Hehe my bad. The bag weighs 0.2 oz.

Cheers,

Gary
Gruppe-S

 

And my wife wonders why I have to stare at this site for dozens of hours before I make a decision and buy a part....

 

the hollow camshafts are nothing more than a marketing gimic. You can't argue with the laws of physics...... Hp loss due to the acceleration of rotational mass will be dependent upon the radius at which that mass is spinning. And it's not linear! The loss will be proportional to the square of the distance from center.

So if you shave 4#'s out of the center of a cam, the gains will be minimal at best. You can calculate it out on paper as a gain, but you won't register it on a dyno.

In rough figures.... 4#'s saved 1 in. from center on a camshaft vs. 4#'s saved 6" from center on a lightweight flywheel. The flywheel savings will have a 3,600% bigger impact on hp savings! Scratch that..... make that 7,200% since it's spinning twice as fast. I didn't measure the camshaft radius or flywheel radius to get dead nut accurate numbers, but hopefully this illustrates the point.

 

but that 4 pounds is about 2' higher up :P

so is helix gonna copy the 280s also?

 

aawwww you took it out of the bag just for meeee....now what about the oil on each one.......





dont worry bout that......btw great post

 

That's true, but the weight savings is not simply from the center of the camshaft. In fact if you look at the hollow coring on the Helix camshaft it is far less in diameter than the stock OEM camshafts. The reason is because billet type material is far lighter than chilled cast material, therefore weight savings exists >throughout< the camshaft INCLUDING the lobes which obviously are the greatest distance away from the center. Good evidence of this is demonstrated by the cross drill marks on the OEM camshafts. The Helix camshafts have no such cross drill marks and coupled with a larger overall lobe should weigh MORE than the OEM camshafts, but in fact it weighs the same. Compare this to say the an HKS or other 272 chilled cast camshaft where the majority of the weight increases are in fact distributed farthest away from the center of rotation - right at the larger lobes. Therefore while it is not going to be a night and day difference in performance, it is most definitely not purely a marketing gimmick - there are real (albeit minor) performance advantages to running lighter camshafts - especially ones substantially lighter than the chilled cast units on the market. I personally think it makes sense to purchase a Helix billet camshaft that costs hundreds of dollars LESS than the HKS units since it weighs less and performs similarly.

As for dyno numbers - engine response, especially as a result of gear-change is usually not properly demonstrated by a dyno graph. We see this problem all the time, especially on ball-bearing versus journal bearing turbochargers - a similar car producing similar torque/HP numbers with a similar curve can often have drastically different performance characteristics because of boost onset associated with a slower responding turbo. Same goes with the lighter camshafts / camgears, I can't figure out a good way to even demonstrate the improved engine response I am feeling aside from doing a 1/4 mile simulation on our dyno - which no one really wants to do.

Regarding the "copying" of the 280's, I can't speak for other brands but Helix did not copy the HKS 272's. If you are to degree the Helix camshafts on a measuring device you will notice that the Helix camshaft have a more aggressive ramp angle and thus more duration under 0.050" than the HKS units. This attributes to what we believe is a better performing camshaft (but rather than start a huge debate, we decided not even to discuss this difference). Ramp angle differences, coupled with lift differences is also why some cams such as JUN, Tomei, etc. perform differently than the HKS units even though they are all sold as "272 duration" camshafts.

Wheh, hope that explains some things.

Cheers,

Gary
Gruppe-S

 

Hahaha yeah, I was thinking about that - I was like man I hope he doesn't call me out on the oil. The oil weighs only a little. I swear!!

Cheers,

Gary
Gruppe-S

 

not trying to be an a$$ or an engineer (but since I'm both ),

someone with a calcuator check my math....

assumptions:

1) combined cam weight savings 2.3875#'s
2) diameter of stock cam is 1.5" (used a ruler, not a micrometer), and Helix cams have 1 full mm more lift than stockers.
3) all weight savings in on very edge of the circle the cam lobe makes
4) checking a data log of my "typical" car (320 whp on a DD dyno), it takes 6.4 sec. to go from 3500 rpm to 7000 rpm in fourth gear.

Using those assumptions, you should have enough information to calculate how much hp it takes to accelerate the extra mass of the heavier camshaft.

Rounding up, I get .008 hp. Can someone confirm?

 

I haven't looked over your specific numbers, but I think there may be a miscommunication (on my part) regarding the purpose of a lightened camshaft. Like a lightened flywheel, a lightened camshaft's purpose is not to increase horsepower by reducing the amount of energy necessary to accelerate it to a certain RPM in a straight line acceleration, rather it is to reduce the amount of stored kinetic energy during rapid changes between acceleration and deceleration - as would occur in a track car. Therefore I believe measuring the amount of energy absorption over time (like a dyno) wouldn't reveal the true benefits of a lighter valvetrain / camshaft, flywheel, etc.

Cheers,

Gary
Gruppe-S