"VTEC" Idea in a boat?
 

Just wondering why there is no type of cam like a VTEC in a Honda in a boat? Wouldnt you get better all around power?

For everyone who dosent know how VTEC works.... For every 2 Valves, there are 3 lobes on the cam, when the engine gets to a certain RPM, a pin is put in place and the valves go from using the 2 fuel efficent lobes to the 1 lobe with more rise and duration.

Tommy

the vtec adds horsepower at higher rpms. a boat motor just uses the higher lift lobes all the time you need the low rpm torque to get on plane. I think of a vtec not as a motor that pulls harder at high rpm but one that doesn't pull at all untill the rpm gets up.
Sorry but I work at a honda dealership and I'm so sick of hearing "my rice burner is fast cause its a vtec.":D

I know, I hear that every day at school!! Have you ever heard a Honda 1.6 w/ VTEC at 9,000rpm? That is one of the neatest sounds I have ever heard...

This is my impression also. It doesn't really do a whole lot down low. I think it's marketing genius for disguising it as an economy feature and not a power building feature.

It de-rates the power down low, not adding power up high.

There has been a form of the vtec motor in a boat. Toyota motor corporation marinized the same V8 that they put in the lexus GS400. the VVTI motor was converted for marine use by toyota I believe 4 years ago, they could not decide on what to do with the motor( choseing a builder to sell them to) so they got into the marine buisness themselves. Along came Toyota Marine Sports. They chose to enter the skiboat market(still not sure why that highly competative niche market?) They built boats for about 3 years, then closed up shop. My mother worked for them until she went to chris-craft.... The boat was a pretty nice boat... they just could not get the "back office" to run smoothly enough to stay open.

And they did put a couple of ZR-1 engines in boats. (sure like to know what they are worth!) The ZR-1 had a valve that closed off the intake port to one valve to improve the low rpm torque. Not as sophisticated as the Vtec, but hey, it's was pretty hot in it's day.

I just thought about this... Wouldnt It help big motor boats with breaking drives? It would keep power down until a certain RPM, then give more top end?

I think that they may have that in the new Honda outboards ?

I think I saw something on Powerboat Show last week.

Efficiency
 

The VTEC is all about efficiency and EPA gas mileage charts.

Boaters don't care as much about efficiency, especially performance boaters.

everything has its niche in the market as do vtecs but theres isn't boats its its jet skis.

Don't knock variable valve timing. It rocks.

In the Honda VTEC application, I beg to differ with you, but the VTEC motors DEFINITELY have more low end torque than they would if they were not equipped with the VTEC system.

Benz used a variable intake cam system on its inline 6's and 4-cam V8's thru 1999. Those motors have killer bottom and screaming topend. Those motors have been replaced with a 3-valve dual plug motor that uses a dual tuned intake for a similar effect. Lexus/Toyota uses an electronic version of valve event timing variation (they still do).

Cars, however, spend a good deal of time under 2000 rpm. There needs to be adequate, or even impressive, response and pulling power at those low engine speeds. Otherwise, buyers drive them and feel like the cars aren't powerful even though they might spit out 300+ hp on top.

Variable valve timing/selective intake valve actuation both offer the engine designer a useful tool to restore usable or impressive low end torque while being able to utilize significant valve overlap for topend performance.

Boats (not talking about tournament ski boats) never need to display big torque numbers under 2000 rpm. Most boats see the planing load at 2500-3000 rpm and top out at around 5000 rpm.

It is easy to cam a boat motor for a flat torque curve in a 2500 rpm window. This is easy enough to do without valves that turn on and off. Since we use single-cam OHV motors, it makes it impossible to offer variable intake timing. The best we could do in a domestic V8 is to offer total camshaft advance and retard which would prove effective, but not nearly so much as moving the intake separately from the exhaust.

As far as VTEC style selective valve actuation, exactly which valve would you choose to not operate? A boat motor has one exhaust valve and one intake valve per cylinder - it needs them all operational. To be able to use the VTEC system, it would need to be a multivalve motor.

Boat motors are always based upon easily available automotive longblocks. It keeps the costs down.


To rehash:
Boat motors need to produce torque within a relatively narrow rpm range when compared to an automobile application.
Boat motors do not need to produce prodigious torque right off idle.
Boat motors do not offer a feasible way to provide variable intake timing or selective valve actuation.