HOHN

Look again and you'll see that my guess was correct

XLR8R

Hopefully, this will clear the confusion: I measured the Helix on 2 occasions with 2 different tools and compared the measurements to RJ's 24V cam. For arguments sake (specifically - to prevent it ), I'm calling 5 thousandths the margin of error.

The H2's exhaust lobe base circle is only ~.007" larger than OEM, so with 100K+ miles of wear on it in RJ's truck - Don likely didn't change that spec. However, the H2's intake lobe base circle is significantly smaller than stock - by .090" So, obviously there's a bunch more room to manipulate the intake valves' window.
Incidentally, the H2's lobe width is quite a bit smaller than the factory lobe... by almost 2/10"! Besides reducing the potential lobe/lifter bearing surface, the Helix is noticeably lighter than the stock cam - makes installation easier when stabbing that last journal.

I think RJ got those H2 specs from Don, but I mic'd the intake lobe as having .060" less lift than the stocker; the exhaust lobe is slightly higher than the original - but again within the expected wear rate of a 100K+ mile engine.

The cam timing is still pretty tame - nothing radical to cause reliability or strength issues... usually, you don't see a cam looking like that outside of an old low-compression V8 with a 2-barrel pulling twenty-something inches of vacuum at idle!

The LSA and lobe profile suggest that "in-cylinder" EGR is reduced while keeping both intake & exhaust valves near maximum lift for MUCH more duration (but again, only in relation to the pointy OEM profile).

Even though the Cummins engineers & Don had different goals in mind when designing the cam profile (500K mile TBO & emissions vs. high performance & RPM), I wouldn't hesitate to recommend a Helix as far as valvetrain wear or life is concerned. One look is all is takes to see that the CTD's upper end was never intended for high RPM operation, but it IS rather well designed for durability, especially in terms of the oiling system; i.e. the cups on the upper end of the push tubes, the oil feed holes & distribution grooves in the rocker trunnions, the slots on the bottom of the crossheads for the valvestem tips, the oil-bathed floating tips on the rocker arms, etc. The added stress to the CTD valvetrain from springs and a bumpstick is a lot less than the typical increases you'd cause when hot rodding a gasser valvetrain.

RowJ

Yup! Corrected my comment. Been on pain pills all weekend and having serious trouble focusing. Not posting anymore today!!

RJ

Mike Holmen

Don's cam has more lift at 0.05 and duration than stock cummins cam. That the reason that the stock valve springs will bind with Don's cam. Cummins could if the EPA would allow it would grind the cam more aggressively similar to what the aftermarket has done. Its mostly to do with the tailpipe nox/co limits (emmissions).
Do you have to fly cut the pistons for his H3 cam? With my cam, I could use the stock springs. I noticed big differences between my old PDR stage 2 head and the cummins recon head. Its tuff to justify spending money on porting on a head that only last a few years. The cummins head doesn't flow any more air past 0.5 of lift on the exhaust side. The main advantage is getting the valve open earlier and remain open longer. This is why most 2 gen HP junkies upgrade to the CR 3rd gen head, its just flows more air. Thats my two cents....

XLR8R

Exactly - not higher gross lift, but a lot more lift under the curve - makes the valves' window a lot larger.

signature600

Told you a long time ago to do that RJ...glad you like it.

Just wish I could drive mine enough to see how mine does...we're getting close to making some power tests

Chris

XLR8R

That's great news about the driveability improvement with your built tranny! A benefit that didn't occur to me...

ratsun

[QUOTE=Mike Holmen;2160064]I noticed big differences between my old PDR stage 2 head and the cummins recon head. Its tuff to justify spending money on porting on a head that only last a few years. QUOTE]

Mike, how big of differences?
Greater than the IC swap, as thats about the same $ right?

98.5Hotrod

Now that I have some drive time on the truck, I love the cam, noticeably smoother idle, engine idle much quieter, motor stronger down low, much quicker turbo spool up, less low rpm smoke, have not checked crusie egts but I suspect they will be lower also. Love the cam thank you Don M. Also thank you Tim at TRE Diesel.

Mike Holmen

The porting is abit more noticable. I hardly really noticed any change with the spearco IC vs the stocker. At wot, there is some, but that using my SOP meter. I did the air horn/IC at the same time. I would spend the money, but at almost $4k every second to third year, its pricey. I have to learn to do it myself. I have a few NFG cores laying around in my garage. I might even cut up my old stage 2 head, if it can't be salvaged. I have a local shop thats interested in replacing the valve seats, so its a wait and see.

Ph4tty

The low end is one of my favorite benefits. I'll run the truck down to idle going around curves and such. I do get a little surge below 1000 rpms, but I know I'm not supposed that low in the rpms in 4th gear so I don't complain.

Tate

I wonder if thats a 24v characteristic? My 12v I will idle around in 4th gear and pull up with no real noise or surging. It'll do it in 5th though. My 24v, it sounds terrible doing the same thing. 3rd gear is as low as I will go at an idle in that. Both have same gear ratio, but the 12v has bigger tires on it. Not sure on the weight differences between the two trucks.

Diesel Doc

Try that in a powerstroke and it feels like your riding a jackrabit.

RowJ

I always assumed it had to do with bigger injectors? I noticed a big difference on (very) low end when I went from Mach 4's to Mach 6's.

kawi600

Ill be installing a helix-2 soon I think. Doesnt look like there are any heavy springs made for the 12v besides the cummins 60lb ones.
If I upgrade to this cam am I going to be held back by the lack of porting in the head?
with 190k on the odo, maybe I should consider one of those loaded cummins reman heads at the same time