Intake air temp discussion
 

We all know that intake air temps really affect turbocharged vehicles. Had a chance to do some back to back runs and and see just how much of a difference 20* F would make. I wrote about the findings in my blog (linked below). So yes, a 300whp k04 MS3 in the winter will not be near that in the summer.

Blog : The effects of intake air temperatures on turbocharged vehicles : Stratified Automotive Controls

As a sidenote I wish there as a general turbo section I can post this in rather than a generation specific area.

Very informative. Since im in hot as balls Florida Ive gone the FMIC and E85 route with the HTP 3" full intake/TIP coming when released.

@Lex did you get the SURE 3" intake on yet?

Sent telepathetically to my Razr Maxx

Yes sir and this brought me to some interesting findings on air filters. Let's just say they are not all the same :) Testing is ongoing in that department.

Thankfully Scotland peaks around 20-22 celcious... We are due 10-15 celcious next week :)
Intake / boost temps must be alot worse for you guys

nice write up. that is a huge power loss for not much of a temp difference 0_o

looks like i might need to start keeping my eyes peeled for an intercooler. colder plugs, a little bit of e85, and a 3.5" intake should help.

Like I mentioned, you get hit in 2 ways:

1. Less airflow
2. The california gas he's using really started to knock as BATs came up so we had to pull a bunch of timing to deal with that.

You say using a bigger intake will help keep the temps down, I've always wondered if I could run a 3'' or 3.25'' intake as part of my first performance mods(w/ TIP)? It's hot here in SoCal!

It will lower the pressure drop across the intake. The intake temps you can't control but you can help the turbo have an easier time flowing the air in other ways. A big intake is one of them.

Nice! Very informative!

Nice, guess I'll be picking up the 3" SURE Intake!

Excellent post. Everyone here always seems to think that BATs are the end all be all for performance, adn as you mentino they do play a very important role. But most people seem to just dismiss the IAT tyring to say the the TC will just heat up the air anyway...

I had suspected that intake/ambient temps play a larger role than people seem to think. As you point out, with hotter air to begin with teh TC just can not compress it efficiently and you end up flow less air overall. Pre-turbo meth injection comes to mind here and works on similar principles. Post TC injection obviously significantly lowers BATs and along with octane helps fight knock, but it doesn't allow the turbo to flow more air.

How were you able to control the IAT in the dyno testing you show?

very interesting lex. Just another thing to add to the things here in CO that are sapping my power.

1. altitude
2. 91 octane
3. intake temps
4. everything else

dryflow > oiled?

Repeated back to back runs on the same road at different times of day. It's a vdyno plot which works well here. Also if you're an avid logger, compare the g/s flow when it's hot out and when it's cold out.

Of the ones I've tried ... will have more on this later.

We have plenty of big maf's in stock if you guys want to grab more power.

It will keep you in route for BT if you plan on going that far :bigok:

Lex, would spraying meth be a great equalizer, or are we talking strictly compressor efficiency?

spraying meth after the compressor will affect BATs and knock threshold, not airflow potential. spraying meth before it is a different story.

ooooh. I like your style Lex. I'll quit posting and start reading.

Hmm interesting. Meth in the TIP......

Sent telepathetically to my Razr Maxx

Its a good method but you need a very fine small nozzle or it will eat away the compressor blades.

I am willing to bet that a bolted MS3 with a K04, large intake, good filter and pre and post turbo meth injection will run close to a BNRS3 running a COBB SRI

Or spend the meth setup money on Bnr and no worries about turbo destruction .

:)


Tappin

recently since it's gotten hot here, i've been getting knock around 5k rpm and beyond (fuck calis 91) at 2-3 degrees when there was no knock before. I had to pull timing and lower boost to get rid of it. I have colder plugs sitting in the garage along with jbr's tigs that are gonna go on together when I clean my intake valves, waiting on injector seals to come in.

yea butt dyno agrees

another interesting observation i have made is that IAT will NEVER be lower then AAT.

i think the ECU has a built in limit thats says Intake air can never be cooler then ambient (which makes sense) but most people just stuff their AAT sensor somewhere and forget about it.

i need to move mine into a great airflow position so that i can get my IAT's down even farther!!!!

I noticed that my IAT were much higher after installing my front mount, I'm wondering if the relocated AAT has anything to do with it as superskaterxes mentioned?

Your talking intakes that are under the hood, how about the CS FMIC w/ram air for the speed 6? I guess it brings in more air flow and cooler air temps. Now could you test this set up? I would really like to know.

Will have to double check but I was pretty sure the aat was simply linked to the information display and that's it.

Bump, for my question.

The ram air from cars I have tuned works very well as well - especially when the car is moving quickly.

the AAT and dash temp are not from the same sensor, i have never seem them even remotely identical

I have also noticed a performance hit recently. I am vding about 10-15hp lower than I was when it was cooler out. Also, I am using about 5-10% more wgdc. This is with BAT's at or near the same temp, however the air it is sucking in is less dense, as the ambient here can reach 95* to 100*

When I do my bnr 3, I will upgrade to a 3inch maf, and tip.

Lex,

You have any empirical data on the pre + post meth injection? My very limited testing of
a DO1 pre and a DO5 post garnered virtually no difference power wise vs the post only.

Inquiring minds, etc.

I have been wondering about this recently. Will a aftermarket tmic make more HP because of colder BAT OR because it was the flow bottleneck? This goes 2 ways I have been thinking. If it is because of the BAT, would a set of TIGs do the same? if it is due to flow does that mean stock TIP makes no gains?

second will change in BAT , given the same tune affect the load? What will a change in BATS affect when it comes to a log? My guess >>I mean colder air is more dense therefor the volume of the air will decrease with temp, since density will not affect pressure, the tune will try and make the same boost with this more dense air therefore a larger g/s maf number? I would greatly appreciate any feedback on this paragraph. This has been and hang up with my tuning and mods.

Good write up and can't wait for these findings


Sent from my dizzLe using RaWr powers!

I do not on the K04 - do you have any data you can share? Airflow? Is your tune setup to drive the turbo as hard as possible near redline? This is an easy way to create a plateau and see if you can bring in more air.

The intake of the vehicle is not a fixed volume. So by lowering BATs (increasing post compressor density) you are increasing the turbo's efficiency and its density ratio with respect to the pressure ratio. Essentially the density ratio is the actual boost increase seen by the engine. In an ideal compressor where air is not heated, the density ratio is the same as the pressure ratio. Since air is heated, the density ratio drops below the pressure ratio (this is relative to the compressor efficiency). So the harder we drive the K04, the more heat we create, the less efficient it becomes, the more we need to cool BATs.
See the image below I stole from Corky Bell's book.
http://www.mazdaspeedforums.org/foru...1&d=1343920596

So lowering BATs has 2 effects:

1. It increases the turbo efficiency = more power
2. It allows for more timing = more power

When selecting the actual intercooler you also have to look at losses across the core. Yes you gain by cooling the air, but you lose due to the intercooler being a restriction and creating a pressure drop. So a really low pressure drop intercooler is obviously best.

@Lex this is great stuff. One thing you should keep in mind, in addition to IAT differece, the relative humidy of the air can play a big role in sapping power too.

As an example you would make more power on a 70 deg day with 50% RH than on the same 70 deg day with 99% RH.

You can experiment with this calculator to see just how big of an effect this is. Engine Tuning Calculator - using relative humidity

Thats why Ive gone the E85 and FMIC route. Florida weather is nothing but heat and high humidity.

Sent telepathetically to my Razr Maxx

If you're really ballsy you can try running just chemical intercooling. Not a great idea on a street car though.

I also moved my AAT sensor. I know it reads about 5-10° higher. But IAT on Mt logs are lower by about that much. I know IAT can't be lower then AAT. I can do some testing on this as well.

AFAIK AAT and looking at the wiring manual is simply for the climate control and dash display. Not used for engine function.

So moving that sensor won't affect the IAT as stated earlier correct?

Why are people thinking the PCM uses the ambient air temperature sensor in it's calculations?
It doesn't. I'd loved to be proved wrong though.

im going to be doing some testing on this to see if i can find any more patterns/correlations

Pre-turbo meth
 

Regretfully, no, I have no data left. I just made a couple or three runs, noted virtually no
difference, and gave up on the thought. This was back in May or so when it just started
to get warmed up.

My tune backs down the boost after 5k or so as well because of the torch like character of
the K04. With the DO5 I'm just keeping even with the BATs on the top end. My impression
has been that I'm plateau'd as is.

I think an efficient Intake setup would be to run a full 3" intake WITH a cold air box, that way you get VE and cooler IAT's.

Or a RAM air system like that from Corksport. When moving you have positive pressure against the inlet of the turbo.

Have you tuned anyone with this kit ?


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Yes a bunch of people in the UK have it. It works well if you get the full fmic system.

What is the best pressure drop to have across the I/C core?

Too little of a drop and it will not transfer the heat to the aluminum, too much drop and it becomes too much of a restriction. There has to be a a happy median.

Also, on an I/C that has the BPV flange on the hot side (like people are going to for the fifth port), do not recirc the air. Heated air from pre I/C will just heat up the inlet, in turn raising IAT'S

I actually liked this kit as well but at the time, had just bought a 300 MSCAI so went with a traditional FMIC.

it was really cool how the air filter was tucked up inside the OE duct work.

I am tuning a guy with a CS intake...not sure that's the same one or do they make more than one...i'll ax him. he has a 2012 so IDK how that setup looks.

What's better?

The CS full FMIC kit which has the stock size MAF housing built into ther piping, or
running a big 3"+ MAF SRI?

It doesn't have to be thought this way. A low pressure drop can mean that either the IC is inefficient at cooling OR that it has a great big core and good design for the airflow you are passing through it. Restriction does not solely pass from the positive interaction that removes heat. Remember that friction between a pipe and gas actually ADDS heat (or costs energy).

The higher the flow, the higher the inlet pressure and the higher the pressure drop given the core stays the same. The size and VE of the motor determine how much air will pass through it at x pressure and x RPM so you have to look at where the motor will be operating most of the time.

In summary, you want to have an IC that does not restrict flow unnecessarily through endtank and core design. You also want a core that is large enough for your application in terms of both heat rejection and flow. Most companies quote CFM at x pressure drop. I would shoot for the largest core I can fit on the car since that limitation will come into play first. The placement of the IC is also very important since the amount of heat it can reject from the air passing through it is related to how much heat it can reject TO the air passing over it.

That is a tough one. There are many systems in play. How do the intercooler cores compare? What about piping size and routing and pressure drops? Also remember that the RAM air system is most effective at high speeds. Also what about packaging inside the engine bay and cost? So better is hard to quantify unless you look at all variables.

Yes CS makes an SRI and TIP as well. The ram air is built in as part of the FMIC system and sits where the OEM TMIC sits.

For what it is worth, this thread finally made me pull the trigger on the CS cold air box for thier SRI. I have been on the fence about this thing for a long time but it doesn't get a lot of love from the MS3 guys. I think you guys have much cooler underhood/IATs to begin with, and peopel always say that the turbo just heats the air anyway so it is pointless. I always thought a little differently and this thread helped to confirm some of those thoughts.

As an aside, last night coming home late from the new Batman it was about 70 out and low humidity. The car felt fucking fantastic compared to driving on the way there at about 90 ambient and sunny. I still had IAT and BATs well into the 100's on the way home but could absolutely tell the difference in power at night.

I actually just switched to a dry flow aem over an oiled kn and did feel a different SOT dyno :) looks like a made a good choice. Also I use a fujita CAI and If i were to just cut the last say foot off and use a reducer coupling to then mate my current 2.75 size to a maybe 3.5 dia size pipe to run a larger diameter filter would that help or hinder cooling and flow? I dont want to scrap the intake, but if more air is needed i need to figure out a way to get it there without going BT and wasting the TIP, and CAI i already have. thanks!

I just switched from a CP-E CAI to a CP-E Nano SRI and the initial findings are somewhat interesting.

Temps are in relation to ambient.

CAI:
+4-5 Degrees IAT cruising
+20 degrees IAT city
+40 degrees IAT traffic

+18-22 degrees BAT cruising
+30 degrees BAT city
+35-40 BAT traffic

SRI:

+10-14 IAT Cruising

+18-22 BAT Cruising

These are just my initial observations since I just put it on last night. It seems like that even though the intake temps are higher with the SRI that the BATs have stayed the same, which surprises me.

Does intake temp matter if my BATs are staying the same?

I was just looking at the differences of my logs with varied temps.

Maybe the 2nd, blue run should be omitted though, I must've done something funky, or.. humidity maybe

Even though the bats are the same due to the small amount of AIT temp difference the turbo should still be seeing the benefits of colder AIT temps I would think. thank you for the post though. Im actually trying to shorten and widen my CAI just a bit to still infact be a CAI but see if i can pull some better throttle response and keep the cooler AITs. By eliminating the last bend in the CAi system and widening the end and filter i should be able to accomplish this. data to follow in the future!

so i put a heat gun right on the AAT sensor and the dash display was super slow to change but it did.

the AAT value on the DH did not change however so im not sure what that is referenced by.

This is what I was getting at when we talked. The AAT in the DH may be referencing something else altogether - we need to know what PID it is looking at.

The AAT on the dash is very slow to respond because it is very dampened since large fluctuations are unlikely to happen in contrast to IAT in the MAF.

damn. With my cobb sri i get +2-4 IAT while cruising though my BATs are similar to yours. I have the stock tmic

Here is my thought on the intake temps:

When running the stock intercooler with intake, the intake is all by itself with no heat source nearby. That would explain the similar IAT and ambient temps.

With the FMIC, the cold side pipe (well colder pipe) runs directly below the intake. You are now introducing a heat source that heats up the intake. That would also explain why basically all FMIC guys have a much higher difference from ambient and IAT.

Anyone think this would seem logical?

Cool new gauges I came across on Prosports website on the subject of intercooler efficiency and charge density, bat sensor accuracy:

Prosport Gauges dual intercooler air temperature gauges with in and out digital display

Nice find but once you have a core chosen the efficiency won't change much unless it gets really coated with oil on the inside or dirt on the outside. The gauges would be most useful if you are trying different intercooler cores.

Sent from Stratified Mobile Headquarters

this thread needs more pre turbo meth

Just thinking out loud here, but me and a few guys were discussing this over the weekend. First off where is the iat measured from? We all assumed the maf sensor.

If that's the case, this is my thought on cai vs Sri. Say a cai has about 2 feet worth of piping to go through, and a Sri is say half that (not sure of real measurements, just for reference). The Sri will obviously have higher iat's. But what about the iat by the time it actually gets to the turbo. If the piping takes the same route, its gonna get hot. The air travels through the hot piping, heating the air.

So if a cai starts out with colder air, how much is it heated by traveling a longer distance through the intake? The same goes for the Sri. It starts out slightly hotter, but has less distance to get heated before reaching the turbo.

I'm sure the difference isn't really that much? I could sound completely retarded (and probably do) but its a thought.

^ Good thoughts there. The silicone or plastic TIPs are pretty good at preventing the "air" from getting heatsoaked as it travels towards the turbo.

However the CAI and SRI will suffer from the same amount of "air heating" from the TIP. The difference here is that the CAI is able to pull in air that is much cooler to begin with compared to the SRI. So let's say for example the air is going to be heated up by 15* by the TIP. By using the SRI you start with 90* and with the CAI you start with 80* then with the SRI you end up with 105* at the turbo and the CAI with 95*.

You're still ahead by 10* with the CAI when you get to the turbo.

However the design and flow through the intake also has an importance and this is where things get more complicated. CAIs are limited to stock size whereas with SRIs we see them as large as 3.5" which outweighs the temperature difference between the CAI and SRI.

I don't know how the sensor mounts but this seems to be the best bet @ looking @ intake temps and the effects of changes.

Prosport Intake air temperature gauge, instant read air temperature gauge.
@Lex, check this out:

http://www.designengineering.com/cat...yo2-air-intake

Lol, that bulb sitting in the intake stream restricts flow. If you're going to go that far might as well spray N2O and call it a day.

Is there any repeated observations of intake air actually heating up do to SRI/CAI length and/or material? I remember reading some data years ago from some highly regarded engineers in the industry that basically debunked this belief. Basically the premise was that the intake tract has such minimal surface area in which to transfer heat plus the massive amounts of CFM flowing through the pipe showed little to no additional heating regardless of the temp of the actual tube. The boundary layer inside the pipe helped to insulate the intake air from absorbing any heat from the tube.

When I see people wrapping their intake and I/C cooler pipes I always figured that was a worthless mod.

I tend to agree that a pipe has as much effect on heating the air as it does at cooling it when it acts as an intercooler if you get what I mean.