On The Water For Longer With Variable Valve Timing
Suzuki VVT Explained: How variable valve timing works inside your outboard motors to increase torque and save you fuel
We’ve all heard that Suzuki outboards are more fuel efficient. But how? What is inside the motor that’s so different from what everyone else is doing? We’ve started the conversation a while ago by looking at Suzuki’s most recent fuel-saving tech, Lean Burn, but a far more fundamental system that Suzuki uses in most of its motors is Variable Valve Timing (VVT).
What is Suzuki variable valve timing, how does it work and – most importantly – how does it save you fuel and keep you on the water for longer? To fully appreciate the genius of this tech, you probably need to take a quick look at how engines work in general.
WATCH: BASIC ENGINE FUNCTION WITH VARIABLE VALVE TIMING
Car engines are a bit larger than outboard motors, so maybe it’s a bit easier to use them to explain the basic concepts of how the valves inject and remove the fuel-air mixture that an engine runs on. So we found a video by CNET that talks about the variable valve timing in Fiat cars, to get us started:
Basic concepts: The valves in any engine open and close to let air-fuel in and out. They are controlled by a completely mechanical process: There are these nodules on the camshaft that push them to open and close as the shaft turns. The same is true in all internal combustion engines, including your Suzuki outboard’s (just on a slightly smaller and more specialised scale, of course).
WHAT’S WRONG WITH NORMAL VALVE TIMING?
Well, if your valves’ open and close cycles are the same throughout the entire range of your motor’s revs and speeds, you get flat spots where it starts to lack power. Now, normally with cars and bikes, engines are designed to give you their best performance at higher revs.
Here’s a graph where the dotted line shows how an engine with standard valve timing performs: See, it starts off with very low torque and power, and then it only gets more power output at higher revs.
But, if you think about it, that doesn’t make sense for outboard motors. Most of us use our boats mostly at lower engine speeds, because we’re fishing, trolling or cruising, not racing. So most fishing and recreational boats require more torque and power at the lower and mid-range speeds.
At the same time though, when you’re trying to get out to the fish or need to get back to dock in a hurry, you need that top-end power to get you moving quickly. So, we also need to be able to adjust how the engine delivers it’s power, from more torque at lower RPMs to giving the juice at higher speeds. In essence, the power needs to be variable. And so, variable valve timing comes in.
HOW VARIABLE VALVE TIMING WORKS
Now, your outboard engine looks a little different to a car engine. For starters, the camshaft sits on the side (not on top), as the piston and cylinder lie horizontally.
And an outboard motor is also on a smaller scale, so it’s hard to really get in there and show you exactly how VVT works on Suzuki’s four-stroke outboards. But we did find a nice video showcasing Suzuki’s new VVT tech for its racing bikes that give you an idea of how it functions.
WATCH: VVT IN SUZUKI’S NEW RACING BIKE MOTORS
Again, your outboard is a little different, and shown here is a cutting-edge mechanical system, so what’s inside your outboard might not be 100% the same. You might find outboards use a hydraulic system, but the core idea is the same.
Suzuki uses variable valve timing tech to make minute changes to the timing of when the valves in the engine open and close. The one end of the timing could be set for best performance at lower speeds, and the opposite end of the spectrum is set for more power at higher speeds. And then there are lots of setting in between to control mid-range speeds.
THE BENEFITS OF VARIABLE VALVE TIMING
So, how VVT save you fuel? Well the outboard’s computer now has variable timings for its valves, and it constantly analyses the conditions and adjusts those timings to give you a) more power at any speed and b) use the most fuel efficient way to give you that power.
For example, by adjusting the exhaust valve ever so slightly to stay open for longer, your outboard ensures that all the burnt fuel-air exhaust is completely removed from the engine chamber. Now, when the next cycle comes around, the chamber is cleaner, which means you’ll get better combustion on your next stroke. And the engine can adapt this whether you’re idling, cruising, trolling or gunning it at top speed.
It’s a remarkable technology that helps save you fuel and gives you more time on the water.
SUZUKI OUTBOARDS WITH VARIABLE VALVE TIMING
Most larger Suzuki motors come standard with this tech. You can always contact Nauti-Tech Suzuki for more info on specific models. But here are a few of our favourite Suzuki outboards enhanced with variable valve timing:
The all-new Suzuki DF150 AP
The powerful Suzuki DF175
The double overhead cam Suzuki DF200 AP
The award-winning Suzuki DF250
The record-breaking Suzuki DF300 AP
The flagship Suzuki DF350 A
Plus: To see how Suzuki really shines in the low rpm sector, check out how Troll Mode turns your Suzuki into an instant trolling motor for your boat.
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