The Toyota GR Yaris is brilliant but on track it over heats as our earlier Yaris blog highlighted.  We have experienced this with our own cars and a number of customers have also struggled with their cars overheating on track. As a result of we began extensive testing on the road, dyno and on numerous track days as we collected data from our Yaris’s Syvecs ECU.

When driving on track we regularly have the oil temperatures exceeding 130 degrees and the intake air temperatures were consistently over 50 degrees with the stock intercooler simply unable to remove the heat.   On a mild day at Silverstone we were able to get the car to overheat within 2 flying laps!

Due to higher boost pressure from a tuned engine and insufficient cooling capacity from the standard intercooler and oil heat exchanger it was obvious that redesign was necessary.  

Having tried some of the other solutions on the market it was decided to produce our own intercooler and oil cooler without the compromises of the standard packaging and utilising our experience and the very latest core technology. 

The benefits of an improvement to an intercooler are far reaching and when designed correctly offer no downsides.  The colder and denser air being supplied to the engine helps it produce more power and aids engine safety.   Selecting the right size of core and end tank design is also crucial to insuring the charge pressure is evenly distributed and the throttle response remains sharp.

Furthermore, an improved intercooling also allows for you to drive harder and for longer with better temperature regulation so that the vehicle can maintain maximum power and torque.

When designing an intercooler, the first and arguably most important element is the core. The core will dictate the majority of the intercooler’s properties and in this instance bigger is not always better.  The height, depth and width must all be carefully considered to enable the most efficient cooling capacity but also to ensure that you do not sacrifice too much space or flow to the radiator behind it. 
It is possible to buy large ‘bar and plate’ Intercooler cores from Asia for very little expenditure but these tend to be very heavy and have a poor internal design.   There density often works in their favor for short runs or laps but then their mass causes them to retain heat for longer.   On a car like the GR Yaris where weight is so important the last thing you want is something to heavy and restrictive hang over the very front of the car.
It is for these reason that we chose to employ the use of high quality, UK made, ‘Tube and Fin’ aluminum core in a taller 300 mm height and wider 620 mm width to allow a large surface area for air flow.  A thinner depth of 62 mm and custom fin pitch were also chosen to allow sufficient and uncompromised airflow to the radiator directly behind whilst still providing a 71% increase in overall volume but also massive 110% surface area for cooling.   To maximise the frontal area exposed to the large grill of the GR Yaris we chose to reproduce the front crash bar in a stronger T45 Tig welded tube, the same material used in our roll cages.  This not only allows more air to the intercooler but it also securely ties the front chassis legs together without using the relatively weak aluminum core to brace the body structure.  

 All pictured below are pre-production crash bar and intercooler/ end tanks, with the final product consisting of billet end tanks and T45 TIG welded steel crash bar.

CAD (Computer Aided Design) was used to design end tanks for the intercooler.  CNC machined from a single piece of billet Aluminum to enable a smooth non turbulent flow as the charge transitions into the core.  The original intercooler utilises plastic end tanks which abruptly change the air through 90degrees. By ensuring smoother flow through the end tanks and across the surface area of the intercooler it will suffer less air velocity losses in the bends and therefore make the intercooler more efficient and response will be improved.

A direct result of our core choice and intercooler design is that we only gain just 2.1 kilos over the standard intercooler.  In comparison a competitor’s smaller stock replacement bar and plate intercooler was tested, and not only was it less effective in cooling but also weighed 4.7kg heavier.

With an initial prototype created we were able to start dyno testing.

Using the datalogging features of the Syvecs system on our state-of-the-art MAHA dyno cell, we were able to show that the new intercooler clearly out performed both the standard and competitor’s models. The data initially showed that the Litchfield intercooler gained only a 3.8°-degree temperature increase across multiple dyno runs, starting at an ambient temperature of 30° degrees and only rising to 33.8°.  In comparison to the stock intercoolers increases by 14°, the difference from 33° to 47° in just one run!

We also observed that against a competitor’s product the Litchfield intercooler consistently remained a number of degrees cooler across the whole run. Furthermore, once tested our intercooler showed absolutely no measurable heat soak across the 5 power runs, which further confirms the core/end tank design choices being correctly matched.

The dynamometer showed the result of these temperature differentials translated to varying levels of power and torque output, with our intercooler showing an increase of both areas under the graph as well as peak figures. This will translating to better drivability and a faster, more responsive engine package. The Litchfield intercooler showed an increase in peak power of 10 horsepower over standard and an increase of 8 lbft of peak torque. However, increases of 10-12 hp were seen across the range as well as 8-10 lbft torque. This figures will increase significantly when you factor in the heat soak the other intercoolers suffer on track and when power levels are raised even further.

Road testing the car confirmed a much more responsive engine and the intercooler helping to provide a crisper and smooth delivery of power.

Pictured below are two additional dyno graphs (one lower boost and one higher) with all 3 intercoolers tested (stock, Litchfield and one competitor) and their power/ torque curves.

Shortly after our initial testing, the final billet aluminum end tanks arrived and the final intercooler could be assembled and fitted along with a complete powder coated T45 crash bar.

Once the intercooler dimensions were finalized we began work on our new engine oil cooler.  We have developed two different size cores to test on track.

Our Circuit testing took place at Castle Combe which features long straights and high speed corners which put the engine under sustained strain.

It was immediately apparent that cooling package was working effectively with far lower intake air temperature and oil temperature. Additionally we observed that water/coolant temperatures remained stable at 90 degrees, not rising despite the intercooler and oil cooler being fitted. This is a direct result of the intercooler and oil cooler core selection.

The initial oil cooler design used a smaller twin pass core and whilst this did drop oil temperatures it was less efficient compared to our second design that features a longer core with a single pass for the oil.  The longer core also fills the top bumper grill more completely to maxmise the cool air feed and as a result also aesthetically looks better.

Combined these cooling options provide a significant improvement to the GR Yaris’s engine cooling issues and are a must have upgrade for customers looking to run their cars on track with higher power levels.   Pricing and details can be found on our website but if you have any questions please contact us.