GR Yaris engine cooling under body panel

[Michael Knight]

Any idea where I can order such a duct online ?

It gets to 80’C quite fast even with oil cooler - point is to have thermostat for the cooling circuit

 

[Yohz78]

I've had positive results with mine along with a DIY oil cooler cooling pipe. Easily dropping 20 degrees in both box and engine oil on 30 degree track days

Hey,

May I ask you a quick question ?

Do you have a quick DIY of what you did ? Did you have to remove front bumper in order to make the hole ? How is the duct held ?

I am really interested as I'm not fond of oil cooler, having had issue on previous car. I don't want to impact oil pressure either.

Thanks !

 

[Yohz78]

I use now that duct to feed extra air to oil cooler. more is more.

Hey,
Since you've mounted that duct, can you please tell me how it affected oil temp ? I'd like to do the same but I don't want my oil to warm up slower as I use the car as the a daily sometime, including during winter.

So I wonder if I should stick to the same system but with a filter to avoid dust going on the engine or of I should engineer a system that would allow to open/close the duct ...

 

[Michael Knight]

Hey,
Since you've mounted that duct, can you please tell me how it affected oil temp ? I'd like to do the same but I don't want my oil to warm up slower as I use the car as the a daily sometime, including during winter.

So I wonder if I should stick to the same system but with a filter to avoid dust going on the engine or of I should engineer a system that would allow to open/close the duct ...

Cannot recall it had much difference but it all depends how you get the air to cooler cell and how air can get out from cell. So whole system affects.

 

[Yohz78]

Cannot recall it had much difference but it all depends how you get the air to cooler cell and how air can get out from cell. So whole system affects.

Thanks for the answer. I may try it myself and see what it is like. The DIY duct is easy to make and will be a good first step for cooling. If temp are still too high on track I may get the underpannel. I'd rather avoid oil cooler as I had issue with aftermarket oil cooler in the past.

I may make a grill at the entrance of the duct though. Both for aesthetic reason and to avoid dust ect going to the engine.

 

[tinsta]

Airtec have released a new tray aimed at cooling and reducing temps.. anyone tried it yet?
With a deeper oil sump, how much clearance do aftermarket trays give with protruding ducts etc?

 

[R-power]

Look like GRMN is better material and even large opening compare to GR garage

This on the right is the mk2 version, equal to GRMN mk1
We have done a test in Italy to be sure: removing from my at8 mk2 and placing on my mk1
It fit plug and play

We have done now a GB from an Italian dealer with 5 friends
We have it for 360e shipped at home..
Not cheap but on my mk1 the oem one loose tightness after every 35000km

 

[Yohz78]

This on the right is the mk2 version, equal to GRMN mk1
We have done a test in Italy to be sure: removing from my at8 mk2 and placing on my mk1
It fit plug and play

We have done now a GB from an Italian dealer with 5 friends
We have it for 360e shipped at home..
Not cheap but on my mk1 the oem one loose tightness after every 35000km

Is it better cooling than mk1 ? Were you able to test transmission & engine/gearbox oil temperature, on track maybe ?

 

[Altocumulus]

Airtec also make a metal undertray with ducting for Mk 1 and 2.

 

[Yohz78]

Airtec also make a metal undertray with ducting for Mk 1 and 2.

View attachment 36834

Do you know if it cools the engine oil or is it only the gearbox / Transfer case ?

 

[R-power]

Is it better cooling than mk1 ? Were you able to test transmission & engine/gearbox oil temperature, on track maybe ?

Not yet
Also because the test with reliable numbers is not easy IMO

the main thing that moves me to change the mk1 underengine is the fact that after some thousand km in racetrack it starts to deform itself towards the asphalt and this is bigger effect if you install some weight as air ducts.
I will study some additional ducts when ready to install

 

[micsub]

RE engine oil the issue as far as my brain could fathom was that the water oil cooler itself is behind the rad and intercooler so literally gets the hairdryer treatment.

Simply blasting it with fresh air along with a slight overfill of the coolant with water wetter and I was the happy side of 120.c even on the hottest days. Surprised myself how much difference it makes.

The issue with a cooler is that your warm up is slower, you always run cool and thr pump works harder. Fine for some applications but not for most.View attachment 13884View attachment 13885View attachment 13886View attachment 13887

Hi Deano, what a coincidence ! I did the same in Feb 2025, two years after you, without having seen this post before.
It works very well, 10-15°C less on oil temperatures.

 

[Yaris San]

after fitting the air Tec red twin scoop have noticed centre console from just behind the gear lever back to behind the cup holders gets quite warm to touch so guessing good amount of air is reaching transfer box

 

[Yohz78]

I have fitted the duct. I added a grill to protect the engine from stones ect that may go through the duct so it may be less efficient.

I can say that the car warm-up at the same speed. I'll give a more detailled feedback when I'll have blasted/ tracked it a bit.