compression question for possible 6.9 build

[Sir AxleRod]

Wasn't in any way taking away from the Knowledge of the Grand Poo-Bahs of this forum, the are a chief part of the reason I am here. I do think, that fresh ideas could be slightly more welcomed... It's your money, if you have the $8k to **** away on the R&D diesel site, building a 400/800 6.9... Rock out with your c**k out....

I think more and more, these engines are like a 6.0. Taken care of, and not modded to the 9's, they will be an enjoyabole and venerable powerplant.

Try for stupid power Expect to throw Stupid money at them..

 

[icanfixall]

Then stop referring to them the way you do as grand poo bahs... You seem to have a tone of arrogance in your posting.

 

[turbo elk]

Wasn't there a guy named Dave Sponougl. (I know I'm spelling his last name wrong) that took off like .30 off his pistons? Lived in WV. had TONES of power, and no problems starting well below zero dead of winter?

 

[IDIoit]

Mel has done the time to be considered a VITAL part of the IDI community.
with my dealings with him, and the issues i had, he in no way shape or form EVER gave me the "IM HOLIER THAN THOU" attitude.
your "king" comment is unfounded.

people have been building these engines for over 3 decades. these engines have proved to be reliable and easy to work on, this is why the 6.9/7.3 are put on pedestals.
not the people that try to make your life better, at their own cost. i suggest you actually do business with someone before making assumptions.

ok, as far as performance goes on these engines, i have done ALOT of research, i too want to build a better IH IDI, some of my threads end up the same.
"cost vs. benefit" if you have the cash, you can RESPECTFULLY ignore this. you can lower the compression to some extent, but you run the risk of lowering it too much
and be fully prepared for the "oah ****" moments.

pistons are cut on a lathe and or mill everyday. not only should you do more research, but you should also be keen on metallurgy and machining.

Gary, i disagree with your comments about the pumps, while a Bull moose is a great pump, to gain substantial power as what was asked by the OP, yioure going to need the 130 or 205 cc pump Mel carries.

if youre going to run one of these "super pumps" you better have deep pockets. not only for the pump itself, but for supporting equipment.
i have not been apart of this IDI family for too long, but im trying to read as much as i can so that i too, one day can have a IDI worthy of ripping down the 1/4 mile with decent times.

numerous threads on "badasss" 6.9's many of them have been caned.

while boost is great, the age old saying stands IMHO
NO REPLACEMENT FOR DISPLACEMENT

 

[marmot]

It baffles me that people would even consider taking an indirect injected 30yo design 200hp V8 diesel and try to tweak it up to over 500hp when for half the money you'd spend doing it you could transplant a DI cummins and have 700hp with almost no engine work. I appreciate the simplicity, ease of wrenching and reliability of these old mills and I am glad I own one. But there is a very real problem with v8's that limit them in high torque high rpm diesel applications, it was already alluded to in the above discussion about dampeners...V8 motors are not naturally balanced. In a v8 due to the 45 degree application of torque there is a tendency, especially under the high torque stresses of a diesel, to create a harmonic spring mass system in the crank (Imagine twisting a spring and having it spring back) which can wreak havoc breaking cranks, busting bearings, etc. In a 6 IL diesel there is virtually no spring mass created because the application of force is 90 degrees to the crank. That is one reason people can turn up the hp so high on a near stock cummins. You could re-engineer a 6.9 block, crank, dampener etc etc if that turns your crank but to me If you want high torque use a motor that is designed to produce it. That said I am fascinated with the people who do take on this type of project and respect their choice to do so. Always fun to watch.

 

[riotwarrior]

Wow....Hmm..

Guess all those guys who kept working on flathead V8's were the kind that would baffle you too eh marmot?

I mean once that engine was stock...why bother hot rodding it beyond that. Oh then there is that other enigmatic engine known as a SBC, guess pouring $ and time into it did nothing...Oh then there is the Coyote engine and now lets talk cummins...people pour money and time into things why...because THEY want to....

It's not about this engine better than that ...

Nope it's about I like this...NOT THAT

Hey why spend money and time on a old OBS or bullnose truck when you could get a new one and have less work...

JM2CW

 

[Waystro]

Wow....Hmm..

Guess all those guys who kept working on flathead V8's were the kind that would baffle you too eh marmot?

I mean once that engine was stock...why bother hot rodding it beyond that. Oh then there is that other enigmatic engine known as a SBC, guess pouring $ and time into it did nothing...Oh then there is the Coyote engine and now lets talk cummins...people pour money and time into things why...because THEY want to....

It's not about this engine better than that ...

Nope it's about I like this...NOT THAT

Hey why spend money and time on a old OBS or bullnose truck when you could get a new one and have less work...

JM2CW

Very well Said.

 

[marmot]

Guess you missed the point of my post. I am 100% for hot rodding motors and if you notice the last sentence of my post that should be evident. And I really admire the people who do it. My point is that in a DIESEL application a 30yo V8 design has some inherent engineering limitations that come into play when you are stacking up big torque numbers. And it is going to take $$$ to get around them. I mean knock yourself out and spend 150k to make a 1000/1500 tri turbo/supercharged MeOH/water propane injected idi I am sure it is possible and I would love to see that happen if it turns your crank(ie you WANT TO). But it is quite possible to spend less than half that on an engine that is better designed to make those numbers and will reliably produce them. Not hating on hot rodding in any way I spent quite a bit of money on wringing HP from obsolete motors over the years. Not hating on anyone...and I WILL NEVER BUY A NEW VEHICLE AGAIN EVER!!!! I like my fleet of 79'-99' vintage diesels. Now go make some horse power boys.