How Do We Dyno A 4WD Vehicle On A 2WD Dyno?

How Do We Dyno A 4WD Vehicle On A 2WD Dyno?

As you probably know already, we have a 2wd Dyno Developments rolling road at our Bedford branch. We’ve had lots of questions about how we dyno a lot of 4wd cars, given the dyno only supports 2 driven wheels. We thought we’d cover this in our latest post!

4wd feature 1

4WD Isn’t Always 4WD…

Despite what you may think, a lot of the popular vehicles we see at Phantom Tuning that are supposedly 4WD, are in fact 2 wheel drive EXCEPT when they NEED to be 4WD. What do I mean by this?

Let’s take VAG’s (VolksWagen/Audi Group’s) Quattro system as an example. Any vehicle that runs on the Golf chassis or smaller, that is Quattro, actually runs a different type of 4WD system than anything ‘Audi A4’ chassis or bigger. Vehicles like: TT, TT S, TT RS, S1, A3, S3, RS3, Golf R etc. all run a Haldex 4WD system. Essentially, this is a front-wheel-drive set up that engages the rear wheels when it needs the extra traction. 90% of the time, these cars run in front-wheel drive only. Whereas an Audi R8 or RS6 has its 4wd system active at all times.

Therefore, there are 2 different types of 4wd ‘Quattro’ systems for the VAG lineup. We are, unfortunately, unable to run ‘proper Quattro’ systems on our dyno, however, we CAN run Haldex systems. We do this by disconnecting the rear wheels via a plug towards the rear of the vehicle.

It’s a similar story with other vehicles as well. A lot of these hot-hatch style 4wd systems tend to be mainly front-wheel drive but engage the rears when the extra traction is required.

How About xDrive?

xDrive is a different story. xDrive is rear-wheel biased and the front wheels are engaged simoultaneously. The xDrive system disconnects the fronts, however, at approximately 110mph. That’s an interesting fact but how on earth can we expect to get an xDrive vehicle on the dyno to 110mph without blowing drivetrain components? Well, we have a unique piece of software called xDelete that enables us to permenantly disengage the front wheels of an xDrive vehicle, making it safe to run in RWD mode on our dyno.

Why Didn’t We Buy A 4WD Dyno?

Ultimately, there are a few reasons we opted for a 2WD rolling road. Firstly, this is our first dyno. 2WD systems are considered easier to run for a first-timer, as an above-the-ground 2WD setup makes it easier to strap vehicles down, whereas a 4WD dyno can be more difficult. Secondly, cost. 4WD systems are twice as expensive as 2WD systems, so as a first-time dyno investor, we mitigated our financial risk by purchasing a 2WD system.

Most importantly however, there aren’t too many vehicles that we can’t run on our dyno as we’ve explained above. A lot of the common and popular vehicles that we see can be run on our dyno anyway and only a small number of vehicles can’t.

We’re sure that at some point, we’ll be in touch with Mike at Dyno Developments to upgrade our system to 4WD, but right now, we and our customers aren’t really missing out by us only having a 2WD system.

What ‘4WD’ Vehicles Can We Run On A 2WD Dyno?

This is by no means an extensive list of vehicles, however, here are some popular ones that we can:

  • Any VW, Audi, SEAT, Skoda that runs Haldex Quattro
  • Ford Focus RS Mk3
  • Any vehicle that has switchable 2WD/4WD built-in
  • Any xDrive vehicle that xDelete supports

Still Not Sure If Yours Can Be Run?

If this post still hasn’t helped you figure out if we can run your 4WD vehicle on our dyno, just get in touch and our team will be happy to help. Send us a message on our contact form, give us a call or contact us on our socials.

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