Kenworth Launches MX-13 in T409 Models

By: Matt Wood

The 13 litre PACCAR MX-13 engine has now been officially launched as an option in Australian Kenworth trucks.

The bonneted T4 range now has a choice of either Cummins or PACCAR power. The 13 litre MX engine is no stranger to Australia with over 1000 examples plying our roads since its introduction in 2007.

However these engines have been powering DAF trucks, in fact the MX-13 is probably best known as the powerplant of the flagship DAF XF105.

MX-13 Power Settings

The lightweight MX uses a Compacted Graphite Iron (CGI) engine block and is available in two power settings, 460hp and 1700lb/ft of torque, or 510hp and 1850lb/ft of torque. It tips the scales at a quite respectable 1,200kg.

The MX-13 is touted to be a lightweight and economical powerplant for applications up to 70,000kg GCM.

The launch of the MX comes at the tail end of over 1.6 milllion kilometres of testing. A further half million kays has been notched up by units that have been purchased during the test program.

The new installation represents a couple of firsts for the Bayswater team; obviously this is the first time that Kenworth has had an in-house engine option. But also this will be the first time that Kenworth has built a completely 24-volt truck.

While this may be seen as Europeanising the KW product, Kenworth has opted to use Eaton transmissions for cog swapping rather than the ZF sourced AMT that currently resides behind the MX in DAF products.

This gives the market a transmission choice of either Eaton manual or UltraShift Plus AMT.   

Test Driving the MX-13

We got the chance to climb behind the wheel of some MX powered T409s at the Australian Automotive Research Centre (AARC) near Anglesea Vic.

The fleet of test vehicles was made up of single trailer and B-double combinations with gross weights ranging from 35,000kg up to the 62,500kg with both manual and AMT transmissions.

There was even a smattering of DAF XF105 prime movers available to drive as a comparison.

This wasn’t the first time I’d driven the Kenworth MX combination, but earlier drives had been in pre-production prototype vehicles. The trucks at Anglesea however were the final result of all that tweaking.


The driveability of the MX is superb; the low flat torque curve of the MX makes it an easy and very forgiving engine to drive. In the manual, progressive upshifting was a piece of cake and the engine pulled strongly from 1100rpm to 1500rpm.

In fact while driving the B-doubles at such a meaty weight I was able to drive the 18-speed as a 9-speed, changing whole gears at a time with ease and making the most of the MX’s well placed torque curve.

One highlight of the package is surprisingly the UltraShift Plus AMT and its relationship with the MX.

I’ve been pretty hard on this transmission in the past; however the low speed clutch engagement of the AMT and MX package was a huge improvement over the past.

In fact I reckon this would have to be the best Ultrashift installation I’ve driven to date. Though I would add that I didn’t get to see how it went dropping and hooking up trailers an area where in the past the AMT has underperformed. On the whole it’s a neat little package.

Kenworth is backing the MX with a 3 year/750,000km warranty. See what Paccar General Manager Mike Dozier had to say about the MX13 variants when they unveiled it at the Melbourne Truck Show by clicking here.     

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