MaxSpool power to 6000 RPM's Congratulation John Weatherby

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dansdieselp said:
7yjahyvy.jpg

I just go by what I'm told. If the owner doesn't know what he has I ask the source. Now I'm not going to get into this pissing match, but I will state what I believe. I have Greg's cam in my truck and it makes peak power at 4000rpm and carries it way out to the right side on the graph. It's a 2.6 Duramax so it's not gonna respond the same as a Cummins with the same grind IMO. I like it and won't give this one up. Now when we are looking at four different trucks running into the same problem you have to look at what they have in common. Jason's truck ran awesome last year. Made a few changes over winter and lost all bottom end power. You figure a better head and charger aren't going to hurt ya much so went back to old injectors. Helped, but not enough. Went back to smaller cam and runs like it did last year. So the cam was the culprit. Now does this make the other cam junk? I don't think so, but I believe that it's too big for a 2.6 truck. The best 2.6 charger is only going to flow so many pounds of air per minute and it can't feed these cams where they want to make power. So now you're driving the charger harder and heating up the air more. Also air is moving faster and spending less time in the intercooler. In the logs I'm seeing intake manifold temps in the 180-250*+ range at end of run. I think these Cummins cams would work better in a big twin setup or drag racing motor. The theory of keeping the intake valve open after BDC is not a bad one. If boost pressure is higher than cylinder pressure as piston is coming up air is still flowing in. More air in will equal more power. Hot air however is gonna kill it though. Sometimes less is more. That is all for now.
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You're not supposed to actually use your brain or put an intelligent post on this thread. I don't claim to be a pro n I know theory doesn't always translate into reality but your logic makes perfect sense.
 
dansdieselp said:
7yjahyvy.jpg

I just go by what I'm told. If the owner doesn't know what he has I ask the source. Now I'm not going to get into this pissing match, but I will state what I believe. I have Greg's cam in my truck and it makes peak power at 4000rpm and carries it way out to the right side on the graph. It's a 2.6 Duramax so it's not gonna respond the same as a Cummins with the same grind IMO. I like it and won't give this one up. Now when we are looking at four different trucks running into the same problem you have to look at what they have in common. Jason's truck ran awesome last year. Made a few changes over winter and lost all bottom end power. You figure a better head and charger aren't going to hurt ya much so went back to old injectors. Helped, but not enough. Went back to smaller cam and runs like it did last year. So the cam was the culprit. Now does this make the other cam junk? I don't think so, but I believe that it's too big for a 2.6 truck. The best 2.6 charger is only going to flow so many pounds of air per minute and it can't feed these cams where they want to make power. So now you're driving the charger harder and heating up the air more. Also air is moving faster and spending less time in the intercooler. In the logs I'm seeing intake manifold temps in the 180-250*+ range at end of run. I think these Cummins cams would work better in a big twin setup or drag racing motor. The theory of keeping the intake valve open after BDC is not a bad one. If boost pressure is higher than cylinder pressure as piston is coming up air is still flowing in. More air in will equal more power. Hot air however is gonna kill it though. Sometimes less is more. That is all for now.
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Why cant all the diesel performance shops be this professional when it comes to this type of debate??
 
khaoskustoms said:
That is a lot of valve lift. Can a cummins head even flow enough to take advantage of that much lift?
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Depends how good your head flows. The more the valve is put of the way the better. At this point I think it's duration which is hurting bottom end power more than lift.
 
dansdieselp said:
Depends how good your head flows. The more the valve is put of the way the better. At this point I think it's duration which is hurting bottom end power more than lift.
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It might be both duration and lift. I like to spec a cam where lift matches what cylinder head can flow and duration is picked according to purpose of the engine then lowered just a little bit.
 
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