Intake air temp discussion

[Lex]

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.

[m249saw]

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

[Lex]

Originally Posted by m249saw 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.

[KevMS6]

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

[exentix]

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.

[Lex]

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.

[xI Leveler Ix]

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!

[Lex]

Originally Posted by xI Leveler Ix 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.

[cbspd3flip]

Nice! Very informative!

[xI Leveler Ix]

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

[BigjohnB20]

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?

[Mortose]

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

[Dano]

Originally Posted by Lex 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.

dryflow > oiled?

[Lex]

Originally Posted by BigjohnB20 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?

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.

Originally Posted by Dano dryflow > oiled?

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

[EdgeAutosport.com]

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

[rfinkle2]

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

[Lex]

Originally Posted by rfinkle2 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.

[rfinkle2]

Originally Posted by Lex 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.

[m249saw]

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

Sent telepathetically to my Razr Maxx

[Lex]

Originally Posted by m249saw 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

[Dano]

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




Tappin

[fredricktsang]

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.

[forcedinduktion]

yea butt dyno agrees

[superskaterxes]

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!!!!

[painfulpillow]

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?

[Tenchix]

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.

[Lex]

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

[Tenchix]

Bump, for my question.

[Lex]

Originally Posted by Tenchix 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.

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

[superskaterxes]

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

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

[G26]

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.

[CosmicArkie]

Originally Posted by Lex 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

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.

[nukepilot]

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.

[ms3rick]

Originally Posted by Lex 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.

Good write up and can't wait for these findings


Sent from my dizzLe using RaWr powers!

[Lex]

Originally Posted by CosmicArkie 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 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.

[Lex]

Originally Posted by nukepilot 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.

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.


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.

[speed14]

@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

[m249saw]

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

Sent telepathetically to my Razr Maxx

[Lex]

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

[Boosted Beluga]

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.