heat/pressure question

[turbo buicks]

i need help understanding how pressure affects heat change. for example will X* air get heated Y amount if put thru a turbo making Z boost? example: WG set at 25 psi. ambient temp is 50* TB inlet temps @ wot are 300* NOW same scenario except ambient temp is 100* what are the TB inlet temps now? are they higher or do they stay constant due to the fact that Z boost will heat the air to a set temperature? im trying to weigh the benefits of CAI vs underhood filter. after taking off my rusted, homemade CAI "kit" (actually it fell off) i put the filter right off the MAF and now when i go to 10 psi and let off i get no knock whereas i was getting up to 7*. i thought CAI was better but the reduced flow hindrance must have meant cooler air was getting in the turbo. helllllllllllllllllllp!!!

:pedro:

[HairDrier]

If you want to know for sure relocate your ATS to the uppipe or manifold.

The cooler the air is to begin with the cooler it will be after the turbo. I think this becomes less and less of a factor the longer you stay in the boost and as the intercooler becomes more and more heat soaked. Once the IC is saturated it wont matter what the inlet temps are

[Bruce]

i need help understanding how pressure affects heat change. for example will X* air get heated Y amount if put thru a turbo making Z boost? example: WG set at 25 psi. ambient temp is 50* TB inlet temps @ wot are 300* NOW same scenario except ambient temp is 100* what are the TB inlet temps now? are they higher or do they stay constant due to the fact that Z boost will heat the air to a set temperature? im trying to weigh the benefits of CAI vs underhood filter. after taking off my rusted, homemade CAI "kit" (actually it fell off) i put the filter right off the MAF and now when i go to 10 psi and let off i get no knock whereas i was getting up to 7*. i thought CAI was better but the reduced flow hindrance must have meant cooler air was getting in the turbo.

Sounds like in fact your CAI, wasn't.
Adding several feet of tubing may in fact raise your MATs. Since there is that much more time for the air going thru that ducting to get heated up. At low speeds/loads, there's not much air flowing thru the ducting.

The only way to tell if a change is really working, is with back to back testing, and maintaining the same AFR. Adding intake tract lenght may serve to richen up the final AFR.

As far as improving MATs there are lots of details that count.
Removing the hood sealing strip, GNX vents, Lower coolant temps., are a few.

[mgmshar]

To answer the original question...

Most likely, your TB inlet temperatures will be warmer if you pull 100F air into the air cleaner rather than 50F air. The temperature rise as the air is compressed in the turbo is a function of the pressure ratio, the inlet air temperature, and the turbo efficiency. The higher the air temperature coming into the turbo, the higher it will be leaving the turbo. Therefore, the higher it will be going into the TB. I can dig-up the engineering equations, if you really care.

The only way this would not be true is if your intercooler is so big and efficient that it can drop the air temperature all the way down to the outside air temperature (100% effective). In reality, that never happens, but a large front-mount will get you close.

It's a balancing act: does the lower pressure drop that you get with a shorter inlet tract outweigh the increase in temperature at the TB inlet? Different people have different opinions on this. I'd like to see some actual data (i.e. measure air density in the intake manifold using temp. and pressure) on this, if anyone has it, before and after a CAI system.

[turbo buicks]

cool guys thatnks. bruce, the thought of the less tract length heating the air less had crossed my mind as i remmebered you saying something about it in an earlier post. mgmshar dont bother looking up the info, i trust ya. hairdrier, id relocate it but thats work and im very lazy but thanks for the idea.