Does anyone stroke diesels like gassers?

Everybody else is running billet blocks larger displacement then 5.9 an sigma pumps, last I checked ben was not running the superior sigma fuel system.
 
Moremph said:
Everybody else is running billet blocks larger displacement then 5.9 an sigma pumps, last I checked ben was not running the superior sigma fuel system.
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Not everyone in the mod class was running billet blocks for the 2010 season.
 
It not as easy as welding the crank and just cuttin the tops of the pistons. if you only wanted to stroke it like .05 maybe then you would only cut .025 off the piston. put why waste the money on that. If your gonna do it i would do at least .250. And there is no way there is enough thickness aboce your top ring to cut off .125 and still deal with the heat. you'll pop the top off that piston. So you would have to have a custom piston made with a shorter comp ht. also a bigger bowl to lower the compression back down if need be. just my .02

chris
 
BigErk77 said:
I believe there is a happy medium of displacement and turbo size. With many hours of research and testing, im sure someone with proper funding could come up with a physics/calculus graphical analysis with displacement/ turbo size/ horsepower/ torque relationships for various engines ie. I-6 and v8's are different animals.

Here is what I am getting to... a 2.0L diesel engine with a 2.6 charger will make less power than a 5.9L with a 2.6 charger, so more displacement = more power, right? how about that same 2.6 charger on a 16L diesel? The 16L diesel will be damn near naturally aspirated with such a relatively tiny charger. So at what point does the replacement for displacement become air compression? If I knew the answer to that, I wouldn't be digging holes for a living. haha! I would be interested in any input or additional comments on this train of thought. If I am blowing smoke feel free to call me out, I'm just thinking on a keyboard.



This is only really to be considered by pullers trying to get as much power as possible with a limited turbo size because if turbo size is not a restriction, bigger is better for displacement and turbos!
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There is so much wrong here I don't know where to start. A 2.0 with a 2.6" charger, once spooled will make way more power then a 5.9. It all comes down to area under the curve, the 2.0 will have a very short power curve versus the 5.9....
 
GRotman said:
There is so much wrong here I don't know where to start. A 2.0 with a 2.6" charger, once spooled will make way more power then a 5.9. It all comes down to area under the curve, the 2.0 will have a very short power curve versus the 5.9....
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So are you saying with a turbo being the limiting factor, a smaller displacement engine is better, provided the turbo is lit?
 
Take for example a 6.7l cummins with a 66/74/14. It will make on average 75hp less than a 5.9l with the same charger, but it spool 300-450 rpm faster.
 
GRotman said:
Take for example a 6.7l cummins with a 66/74/14. It will make on average 75hp less than a 5.9l with the same charger, but it spool 300-450 rpm faster.
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I'm glad you picked up on how I alluded to false information with the small motor and big turbo, but there was a point to it. The replacement for displacement is air compression. With a turbo being the limiting factor in pulling, a smaller motor would be more desireable as long as it can spool the charger (no limit on rmps, eh). Which leads me to the question, why do people want more displacement?

I know this now leads to the hp vs torque argument and area under the curve but does area under the curve really matter in pulling? Let me rephrase that, does power under 3k rpms really matter in pulling?

Now it gets interesting...
 
I think it's because more displacement will move more air if you can reach the rpms. Essentially, a motor is a giant air pump, the more air you pump, the more power it will make. Smaller motors are great if they can move the same amount of air as a bigger motor, which some do because the rev higher. Thats why bigger motors spool bigger turbo's easier, they move more air.

I think.
 
BigErk77 said:
I'm glad you picked up on how I alluded to false information with the small motor and big turbo, but there was a point to it. The replacement for displacement is air compression. With a turbo being the limiting factor in pulling, a smaller motor would be more desireable as long as it can spool the charger (no limit on rmps, eh). Which leads me to the question, why do people want more displacement?

I know this now leads to the hp vs torque argument and area under the curve but does area under the curve really matter in pulling? Let me rephrase that, does power under 3k rpms really matter in pulling?

Now it gets interesting...
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With a cylinder head that flows as badly as a cummins head, absolutely rpm comes into play as well as cubic inch.
 
NickTF said:
More common in naturally aspirated stuff, diesel or gas. Not so necessary when you can cram 40-300psi of air into the motor.
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BigErk77 said:
....The replacement for displacement is air compression
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Again, just not needed. Like Glenn said these heads suck and unless you can feed the beast why increase its size. There are always exceptions to the rule but I would think it is safe to say 90% of those frequenting this board will find their money spent wiser on more air than displacement increases.
 
It really comes down to what you are looking to do with the engine. A relatively low rpm street motor will benefit from the added displacement by spooling faster and making more torque, with the sacrifice of some horsepower given the same size turbo as what you would run on a 5.9.
 
NickTF said:
Again, just not needed. Like Glenn said these heads suck and unless you can feed the beast why increase its size. There are always exceptions to the rule but I would think it is safe to say 90% of those frequenting this board will find their money spent wiser on more air than displacement increases.
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GRotman said:
It really comes down to what you are looking to do with the engine. A relatively low rpm street motor will benefit from the added displacement by spooling faster and making more torque, with the sacrifice of some horsepower given the same size turbo as what you would run on a 5.9.
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You could go to all the trouble of few hundreths of an inch more stroke or look into some of the variable geometry products hitting the market. Wanna guess which is easier and 1/50th the cost? :p
 
GRotman said:
It really comes down to what you are looking to do with the engine. A relatively low rpm street motor will benefit from the added displacement by spooling faster and making more torque, with the sacrifice of some horsepower given the same size turbo as what you would run on a 5.9.
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Exactly. Thats the thing, on a low rpm street truck you can simply just get a bigger turbo... I was talking about limitations on a turbo size such as in pulling. So more displacement is not better. Getting the head to flow (p+p, bigger valves, fly cut pistons, big cam, etc.) is more important, then stacking it with a stock displacement 5.9.

A "street truck" probly wouldnt be stroked anyway since it is just a street truck, it can do just as much if not more with a set of twins and injectors for alot less money.

This is what I wanted to get to but didn't think anyone would catch on to a theory that says less displacement = more power. Glad we are on the same page.
 
I'm not sure how excited I'd be about stroking one of these, the piston speed is already pretty damn high as it is. Maybe look into boring it? Might run out of room quick though I can't remember the specs...
 
i believe .06 is max overbore but dont quote me on that. piston speed isnt that high actually. Especially since you consider someone that is gonna do this is probabaly gonna run a mahle piston or some sort of good forged aftermarket unit. and high rpm on these is 6000. we run a drag car at 8200 rpm with a 4.250 stoke. thats pretty high speed. these are only what, about, 3.56-3.58 stroke?
 
mprmn08 said:
i believe .06 is max overbore but dont quote me on that. piston speed isnt that high actually. Especially since you consider someone that is gonna do this is probabaly gonna run a mahle piston or some sort of good forged aftermarket unit. and high rpm on these is 6000. we run a drag car at 8200 rpm with a 4.250 stoke. thats pretty high speed. these are only what, about, 3.56-3.58 stroke?
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With a stock 5.9l stroke (4.72"), I get worried about piston speed somewhere around 7100rpm.
 
i wouldn't increase stroke but bore maybe, i know i wouldn't have if the block was in good shape when i went to rebuilt my motor last year. but my trucks is just a street truck but it's bored .040 over and it's instant tq with stock turbo and 4.10 but i love it.
 
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