Performance Cam

[Matt Bachand]

I'm guessing the 400 (6.6) or 454 (7.4)...

So he must mean using the 'profiles' to help reduce costs of having a 6.5 cam made then.

 

[dragogt]

That's my thoughts.

 

[chevyinlinesix]

A 454 and 400 have too different of bore and strokes, the Duramax is closer, but the 396 provides the best profiles IMO. Depends what you are using it for too, a 396 BBC profile for supercharged applications won't work very well with a restrictive exhaust, you need a very well matched system to use those profiles. However, they can be used to point in the right direction.

 

[buddy]

If all the valve timing was the same and you only increased lift, would it at least seem like flow into and out of the cylinder would be easier?

If the valve timing was such that exhaust valve actually closed at TDC, so the most exhaust possible is expelled would there not be more volume for fresh air/oxygen on the intake stroke?

Are these simple views on valve timing and port area (lift) at least somewhat desireable?

For those that have an ATT this is largely how they have more efficiency and power. Larger port through the turbo for exhaust to flow and reduced exhaust backpressure, so less compressed exhaust in the cylinder and less work to push it out of the cylinder.

If the head intake port is 1.8" diameter like the valve head is 1.811 in diameter, then the circular area at the port exit is 2.4535sq in, taking into accout the valve stem cross section area. If stock lift is only 0.41 inches (or actually less) then the area of the cylindrical nozzle is only 2.32 sq in. To match the nozzle size with the port size the valve lift should be at least 0.435 in. So what is the size of the intake ports in the head?

 

[Goldsburg]

A 454 and 400 have too different of bore and strokes, the Duramax is closer, but the 396 provides the best profiles IMO. Depends what you are using it for too, a 396 BBC profile for supercharged applications won't work very well with a restrictive exhaust, you need a very well matched system to use those profiles. However, they can be used to point in the right direction.

I think that you DO realize that having a similar cubic inch means nothing with regard to whether a particular lobe profile is "ideal" for another engine of similar displacement, right? This is to say that cylinder head flow numbers, operating RPM, even the induction system type, valve overlap, and not to forget valve to piston clearance (near overlap) are all very critical parameters to know when creating a "new" diesel cam.

As stated in previous discussions on this topic, more power can be had from the 6.5 diesel. Just be prepared for an enormous loss of bottom-end torque when playing with these specifications. All of your new found power will come at a price!

FYI - I have been designing and building custom cams for gas and diesel pulling tractors for approximately 15 years. I have pretty much been there and done that with regard to induction system design, modification, and camshaft interaction with such. IMHO, you would do well to stick with a stock cam and install the higher ratio roller rockers. Otherwise you will face horribly unacceptable results from your cam timing. That is of course, unless you plan on running 4000 to 5000 RPM most of the time!:thumbsup:

Believe it or not, for 99.9% of 6.5 diesel users out there, GM did a pretty good job with the cam. Now that GM-X turbo on the other hand...

Regards,

 

[chevyinlinesix]

I realize that engine cubic inches does not affect camshaft lobe profiles and how suitable they are... Lucky for me piston-to-valve clearance is not an issue

You have lots of camshaft designing experience, so you already know why I'm starting with profiles designed for supercharged engines. Yes, you are right, I am moving the power to the high end of the RPM range, bottom-end loss is perfectly okay with me However the specifications are something that won't be "released" ):h

A higher rocker ratio accelerates the valve train too fast for such high RPM's, and won't change what needs to be changed. I am NOT designing this camshaft by myself (I am by far an expert on anything to do with engines) that would be nuts IMO, the company that is grinding the camshaft is helping big time.

I agree Goldsburg, if you read any of my previous posts on either site, you will find that I say over and over again the GM did an excellent job on the 6.5 camshaft, given it's operating conditions and engine configuration.

 

[Slim Shady]

If all the valve timing was the same and you only increased lift, would it at least seem like flow into and out of the cylinder would be easier?

If the valve timing was such that exhaust valve actually closed at TDC, so the most exhaust possible is expelled would there not be more volume for fresh air/oxygen on the intake stroke?

Are these simple views on valve timing and port area (lift) at least somewhat desireable?

For those that have an ATT this is largely how they have more efficiency and power. Larger port through the turbo for exhaust to flow and reduced exhaust backpressure, so less compressed exhaust in the cylinder and less work to push it out of the cylinder.

If the head intake port is 1.8" diameter like the valve head is 1.811 in diameter, then the circular area at the port exit is 2.4535sq in, taking into accout the valve stem cross section area. If stock lift is only 0.41 inches (or actually less) then the area of the cylindrical nozzle is only 2.32 sq in. To match the nozzle size with the port size the valve lift should be at least 0.435 in. So what is the size of the intake ports in the head?

This is only part of the reason why the ATT works, If just putting a larger turbine housing on made an engine more power, then any turbo would give increased performance, ::: (IF you have enough drive energy,) The turbine wheel is configured for the right drive pressure and energy for a given rpm range, then we get into whether the turbine wheel has enough drive energy to turn the compressor wheel efficiently through an rpm range. Make the compressor wheel design wrong and you won't be able to spin it when you need to, make the compressor wheel to small and you over drive it, just as bad.

Change the bite of air and now you affect speed and drive energy again, Turbo charger design is an art and partially science. The guys that design them have fluid dynamic brains that make better calculations than computers do, the computers just help confirm what they think, might work. Wonder how they did this before all of the cad cam design and super computers?

 

[Matt Bachand]

Is there any room for modifying the GM cam for MORE low end power? Or is it already 'maxed out' in that regard?

I have no interested in anything over 2500 rpm. I wouldn't even mind if My PCM governed it to 2500.

Not that I really need more, but the topic of diesel Cams really interests me.

 

[buddy]

I am thinking low end performance will not be adversely impacted at all with the modification I would want. A little more lift, which could perhaps be achieved with a greater ratio rocker arm. And less gap around TDC, basically 10 more degrees of exhaust and 10 more degrees of intake. I would not be playing around at all with overlap, there is none, so no way would I be modifying the scavenging affect because there is none. I wouldnt even mess with the timing around BDC.

Together with
Beefier Rocker assemblies/springs
thicker head gasket
ARP head studs
ATT
maybe Extrude Honed exhaust manifolds

Right now a set of exhaust manifolds costs $750 to extrude hone, but I was told there could be discounts if doing several. I dont think its viable until its more like $400, or something close to what I paid for headers on my Z28 which was only like $300.

 

[Goldsburg]

I am thinking low end performance will not be adversely impacted at all with the modification I would want. A little more lift, which could perhaps be achieved with a greater ratio rocker arm. And less gap around TDC, basically 10 more degrees of exhaust and 10 more degrees of intake. I would not be playing around at all with overlap, there is none, so no way would I be modifying the scavenging affect because there is none. I wouldnt even mess with the timing around BDC.

Together with
Beefier Rocker assemblies/springs
thicker head gasket
ARP head studs
ATT
maybe Extrude Honed exhaust manifolds

Right now a set of exhaust manifolds costs $750 to extrude hone, but I was told there could be discounts if doing several. I dont think its viable until its more like $400, or something close to what I paid for headers on my Z28 which was only like $300.

buddy -

If you are adding 10 deg to each of the intake and exhaust durations "around TDC" then YOU ARE changing the overlap. Just because it is not a positive number, doesn't mean there isn't an "overlap value". This is called negative overlap and adding or subtracting any duration again "around TDC" without altering the lobe centers to maintain stock negative overlap, is altering the overlap.:rolleyes5: Have you also forgotten that intake tract air and exhaust tract gases have momentum?

Folks, this is why cam grinds should be left to those who understand cam grinds...

Also buddy, do you know what the effective impact of adding higher ratio rocker arms does to the power band of an engine? Do you understand the duration implication of higher ratio rockers? If you did then you would probably understand why you will lose bottom end torque when making these modifications. Do you also understand that there is more to the duration, overlap, and centerlines than "scavenging effect"? What about intake valve closing timing? What about exhaust opening timing? There is nothing that can be done to regain the loss of torque after these mods have been made.

Do what you want, buddy. But don't say you weren't warned...

Regards,

 

[chevyinlinesix]

buddy -

If you are adding 10 deg to each of the intake and exhaust durations "around TDC" then YOU ARE changing the overlap. Just because it is not a positive number, doesn't mean there isn't an "overlap value". This is called negative overlap and adding or subtracting any duration again "around TDC" without altering the lobe centers to maintain stock negative overlap, is altering the overlap.:rolleyes5: Have you also forgotten that intake tract air and exhaust tract gases have momentum?

Folks, this is why cam grinds should be left to those who understand cam grinds...

Also buddy, do you know what the effective impact of adding higher ratio rocker arms does to the power band of an engine? Do you understand the duration implication of higher ratio rockers? If you did then you would probably understand why you will lose bottom end torque when making these modifications. Do you also understand that there is more to the duration, overlap, and centerlines than "scavenging effect"? What about intake valve closing timing? What about exhaust opening timing? There is nothing that can be done to regain the loss of torque after these mods have been made.

Do what you want, buddy. But don't say you weren't warned...

Regards,

Variable duration valve lifters

 

[buddy]

Yes I understand that, but my point about not impacting scavenging is valid, and I was not planning to mess with rocker arm ratio, it was mentioned by let see, Goldsburg. You didnt seem to understand me and I understand you might have a lot of experience, but you dont have to "warn" people to make it sound like their retarded. So once again, a lesson from Goldsburg, everyone do your homework.

Maybe its not obvious that I wouldnt be doing this myself and that a Cam expert would be performing the modificaiton.

 

[Goldsburg]

Yes I understand that, but my point about not impacting scavenging is valid, and I was not planning to mess with rocker arm ratio, it was mentioned by let see, Goldsburg. You didnt seem to understand me and I understand you might have a lot of experience, but you dont have to "warn" people to make it sound like their retarded. So once again, a lesson from Goldsburg, everyone do your homework.

Maybe its not obvious that I wouldnt be doing this myself and that a Cam expert would be performing the modificaiton.

It's like your reading and the information is passing straight through the void between your ears. You ARE going to change the "scavenging" because you are changing the timing around overlap. The columns of air and gasses entering and leaving the cylinder have momentum, meaning that they don't like to start moving and (once moving) they don't like to stop.

Negative overlap cams have been around since the invention of the internal combustion engine. If ANY overlap less than zero made NO DIFFERENCE whatsoever, then why are there nearly an endless number of cams with varying degrees of negative overlap? I am telling you THAT THE AMOUNT OF NEGATIVE OVERLAP MATTERS.

I am done trying to explain to you why you will not achieve your objective they way you are approaching it. Diesel cams (like the one in the 6.5) and tractor cams have much in common. I have done the analysis on the 6.5 cams previously. I guess that I don't know any other way to tell you that you are barking up the wrong tree and that YOU HAVE BEEN WARNED.:nono:

Do you honestly think so highly of yourself that you believe you're the ONLY ONE EVER to attempt to get higher performance out of the 6.5TD?

Regards,

 

[buddy]

Who is the arrogant one here???? Anyone that has ever changed out the cam on their 6.5 or have data from someone that has please raise your hands ......anyone.....anyone.......still have not heard of anyone that has, and if you haven't tried and succeeded or tried and failed then you haven't tried at all.

OK, I hope to have a positive affect on scavenging, getting more exhaust gasses out...is that better, no adverse impact to the scavenging from overlap and reversion. Pushing more exhaust gas volume out should increase exhaust velocity through the turbo. The momentum of the intake air would only affect the BDC timing of the cam which I said I wouldnt plan to mess with. The momentum of the exhaust gases will be what when you have to push them out, compressing them to the amount of backpressure? The momentum will be in the direction of the valve closure if there was negative pressure, so are we worried that the spring wont be strong enough to close the valve with backpressure, which we already have that situation??? The negative overlap can be to prevent the valve from hitting the piston at high compression. As long as there is clearance it should work fine, since with reducing negative overlap, there is still no overlap (in its general sense).

When there is substantial backpressure, I dont really consider the scavenging to work. We are relying on the work of the Piston to push the exhaust gas out. There is no negative pull from the exhaust when the turbo is restricting it. Therefore, in my eyes no "scavenging" in the way I understand it. If you call scavenging just the act of pushing exhaust gases out then its all scavenging. In which case everyone that has put a 4" exhaust on has impacted scavenging, and the ATT impacts scavenging. And I'm hoping to take advantage of those features that have reduced the amount of positive pressure on my exhaust ports. If there were scavenging going on my gauge on the turbine drive pressure would read vacuum.

 

[Goldsburg]

Who is the arrogant one here???? Anyone that has ever changed out the cam on their 6.5 or have data from someone that has please raise your hands ......anyone.....anyone.......still have not heard of anyone that has, and if you haven't tried and succeeded or tried and failed then you haven't tried at all.

OK, I hope to have a positive affect on scavenging, getting more exhaust gasses out...is that better, no adverse impact to the scavenging from overlap and reversion. Pushing more exhaust gas volume out should increase exhaust velocity through the turbo. The momentum of the intake air would only affect the BDC timing of the cam which I said I wouldnt plan to mess with. The momentum of the exhaust gases will be what when you have to push them out, compressing them to the amount of backpressure? The momentum will be in the direction of the valve closure if there was negative pressure, so are we worried that the spring wont be strong enough to close the valve with backpressure, which we already have that situation??? The negative overlap can be to prevent the valve from hitting the piston at high compression. As long as there is clearance it should work fine, since with reducing negative overlap, there is still no overlap (in its general sense).

When there is substantial backpressure, I dont really consider the scavenging to work. We are relying on the work of the Piston to push the exhaust gas out. There is no negative pull from the exhaust when the turbo is restricting it. Therefore, in my eyes no "scavenging" in the way I understand it. If you call scavenging just the act of pushing exhaust gases out then its all scavenging. In which case everyone that has put a 4" exhaust on has impacted scavenging, and the ATT impacts scavenging. And I'm hoping to take advantage of those features that have reduced the amount of positive pressure on my exhaust ports. If there were scavenging going on my gauge on the turbine drive pressure would read vacuum.

My numerical analysis told me there was nothing there...what did your numerical analysis reveal? Anyone...anyone...buddy?...still don't hear anyone! I guess that puts me at least one leg up on you "buddy". I have done my homework while your still off in the weeds postulating and theorizing. Pardon me for trying to be (at least somewhat) helpful in steering you away from your present camshaft misadventure, I guess I consider that my charity contribution for the year (ya know preventing the self-proclaimed "retarded kid" from disappointing himself). Sometimes you have to realize that "The Box" is there for a reason and thinking outside of it can lead to undesirable outcomes.

Paragraphs 2 and 3 of your diatribe above only serve to prove again that you really know NOTHING about camshaft design, especially in a diesel engine. What happened to that so-called "professional" cam grinder that you had waiting in the wings to grind "das wundercam" for you? Did He/She tell you to say those things? If so you will want to go back and re-read the script, 'cause I think you got some things wrong.

buddy, maybe this thread should be locked down until you have dyno results to refute the analysis that I performed 2 years ago, because it sure seems like you have already got everything figgered out. BTW:Calling me arrogant will not stop me from refuting / rejecting much of the tripe that you post about here on the board. When you have proven me wrong with your results, then I will more than accept the moniker of "arrogant" and at that time you can tack on "ignorant" as well. But until then, you are just the little (self-proclaimed) "retarded kid" in the corner.

Regards,

 

[buddy]

Its funny because you say you did something, and youve said youve explained something, but nowhere do I see anything from you Goldsburg, so as far as anyone knows youve done nothing and are just talking out your ass as you being the self proclaimed cam expert. Maybe people should just stop posting anything on this site at all, then everyone will love this site for sure. I wonder why there are still so many more users at the other place.

When I prove you wrong, no one on this site will know about it, unless you read it somewhere else.

 

[Matt Bachand]

Guys lets not forget here that we all share a rare common interest in the 6.5. I read this thread to learn about cams, and cam design, specifically diesel, for the 6.5. The last few posts here have absolutely no information whatsoever in them.

Why the hatred?

IF someone is mis-informed, why not explain why that is? So we can all learn and build upon what we've learned.

:grouphug:

 

[Wrecker]

Guys lets not forget here that we all share a rare common interest in the 6.5. I read this thread to learn about cams, and cam design, specifically diesel, for the 6.5. The last few posts here have absolutely no information whatsoever in them.

Why the hatred?

IF someone is mis-informed, why not explain why that is? So we can all learn and build upon what we've learned.

:grouphug:

Good call Matt. Need to refocus and show the diesel luv.

 

[ak diesel driver]

sure makes me wonder

 

[turbonator]

sure makes me wonder

X-2.....

KBC

When I think of all the negative that was shown towards Buddy and this idea when these two threads were running, and the experts that said that this has been tried, and will not aid......got to give it to Bill, "sliced bread again".....wonder if we will have actual dyno results this time to substantiate the claims. Makes me wonder when the new and original programmable chip will be released....(5 maybe 6 program chip??).