airflow map

[tnord]

i'm a bit confused as to the path that air takes on a turbo engine........is it from intake-turbo-intercooler-manifold-combustion-manifold-turbo-exhaust??? it's just something i've never been quite clear on but would like to know, where the intercooler lays in this i'm particularly lost, i know the function of it, just don't know it's place in the path of airflow
-thanks guys

(Edited by tnord at 10:14 am on Feb. 11, 2002)

['91 D21 beater]

Okay:

Path for air on typical Mass air based ecus:

Air goes through the air filter, then the MAFS, gets "sucked" into the compressor blades and gets compressed. Compressed air (now much hotter) leaves the compressor housing outlet, into the I/C, gets chilled, and onto the throttle body. After that, goes into the intake manifold, through an intake valve. Get's compressed by a piston, and the air/fuel charge gets ignited by an ignitor. The mixture burnes and expands, then gets expelled out the exhaust valve, into the turbo manifold. In the turbo manifold, it goes into the turbo turbine housing inlet, and does work on the turbine wheel, then does down the turbine outlet into the down pipe, pass the cat, and into the exhaust system, and out the back of the car.

[yenpit]

yup....just keep in mind the turbo is "spooled" first by the exhaust flow, which in turn spins the turbine on the other side of the turbo to create the compressed intake-i/c-mfld air charge into the combustion chamber.
remember there are int pipes....from filter to turbo IN, turbo OUT to i/c IN, i/c OUT to mfld. the air-to-air i/c is like a small radiator mounted off to one or both sides ie 300zx, in front bumper ie Lancer or most aftermarket setups, or on top of engine ie WRX. i/c's are always located so outside air can pass thru them to "cool" the air charge inside, just like a radiator with coolant. if you set up a "water mist" squirtter on the front of the i/c to squirt thru the i/c, that cools the inside air even more. often called water injection. IIRC, ZEX nitrous systems just released a kit to mount a "nitrous mist" squirtter on i/c's (like the water system), and nitrous is extremely cold and cools the air charge better than anything thus far! very cool kit (no pun intended :biggrin:). keep in mind the colder the air charge (on any intake whether t'd, superchg'd or N/A'd) the better the combustion capabilities, thus the more HP produced.
hope this helps clarify!  

[AceInHole]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from yenpit on 11:15 am on Feb. 11, 2002
yup....just keep in mind the turbo is &quot;spooled&quot; first by the exhaust flow, which in turn spins the turbine on the other side of the turbo to create the compressed intake-i/c-mfld air charge into the combustion chamber. </td></tr></table><span id='postcolor'>
but if air isn't drawn into the engine first... there's no exhaust gas to spool that turbine. &nbsp;So really, it's air get's sucked in by the engine through the MAF, turbine, intercooler, throttle body, intake manifold, and intake valves, into the the combustion chamber, ignites, and exits through the exhaust valves into the exhaust manifold and into the turbine, which then is spooled by the force of the exhaust gases, which then spins the compressor which sucks air in through the filter and MAF, and blows it into the IC..... etc etc.

[yenpit]

update.....Zex did not release the nitrous mist kit, Nitrous Express did.

[AceInHole]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from yenpit on 11:15 am on Feb. 11, 2002
keep in mind the colder the air charge (on any intake whether t'd, superchg'd or N/A'd) the better the combustion capabilities, thus the more HP produced.
</td></tr></table><span id='postcolor'>
actually, isn't it that colder air = denser air = more air by volume? &nbsp;does the stock temp sensor actually aid in this by telling the ECU to compensate and inject more fuel??

[tnord]

first off....... thank you deleted member for tolerating my primitive knowldge of engine mechanics and dyno's today. I thought i was right but wasn't ever very confident in my understanding. Now in order to improve my understanding of forced induction i have a question about how the turbo itself actually functions.

I understand that the intake charge gets compressed by the turbo, but exactly how is this accomplished? Am i correct in assuming that exhaust gas, moves much faster (because it is hotter as one of many reasons; i have little knowledge of thermodynamics) than intake &quot;gas.&quot; Thus spinning a pinwheel like device that is connected to the same type of device on the intake side of the turbo. &nbsp;It is this &quot;pinwheel&quot; that compresses the intake charge. &nbsp;I guess i just don't understand how a &quot;fan&quot; can cause more air to be cramped into a smaller space. &nbsp;It will probably take a mechanical engineer to answer my question, but my automotive curiosity knows no bounds.

Ace, in an ideal world i would hope that the MAFS and ATS could work in conjunction with each other and relay the information to the ECU, and in turn injecting the appropriate amount of fuel. &nbsp;I assume that very basic programs are created (read:cheap) to do this, and that aftermarket ECU's use much better software to utilize the information that the MAFS &amp; ATS is sending it, thus producing more power.

['91 D21 beater]

hehe, I'm a mechanical engineer... it's sort of difficult to explain it without visual aid. I would first suggest couple of options: www.howthingsworks.com is a good one and the other is a fairly entry level turbocharging book by Corky Bell &quot;Maximum Boost&quot;. That would get you started.

I'm just afraid that I might get too much into details and totally ignore work... hehehe (It does help to understand thermodynamics and fluidynamics...)

[AceInHole]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from tnord on 4:12 pm on Feb. 11, 2002
Ace, in an ideal world i would hope that the MAFS and ATS could work in conjunction with each other and relay the information to the ECU, and in turn injecting the appropriate amount of fuel. I assume that very basic programs are created (read:cheap) to do this, and that aftermarket ECU's use much better software to utilize the information that the MAFS &amp; ATS is sending it, thus producing more power.
</td></tr></table><span id='postcolor'>
my only wonder would be the ATS's range for one thing. &nbsp;For another, if the air cooled in the intercooler is colder than the air flowing by the ATS, how would the ECU compensate?? &nbsp;The ATS is placed before the MAF in stock form on the S14's......

['91 D21 beater]

How does the ECU compensate? Easy, O2 sensor... The intake temperature is more of an emission item.

And in WOT, the ECU defaults to a preset air/fuel map.

[yenpit]

ace, ur right, i was speaking in terms of the actual spooling of the turbo OFF idle, since the power generated by a turbo really isn't seen/felt until a certain rev point.....off idle. but yes, the VERY first step is to draw air in at initial startup.
second ace, to break down the &quot;colder air&quot; theory further into detail......yes, a more detailed description of a cold air charge is just that.....well put!
third ace, the air temp sensor often found within the intake pipe really doesn't do much. its effect on additional fuel is minimal. IIRC its main purpose is to aid in &quot;cold&quot; starting.....cold air at initial startup passes past the sensor, and it tells the ECU to dump a little more fuel to help a cold engine start. very minimal. that sensor is usually way up near the filter.
IIRC the O2 sensor also has minimal effect on adding more fuel. it too sends signals to the ECU, but only reads if lean or rich within parameters, and that system is only capable of altering the fuel input by a small amount. proper fuel management is key on a t'd car, that's why many install products like Apexi's S-AFC to alter the fuel curves on a much larger scale. they offer the ability to dump much more fuel at certain rev bands etc, ie when the turbo spools up and requires more fuel cuz of the compressed air charge.......of course, the epitomy of all products may well be the stand-alone laptop fuel mgmt systems where you can set every drop of fuel at every RPM....... killer stuff! hope that helps. &nbsp;

[AceInHole]

the only reason I ask about it is to see if slightly colder air will really have some huge affect on performance compared to normal temps. &nbsp;Of course, the difference is noticeable in the weather, but how much is too much I guess.

[yenpit]

slightly colder, huge effect.....no, but the colder the better! thats y so many companies r making these &quot;cold-air&quot; intakes. on a stock engine the cold-air int's usually only make a few more HP than the short ram int's (some cars respond better). weather can make a diff, but again not a big diff. is it worth buying a cold-air int...... yea, we always want to squeeze as much HP out as we can, huh??!!

[idunit]

Doesn't someone one have a nice pic of all this that shows a sectioned out motor with colored arrows and stuff? &nbsp;I'm sure they do.

[yenpit]

:confused:

[mrfly]

Here is an small essay that my friend Allen George did on turbos. It isn't in very much detail, but his visual aids are very good for a basic understanding.
http://redline88.tripod.com/240sx/turbo.doc