Let's talk cam design

[SmokeShow]

Anyone care to discuss high performance diesel cam design? I really feel the future big steps in Dmax performance will be more advanced cam design.

So what's your theory on this? Lift. Duration. Int vs exh. Etc.

 

[duramaximizer]

I know nothing, but I heard overlap is a good thing. oke:

Just trying to get the discussion started.

 

[TrentNell]

I have little to add because i know very little about what cam changes work well in a diesel .

I know more lift is good , and figure more exhaust and intake duration also , the kicker is i have no idea of the downside of going too much ? other than the pistons need to be modified after a certain amount of lift .

 

[S Phinney]

Pistons will need to be modified. More duration, lift and a change in lobe separation would be areas that you would look at. The diesel motor doesn't know that it is a diesel. The same rules should apply to a point when it comes to improving air flow and fuel capabilities. Too much over lap and you loose cylinder pressure. Too much duration and you loose responsiveness. You can alter lobe separation to change the rpm range your looking to run the motor in along with duration. Moderation would suit your build well when picking any after market improvement. The biggest stick doesn't mean you got the best truck out there.

 

[MMLMM]

Added duration can be a good thing, if you can avoid piston striking. Isnt that the biggest deal with cam design in these motors?

 

[MadMaxx61]

I am sure Guy (Trippin) could tell you a bit about them as he has a few

Duramax Camshafts

 

[hoot]

There is no room when the piston is TDC so timing is crucial.

The piston is flush with the deck and the head is flat.

 

[sweetdiesel]

I would think that no one would install just a cam. I would think they would be building there motor and swap to a new cam when rebuilding.....no?

That is what i did and made sure there was enough valve relief in the pistons to run a large cam.

I think the biggest decision is what RPM you want to run and this is also a decision that needs to be made before you even build your motor.IMO

IIRC the comp cam im running can be used in a stock application or stock pistons

 

[McRat]

I'm thinking flow is flow, and looking at successful turbo grinds on engines of similiar cylinder displacement and RPM for gas engines would be a good starting point.

 

[McRat]

There is no room when the piston is TDC so timing is crucial.

The piston is flush with the deck and the head is flat.

Not entirely true. You can sink the valves down into the head and run a thicker gasket if you don't want cut pistons.

But yeah, like most modern V8's the Dmax is an interference engine. Get the cam 11 deg off, and you'll bend a bunch of stuff on the Dmax.

 

[Magilla]

I'm thinking flow is flow, and looking at successful turbo grinds on engines of similiar cylinder displacement and RPM for gas engines would be a good starting point.

Good point. Although a gas engine is going to RPM higher due to the nature of the burn rate of the fuel. Diesel burns relatively slow.

 

[mytmousemalibu]

Since we have no throttle/manifold vaccum, and dont rely on intake charge to carry our fuel and have boost to push the air in, in my head it seems our engines would be less sensitive to more radical duration than a gasser? Meaning, can we get away with more and not loose drivability? I understand there is a a line to cross there though too. I would also think that less or no overlap would be advantageous too. overlap will bleed off some air charge/cyl pressure but at the same time, would a tad be good to fully purge exhaust out of the cylinder?

Camshafts......An argument/question that has gone on since the dawn of performance:spit:

 

[SmokeShow]

Anyone of any good reading material on cam design for CR diesels?

I know so little about cams that I need a course in the terminology. I'm starting to get a grasp but some good reading would be nice.

 

[mytmousemalibu]

http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html

Heres a good artical for gasser tech but good none the less

 

[McRat]

Diesel cam stuff is kinda bizarre. I remember when I was a newbie to diesels, and I asked a SuperSecretCamMaster who was posting on the board, what the cam specs were for a stock engine. He got mad IIRC, because that would be giving away trade secrets.

At least in the Dodge world the name of the cam is the most critical part. A TripleWhammyVortexIII would be vastly superior to DoubleWhammyVortexII for all applications. What they dyno with no other changes is top secret as is their dyno curves. It is a felony in most southern states to even ask what the lift and duration is on an aftermarket Cummins camshaft.

In the gas world, they just give them a part number, spec sheet, and RPM range. Way different.

 

[Turbo Buick 6]

Too much overlap on any turbo motor makes for a laggy turbo at lower RPMs. On small block gasser you can make 1500hp with 116 lobe sep, I run 118 in my gasser, I would think a diesel would be the same

 

[MMLMM]

Should head design be seriously improved before cam design?? Im not talking port the head, Im talking full re-design.

 

[05smoker]

http://www.dieselplace.com/forum/attachment.php?attachmentid=28363&d=1163302554

Here is a link to what Guy posted on DP a while back. Comp Cam info.

 

[duratothemax]

Mitch you have a PM