TD42 Turbo Upgrade Guide: UFI 16G vs 18G vs 21L vs 23L

A stock TD42T makes around 130hp (97kW) at the wheels on our Mainline dyno.

A UFI TD42 turbo is the first step almost every TD42 build takes after that.

16G, 18G, 21L or 23L.

Low mount or high mount.

11mm pump or 12mm pump.

There’s no simple answer to which option you should get, but based on our years of experience building and assembling these TD42s, this is what I can tell you.

Each level of performance upgrade is there to cater for different needs and different risk tolerances. At the end of the day, the TD42T engine has proven to be a worthy advocate for a performance upgrade. They are very reliable, even with the performance at nearly double the factory power, but there obviously are going to be some drawbacks with each power level that you step up to.

Before we go any further, I just want to point out that my personal favourite setup is as listed below:

Which UFI turbo should I put on my TD42?

This is a GU TD42 we tuned with a UFI 18G and a UFI 12mm 230hp pump. A 230hp pump will usually make about that on its first run on the dyno, and this one made 224.4hp (167kW) before we touched it. There’s still a bit of headroom in it, though. Once it was set up on the dyno, it made 243.6hp (182kW) and 612Nm at the wheels.

All four are built on a TD05 platform and assembled by United Fuel Injection for the TD42. UFI sets them up for low-down torque, so a bigger turbo doesn’t mean giving up drivability around town.

The way I try and describe what turbo lag is is not based on boost by RPM, because different setups and different tunes can achieve pretty much the same boost by XYZ RPM, no matter what size of turbo on it (unless it’s completely wrong for the application, in which case, good luck).

The easiest way I find I can describe it is that there is going to be a latency in the time taken to achieve that boost by that RPM. If you put your foot down with a 16G, you’re going to see boost within half a second, reaching its max potential. Whereas if you go to the 21L, 23L, it’s going to be an increased period of time before your engine reaches its desired RPM as the turbo speed increases. However, it may still make peak boost at 2,000 RPM. It just takes longer to get there from 1,500 RPM.

It’s a shame more dynos are not measured based on time and not just RPM. This would truly reflect the difference between turbocharger response.

Every size bolts to the factory T3 style flange, the same as the factory TD42 turbo. They suit the TD42T and TD42Ti, with or without an intercooler.

18G or 21L?

This is the question we get most.

The 18G is the turbo for a tuned TD42 that tows, tours and gets driven every day. It runs out of puff around 230hp (172kW) ish.

The 21L is for 250hp (186kW) and up. It needs more fuel and a better manifold to work properly. Bolt one onto a stock pump and a log manifold and it’ll feel lazier than the 18G.

The turbocharger manifold is one of the biggest driving forces when it comes to actually getting the best turbocharger response out of your TD42. We do not, under any circumstance, recommend the log-style manifolds out there. They completely hinder turbocharger response and drive up your manifold and cylinder pressure substantially

If you think you’ll want 250hp (186kW) down the track, buy the 21L now.

While we’re on the topic, there is a myth being perpetuated online that an 18G is what causes the TD42 to snap cranks because it is more responsive than a 21L. People have been unnecessarily purchasing the 21L and sacrificing perfectly good turbocharger response because of a myth that they heard on a Facebook forum. This is absolutely not true and has no effect on the crankshaft whatsoever. They are quite small in terms of the size increases between each turbo, and the manifold pressure would be equal between both of them. There is more response out of the 18G, but no more than a factory turbo would have anyway. If you want to talk about crankshaft risk compared to the extra load of a turbocharger, the factory one is the smallest one out there.

My advice is to pick the turbocharger that supports your horsepower level as stated in this description, and you’ll have a fantastic driving experience with your Nissan Patrol while getting all the power you wish to achieve. I generally say pick a horsepower number that you want, then find the smallest turbo that will support it. That’s going to give you the best combination of drivability and outright power and torque.

Does the manifold matter?

Yes, more than people expect.

The 16G, 18G and 21L are happy on the factory manifold.  Although, if you want to replace it with a better-performing stock-position low-mount manifold, the Tillix low mount merge-style manifold would be the one to go for.

The Tillix low-mount merge manifold is suitable all the way up to 350 wheel horsepower (261kW). The manifolds are CFD-designed, and we’ve found up to a 10% increase in performance using a Tillix manifold on the 1HD-FTE and 1HD-T platform. The performance metric was judged by boost control duty cycle efficiency. With the manifold swapped out for a Tillix, we were able to drop the duty cycle percentage on the electronic boost controller down by a full 10% and improve turbo response by 200 RPM, while also delivering a 10% improvement in both torque and power. These same benefits are seen also on the TD42 engine.

Don’t run the 21L or 23L on a log style manifold. These two need a high or low mount merge manifold. It’s a strong cast manifold with a split pulse collector.

When you order the turbo, you choose your manifold option that you have fitted or that you are also purchasing at the same time.

We supply a Radius Fabrications 3-inch dump pipe with an EGT bung to suit the factory manifold and Radius manifolds.

For any other unknown brands of manifold, you get a dump flange so a pipe can be made to suit.

When selecting your turbo, the Radius high-mount merge dump pipes also work with the Tillix high-mount merge manifolds.

They are both situated in the same spot, so the dump pipes are completely interchangeable between both brands of manifold manufacturer. This also applies to the low mount manifold as well.

What comes with the UFI TD42 turbo?

• The turbo, built for your chosen size
• Nuts
• Oil lines
• Hose clamps
• A Radius Fabrications 3-inch dump pipe with an EGT bung (factory and Radius manifolds)

There’s no gasket between the rear housing and the dump pipe. Both faces are machined flat. A thin layer of RTV on the dump flange is all it needs.

The UFI TD42 turbo upgrade for the GQ and GU is $2,450 to $2,799 depending on size and manifold.

What supporting mods do I need?

Fuel

Fuel is what makes the power in a diesel engine. A TD42 turbo upgrade goes hand in hand with an injection pump.

• 11mm pump. Pairs with the 16G and 18G for builds up to around 230hp (172kW). See the UFI 11mm TD42 injector pump.
• 12mm pump. Built to order at 230, 250, 270 or 300hp (172, 186, 201 or 224kW), and adjustable within about 10% of that. This is the pump for the 21L and 23L. See the UFI 12mm TD42 injector pump. UFI builds each one to order. Allow 10 weeks.

Both are brand new outright, with no exchange needed, and are fitted with a ‘MOD TOP’ style boot compensator. It’s a mechanical pump, so there’s no ECU tune. For any 12 mm pump, this is where you’re going to want to start considering dyno tuning to achieve certain results above 250 horsepower (186kW). As you’re starting to get into the upper echelon of what these engines can safely handle, you’re really going to want to make sure that that’s set up and checked on the dyno.

Have a TD42Ti? The UFI pump converts it to a fully mechanical pump. The Ti’s number one injector has a wire running back to the pump for a timing signal. You’ll need a set of genuine Zexel injectors and rail to go with it.

If your injectors have done more than 100,000km, or you’ve no history on them, replace them when you do the pump.

Intercooler

For anything past a mild 16G setup, run a front mount intercooler. Our packages aren’t designed to run a hot pipe. PDI make front mount kits for the GQ, the GU Series 1 to 3 and the GU Series 4. Expect some trimming to fit.

Clutch

The factory clutch won’t hold the extra torque. Options include the Safari or UFI 850Nm clutch kit and the BRC 1000Nm heavy duty clutch kit.

Airbox and exhaust

Bigger builds need an aftermarket high flow airbox, with an intake pipe made to join it to the turbo. A 3-inch turbo back exhaust finishes the job. Manta make systems for the GQ, the GU wagon and the GU ute with a UFI turbo.

We supply, recommend, and fit the Fatz Fabrications airbox for the Nissan Patrol GU wagons and Utes. We do not currently have a GQ option available, but we are working on it.

Cooling

The UFI fan upgrade can be found here.

The packages

We’ve grouped the turbo, manifold and pump that work together into packages for the GQ and GU:

The 250hp+ (186kW+) package makes around 250hp (186kW) at the wheels on our Mainline dyno, with supporting mods. That’s close to double a stock TD42T.

What about a non-turbo TD42?

The NA TD42 can be turbocharged with the non-turbo TD42 turbo conversion kit with a UFI 16G.