LandCruiser 79: How LowRange's Gleno gave it the berries
Gleno's 79 is rigged for serious offroad adventure.
Let's have a closer look not just at the mods themselves, but what they actually do, and how they do it, so you can apply the knowledge to your own 4WD.
The basics of how any internal combustion engine works are pretty simple. Mix in some fuel, add in some air, squeeze it till it's about to burst and then do something to make it all go bang. In a four-stroke engine it'll run on two cycles, sucking the air in, compressing it, ignition and then pushing the spent exhaust gases out.
The semi-official terminology is suck, squeeze, bang, blow where Intake = Suck, Compression = Squeeze, Compression = Bang, and Exhaust = Blow.
Petrols and diesels each work differently but the basic idea is the same. With a petrol engine the petrol is sprayed in as a thin mist, compressed as the piston rises up and then ignited by the spark plug. With a diesel the compression starts when it's just air in the cylinder. Right at the last minute a mist of diesel is injected in causing the mix to ignite and make power before starting all over again.
Bear with me here, I am going somewhere with this.
So what does a chip do?
While a diesel engine is pretty simple in theory. there are a few things that control exactly how much power they make.
The size of the motor and a turbocharger strapped to the side of it obviously make a big difference but there's generally a whole heap of room to tweak what the factory gives us, and that's pretty important when the best words Gleno can describe the 79's engine are "a complete slug".
By running a piggy-back ECU, Gleno has basically been able to trick the standard computer into seeing whatever he wants it to see.
With a bit of custom tweaking this means he can do things like bump up the fuel pressure going in (provides a finer mist and therefore greater surface area of fuel and a cleaner burn), the injector duration (physically keeping the injector open for longer to get more fuel into the cylinder) or even injector timing (controlling the exact moment fuel goes in) - as a general rule the more advanced, the more potential for a stronger burn and the more power.
The idea behind tuning what the factory gave him, rather than throwing on a bigger turbo, is that there's generally a whole lot of leeway in the factory tune. The manufacturer basically works on the assumption fuel will be seriously bad, air quality will be shocking and that it'll receive sporadic servicing at best.
If you promise to be good you can ramp it right up to what the motor was built to handle without having negative effects.
Do big exhausts really make that much of a difference?
There's a few reasons bigger exhaust upgrades are such a common modification.
First, the factory exhaust is generally ridiculously restrictive, mainly due to cost saving in the design and manufacturing process to protect sales margin. By going to a freer-flowing design, gases are able to get away from the engine quicker, meaning things work smoother and therefore produce more power, earlier in the rev range.
The second reason is one often overlooked. Turbochargers make a lot of heat, upwards of 900° in extreme circumstances. A bigger exhaust is able to get the gasses and therefore the heat out more quickly, meaning increased engine life and less load on your cooling system.
The third option, and probably the main deciding factor for Gleno, is the 4.5L V8 Turbo-Diesel in the 79s just flat out sounds horn with a big set of pipes.
But what does it all mean?
All of this information and electronic wizardry is all well and good but what difference does it actually make?
In Gleno's 79, actually a fair bit. You can see below the dyno printout from each round of modifications, and while some people just circle the biggest number on the page and pat themselves on the back the real information comes from the lines.
Luckily they're pretty easy to understand. The higher the curve goes, the more peak power, the earlier the curve starts rising the more lowdown grunt and the smoother the line, the smoother the power.
By running the 79 up on the dyno to watch the effects as each change is made Gleno has been able to get a 26% increase in horsepower consistently across the rev range and smoothed out the factory drop in power at 60kmh, so there's no change to driveability - it just drives like there's an extra couple of pistons firing away under the bonnet.