6.9 rebuild time

[hesutton]

The limiting factor are the head gaskets for sure! I remember a thread that talked about this topic, but I can't quite remember what was said. What is the best way to go as far as head gaskets that are actually manufactured or are available?

Hypermax has "C" firerings and a matching headgasket for these IDI's. Those "C" rings have been used and are being used in pulling tractors making way more than 150psi of boost pressure. Eric has them on his IDI build, but like stated above, still waiting to hear how they hold up with the S400.

Heath

 

[bike-maker]

I am aware of those C-ring gaskets, but IIRC the price on them was approaching redonkulous

 

[hesutton]

I am aware of those C-ring gaskets, but IIRC the price on them was approaching redonkulous

The price for a set on a DT is not bad ($300 or so). For the IDI, I haven't seen/read it. Sounds like they are pricey eh?

Heath

 

[trapper]

last i heard wasn't they a grand ?

 

[hesutton]

last i heard wasn't they a grand ?

Just found some info on the Hypermax head gasket/c-ring kit $860. Wasn't expecting it to be so much. But, they are supposed to be reuseable. Tractor pullers using that design reuse a set for several years and multiple rebuilds. Still, that is a lot for headgaskets/c-rings.

Heath

 

[trapper]

that is quite a bit but if your building a high boost engine it may be worth it

 

[grog85]

I still believe that you should be able to push 25-30 psi into an idi with studs and stock gaskets, with good machining on the heads and deck. Following the NMB2 story for results,but its promising. You shouldn't have to lower the comp ratio at these boost levels to keep it running.

 

[trapper]

if i remember correctly nmb2 also said he was running something other than stock head gaskets in one of his posts

 

[bike-maker]

I believe NMB2 is running some sort of experimental head gaskets that are not yet available; but thee is a good chance that these are one of the "new products" that Ken @ DPS will have coming out some time this summer.
So no one ever answered my question; what happens when you have too high of compression in a diesel. Everyone has always said that you need to decompress an IDI to run more boost. What would be the result of running too much boost with stock compression assuming the head gaskets had the capability of holding up?

 

[grog85]

On the high-compression side of it,I've never heard of anyone running more than 22:1 (I may be wrong). But I know of one Cummins running 21:1 with 80 psi making 890 hp, I know its a whole different animal, but with studs and a good gasket an IDI should be able to hold up reliably under more boost than most people have run. And you're right Trapper, I forgot that NMB2 was running a different gasket as stated. Thanks for the correction.

 

[Diesel JD]

I believe NMB2 is running some sort of experimental head gaskets that are not yet available; but thee is a good chance that these are one of the "new products" that Ken @ DPS will have coming out some time this summer.
So no one ever answered my question; what happens when you have too high of compression in a diesel. Everyone has always said that you need to decompress an IDI to run more boost. What would be the result of running too much boost with stock compression assuming the head gaskets had the capability of holding up?

Good question! I would expect it would just be a lot more dynamic pressure on everything and that at some point (we don't know 550 psi, 600, 650?) and X_2 level of boost (20? 25? 30? 35psi?) we'd find the next weakpoint or the whole bottom end would become unglued. That's an educated guess. As far as a build, I would use a stock set of Victor Reinz gaskets coated with Hylomar as RLDSL does on his builds. I'd then use a turbo that can be adapted to a 6.9 without too much trouble and throw down 20 psi and still be on the map with room to spare. NMB2 thinks that a slightly modified ATS 093 can do this, and that is also what Dave S on FTE is running. At this point also stud the exhaust manifolds and intake, really only a small extra cost and copper coat or hylomar coat the intake runners/valley pan as well. Trapper, I hate to say this man, but unless you can find some New Old Stock, there are no longer any low compression pistons made for the 6.9. Here's what you could do about that: Option 1: Get some standard 6.9 pistons and mill off enough material to get the CR down to around 20.7:1 like the "A" higher emissons 83 and early 84 6.9s were. You need to talk to Mahle or whoever manufactures your pistons to see how much you can cut off the top without compromising the integrity of the piston. Icanfixall asked Mahle but I can't remember what they told him nor the resultant CR. Option 2: Find some NOS factory 83-early 84 6.9 A pistons. This might work well especially if your engine is in good enough shape that it doesn't need to be bored over. These might already be tough to find though. Option 3: Have some 6.9 low comp pistons custom made to your specs. The cons to this are you'll be paying for a one of part and you'll be the guinea pig to see if it holds together. If I went this far I'd drop the CR to about 18.5 or 19:1 and get the piston pin holes made especially to accept 7.3 IDIT rods. I don't know what the effects of 19:1 CR would be. It would certainly be less powerful at equal boost levels but with the potential to take a lot more without breaking stuff. I like NMB2's build for retaining the high CR for maximum power and minmum emissions but even with 10K miles I'm still not convinced that it will last like it should. Even if it blows up though how are we to say it was his build that caused it? That engine already has had a full life and probably well over 100K hard miles on it. We're probably not going to prove in this lifetime the durability of something like that unless we had another member who did work similar to what Oldmisterbill used to do hauling stuff around the country with an IDI and putting 200-300K miles on them in just a couple of years. And does it really matter if they don't have a 300K mile life span? In my almost 8 years of owning the truck, it's my DD and I have taken some short roadtrips with it and have only logged about 70,000 miles on it. It would probably be a lot of years before I'd wear out even a slightly weaker than factory 6.9 or 7.3

 

[88 Ford]

Hypermax has "C" firerings and a matching headgasket for these IDI's. Those "C" rings have been used and are being used in pulling tractors making way more than 150psi of boost pressure. Eric has them on his IDI build, but like stated above, still waiting to hear how they hold up with the S400.

Heath

Those definitely seem like the way to go. $860 is a lil expensive but is worth it I'm sure. Do they require head work?

 

[hesutton]

Those definitely seem like the way to go. $860 is a lil expensive but is worth it I'm sure. Do they require head work?

No head work at all. But, the block does need to be machined to accept the rings. They set in the block and the drop down onto them with Hypermax's special headgasket. Per the info I was given, that gasket is just to keep the coolant and oil in there separate worlds, not to hold compression. The rings do that job.

Heath

 

[trapper]

I'm running the low comp turbo piston from them and milled 14 thousands off the tops.. then ceramic coated them with CBX from Tech Line in Murriata Ca.... Works for me so far....


this is what i found searching a little from icanfixall

http://www.dps-performance.com/media/sounds/DIESEL.WAV

apparently this is a sound clip from kens 19 - 1 idi