Camshaft swap question

[SBashaw]

Reading my last issue of TDR, I noticed that one of the changes between a 03 and an 06 was the "emission camshaft. Here is my question.



With my 03 I was getting an average 2 MPG better than my 06. If I installed an 03 camshaft in my 06 would I loose power and gain MPG ?



Is the emission camshaft changing the timing and duration only?



Excuse me for my questions as I am not a gearhead



Thanks,

 

[AH64ID]

While many people talk about the grind from 03-04 being different than 04. 5-07, its not. I have talked to many cam builders and the p/n is the same, as is the grind.

The mileage is mainly from timing and the 3rd event, the black as the night oil is from the piston design, which in conjunction with the cam creates the in-cylinder EGR effect.

 

[cerberusiam]

The cams between 03-04 and +4. 5 have some significant differences in their profiles. If all you want to talk about is lift and duration then they are they the same, but, thats not all there is to a camshaft function. The specs between the years indicate the LSA (lobe seperation angle), valve overlap, and duration at . 050 lift are different.



In short, the cams are different because the programming is different between the year breaks.



Generally, you can swap the cams between engines and given everything else stays the same you will see only minute changes. If you had a solid log of mpg's in consistent situations and solid info on power curves you can probably pick out what changed and where. Odds are high the SOP meter or fuel logs are NOT going to show significant changes.



The question was asked, will I loose power and gain mpg? Short answer is no unless you make other changes. All you would do is move the power around on the rpm band a bit. Both of the former observed phenomena are more a function of fueling rates and timing than they are of a cam profile.



The emissions camshaft does not change duration much if any. What it does change is valve overlap and duration at . 050 lift. In short it changes when the valves are opening and closing in relation to the piston position. In a naturally aspirated motor this would make a sgnificant difference in power profiles, but in a turbocharged engine the boost overcomes a lot of things and the differences are not as noticeable, 30 lbs of boost overcomes a lot of power robbing emissions changes and still allows the engine to meet EPA regs.



The good news is the 600 engines can be tweaked to meet and even exceed mileage and power of the earlier design, you just have to go a little farther to achieve it. Along with the cam, you need a programmer capable of changing injection timing curves and fueling maps.



The ISB is a low rpm engine and the best BSFC is achieved around 1900-2000 rpms in the CR design. However, that is counter-productive to meeting emissions of NOX so the fueling\timing maps stretch the power band over a broader rpm range to better control cylinder temps. Hurts the mpg side of things because rpms is HP and HP is fueling.



Remapping timing and fuel curves to a 2 event system, along with a cam that is designed to utilize it, generates a much more efficient engine and rpm range for the way the engines like to run. Totally screws emissions up but makes more power in a usable range with less fuel.

 

[AH64ID]

Do you have a solid reference for the specs?

As I said I have been told by multiple cam companies, and several diesel shops that there is no difference in the cam's from 03-07, even the part numbers are the same. From all I have found the difference is pure folklore.

 

[cerberusiam]

Do you have a solid reference for the specs?



As I said I have been told by multiple cam companies, and several diesel shops that there is no difference in the cam's from 03-07, even the part numbers are the same. From all I have found the difference is pure folklore.

Yes I do and its proprietary info. No, I can't\won't share because it is proprietary and the last time I tried without revealing too much it got ugly. #@$%!



My advice is find somebody that doesn't have a cam to grind (bad pun ), the story is a bit different. FWIW, I have seen the profiles on a 24V, early CR, and late CR cams. Lift and duration are close and identical on some. LSA and duration @ . 050 is where the difference lies. At 20 psi or higher the differences are meaningless. However, when we build for efficiency they are not.



OE part numbers supercede all the time. All it means is the older profile\part\design is no longer available and the new one will generally perform the same duties adequately for stock purposes. Don't read too much into a part number, the specs are what is key.



Like I said, the cam is only a part of the equation. Fuel curves and timing will have a much higher impact on efficiency. The cam changes the shape of that efficiency, not the overall effect.

 

[Prairie Dog]

Ah, the old "I could tell ya but I'd have to kill ya" routine. .

 

[AH64ID]

Interesting...


Well either way, the OP would do better with an aftermarket grind like the Colt Stage 1, PDR, or the Hamilton 175/206. . which are all a mild, tq, efficiency cam.

Even if the early CR and late CR cam's are different, they still have the longest intake duration, and shortest exhaust duration of any OEM cam in the CTD Dodge pickups, not the best setup for efficiency!

That being said, while I noticed a nice change from my cam, the restriction on the turbo (or lack there of now) was a bigger change.

 

[SBashaw]

Cerbersiam, AH64ID, Thanks for the replys as I have read many many posts from both of you and you both seem very knowledgeable.

Guess I was hoping that the cam would be a easy way around the emission cops and still gain some MPG.





AH64ID... . If you don't mind, what cam did you go with, results?

 

[AH64ID]

I have the Colt Stage 1 cam. I like it, it made the bottom end a little more responsive and the motor sounded happier. It's hard to say what kind of mileage gains I got because I stopped using the truck as a DD just before adding the cam, and swapped to a taller, more aggressive tire shortly after. I probably see up to about 10% at times, but like I said really hard to quantify, even with the excessive notes I keep on mileage.

 

[cerberusiam]

Ah, the old "I could tell ya but I'd have to kill ya" routine. .

Exactly!! Or somebody would question the validity of the numbers and its ON!! :-laf :-laf

Even if the early CR and late CR cam's are different, they still have the longest intake duration, and shortest exhaust duration of any OEM cam in the CTD Dodge pickups, not the best setup for efficiency!



That being said, while I noticed a nice change from my cam, the restriction on the turbo (or lack there of now) was a bigger change.

No disagreement there. Like I said the differences get covered up by the boost levels. Changing the cam profile gives it a nice bump back in the low to mid range where it is needed but I suspect your Smarty has lot to do with that also. Throw in that new turbo an you have an excellent setup. I am envious.

 

[AH64ID]

The Smarty does do a lot, the cam is much more noticeable as far as smoothness and EGT's in stock tuning.

 

[Tinman]

My Piers cam has the same part # as the stocker as they use blanks from Cummins and grind them.



Cerbersiam: I understand that the cam timing and advancing the injection timing as a way to improve the efficiency of the stock engine. I also recognize that opening up the turbine housing will help and getting rid of the 3rd event will save fuel also. Could you elaborate more on the fueling curve, and piston. How does the smarty's fueling compare to stock. I have always felt the smarty actually fuels a little too fast - ahead of boost, leading to more smoke and less efficiency, but great throttle response.

 

[cerberusiam]

Depends on how you tune the Smarty with levels and TM. The Smarty is going to put more fuel back into the low\mid range rather stretch it across the range and its going to be sooner in the timing range to use it better.



Unfortunately one of the side effects without changing out things like the cam and tweaking pressure cause more smoke at times. Every release of sotware seemed to get better at it the smoke issue.



Some of the smoke is going to depend on driving habits and how tight the TC is for autos, how its launched and driven with a manual.



Looking at the dyno sheets with the Smarty loade dit starts looking a lot mor elike the jerk pump graphs with a big TQ spike down low instead of the typical flat curve of a stock CR.

 

[BIGNASTY]

cerberusiam could you put all this wonderful info in NOVEL form my wife said I should read more. She didnt say what

 

[Wingate]

Yes I do and its proprietary info. No, I can't\won't share because it is proprietary and the last time I tried without revealing too much it got ugly. #@$%!



My advice is find somebody that doesn't have a cam to grind (bad pun ), the story is a bit different. FWIW, I have seen the profiles on a 24V, early CR, and late CR cams. Lift and duration are close and identical on some. LSA and duration @ . 050 is where the difference lies. At 20 psi or higher the differences are meaningless. However, when we build for efficiency they are not.



OE part numbers supercede all the time. All it means is the older profile\part\design is no longer available and the new one will generally perform the same duties adequately for stock purposes. Don't read too much into a part number, the specs are what is key.



Like I said, the cam is only a part of the equation. Fuel curves and timing will have a much higher impact on efficiency. The cam changes the shape of that efficiency, not the overall effect.

Sounds like you may be able to answer a question for me also..... I have wondered if the little Cummins is an Otto or Miller engine???

AASN, we have been converting to "early closing" camshafts for years in some applications to effectively alter cylinder pressures... Emissions Emissions Emissions!!...

 

[AH64ID]

The smoke from the Smarty Jr is a function of timing and the cam design. SW1 on the SJR is timing only, especially if you have stock TQ set. I have messed with the TM settings on the JR and they are what makes the smoke, and the cam with the stock turbo made a small change, but the cam with the new turbo made a huge change. My smoke is probably 80% gone at low load/low boost. . and the boost is down, the stock turbo just chokes the motor even at low flow. Now I can still roll coal if I hammer down at the wrong rpm, but that is the over-fueling you talked about.

 

[cerberusiam]

I have wondered if the little Cummins is an Otto or Miller engine???

Neither, its a Clessie. :-laf:-laf



Good question though, where does the line between the cycle types get drawn? If a given engine implements part of the other type is it patent infringement or only a variation of the base?



In its original configuration pretty sure it would be considered and Otto cycle engine. However, with the emissions\power balance its verging on a Miller, but not quite. It could be said to implement a portion of the Atkinson cycle in a broad sense also.



I think its a "Clessie" though.

 

[Tinman]

Now I can still roll coal if I hammer down at the wrong rpm, but that is the over-fueling you talked about.

Yeah that's kinda what I mean. I only run stock TQ and I can put out an quite a cloud if I punch the throttle in a low boost situation (high gear, low rpm or a standing start). Fuels ahead of boost. The cam made the single biggest difference and quite frankly, I would have got rid of my smarty b/o smoke if I didn't have the cam.