Big Air in Big Air Out Question

[Papa Delta]

I have read nearly every post using the search feature about Intakes and Exhausts. I have talked to multiple vendors on the subject as well. My concensus at this point is that when adding fueling which is the only real way to get more power from the cummins it is necessary to flow more air in and to free up air out for the sake of efficiency ie low EGT. My question is what is the air flow in cfm from the stock filter, intake baffles and silencer ring. What is the stock air flow again in cfm from the stock exhaust. It seems the Cummins engineers designed this parameter to be safe for 325HP and 600lbft of torque. It seems to me that as we add power to these engine we should look at products and setups that keep this ratio although the ration may not be linear as you increase power.



It is my understanding that the intake baffles and even the design of the silencer ring is to straighten and accelerate air to the turbo making it more efficient. Most folks believe they are there to quit the turbo. Am I wrong in believeing this? If this is true, most of the products I have been considering for intakes would make the flow more turbulent so the ration would be sacrificed accordingly.



Most of the guys I have talked to read about that claim they are X cummins employees or engineers believe that the stock intake, filters dirt the best and should continue to filter up to high horsepower numbers. They believe in paper instead of oil gauze. I guess I'm trying to get some hard data before I make some choices that are going to force me to rebuild my engine at 150,000 miles instead of 300,000 miles. I love my truck, paid a lot for it and want it to last. Anybody out there with some more hard data? In addition to the air flow numbers, what is the cummins spec for silicon contaminent from oil analysis?

 

[JThiessen]

You've asked a lot of questions that "normally" get answered here with more opinion than fact.



DLeno and an ALaska Memeber did some fairly extensive testing on AFE flow and filtration. If you go onto the DTR (DieselTruckResource) website, and search for AFE, you'll come across a VERY long thread on this subject. If you actually develop a firm stance on the subject, you be one of very few.



IMHO... . The AFE/Scotty systems and higher flow exhaust will give a little bit of EGT assistance when I get into a situation where I'm running hot. No, they probably wont filtrate quite as well as the stock system, but I'm willing to risk that over heat issues, as long as I'm dillegent about maintaining the filter.

 

[nickleinonen]

i believe in paper elements too, which is why i went with the bhaf paper element [10. 5"x10. 5"Ø] it gave me an egt drop of about 150°f...



as for silencing the intake, my 05 brosure says that the silencer ring and baffeling is there to reduse the turbo noise... probably was there for 03, 04 for the same reasons. in industrial application, there is no silencer rings...

 

[Joseph Donnelly]

Check my article in TDR #37.

 

[rbattelle]

Check out this test. . [I post that link so often I should get royalties for it! ]



-Ryan

 

[Papa Delta]

Thanks For the Replies

Joseph Donnelly - I would love to read your article but I don't have that issue and they are sold out. Any way you can send it via PM?



nickleinonen - One minute I'm like you and leaning towards paper and the next I'm minute I'm thinking oil gauze might be OK if you stay on top of it. JThiessen directed me to the Diesel Truck Resource forum where I got more of the type of hard data I was looking for. There seems to be some pretty intelligent fellas there that are continually looking for that magical combination of the flow we need for big horsepower and the proper filtration to protect our engines. If you haven't read the 15 pages of the dicussion it is well worth it. It will at times give you a headache.



JThiessen - Thanks for the reference to DTR. I'm a registered member there but haven't searched there as much as here. I will need to do that more. There is a lot of good information there as well.



rbattelle - I have read this. I believe many things in this test, however it would have been more convincing if the testing had been done with my model year truck. I think there are too many differences in a V8 Diesel vs an inline 6 to compare properly.



In general I am looking to add an intake exhaust, and fueling box. I have been intrigued with TST and have talked to Mark on several occasions. The more I hear about one product being too aggressive or another product I begin to wonder how much HP & TQ can we reliably expect to add to this engine? I'm beginning to think it should be under 400HP and 800lbft.

 

[DLeno]

woh, papa delta you pretty much nailed all the relevant questions. As you probably already have found out, there is a general lack of hard data. I'm planning some J726 tests and also I'm doing oil analysis as well, in the interest of science.



the problem with looking at cfm numbers is that they don't make any sense without the context of restriction. For example, the stock panel filter specs out at 452 CFM, and the AFE proguard 7 specs out at 300 CFM. But guess what -- when the stock panel filter is subjected to 452 CFM it introduces a restriction equal to 4. 7 inches of water. When the AFE is subjected to 300 CFM it introduces a restriction equal to 1. 5 inches of water. you gotta be careful when interpreting numbers.



We have a similar problem trying to express flow in CFM for the exhaust. To my knowledge there are no meaningful flow specifications published for the entire intake system, nor for the stock exhaust. You can find flow and restriction numbers for Donaldson, Nelson, and other mufflers but I've not see such for the stock muff.



Theories abound as to what the purpose of the stock intake tube baffles is. to me, if they are to introduce more laminar flow, then they are a poor example compared to a TAG. As for suggesting that after market intake systems might increase turbulance, note that measureable (although very small) horsepower gains are obtained when replacing the stock intake system with after market systems with open intake tubes. this could be interpreted as an improvement in the filter media (flow) or that the guts of the stock tube are not seriously contributing to laminar flow anyway. I'd lean towards both.



I note that at intake flow rates associated with fuel modified trucks, a 4" tube without anything in it is already "turbulant" in the fluid dynamics sense (Reynolds number). So any improvement related to "turbulance" has to come from reducing turbulance in the filter media itself (face velocity). This appears to be accomplished by the open element cone filters, where there is a very high surface area.



The closest I have to hard data that I have collected myself is not complete. I am doing oil analysis, changing oil every 3,000 miles and switching back and forth between the stock and an AFE PG-7 intakes. I have one data point so far for each intake, showing the level of silica (dirt), and wear indicators (chrome and iron). If I published my numbers I would be no better than any other single data point experiment out there, so I have chosen to stress that one data point doesn't prove anything as to the filtration efficiency of a particular unit. Most guys that have reported oil analysis single data points are showing that silica levels are lower with the AFE PG7 than with the factory box. But when I have a more consistent and valid set of data I will report my results, by interleaving stock and AFE filters to factor out driving conditions and weather. As a side note, AK RAM over on the DTR had a pretty bad experience with a PG-7 element, showing dust in the intake tube and very high silica levels. this result has not been duplicated by anyone that I know of.



There is no cummins spec for silica levels in the oil. This is one of those areas where the absolute magnitue of a number is less important than trend analysis. you have to establish a trend for your truck before any measurements will be meaningful. Thats why I am testing each (stock and AFE) filter several times, to see if multiple data points will produce a result that is worth interpreting.

 

[p-Bar]

woh, papa delta you pretty much nailed all the relevant questions. As you probably already have found out, there is a general lack of hard data. I'm planning some J726 tests and also I'm doing oil analysis as well, in the interest of science.



the problem with looking at cfm numbers is that they don't make any sense without the context of restriction. For example, the stock panel filter specs out at 452 CFM, and the AFE proguard 7 specs out at 300 CFM. But guess what -- when the stock panel filter is subjected to 452 CFM it introduces a restriction equal to 4. 7 inches of water. When the AFE is subjected to 300 CFM it introduces a restriction equal to 1. 5 inches of water. you gotta be careful when interpreting numbers.



We have a similar problem trying to express flow in CFM for the exhaust. To my knowledge there are no meaningful flow specifications published for the entire intake system, nor for the stock exhaust. You can find flow and restriction numbers for Donaldson, Nelson, and other mufflers but I've not see such for the stock muff.



Theories abound as to what the purpose of the stock intake tube baffles is. to me, if they are to introduce more laminar flow, then they are a poor example compared to a TAG. As for suggesting that after market intake systems might increase turbulance, note that measureable (although very small) horsepower gains are obtained when replacing the stock intake system with after market systems with open intake tubes. this could be interpreted as an improvement in the filter media (flow) or that the guts of the stock tube are not seriously contributing to laminar flow anyway. I'd lean towards both.



I note that at intake flow rates associated with fuel modified trucks, a 4" tube without anything in it is already "turbulant" in the fluid dynamics sense (Reynolds number). So any improvement related to "turbulance" has to come from reducing turbulance in the filter media itself (face velocity). This appears to be accomplished by the open element cone filters, where there is a very high surface area.



The closest I have to hard data that I have collected myself is not complete. I am doing oil analysis, changing oil every 3,000 miles and switching back and forth between the stock and an AFE PG-7 intakes. I have one data point so far for each intake, showing the level of silica (dirt), and wear indicators (chrome and iron). If I published my numbers I would be no better than any other single data point experiment out there, so I have chosen to stress that one data point doesn't prove anything as to the filtration efficiency of a particular unit. Most guys that have reported oil analysis single data points are showing that silica levels are lower with the AFE PG7 than with the factory box. But when I have a more consistent and valid set of data I will report my results, by interleaving stock and AFE filters to factor out driving conditions and weather. As a side note, AK RAM over on the DTR had a pretty bad experience with a PG-7 element, showing dust in the intake tube and very high silica levels. this result has not been duplicated by anyone that I know of.



There is no cummins spec for silica levels in the oil. This is one of those areas where the absolute magnitue of a number is less important than trend analysis. you have to establish a trend for your truck before any measurements will be meaningful. Thats why I am testing each (stock and AFE) filter several times, to see if multiple data points will produce a result that is worth interpreting.

Can't wait to see the results