Prasius

iTrader: (1)

(Another question from the wealth of information that comes from my ECU!)

What relevance does intake temperature have on a turbo charged engine?

I had to pop out in the car last night and kept an eye on the intake temperature, and its relation to the knock correction data.

The outside temperature was 3 degrees C, for much of the Journey, the intake temperature was also at 3 degrees C. As the engine reached operating temp the intake temp began to rise to around 4/5 degrees C. During this time I noticed KC was advanced 0.5/1.0 higher than it usually was at throttle openings between 5% and 30% When I reached my destination and came to a halt, I noticed that my intake temp began to rise as roughly 1 degree every two seconds.

After a short stop with the engine off, I returned to the car to find that intake temp had risen to 27 degress C! After I set off again this dropped quickly but only to around 9/10 degrees C where it remained pretty constant.

Now, we all know cold air (dense) is good and hot air (err.. not so dense) is bad.. but how much of the difference in intake temps is actually seen in the combustion chamber - after it has passed through a bloody hot turbo and through the intercooler.

Would a CAIK such as the APS suffer less from the "heat soak" the OE Plastic box endures? Would either the CAIK or the OE Plastic intake benefit from additional heat shielding? Is there actually any point in worrying about intake temps?

I have my own suspicions regarding the answers to these questions - but it would be good to get an informed technical answer in plain English!

scoobysmiff

iTrader: (2)

I would honestly speak to Harvey Smith on this, i know he has done extensive testing on this subject and would have some startling facts for you!!

dynamix

iTrader: (3)

Thats why it is very useful to fit a charge temp gauge to measure the temperature of the air going into the engine.

The intake temp is used by the map to determine enrichment proccedures and if it gets to above 30 deg it will retard the ignition.

Charge temp is far more useful as it shows the efficiency of the turbo/intercooler and complete system. I have spent a lot of time getting my charge temps down - it is essentially free power

dynamix

iTrader: (3)

re shielding and whether it is worth it.

Get a charge temp gauge sorted first then you will be able to judge whether any changes you make at the various points of the system effect the final temp entering the engine.

Gauges are only £50 or so.

Prasius

iTrader: (1)

Take note those of you who run unshielded induction kits then - because from what I saw last night, even on a cold night under bonnet ambient temperatures easily reach 30 degrees.

Dunc, can you suggest anywhere I could get a charge temperature gauge? I might get one in the next couple of months just to quell my curiosity!

dynamix

iTrader: (3)

DaOne got one recently, prob easiest to speak to him. I use an SPA Design dual boost / charge temp gauge which is a little more exspensive.

Several things I noticed on mine:

With std snorkel and resonator box: cruise temp = ambient + 5/6. WOT runs were very high.

With cold air feed direct to airbox: cruise temp = ambient + 3

With throttle body coolant feed removal: cruise temp = ambient + 1 (and would not rise so quickly in closed throttle situations) WOT temps would rise fairly rapidly depending on how much boost you run and for how long. Quite often by 20C such as up the long hill at nurburgring or a full through the gears WOT run.

Now with the APS DR725 FMIC

Cruise charge temps: Ambient or ambient -1. WOT: the charge temp drops about 4 deg below ambient initially then rises to around ambient + 4
Full track session never saw charge temps over ambient + 6 deg

I can safely say that the APS FMIC does a great job based on FACT

Prasius

iTrader: (1)

Thats seriously impressive.. but its a little OTT for my needs!

dunx

iTrader: (3)

The heat rise is due to the heat from the engine and not really relevant to a moving car, but agree the actual charge air temperature is far more important. That's why I went for an FMIC early in my cars "development".

DunxC

Varboy

I recommend a book called

Forced Induction Tuning by A Graham Bell

I's a great book that covers topics such as this and also walks you through the calculations.

dynamix

iTrader: (3)

Strangley the main culprit for the rising temps when standing still was the coolant feed that circulates 90C water around the throttle body to stop it icing up. This has a huge impact on the initial gulp of air that gets consumed by the engine on re-applying the throttle.

Without it, the air temp there rises by 0.1C every second or so.

Never had a problem with icing up even when driving in -5C in germany at end of october.

Ian

iTrader: (10)

any info on how to do this mod?

Butty

iTrader: (2)

Clamp the coolant hoses going in and out of the TB. Put rag under TB.
Disconnect coolant hoses. Soak up spilt coolant. Join coolant hoses together with section of pipe. Seal TB coolant pipes. Try bleeding coolant system over the next couple of days to remove any trapped air.

nick

Tidgy

air inlet temps make a huge difference, as much as 1 degree per bhp iirc, have a read of this

http://www.scoobyclinic.com/download...coolertest.pdf

P1 FEK

iTrader: (1)

What diameter are the hoses?

Ian

iTrader: (10)

rather then joining them together, are they long enough for 1 to loop over to each other?

The rookie

iTrader: (1)

No, neither are long enough for you to delte the other, I used a section of pipe from an old manual choke conversion kit to bypass mine!

Simon

Ian

iTrader: (10)

just looked at mine, and they look clsose enough together to me, take one of the water pipes that go the the TB, disconect it the TB end, and re join it to the other end of the water pipe

silent running

'Forced Induction Performance Tuning' is absolutely essential reading. Cuts right through a lot of the bull**** you here on SN. He says nothing without having been out and done it himself first.

Having delved into these issues mainly on my old turbocharged Clio 16v, but also in a less involved way on my Scoob I'd say this (I'll keep it brief):

• Temps at the filter do make a difference. 10 degrees colder at the filter usually gives the same 10 degrees less at the intake, assuming a relatively efficient intercooler.
• Extra bonnet scoops for the filter are a total waste of time unless your filter is actually sticking out into the airflow.
• Most mods and innovations in induction kit design are basically getting closer and closer to the ideal - a sealed airbox. What's the point of fitting an induction cone then boxing it in? You might as well just keep your airbox unless there's some reason you can't.
• Once your airflow requirements get beyond a certain level, the ambient air temp that your cone is sucking up is pretty much irrelevant compared to the heat that your turbo is putting into the charge. The important bit is getting your intercooling capable of the boost pressures and charge temps that the turbo puts out. Air filter mods are a waste of time.
• Running a big pipe down to say your bumper and then pointing the other end at your filter is a complete and utter waste of time. The pressure inside your engine bay is far too high to get any useful airflow through the pipe. The only way this kind of thing works is if it's ducted to a sealed filter which is pulling a vacuum...oh, isn't that an airbox?!

All IMHO and backed up by actual real life testing.

dynamix

iTrader: (3)

well said

dunx

iTrader: (3)

Cheers Duncan,

While fitting my fuel reg. it will be time to by-pass that "heater" then !

Thanks for the info.

Other Duncan

Dr B

intake temp is important , even though the turbo will heat it . Your maf temp greatly affects the ignition timing and fueling .Hot inlet temps at the maf will cause u to build less power , Even though u may have a CAI , look at the maf housing , it thens to get very hot due to the radiator blowing very hot air when the fans come on . solution cold air to filter and protect maf housing from heat . Cold charge temp , make power yes , but the ECU works off the inlet temp at the maf .

Enginetuner

At least one distinct advantage of the Simtek ECU is the lack of MAF sensor.
The inclusion of charge temp monitoring and correction makes much more sense for the high boost versions.
The actual amount of correction for intake temps on a MAF equipped car isn't as much as all that in any event, and is tweakable via Ecutek. The major problem with various after market air filter systems is the effect on the MAF monitoring of air flow, rather than actual intake temperatures.