Friday, August 25, 2017

The Most Empirically Effective Cold Air Intake for the Q50S HEV

Using this cold air intake setup my Q50 is achieving 97.7% temperature efficiency in cold air intake, which is pretty damn good. 
Intake Temperature as Read by MAF

What? How? Where? Who?

So here is my setup:

1. Q50S HEV with the Cold Air Ram Intake setup.

2. An OBD II Bluetooth Transmitter that can read live values from the Q50 while driving.

3. An android application that can read and record the OBD II - MAF (Mass Air Flow) Sensor Air Temperature, Air Volume, speed, etc.

4. Multiple readings taken of outside ambient temperature and comparative MAF temperature reading immediately at different situations e.g. after Cold Start, warm start after heat soak, stop-and-go traffic, highway cruising.


Why the MAF temperature? Because the computer or ECU uses the air volume and temperature reading from the MAF to adjust the fuel level injected into the cylinder which ultimately produces the power at that moment. Of course, other factors go into it as tuner will tell you, but basically if the air temperature can be kept lower and as close to ambient temperature, then it is has most density per volumes and therefore more oxygen molecules in that volume and  therefore more combustible.
Read more about the MAF here:

Another important thing to note is that on a vehicle that has not been after-market tuned and is not a turbo-charged car in which boost has been altered, there is really minimal impact that increasing volume i.e. air flow to make more power, unless it is very restrictive. This is because it is tuned to accept only so much air, so ramming more air will not produce power because the car cannot compress that air any further prior to combustion (as opposed to a turbo where boost can be increasedby tuning). Thus, really only temperature can be lowered to keep air as dense as possible for maximum power, hence the need for a cold air intake or CAI.


MAF Temp of Air #1
This cold air ram intake is exceptionally efficient. While cursing, fully warmed up, at highway speeds of ~ 80mph on a 77 °F day. MAF temperature reading was 78.8 °F. This means a rise of air temperature of 1.8 °F from outside to MAF. Which is pretty damn good.
Outside Temp 77F and Speed ~80 mph #1

Another reading done earlier in the month on an 85 °F day. Engine not just warmed up, had just completed multiple 0-60 runs in an attempt to record the best time. This means hard driving with repeated quick stops. The MAF Temperature of 87.8 °F, which means an increase of just 2.8° F. I will post my best 0-60 times using this air intake in another post. I'm impressed by my Q50 hybrid sport.

MAF Temp of Air #2
Outside Temp  85 F and Speed ~48 mph # 2

Overall, I have not seen the Q50 with this intake go higher than 3 F. It may be very high i.e. 10-20 °F more when restarting the Q50 after being parked as engine heat is soaked in, but it very quickly drops to that less than + 2-3 °F range within a 2-3 minutes of driving.

(Updated 8/26) To put some data behind this observations in head, I hooked up the OBD-II and started recording metrics to phone. Started the car cold (garage temp of 78 °F ) and went to get my dry cleaning a few miles away. Outside temp was a brisk 67 °F (so ~11 °F lower than garage). Good test of how quickly my cold air intake can get rid of heat soak and also while the engine is warning up. Took only less than 3 mins of under 40 mph to get down to exactly outside temp. As the car was stopped to get onto highway the heat soak starts again and before I even merged onto highway, intake had cooled to ambient air.

Here is the interesting graph of this below. Units on left are both mph and °F. Red line is outside temp.
Cold Start from warmer garage to colder outside & engine warming up simultaneously
Conversely, here is a hot engine that has been sitting for 10 mins to allow decent heat soak after driving. Again it went from over 12 °F above ambient to ambient air temp in under 4 mins of ~ 35 mph driving with stops. The moment the speed went over 40 mph, intake stayed cool. Just for fun. Stopped the car, but did not shut off and observed the heat soak in EV mode, since it wasn't as quick in 2 mins, opened the door to kick on the engine idling to increase heat soak. Took it to 86 °F and started moving again, this time > 40 mph and within 2 mins the intake had cooled off. Quick to soak in heat means quick to get rid of it.

Here is the chart from this OBD II data.
Heat Soak and Dissipation Excercise 
So basically this intake is keeping air-intake temp within 1-2 °F of outside air. Which will have a negligible effect of hp changes at normal engine speeds.

Note that the MAF temp dips below the outside temps is observed. Basically shows the shady areas of driving around around  which the outside air is cooler than average. It sucks that up and quickly registers that, quicker than ambient air temp sensor. I had to drive around to figure it out.

We are talking about a very quick heat soak of max of 10-12 °F, which is pretty low and very quick dissipation of that in ~3 mins in stop and go an under 2 mins at > 40 mph speeds. Not bad at all. The videos linked below shows that you need to have 10% change to have noticeable gain or loss iN HP.

I have been really impressed and I would recommend this air intake to any Q50 non-turbo engine. I do not have a turbo one to do the same tests and compare, though I could get one for a day from my local dealer if there is interest and do the same. 

So what air intake is this? Well, here it is with the covers removed:

Giant Ram Air Intake Opening
The underside of it looks like this:
Huge Air flow ducts underneath that expose the filters

If you did not realize it, this is 100% completely stock using stock paper air filters (not any K&N garbage or any other)! Yep 100 % complete stock! It cost me absolutely $0 in mods and no time spent in installing it. Other than to remove it to take pics. 

I would really like to see what the aftermarkets so called “cold air ram intake” manufacturers can show that their products achieve with some empirical evidence to justify their designs and cost. Do they reduce the overall intake temps? Do they reduce heat soak or do they bring the air down to ambient quicker? Surprisingly I have found absolutely no data, just shiny pipes with lots of welds or bends and crappy air filters on top of them to suck iN more sand and water. Every other car from older pathfinder, frontier, Altima SE-R, G35c that i have had have all shown that stock was better and in fact the lowest temp differential of all my current cars is the stock Q50 setup. Having better piping after MAF is pointless too, since the computer has already decided on MAF temp.  Again unless it's restrictive to stay with.

If you want to have a good laugh watch this Cold Air Filter Mythbusted:  The irony is that this is on a turbo charged GT-R, a non-turbo will have no difference.

It really burns me sometimes that there is an entire aftermarket industry that claims to better job than the 100s, maybe 1000s of mechanical, thermodynamic and fluid mechanics engineers that are employed by giant companies such as Nissan that spend Billions of dollars on R&D and race development.

I'll post up my 0-60 times and see if there are any CAI setups that can achieve the same or better on a stock tune with non-turbos.