• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Cams & cam regrind discussion as a performance adder

More valves per cylinder. A serious re-think would take head re-design into account ... If you've working with a high-compression, low-clearance head, worrying about scavenging, backpressure, and TDC vacuum, it seems intuitive that head re-configuration (including perhaps a piezo-elec TDC relief) would be in order.

Superficial modifications will likely run into the same design barriers that have haunted us in the past... there is only so much extra you can get from a closed design. If you're gonna think outside the box, start outside the box.
 
From what I can find, you dont lose low end on the cams available today that are direct replacement that have no valve clearance issues. Most feedback seems to be on the Delta 206 on the other place.

Since there is no overlap or scavenging, as long as you keep it so there is no overlap and keep the pistons from hitting the valves, extending the duration closer to TDC can only help. Its just really difficult to do on high compression with such low valve clearance. By getting the exhaust closure closer to TDC you can generate much better spooling, since the valve closing is cutting off the source of drive pressure and sealing combustion byproducts into the cylinder for the next intake stroke.
 
turbonator said:
That is one of the reasons we are closer now, many are already lowering compression and usually this gives more clearance at TDC (.020-.030").
Click to expand...


This is a good point - lower compression pistons give you a quantitative measure to work with, as far as valve clearance goes, but remember that you aren't talking linear functions... as the piston nears TDC, flow through a rapidly-closing valve decreases because the cylinder pressure drops and the flow becomes much less laminar due to the venturi effect of the valve lap interface..

Having a different squish angle would give greater clearance to the exhaust valves and would let the exhaust flow more freely - the true way to maintain exhaust pressure balance is to manage that closure rate as a function of cylinder position, and that means not just the overlap ratio, but the duration of the closure rate, and there is where the rocker design can help.

What I'm saying is that this is a multivariate system; playing with single variables will be instructive, but is unlikely to give you the answers you're after. Taking a systemic approach will give you the opportunity to design toward a defined endpoint, rather than trying to overcome design limitations at each turn.

CIL6 over on the other site was taking such an approach, looking at a custom header configuration with twin turbos - he spoke of somebody who had redesigned the valve configuration on there, but then when they banned his ass for not agreeing with a mod, everything quit happening.
 
He was - decided not to come. Too bad ... the ideas were promising, and even better, he was actually following through and building them, which is the whole point of this little section.

At one point, I saw pictures of an entire new valve-train design... and then nothing.

Maybe cost/benefit is an issue ... I paid $550 gladly for reliability and piece of mind, but I doubt I'd pay that much for an extra 30 hp.

And doing it right is also an issue... I know lots of people who wouldn't pay for a Heath Turbo-master, prefering to make their own - and then when their home-made one caused their fuel mileage to drop, condemned the whole thing. Mine, I actually got better mileage with.

Maybe it was the design/fabrication, not the idea that was the problem.. saved money on one, lost money on fuel. The same kind of issues are in this thread...

It might cost a lot more to R&D a decent head/valve/cam combination, but then again, what's the reputation cost of a skimped one?

I'd really like to see somebody sit down with blank paper and design a system, rather than trying to keep as much of the old iron as possible.
 
How about a solid roller cam with adjustable roller rockers ? Don't really need it for rpms,but the lobes can be sraight up.
 
If we had the money to cast a new engine and parts then all bets would be off, but we work with what we have. Machining what we have, but still working with it. We could all just get a new DMax engine, that was GMs blank page, but then we would be trying to modify it.

CIL6 and I used to discuss these things quite a bit, but I am not sure why he put his 6.5 project on hold, not my place to pry.

The engine being built that impresses me the most is the Ford 5.0, because its everything that I would do with an engine. It was designed by smart people thats for sure, and they didnt compromise from the looks of it. It has a real impressive valvetrain.
 
ak diesel driver said:
that's called a new and diff engine then.
Click to expand...

Not really - just new and diff heads. Changing the comp ratio is still the same engine, changing the rocker geometry is still the same engine, why not changing the deck depth or squish angle? Penninsular's P400 made much more radical changes, and we still consider it the same.

buddy said:
If we had the money to cast a new engine and parts then all bets would be off, but we work with what we have. Machining what we have, but still working with it. We could all just get a new DMax engine, that was GMs blank page, but then we would be trying to modify it.
Click to expand...

As above. All I'm sayin' is, instead of complaining about how the existing geometry compromises efforts, why not consider how to change the geometry? You want the thing to breathe better - I get that. Consider everything.
buddy said:
CIL6 and I used to discuss these things quite a bit, but I am not sure why he put his 6.5 project on hold, not my place to pry.
Click to expand...
Mine, either - if Will wants to come around, he knows where we are.

buddy said:
The engine being built that impresses me the most is the Ford 5.0, because its everything that I would do with an engine. It was designed by smart people thats for sure, and they didnt compromise from the looks of it. It has a real impressive valvetrain.
Click to expand...

Yes, and they didn't stop by just looking at rocker arms, true?
 
NOT really if the only difference is the cam journals are smaller than the 6.2 /6.5 ones they can be welded up and turned down for a prototype build. I still can't believe a cam company doesn't have a blank that would work on our truck. I do have a guy that would do the necessary fab work welding the journals and then turning them down on a center-less grinder. How about the oil pump drive gear is it the same as the 6.5?
 
I have discussed this with several of them and none of the big names had much 6.5 knowledge. I went with a small shop in Oregon, with a real nice guy that didnt mind working out the specs with me, and didn't act ignorant when asked about the 6.5 diesel, and he had best price on a regrind. But I had to go a bit bigger duration than planned to get the lift I wanted. A billet would not only allow you to make exactly what you wanted, but also be lighter and stronger, but cost 3 times as much as the regrind. The regrind was under $200.

I wonder what the weight difference is between the cast and forged cranks are, if a forged crank while being strong would also be lighter to help higher RPMs and efficiency.
 
buddy said:
I wonder what the weight difference is between the cast and forged cranks are, if a forged crank while being strong would also be lighter to help higher RPMs and efficiency.
Click to expand...

Ok, now that one got by me ... if the rotating assembly is properly balanced, shouldn't the inertial moment zero out? If that's true, then the losses would all be frictional, and unrelated to the weight of the crank. Ergo, crank weight shouldn't have much effect on achieving higher RPMs...

What am I missing here?
 
JiFaire said:
Ok, now that one got by me ... if the rotating assembly is properly balanced, shouldn't the inertial moment zero out? If that's true, then the losses would all be frictional, and unrelated to the weight of the crank. Ergo, crank weight shouldn't have much effect on achieving higher RPMs...

What am I missing here?
Click to expand...

My understanding has always been lighter flywheel will spin up faster, so lighter crank would add up to the same effect as a lighter flywheel
 
You look at a 6.5 crank, it got huge counterweights with a moment of inertia far away from the center, the more weight further from the center the more torque it takes to get it to accelerate. Thats why edge knifing or trimming crank weights can produce decent gains in horsepower at higher RPMs and get to higher RPM faster. I'm not saying we should be knifing our cranks, because of their historic weakness, but if we had a stronger crank then trimming some of it could help. One of those things that if using a new material the actual design could have been reconsidered.
 
You must log in or register to reply here.
Back
Top