in the truck, when we get to Florida, I'd do studs, gaskets and freshen up the heads. I've got a good machine shop down there that I trust not to booger things up.

 

[Dieselcrawler]

then there are us odd ball lucky ******** who throw a turbo on a stock 6.9 with 200k on it, crank fuel up two flats and run it at 12 psi. yes it pushed coolant out externally at high RPM, but a bottle of Kseal fixed that right up. 6 years later that engine is still chugging along. turbo has since been removed, but its the engine powering my 86 in my sig.

 

[Tristan]

So is it the newer style head gaskets that make the bigger difference or the studs?

 

[saburai]

So is it the newer style head gaskets that make the bigger difference or the studs?

??

 

[Thewespaul]

Both make a huge difference

 

[saburai]

Am I correct in that doing the heads/studs in the truck is a no go?

 

[Hydro-idi]

Am I correct in that doing the heads/studs in the truck is a no go?

It depends on your ability & if you have a cherry picker. I had both heads off (in frame) in about 2.5 hours. Had them back on & engine running in 4hrs. That was second time doing it in frame so it was easy for me. An engine hoist is a must.
It really comes down to how far you want to go with your truck & engine. If you want to keep it for a long time & log lots of miles on it, take those heads off, replace HG’s, get heads rebuilt & slap on some ARP’s. It’ll now be bullet proof.
If you plan on using it occasionally or don’t plan to have the truck forever, slap a turbo on er and call it good. When gaskets blow, scramble up some eggs and dump it in the radiator