5.9 cr or 6.7 for conversion?
- Thread starter skav
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tylerdillard
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I'm pretty sure bean has also. Several have had issues. The problem being is a 6.7 has a larger bore and a powdered rod and make alot more torque at lower rpm and it can cause the rods to wad up causing a nice little window in the side of ur block. I don't know the plans of this guys motor but if I was building one with high hp goals it would have a set of 12 rods in at at least or a good set of R&Rs or carrillo. But what do I know?
tylerdillard
New member
5.9s have already been proven. Look at your high hp pulling motors. My truck, Tyler Witt,Rodd Tarr,Brad Ingram. All run 5.9. I know mine has atleast 100+ runs on it makin over 1000hp and hasn't been touched except for oil changes
If the 6.7s are cracking the block, nobody is talking about it.
http://www.google.ca/#q=cummins+6.7....,cf.osb&fp=7fa77273176bc956&biw=1366&bih=613
http://www.google.ca/#q=cummins+6.7....,cf.osb&fp=7fa77273176bc956&biw=1366&bih=613
Radio
New member
I just read a thread the other day on another site about a guy chuckin a rod on a 6.7. He had twins and nozzles i believe.
forcefed6.4ford
New member
Its not a matter of the block cracking as it is about the rods giving out and windowing the block. Like Tyler said. If you are planning on a big #'s build. Ditch the stock rods and run 12v or carrillo's
tylerdillard
New member
tylerdillard
New member
Bean apparently has had some issues in the 6.7s with 12v rods.I wasn't aware of that. I just knew in a 5.9 they seem work pretty decent
forcefed6.4ford
New member
Just read that too.
But he is also pushing way harder then anyone would on a daily driver set up.
But he is also pushing way harder then anyone would on a daily driver set up.
I don't think there is anything wrong with the 6.7 parts. I think the 6.7s make more power.
http://www.competitiondiesel.com/forums/showthread.php?t=94914&page=2
Furthermore, none of this comes into play with street truck power levels.
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tylerdillard
New member
Maybe he wants to make more than 700 hp I dunno. I just know what I would do but opinions are like ass holes,everyone has one. I just think yours stinks
LOL agreed DD a 400hp truck is a thing of the past.
There are lots of 6.7s around with stock block and rods making 6-700 HP. I've been watching for failures and they aren't common.
I think the 6.7s build better boost at lower RPMs due to more air flow from more displacement. That allows more fuel at lower RPMs and thus stresses things more.
It wouldn't take much in EFI-Live to keep the fuel rate down at lower rpms. It would be easier on the transmission too.
I'm building a tow pig engine. I'll probably go with a stock fuel system, a single large turbo and tune with EFI Live. I'm shooting for 450HP/900 ftlbs at the flywheel, all day long, which I am sure the 6.7 is more than up for.
The OP asked about a 5.9CR which I am sure is no stronger than a 6.7. 12V is another story, but I wouldn't want to run one in my truck.
I think the 6.7s build better boost at lower RPMs due to more air flow from more displacement. That allows more fuel at lower RPMs and thus stresses things more.
It wouldn't take much in EFI-Live to keep the fuel rate down at lower rpms. It would be easier on the transmission too.
I'm building a tow pig engine. I'll probably go with a stock fuel system, a single large turbo and tune with EFI Live. I'm shooting for 450HP/900 ftlbs at the flywheel, all day long, which I am sure the 6.7 is more than up for.
The OP asked about a 5.9CR which I am sure is no stronger than a 6.7. 12V is another story, but I wouldn't want to run one in my truck.
tylerdillard
New member
The OP asked about a 5.9CR which I am sure is no stronger than a 6.7. 12V is another story, but I wouldn't want to run one in my truck.[/QUOTE]
This has been my debate the entire time is that a 5.9 CR is stronger being that the 6.7 has a longer stroke,longer stroke equals greater rod angle. More of a rod angle means more stress on rods and rod bolts. Still the 6.7 is making more power at lower rpm causing greater cylinder pressure. U say remove fuel to compensate for less power down low. So I don't see the advantage now. I'm sure at 450hp it'll never be an issue but that might as well be a stock motor. Alot of your guys aren't wanting a 450hp at the crank motor. The OP said something about twins so I would think he had higher hp goals in mind. Yes I'm aware there are several higher hp 6.7s without failure but it's a risk I don't see worth taking. If u do the research it is several rod failures that have happened.
This has been my debate the entire time is that a 5.9 CR is stronger being that the 6.7 has a longer stroke,longer stroke equals greater rod angle. More of a rod angle means more stress on rods and rod bolts. Still the 6.7 is making more power at lower rpm causing greater cylinder pressure. U say remove fuel to compensate for less power down low. So I don't see the advantage now. I'm sure at 450hp it'll never be an issue but that might as well be a stock motor. Alot of your guys aren't wanting a 450hp at the crank motor. The OP said something about twins so I would think he had higher hp goals in mind. Yes I'm aware there are several higher hp 6.7s without failure but it's a risk I don't see worth taking. If u do the research it is several rod failures that have happened.
forcefed6.4ford
New member
It is a huge deal depending on the application. 500hp daily driver? Not really. But once you start throwing twins and more fuel at it, it start to become a concern. Mild builds for a CR push upwards of 750-800hp. I would definitively look into aftermarket rods with any twin set up on a 6.7.
Bean
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Rod failures are happening at anywhere from 600-1000hp. Yes there are some that are running fine at 800hp without problems but that doesnt mean you can go out and twin one and expect nothing to happen. 600hp and down, would not be scared at all to run a 6.7 there. 600-800, getting into the brink zone could be fine could chuck a rod. 800+ its only a matter of time.
Differance is there are plenty of 1000hp 5.9's on 12v rods that do not break rods. You wont find many 6.7's doing that without billets.
Differance is there are plenty of 1000hp 5.9's on 12v rods that do not break rods. You wont find many 6.7's doing that without billets.
Jason
New member
I'd venture to say Sean is wanting upwards of 600, seeing as his 7.3 makes almost 600 at the tires as it is....
There's nothing wrong with wanting to build a 400-450 hp diesel...not everybody wants to build a 1000hp truck. That's the problem with the diesel community now IMO, if a guy comes in and wants opinions on building a reliable 450hp dd, guys start trying to get him into bigger injectors, a huge ass single...then that single could get a little laggy if you want to tow, so maybe a set of compounds to help spool when towing etc. Some guys just want a little more kick to their dd while being stone stock reliable, and be able to tow to the trucks limits, without ill side effects.
Me2, stop jacking threads, with ideas, and what you plan to do, with your sodomized clapped together builds. Air ride cab, rear suspension etc....good ideas, but not the way you go about doing them, your body lines never lined up in any of your last trucks pics, your cab sat ass up. You want air ride cab, seats, 18 gears, and high hp, buy a ***ing peterbilt to drag your damn trailer around and stop molesting pickup trucks.
There's nothing wrong with wanting to build a 400-450 hp diesel...not everybody wants to build a 1000hp truck. That's the problem with the diesel community now IMO, if a guy comes in and wants opinions on building a reliable 450hp dd, guys start trying to get him into bigger injectors, a huge ass single...then that single could get a little laggy if you want to tow, so maybe a set of compounds to help spool when towing etc. Some guys just want a little more kick to their dd while being stone stock reliable, and be able to tow to the trucks limits, without ill side effects.
Me2, stop jacking threads, with ideas, and what you plan to do, with your sodomized clapped together builds. Air ride cab, rear suspension etc....good ideas, but not the way you go about doing them, your body lines never lined up in any of your last trucks pics, your cab sat ass up. You want air ride cab, seats, 18 gears, and high hp, buy a ***ing peterbilt to drag your damn trailer around and stop molesting pickup trucks.
forcefed6.4ford
New member
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