Power and Performance

The 1VD is certainly a step up from the 1Hz-turbo in overall performance although it's not the huge leap you might expect, especially if your 1Hz is equipped with a 3" exhaust and running 12lb of boost as mine was. The engine's big advantages are a beautifully flat torque curve and amazing fuel economy.

Although I was pretty happy with the performance, it didn't take too long before I started looking at the range of aftermarket performance chips available for the new engine, to improve it even further.

After considerable research into the plethora of options available,
I decided on the V-CR chip from Tunit.

The decision to go with Tunit over other brands was based on the following:

• Reputation: Tunit have been in the business longer than just about anyone else and a few people I know with these chips have nothing but praise for the product.

• Performance: Dyno testing showed nice power and torque gains without adversely affecting economy.

• Tunability: Apart from the simple 9-stage setting dial, I liked the idea of further fine-tuning with a laptop.

• Easy installation: Literally a 5-minute job of plugging the chip into the wiring loom at the fuel rail pressure sensor.

• Portability: This chip suits every Toyota D-4D engine plus a large range of other common-rail engines, so it's possible to remove it before I sell the vehicle and then use it on the new one. All that's required if I change from Toyota is a new wiring loom. Tunit Australia also offer a tradein service if your new vehicle requires a different model of chip.

Tunit V-CR chip installed

The day after installing the Tunit, I loaded up the family for a trip to the NSW Snowy Mountains. The difference in performance was immediately apparent and spectacular. On the Hume Highway's Skyline hill, where I'd usually be forced to drop to 4th gear and 100km/h, I comfortably held 110 in 5th at only about 25% throttle. Not a single hill showed down the 100 on the trip south, and I constantly found myself having to lift the right foot after instinctively putting it down while climbing hills. Even during the climb from Jindabyne to Thredbo, I never once had to drop back to 4th gear!

Tunit claim that the chip takes the 1VD from 151 to 173kW and 430 to 536Nm. But the numbers don't do the chip justice, and it feels like a much larger increase. The biggest gains from the chip are at low to moderate revs, where the difference is literally night-and-day. I don't think I've ever made a performance modification that lives up to it's claims quite like this chip.

I'm gradually adding to a comparison table at the bottom of this page, so you can see what differences the engine and chip have made to performance in the real world.

Fuel Economy

This is possibly the single biggest advantage of this engine compared to either the standard engine or any other possible conversion.

To put it bluntly, it is remarkable.

On general running around town or on trips I'm achieving figures of 11-12L/100km. If I drive for economy, I can achieve 9-10L/100km.

To put this in perspective, even when the 100 was new with no turbo and no additional accessories or aggressive tyres, I was using over 12L/100km. Once I'd fitted a turbo and a range of accessories (Bullbar, winch, rear bar, 33" tyres, long range tank etc), I was down to 14L/100km around town and at least 16L/100km on a trip.

On a recent trip around hilly Tasmania the re-engined (but unchipped) 100 averaged just 14.5L/100km fully laden and towing a 1000kg camper-trailer! On exactly the same trip, a friend in a naturally-aspirated 4.2L diesel (1Hz) 100series averaged over 17L/100km, and he wasn't towing a trailer.

So how did Toyota make this engine so efficient?

• Common-rail injection: As with all modern diesels, this engine employs common-rail fuel injection technology. Basically it's the equivalent of electronic fuel injection for diesels. Instead of a basic, uncontrolled injector pump, it employs ultra-high fuel pressure with an engine management system controlling individual injectors for each cylinder, delivering a precise amount of fuel.
• Ambient condition compensation: Traditional diesels are tuned for just one set of conditions. Optimised for a certain temperature, altitude and air density. If the conditions aren't within this optimum range, the engine is not running at it's best. In this engine, sensors optimise the fuel delivered for the conditions, eliminating wasteful over-fuelling and power-robbing under-fuelling.
• Injector Shutdown: The computer automatically shuts down fuel injection when decelerating or on a trailing throttle. So whenever you're changing gear, slowing down or descending a hill the engine doesn't use any fuel at all.

I'm still assessing fuel economy after installing the Tunit chip. On the first trip with the chip installed I used about 12.5L/100km, which is slightly higher than trips pre-chip. However the trip was to the Snowy Mountains, at high altitudes with lots of hillclimbing, and I was enjoying the newfound power. I'll perform additional fuel consumption tests and add the results to the table below.

Update 25/8/10: I have just done the sums after my first tank of general driving since I installed the Tunit chip. With all the extra power I was expecting a bit of a hit from the 11.5L/100km I was getting pre-chip, but to my surprise it came back at an incredible 10.4L/100km, even though the driving included two trips to Lithgow and back.

More power and better economy? I've got no idea how they managed that trick, but I can't recommend it highly enough. If you have a modern diesel, I can't think of a better way to improve the performance of your vehicle.

Comparative Figures - 1Hz Turbo vs 1VD vs 1VD w/Tunit

About the vehicle and tests

Bear in mind that the figures above would not apply for a lighter, less modified vehicle. They are just for comparative purposes between the three versions of the same vehicle. The 'Cruiser is set up for touring and off-road work, with a heavy steel bullbar, winch, rear/tow bar and wheel carriers, fridge, 33" tyres, long range tanks etc.

Also note that overall gearing with the 1VD and new gearbox is somewhat higher than with the 1Hz, so some of the 4th/5th speed testing is not directly comparable due to RPM differences.

• 1: A short standing start run up a hill. The speed is that at the finish point.
• 2: A rolling start in 4th or 5th gear up a long highway hill which gradually gets steeper. Starting speed of 80km/h, where full throttle was applied. The 2nd speed is the maximum speed achieved and the third is the speed at the top of the hill.
• 3. Standing 0-100km/h on a slight uphill grade.
• 4. In-gear acceleration in 4th or 5th gears. Level surface.
• 5. Average fuel economy achieved in a mix of town, mountain and freeway driving.
• 6. Average fuel economy achieved loaded for a trip with a mix of road conditions.
• 7. Average fuel economy achieved loaded for a trip, and towing a 1000kg camper-trailer.

Reported oil consumption

There have been reports doing the rounds of 1VD-FTV engines consuming oil at an abnormal rate. The cause seems to be a mystery, with some suggesting it's due to faulty vacuum pumps or high viscosity oil. With this in mind, I've followed the advice of some of these drivers and used a slightly thinner engine oil than the 15W40 recommended by Toyota. HiTec oils produce an excellent heavy-duty 10W40 Euro4 spec oil, which I've used since installing the engine, and I haven't had any noticeable oil consumption after almost 15,000km.

What's left to do?

The items still to be done include:

• Connect the dash tacho to the ECU. I have spoken to an instrument specialist about this, and he advises that he should be able to create a conversion box from the ECU square-wave output to the 100's sine-wave input.
• Connect the ECU's speed input. This isn't a must, but it would be nice for cruise control and fuel consumption data. Again, I should be able to use a conversion box to enable this.

What does it look like?

Here's a video of the engine installed and running in the 100, and a photo of the installed engine. I'll add more photos and videos of the installation in the future:

(Click photo to enlarge)

Choosing accessories

I'm a big supporter of Australian products for their quality, durability and benefits for the country. Why buy imports when we have the best products right here? The great Australian-made products on the 'Cruiser include:

• ARB Air Lockers and Bullbar
• ROH Alloy Wheels
• Safari Snorkel
• King Springs
• Bluescope steel (for the rear bar and wheel carriers)
• GME UHF radio and aerials
• Stratos seats
• Trailblaza fridge