Cubic Inch

Smoking S

Smoking S

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Nov 23, 2006
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What's the max cubic inch you can get out of a Cummins, Powerstroke, and Duramax? I've heard Cummins is around 450, as for Powerstroke and Duramax i have not a clue.
 
Good question...I am curious to find out how much you can actually bore these 5.9's out to. Doing the math to get 450 cubes out of a 5.9 with out stroking it you would have to bore it out to 4.5" from the stock 4.02"...I would say thats impossible!

With all the R&D that the tractor pullers have put into there engines with increasing Cube's it makes me wonder how many actual Truck 5.9 guys out there are playing with there cranks to get more stroke.

RyanB
 
cubic inches available are directly proportionate to the cubic dollars available.
 
That's something I've always wondered as well. would the 6.7 liter crank drop in with little or no mod into the 5.9?

It was the only think typically missing from a "building a fast motor" thread. The fact the the bore and stroke were always stock. Sometimes compression lowered, but that's it. (at least from a CTD perspective)
 
Yeah I've always wondered why nobody has messed around with boring out a motor? Seems thats what alot of the gasser guys do to make more HP, same w/ pulling tractors...:pop:
 
I started at thread on here about the difference between the 6.7/5.9. Wether it was a simple bore/stroke job, I'll try to find the link....Personally, think of the TQ #'s a Cummins makes stock, then think about the added TQ from stroking it....I would think if it was possible more people would be doing it. I'm not schooled in all the Cummins internal info, was just a passing thought while I was driving down the road last week. Here is that link....I think it could be relevant to this conversation. http://www.competitiondiesel.com/forums/showthread.php?t=15923&highlight=6.7+questions
I just wish I had the money to experiment.
 
I have a 6B block and at this point I am waiting for info on wall thickness. (cyl wall) It is my feeling that there will not be enough meat left to effectively support 4.5" bore. I'll post up and let ya'll know. My thought was that we could maybe bore block for custom inserts bored to 4.5 May have to fill block though.
 
I think 4.2 or so is what some fo the guys are doing with out filling the block. I would not be a big fan of stroking the engine especially if your looking at big rpm.
 
RSieck said:
Yeah I've always wondered why nobody has messed around with boring out a motor? Seems thats what alot of the gasser guys do to make more HP, same w/ pulling tractors...:pop:
Click to expand...

What makes you think nobody is doing it?:hehe:

It's one of those things that no one will speak up and tell all, why give away your secrets sort of a deal.

It is being done...$.02

Now, how large of a bore can you go with? To get from 4.02 to 4.5 you would have to increase the diameter almost 1/2 inch (obviously). The next time you have your head off your block, look at how much space is available between two cylinders. Now take out another 1/2" of material right there, how much room is left for the headgasket to seal up between the two cylinders? If I remember correctly, you can't go that big.

Take a look... not much room available

http://s40.photobucket.com/albums/e228/RedStroke/Superduty Cummins/?action=view&current=100_1330.jpg

Just did a quick search, here's a link to the responses I got last year asking the same sort of questions on tdr.com

http://www.turbodieselregister.com/...igger-sleeves-pistons-cummins-more-cubes.html

STRALEY said you could get to 440-450 cubes, and I would assume he would know, apparently there may be enough room to get that far?
 
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the 6.6 most you can bore it safely is .02-.03 over makeing it a 6.7-6.8 like a 415-420 inch block


i know some one is toying with the idea of putin a 7.8 I-6 d max in a truck.......
 
Yea i would have to agree with what many other ppl have said so far. You bore it out and your not left with much room for the head gasket to seal. When you throw 100 lbs of boost at it something will be bound to give out without that much space between cylinders. Can be done but ur service dollar may increase.
 
Offset grind the crank and some sleeve work... That should tally up some cubes. Just my$.02
 
if you take a 6.7l cummins at 4.21 bore and 4.88 stroke and bore it .20 over you have yourself a 447cid that you could probly use a standard headgasket, just a though.
 
So who will be the first one with a P-pumped 6.7, meaning the new one? Any takers?

-Tom
 
why not just stay with the infinite tuneablity of the CR's put everything off a 5.9 CR and put it in the 6.7L along with a TST and Smarty big a$$ set of twins (or a big single for you Tom) and call it a pulling champ! No replacement for displacement!
 
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