OT-OF-Here said:
I've read Don's info on the various grinds for the Helix Cams. I haven't seen a breakdown on the Max Spool Cams,... so does a higher number Max Spool indicate it is more agressive and for a more performance oriented usage than a lower number for say towing applications,... anyone know for sure?
Also wouldn't it be a good idea to have someone put a degree wheel on these various cams and post the specs. I'm sure there is a reason for all the mystery but in the gasser world you purchase a cam by the specs and not because it's a 1, 2, or 3 level cam. Confused on this marketing strategy.
I've got the Helix 2 and have been happy with it but I'd still like to know the specs. With the close tolerances involved I'm not all that sure performance wise that one can be all that much stronger performing than another unless you'd change out pistons or whatever to accommodate a higher lift or more duration.
Anyone know of a little higher ratio rocker that could get a bit more lift that would help performance without kissing the pistons?
Maybe Don or Greg will enlighten us on some of this hopefully.
Pat,
You may already understand this, but for anyone that cares: The main differences in our Diesels and the run of the mill normally asp. gasser engine are in how the fuel and air are delivered to the chamber. Gasser cams are much different since the gasser engine is sucking in a mixture of air and fuel together. The Diesel only takes in air through its ports. Gassers that want more fuel to end up in the chamber simply change the cam duration profile from shorter to longer. This allows the "mixed" air/fuel more time to make its way into the cylinder. Actually gassers dont suck in air at all. It is pushed in by atmo pressure, but that is another long argument for another day.
Gasser guys can pick a cam profile by duration. Everyone that has played the gasser stuff knows what a 268, 292, or a 305 cam is. This is degrees of duration and these cams can be choosen by their numbers easily. Bigger cams almost always mean bigger power. Caveats of course.
Diesels are NOT that way at all. Diesel cams are very short on duration when compared. When we want more fuel, we just inject more through the fuel delivery system. Diesels also have a very wide range at which the air/fuel will burn and continue to make power. Gassers dont. They have a very thin range of making efficient power with parts per air and fuel.
Diesel cams come very optimized right from the factory and the further you play outside a window of what works, the worse things get. This is part of the reason we see so many flops in cam grinds that are supposed to enhance performance. Adding duration to a Diesel cam can get one into trouble fast. We only need to look at some of the fastest 12V trucks running around the drag strip to see that stock cams are super. Of course the fastest VP44 and CR engines are using an aftermarket cam. The H2.
Regardless, we cant look at a radical number on a Diesel cam and say " that one is better" or "it makes more power" on a Diesel like with gassers. Honestly I think it would cause more confusion and less performance in the end if the numbers were published.
Tricks of efficiency are what the H cams use. More airflow, hence lower EGT. HP is rarely found with a Diesel cam change and if so it is on the order of 20 or less at peak. Power band changes or when the power comes on is the best anyone can do.
Going radical is fruitless. Big numbers are bad.
I have dyno tested some radical stuff we tried and cam profiles from the more dirt oriented puller stables. It was all junk and cost, in some cases over 100 HP.
You cant gain big with a Diesel cam, but you can certainly lose. Thats not counting the countless bent push tubes and valve float from using unmatched springs and lobe designs.