Cams - kill engines?
 

Hi tech-heads... A question for you.

My mechanic (who is very good and who I have a great deal of respect for), maintains that fitting a performance cam will significantly shorten the life of an engine. His explanation is that the shape of a high performance cam means the valve's transition from open to closed is far more aggressive than on a standard cam and therefore the force with which the close is greater. This greater force, he says, will ultimately and significantly shorten the life of these valves and increase the liklihood of valve breakage / issues.

Please don't pick holes in specifics I may have made one or two errors in the re-telling. In principle however, this is what he said.

Oppinions?

Any Performance Modification has the potential to reduce the Engine life. But the Engine lifespan is also a big variable.:icon_confused:

Manufacturers made their Stock engine within a set of tollerances to give them the most cost effective product. This includes giving an amount of performance this is about right to ensure the engines last long enough, has enough performance. :icon_confused:

It all depends on what has been done to the cam profile, lift or cam lobe centers.

I do agree with your friend, basically some performance modifications done to camshafts will shorten the engine life of a standard motor. If done correctly the head should last with no problem, what I am talking about would be new valves, valve guides, valve seats, valve springs & retainers all replaced with performance parts.

If these are replace the head should last longer then using the standard valve train with a high performance camshaft..

The problem does not stop there the rest of the motor is put under strain & therefore will not last as long as a none modified motor.

I believe that any motor can take some modifications up to a point that are not harmful. Let's say you can get a little percentage of power with no risk.
Of course if you overdo it... trouble is around the corner :hismiley:

I do agree George, there is a small % before you really start loosing reliability.

I think we are talking about high performance camshafts here, like a stage 3 Hot Cam & a few other ones that are used in the Raptors that have a big valve lift & durations, that are designed to produce the power much higher in the RPM range than a standard cam.

So what about a hot cams stage 1 or 2 or an off-the-road cam ? Would you run performance vales, buckets, springs etc with them too?

So what IS the % power increase that you can play with safely? I mean just doing the pipes, airbox and pc111 has increased my bikes output by 16-18% which is heaps. Surely that can't put much / too much additional strain on the motor as all one is doing is freeing it up to work more efficiently rather than aggressively modifying it ?

Going by the feed back from the Raptor conversions the stage 1 & 2 cams do not require any head work, they seem to be reliable as well.

There are many cams out there for the Raptor 700 motor besides the Hot cams. The hot cams are classed as a mild mod compared to the X4 cams etc, which need the rocker arms to be ground away because of the valve lift & new valves & springs etc.

The XT660 motor is still really unknown to see how long it will last fully modded. We will soon find out over time.

There are also instances where performance parts can improve reliability. For example; The stock Yamaha piston has a 1mm offset piston pin that is offset toward the front of the engine (thrust side), which is designed to reduce the chance of cold start noise. This is done to reduce warranty claims from "mystery noises". It adds a fair amount of excess friction due to cylinder wall loading, and the factory cylinder coating is known to be soft compared to aftermarket nikasil.

Designing the aftermarket piston properly greatly reduces the wear cause by this offset. The factory piston is also known the fail at the pin boss in some conditions. I use the only piston that is made from 2618 material which is far stronger than the 4032 material used in other aftermarket designs.

Another benefit is the ability to design the piston with proper deck clearance. Bringing the piston to -.015" compared to -.050"(factory and most aftermarket), is worth about 2 hp over another piston rated at the same compression. Closing this "quench" area also improves efficiency and makes the engine less octane sensitive.

I know that it is difficult to read through what seems to be obsessive attention to detail on a single part like a piston, but if done correctly, it can improve performance and reliability.:glasses10: