Anyone every bored out a cummins 5.9 for more power?

[DPelletier]

Rather than write a page long response (I wrote a paper on turbocharging in University), I'll just say that Vaughn, Rusty and the others are right. You CAN make up for displacement by feeding more air. Period. To put it in perspective, adding 5 - 6 pounds of boost (and the corresponding additional fuel) would be the same as increasing the displacement up to about 450 ci. Or to look at it the other way, boring the engine to say 370 ci, would be roughly equavalent to adding less than 1psi of boost (and fuel).





Dave

 

[Rman]

Dave have a copy of your paper handy? Fun stuff to read. I got to thinking of the cubes thing. If you left your turbo alone, left your fueling alone but simply raised the cubic inch size of your engine... would any thing happen? Would you actually lose power? This would lean out the mixture (assuming all things equal). It'd be interesting to see what exactly happens when simply cubic inches are increased.



Wouldn't boost pressures be lowered as well?



That's it, i'm punchin my block and doing analysis! (i wish)

 

[Forrest Nearing]

don't get me wrong... cubes are good... very good... a 450cid engine at 150psi is gonna make a lot more power than a 359cid at 150psi.



the question is how far can you bore a 5. 9 and still maintain wall thickness required to HOLD the power you're wanting to make...



untill that is answered, we're just line dancing...

 

[RustyJC]

Originally posted by rhickman

Dave have a copy of your paper handy? Fun stuff to read. I got to thinking of the cubes thing. If you left your turbo alone, left your fueling alone but simply raised the cubic inch size of your engine... would any thing happen?

Increasing engine displacement with no turbo changes would be the same as putting a smaller turbo on your current engine. What would the effects be if you went from, say, an HX35-12W to an HY35-9W? More boost and quicker spool on the low end (the turbo/engine match effectively moves lower on the engine's RPM curve), but higher EGTs, high drive pressure and lower air mass flow on the top end.



Rusty

 

[Forrest Nearing]

if you increase displacement without increasing the turbo (or cylinder head flow) your peak power numbers will increase a little... torque would go up and come up quicker and the turbo would spool up quicker...



generally you need to increase cylinder head flow (and intake/exhaust manifold to match the head) to correspond with the increase in displacement to really make the engine "bigger", and, of course, the turbo will need to be spec'd for more volume, or you'll be off the map.



Forrest

 

[F8LDOSE]

you can get pistons in . 020 and . 040 overbores, but i believe . 020 is the most you want to go. I certainly wouldn't bore your block unless you need to clean up the cylinders. To bore your block properly you need a deck plate. This is a problem i ran into, and hardly anybody has one..... $1000 later i do.

 

[F8LDOSE]

you can get pistons in . 020 and . 040 overbores, but i believe . 020 is the most you want to go. I certainly wouldn't bore your block unless you need to clean up the cylinders. To bore your block properly you need a deck plate. This is a problem i ran into, and hardly anybody has one... . two months later i finally got one, and their not cheap.

 

[akdiesel]

I was under the assumption that a 6b and 6c were essentially the same block with different size cyl. liners. Could you maybe turn it into a 6c by changing to 6c liners making it an 8. 3L? (I understand that the stroke may be different on a 6b)

 

[Forrest Nearing]

stroke is different and the B series is a parent bore block... no liners.



Forrest

 

[akdiesel]

Thanks for the correction!

 

[Forrest Nearing]

if anyone's interested, I've got a standard bore C series liner sitting here, and the wall thickness is ~. 2474"



that's pretty dang thick, but I know diesels need thicker cylinder walls than gassers, and when cylinder pressures start getting really crazy (big boost), thicker is better!



not sure what the B series cylinders spec out at. I'd be interested to learn.



I'd imagine a set of custom pistons with these dimensions would probably cost a pretty penny, and ultimately, cylinder head/intake/exhaust flow dictate power, cubes just dictate what RPM you make that power at... (course, with a diesel, there's a point where more RPM won't make more power due to the diesel combustion process, but more boost and fuel sure will!)



that's how guys can get 1,000+hp out of a turbocharged 289 small block. lotsa boost and a little RPM. (and like I said, a little boost and LOTSA RPM will get you 1,500+hp out of a 1. 3 liter engine)



Forrest

 

[Rman]

I punched a 460cid . 060 over and the walls weren't even close to that thick. I wasn't charging the intake at all though, N/A. I had such a low rpm cam anyway it was a torquey thing but had no top end. I used it for a rock crawler.

 

[JDailey]

Forrest-you are correct about wall thickness. The sleeves for my big inch B are . 272" thick. I would not bore a block any over . 020". The pistons I am using aren't custom or expensive. $300 for pistons and sleeves.



rhickman-if I am udderly wrong, prove it to me. I don't care how it looks on paper. And I could care less about thermodynamics. I have seen and worked on lots of engines... . gas and diesel... . small ci to big ci... ... if everyone else has more inches than you..... you will LOSE.

 

[Rman]

Originally posted by JDailey



rhickman-if I am udderly wrong, prove it to me. I don't care how it looks on paper. And I could care less about thermodynamics. I have seen and worked on lots of engines... . gas and diesel... . small ci to big ci... ... if everyone else has more inches than you..... you will LOSE.

You just answered you're own question. You "don't care" and you could care less about thermodynamics. Well sorry you wouldn't be working on diesels, or even cooking in an oven without thermodynamics.



So you're telling me that a 460 cid engine... will always beat a 302 cid engine? I have a buddy that would sure put that to shame with his.



His blown 302 would knock the pants off of a 460, even with nitrous... guess why??? that blown 302 has the power of a N/A 762 cid block... . how??? thermodynamics and charged air.



You have to know these things and I don't understand your arguement.



I do concede that all other things equal... a larger CID will always perform better than a smaller one. But that's just it, charging intake air is the variable, something much MUCH more easily changed by adding larger and larger turbo's than it is to punch a block and insert bigger pistons (ok sometimes it's harder but i mean the intrusiveness)



How else can I prove this if you're unwilling to reason?

 

[TxDieselKid]

I think in HillJack School thermodynamics is how to use a microwave.



But man do those hilljacks know how to build a pulling truck or tractor.



So tell me how Stonehenge was built?

 

[98rammer]

how about havin' some maturity and keeping the personal attacks down. interact, you may not always be right, or everyone else may be wrong --however, be respectful.



as far a the area of the piston with force-the bigger the more force-that's true. but is that necessarily as true with air than with liquids (the principles of hydraulics, considering that those fluids are only compressible to a much smaller point than air).



regardless of the boost #'s, you still need colder air (more density). having an extra 10 pounds of boost going into your motor (at higher boost #'s generally speaking) wouldn't be good if your charge air went from say 150* to 400* for horsepower numbers.



just too many ways to look at it...



Tom

 

[Rman]

there sure is a lot of ways to look at it. 9 times out 10 the bigger the better... but the 1 time the little guy goes screamin away from ya. How? sure isn't magic, or is it?



p. s. what personal attacks?

 

[DPelletier]

Ever see a 231ci Buick Grand National turbo blow away a 302ci mustang GT. I have. Lots of times.



Dave

 

[Rman]

Since I was in highschool i wanted one of those. Those twin turbo V6's can scream. There's one or two around here that I've seen. There was a write up in Super Chevy mag a while back on one.

 

[JDailey]

No personal attacks from me.



rhickman- I don't doubt a blown 302 couldn't smoke a 460. But a blown 460? Don't think so. Equal to equal, or close to it..... big inches will win.



I understand what you are saying about adding more air. That is easier and cheaper than boring and stroking, no doubt about it. But, you reach a point where adding fuel and air isn't enough. An engine can only take so much and live. Then you need to go bigger. cold air is a must. That is where water comes in. You are right..... there are to many ways to look at it. See, I can reason with ya!



TDK-what's a microwave?? lmao