RowJ

Been said before.... but not for a while! With the new lower prices, I thought I would pass this info along.

Installed Helix 2 Cam, from F-1 Diesel yesterday. Big thanks to member 'XLR8R' from LazarSmith Diesel for his expertise and assistance. LONG day but definately worth doing on a 2nd Gen. Better breathing contributes much improved low end response and acceleration. For anyone with big injectors and big tires (especially on an automatic) the difference is very nice. No longer need to lock out OD below 1700 rpm, and the cam does away with the drive shaft harmonic 'slapping' if stuck in lugging scenario (like slower traffic on hwy then accelerating from 50 - 55 mph in high gear).

Top end breathing is better too. No flat power spots at higher rpm's. Only played with it up to 3300 rpm but the promise is definately there. I'm still evaluating the new cam but so far it's a real winner. I've got that 'whole new truck' feeling again! Thanks Don M. for a great product! (You might however consider minor change in directions. On mine, at least, stock cam took a 20 ton press to get the gear off. Still be trying to get it off otherwise, IMO.)

Thanks to all the members I 'bugged' for info on the H-2 Cam over the last yr. Turned out to be the perfect last step to get my truck exactly where I want it! I strongly recommend the H-2 Cam and the Pro Sportsman Valve Springs... especially with the reduced prices out there now.

Note: I've had the F-1 valve springs for 2 yrs. For anyone curious about it, I was interested to see no signs of wear on the factory cam from stronger springs.

RJ

mishkaya

Have had the Helix 2 installed for a couple of years now, and I am still very happy with the results it provided. Didn't do the install myself, but it did wake the truck up for sure. Glad you are happy with your setup.
mishkaya

ratsun

Just like icing on the cake isn't it

haloman

Congrats on the install!

CapnRam

For anyone with this cam, how did your mileage change or did it? I'm thinking about the H-2 myself, also how would elevation affect this? i'm about 3600ft.. thanks

Capn

RowJ

Would be even more important to have better breathing at altitude, IMO. Your not way up there but high enough to feel the difference from sea level.
With your Smarty/TST stack you must be a bit overfueled as it is?
I believe you would see bigger difference than did I. Just a calculated guess from one who spends a fair amount of time up at 6000'.

I've heard reports of better mileage but to soon for me to comment. Others will chime in, I sure. Would like to know myself.

RJ

98.5Hotrod

I also installed Helix 2 today. Just finished, started truck and broke cam in. Truck sounded good no strange noises or anything. Will install bumper tomorrow and go for a ride. Did any of you see a reduction in low speed smoke, egt's? Can't wait.

crobtex

Major undertaking that I know you are glad is over. Good to hear that it's doing what you expected.

Now what?

HOHN

I'd like to start this post by saying that I trust Don M as much as I could trust any vendor. His products all seem to be of the highest quality.

But I'd REALLY like to see some of the analysis he's done on the effects of the modified cam specs on the rest of the engine.

I never really gave this much though before-- but since I started my current job, I've seen just how much goes into the development of an engine. Cummins doesn't pick specs out of thin air-- they are tweaked based on the stress on the valvetrain.

Think about all the possible failure points, and it gets pretty overwhelming. There are Cummins specs for the maximum velocity of the valve hitting the seat, for the maximum stress on the crossheads, for the maximum stress on the pushtubes (pushrods in normal english), etc.

Heck, we run the engines with half a million dollars worth of sensors on them measuring things like pushrod deflection, crosshead flex, valve guide loading (i.e., sideways deflection of valve within the guide, etc).

govspringbounce

There was a thread over on the TDR. It's old. The discussion covered a lot, including the stress on parts because of a smaller base circle with cams ground from a stock cam.

Good luck.

linetrash75

RJ, did you install new lifters or stay with stock? And did you get a lobe for mechanical lift pump? If so low pressure or high pressure?
JED

RowJ

No wear on stock cam lobes; none at all!! So no new lifters. Journals show some very minor scoring (155,000 miles)
All bolt on, F-1 cams come with the mechanical fuel pump lobe. I'm not using it.

Justin - Gets even more interesting when you compare measurments on the two cams. Don's exhaust lobe is shorter (.011") than stock but longer duration....... intake lobe is taller (.026") AND longer duration. Given these subtle differences and Cummins over-engineering, hard for this non expert to see how there could be a serious concern??

RJ

dzlfarmboy

I just in installed an H2 last weekend in a CR and aswell the customer was very pleased in the spoolup results since he was running a 66/13 over a S480 better spool helped alot.

Brett

HOHN

Ok, RJ-- I'm all because I see exhaust up there twice..

I suspect the first exhaust is exhaust and the second exhaust is actually intake-- right?

Given the poor exhaust flow of a B-series head, I can see why Don would go that route. The port won't flow any more with increased lift, so why stress the valvetrain with unnecessary lift? What the port needs is more TIME to empty the cylinder, hence the increased duration on the exhaust side.

Emissions considerations dictate that most factory cam profiles are far from optimal for breathing potential. In fact, many are purposely designed to reduce breathing efficiency so retain some exhaust in the cylinder, serving as a crude form of EGR that will raise EGT but lower peak cylinder temps/pressures and hence lower NOx.

If I were designing a cam for these engines, I'd do it like Don did.

I wonder if he narrowed the lobe separation angle as well? The proper LSA is instrumental in using the exhaust to help the intake breathe. This can be a key part of the Boost/TIP pressure balance. Most factory LSAs are on the wide side. A 4V had needs a wider LSA than a 2V head, but the factory spec is probably still a little too wide for an application where power and EGT control are the main governing objectives. Of course, this depends a LOT on the turbo configuration. If you are running a smallish turbo and have high TIP, then you'd want to go even wider on overlap to reduce the amount of reversion flow. So turbo setup is a huge variable that has a big impact on the "ideal" cam. The overlap consideration is also very different from a gasser in that high overlap will throw fuel out the pipe of a gasser, while a diesel will just have some fresh air thrown out the pipe.

We often look to boost=TIP as a measure of efficiency, but a well-designed setup should have boost HIGHER than TIP to evacuate the cylinder.

Assuming the turbo(s) is/are spec'd properly, the biggest ingredient in the turbo's efficiency is the cam design.

I'd really love to do the H2 cam and Pro springs!

Justin
(see sig)

RowJ

Sorry about mis typing.... and your guess is correct!! (made corrections to Post #12).
Exhaust is .011" less and ALOT more duration......... Intake is taller than stock with some added duration also!

Those #'s come from Don M. here ....... http://www.competitiondiesel.com/for...ad.php?t=32146

Actually I'm a little confused. Since H-2 Cam is same for 2nd Gen and CR (according to RIP) I assume the stock Cams are the same also? Anyone know?

RJ