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Testing our GR Corolla intake went better than expected! Gains were reached up to 14whp over 5300rpm in dyno tests on two different dynos at two different locations under different ambient conditions!
We have observed several comments on GR Yaris intakes not producing gains. However, we think since the GR Corolla has higher factory power and runs higher factory boost, there is more demand on the intake system and we have crossed a threshold of improving intake characteristics resulting in gains where there is the most draw thru the intake system.
We designed our new system with the following goals:
- Reduce pressure drop
- Increase flow
- Improve intake air temperature
Increase in flow and reduced pressure drop were done with the following features:
- bigger, conical oiled air filter
- bigger airbox
- bigger intake tube outside of MAF section
- maximized intake air scoop from front grille
- MAF housing retained for no CEL and OEM fuel trims
In order to help with intake temps, we relocated the OEM extra air feature of the OEM airbox to the driver side of the airbox, opposed to the OEM location in the front of the box which happens to be fairly close to hot coolant hoses.
Let's begin with our intake air temperature testing. We have a 4-channel thermometer with datalogging capability. We chose 4 places to measure temperatures in the intake system.
- Front of the OEM air scoop near the grille
- Inside the air filter
- Back of the intake system at the turbo inlet joint
- In front of the OEM extra air flap (OEM Intake) and next to the SXTH air entry (SXTH Intake)
Please note, the thermocouple for the OEM extra air flap was located one inch in front of the flap opening, in front of the OEM airbox. The SXTH intake opening is on the driver side of the box. See this picture for locations:
For the test, we drove the car on both intake systems on the same route in the same ambient air conditions. The car was paused to idle in specific spots to help track behavior in the thermometer log, since it only logs temperature vs time.
Below we have the temp datalog for the OEM intake system. Wide open throttle pulls were performed twice.
Please note the thermocouple numbers and locations, which remained the same for both system tests:
- T1 - Grille Entry
- T2 - Engine Bay location (in front of OEM Airbox Flap)
- T3 - Inside Air Filter
- T4 - Turbo Inlet connection
Here is a breakdown of the timeline:
- The first minute was starting/idling and leaving the shop. You can see idling in place with no airflow across the car and engine has temps slowly rising until the car starts moving.
- Just after 15:37, we are moving down the side street. Air is flowing into the engine bay and airbox. Temps are coming down.
- Now at 15:38, we are on the main road doing decent throttle and speed. Engine is heating up and ambient heat from the coolant hoses is influencing the T2 sensor.
- Just before 15:40, we are slowing down to turn on to the road for wide open throttle. As speed slows and airflow stalls in the bay, T2 rises for a moment then we go wide open throttle.
- Now look at T3/T4 when we mash the throttle, WHAM, HOT AIR BLAST!
- Wide open throttle prompts the OEM airbox flap to open and any air in front of it gets sucked in and the T3/T4 sensors see it immediately. That's not good for power!!!
- Next we slow down and make a u-turn to come back and go wide open throttle again. You guessed it, HOT AIR BLAST again!
- What is cool is seeing T2 in front of the flap come down as the engine vacuum sucks the hot air out of the way. The T3/T4 spikes directly correlate with drops in T2 at the same time!
- The rise in T1 before 15:44 is the car sitting at a stop sign. You can see with no airflow over the car or bay, engine heat is effecting the front T1 sensor.
- Lastly, you can see when we pull back into the shop and let the car idle inside. Temps rise with stagnant air and engine heat radiating everywhere.
- One real last thing to notice here is the temperature difference between T1 and T3/4. Ideally, you'd want the air entering T1 to stay the same all the way thru the intake. Just look at those differences in temps during the drive!
Now let's swap the SXTH intake and take the same drive. Thermocouples were installed in the same places, except for T2 was located next to the air entry for the SXTH intake, which is on the driver side of the box. Below is the same drive route with wide open throttle performed in the same locations for the same amount of time.
Now let's go over the big differences here:
- Again, we start in the shop with the hot engine idling. Then we leave around 17:43 and temps start dropping from airflow.
- The first thing we notice is how isolated from influence T2 is on the driver side of the box. T2 is much lower average if you compare OEM vs SXTH. Much less heat influence while moving, and you can clearly see when the car stops that the sensor starts to rise but quickly comes down once moving.
- Here's the good part, you can barely tell when we go wide open throttle because almost NO deviation between T1 and T3/4 sensors!!!
- Look how much more consistent temperatures are inside the filter and intake tubing. Much cooler when it matters!
- You can even confirm this further when we have an extra long stop at the u-turn point at 17:47. We had to wait here to make our u-turn to repeat the wide open throttle pull before stopping at the stop sign on the way back.
- Like the last point about the OEM test graph above, you can see T3/4 sensors show temps much closer to T1 entry temps. Everything is cooler!!!
In summary, our system allows for more consistent and cooler intake temperatures measured inside the intake system during road driving conditions.
Now let's see what this does on the dyno!
Next we wanted to see if any of these new characteristics and confirmed temp drops would show anything on the dyno. We did dyno testing not only at our shop on our in-house DynoJet, but we took the car and performed the same before and after test at a 3rd party shop with a Mustang Dyno.
Here is a list of criteria for the tests:
- car was tested in 2WD mode on both dynos
- dyno mode was performed using 2WD suggested method from the Toyota factory service manual (remove driveshaft, disable 4WD, hold TC off)
- 3 runs performed back to back with 15-20 seconds in between runs
- Initial runs were started with similar coolant/oil temperatures
- runs were performed within temperature controlled shop environments
- All dyno tests were performed on the same tank of 93 oct gasoline
- There was no "resetting" of any kind, AKA pulling negative cable from the battery to do any re-learning or anything like that
- The ONLY change between sessions was intake swap, that's it!
Below we have an overview of all 6 runs. The first 3 are OEM intake (Red/Blue/Green) and the next 3 are SXTH intake.
Looking closely, you can see the OEM runs are all consistent with each other. The Red/Blue/Green curves are very close together.
Then we swap the SXTH intake, bring the engine back up to temperature and run again. Across these next 3 SXTH runs, you can clearly see TQ and HP are higher from 5300rpm to redline.
Let's zoom in for a better look. See below.
Above, you can see the differences are even more above 5300rpm. Now let's just compare the best OEM run to the best SXTH run. The best SXTH run even happen to be the 3rd run where engine temps were the highest, while the best OEM run was the first initial run. See below, with timestamps at the bottom of the sheet that show the time each run was performed.
Now let's zoom in and see how the gap is there for power and torque. See below.
While peak torque was no different, above 5300rpm wTQ and wHP differences are at least 10 across this entire part of the rev range! Not bad!
Now let's see what happened on the Mustang dyno. Please note the following:
- The same 2WD dyno procedure was followed, to eliminate that possible variable. No need to dyno in 4WD here, it wouldn't let our before/after comparison be apples to apples. We aren't concerned with overall number anyway.
- Dynos ARE TOOLS FOR MEASURING CHANGES. DO NOT GET HUNG UP ON THE OVERALL POWER MADE, WE JUST WANT THE DIFFERENCES MADE BETWEEN INTAKES.
- Mustang dynos operate by applying their eddy brake to the run to simulate things like vehicle weight, rolling resistance from aerodynamics, etc. This is why they are referred to as "heartbreaker" dynos, because applying these features make them read lower HP numbers compared to DynoJets like ours.
- They do this with pre-programmed settings from the mustang software. Since the GRC is so new, these specific vehicle dynamics were not applied in the test. The dyno operator used an N/A Corolla option from 2019. This was so we could even get the runs started. This is why the overall numbers are what they are.
- With that being said, this will effect the OVERALL numbers for the power displayed for the car, NOT OUR GOAL OF MEASURING BEFORE/AFTER!
***PLEASE NOTE AGAIN THAT THESE OVERALL NUMBERS SHOWN BY THIS DYNO ARE NOT EMPIRICAL TO THIS INTAKE TEST. WE ARE ONLY INTERESTED IN OEM POWER MADE, SXTH POWER MADE AND THE DIFFERENCE BETWEEN THE TWO SYSTEMS.
WE WANT TO KNOW HOW MUCH WAS GAINED FROM THE INTAKE SWAP, AND THAT'S IT.
Due to this shops Mustang software (I am not too familiar with it) we could only display up to 3 runs at a time. Below we have power with OEM intake.
As you can see above, OEM intake runs were consistent with each other as the dynojet runs.
Then we swapped in the SXTH intake and ran it with the same coolant and oil temperatures. Here are the 2nd and 3rd runs below. The first one had a dyno operator error and the run did not record properly for graphing.
Looking at the SXTH peak numbers above, you can see the numbers are higher than the OEM intake, SIMILAR POWER GAINED!!!
Now let's overlay the OEM power vs the SXTH power. You can clearly see the same upper range gains above 5300rpm. See below:
Looking at the comparison above, it is pretty clear to us our intake is working better than OEM being verified on a different dyno machine in different ambient conditions.
It is most likely a combination of better flow and the better intake air temperatures demonstrated at the beginning of this post.
In summary, we suspect our 10-14whp upper rpm gains come from the following:
- better flow in the parts reducing pressure drop
- better intake air temperatures at wide open throttle
- Since the GR Corolla runs higher factory boost pressure vs the GR Yaris, there is more demand on the intake system and removing the restrictions along with helping with temperature allows for an increase in high rpm power
- No CEL and fuel trims within OEM specs
We are surprised by these results and even if they would have shown nothing, we love to show the testing process to the best of our abilities. As with some of our Hyundai N applications, sometimes the OEM system is good enough up to a certain point and intakes do not make gains off the bat on OEM tuning.
It is cool to see the GR Corolla see some power come out right out of the box with our system. This design will now get some slight refinements for manufacturing processes but we will go full steam ahead on production seeing the results of these tests.
Thanks for reading!