Hollow Camshafts

I can't see much advantage, except a little weight saving which would help in a racing engine.
Maybe it allows simpler cheaper manufacture, or some secondary feature like providing an oil path. The weight saving would be more important if it was in a reciprocating part.(Or if I had to carry a sack of 'em)
Del

As in the cam illustrated below, being able to adjust intake and exhaust timing independently by the ECU algorithm can extract the highest efficiency and/or power at any given RPM, gear and load condition. Previously that could only be accomplished with independent intake and exhaust cams and all the extra components (read: weight/expense of incorporation/vulnerability to failure, etc.) necessary. The ability to efficiently deliver lubricant to upper cylinder components is an important advantage but in the age of environmental protection, high fuel prices and the desire for vehicles to perform as well and generally better than those we have experienced in the past, it has been overshadowed.

Although it looks like one camshaft with a phaser at the left end, it's really a hollow tube-type shaft with a second, solid shaft through it, with the phaser connected to both. The intake cam lobe assembly (A) has a pin that goes through a slot in the hollow camshaft and is pressed into the solid cam. The exhaust cam lobe assembly (B) is pressed into position on the hollow camshaft.

Now that's a hollow cam. It's from a Viper V10.

All modern day CamShafts or 'Bump Sticks' are 'hollow' in the sense that they have an oil passage through the center of them that takes in oil from one or more of the camshaft bushings and distributes it out to each cam lob to lubricate each lobe and follower. In this manner they are the same as CrankShafts. This is unlikely what you are asking about though.

The valve train in a 4 stroke Otto engine are the most highly stressed components in the engine. Even on a normal. Low powered, plain Jane consumer engines, they typically undergo acceleration rates of 100 G's in normal operation.

As other postings here suggested, it is quite likely to accommodate variable valve timing which is a VERY significant factor in 4 stroke Otto ICs. There are a number of variable valve timing mechanisms now.

FYI: Renault Formula One racing engines which have reved to over 19,000 Revs/Minute have no CamShafts. The vales are operated by compressed air.

Hollow shafts, cam, crank etc work the same as solid. Hollow only to reduce mass( weight). Quicker accelleration and lighter engine. All this means perhaps more economy. Stu.

I have a 1999 Grand Am It had a hollow camshaft in it. Note the past tense Had. There was no extra shaft running down the middle Nor were there any oil journals in it. I was for all intinsive purposes the same as a solid shaft.

It broke in half. It is now being replaced with a solid shaft.

In this particular instance see it as a way for the manufacturer to save a few bucks and that is all. I wil let you know this spring if the performance is affected by the solid shaft which weighs about a pound more. I am completely rebuilding the entire motor as when the shaft broke it destroyed the cam bearings.

Personal opinion based on this discovery, I'll stick with solid.

Hollow shaft is lighter thus less fuel is consumed during acceleration. Also it is usually cast technology involved so less waste of material during manufacturing and less energy is needed to produce the shaft. The hollow shaft is in Suzuki 993 cc gasoline engine that is probably best designed engine of all, because everybody adopted the design today.