monitoring intake temps

[Jeff Lucius]

I have "tested" the IC efficiency only once so the results below are hardly scientific.

Ambient air temp: 75ºF (early June morning in Denver, CO area on highway)
Ambient air pressure: 12 psi (I was at ~5600' ASL)
Temp before IC: ~286ºF
Temp after IC: ~130ºF (usually got 125 to 130 peaks on this run at 15.6 psi boost)
Pressure in plenum: ~15.6 psi (1.1 kg/cm2 on GReddy gauge)
Pressure after turbo: ~17 psi (assumes a 1.4 psi loss in IC system)

IC efficiency: ~75%
Overall pressure ratio: ~ 2.3
Overall density ratio: ~2.2

I really need to do more tests at different ambient tests, at different boost levels, and to place a temp probe from my DMM in the engine bay to monitor air temp near the air filter to get more meaningful results.

[jeff97vr4]

Originally Posted by Multiades

I know I've seen devices like this before, but where can I purchase an inexpensive fast-reacting air temperature gage, or possibly a differential temperature gage (obviously with two inputs).

It would be very useful to be able to quote peak air temp in the plenum.

-Chris

http://www.3si.org/forum/showthread....um+temperature . The Fluke 52 II meter wasn't inexpensive but does offer a lot of versatility. The thermocouples can be easily moved to different locations under the hood or just for general shop work.

Jeff

[smokinvr-4]

I like the SP engineering piece, that thing is pretty slick, I am curious about this as well, it give you a little insight as to where the turbo starts to lose its efficency

[cbatters]

Subscribe... (needed some #'s for comparison with the logging that I'm doing...)

Comments / questions.

1. Based on my calculations (based on vague memories about gas laws) I believe there is a ~1% power loss for every 3 degree C rise in the plenum air temp. (This is assuming that HP is directly linked to the # of air molecules you can stuff into the combustion chamber which I believe is correct.)

2. Is the larger issue that higher intake charge temps can lead to detonation which will retard timing?



Clint

[cbatters]

Originally Posted by Jeff Lucius

I have "tested" the IC efficiency only once so the results below are hardly scientific.

Ambient air temp: 75ºF (early June morning in Denver, CO area on highway)
Ambient air pressure: 12 psi (I was at ~5600' ASL)
Temp before IC: ~286ºF
Temp after IC: ~130ºF (usually got 125 to 130 peaks on this run at 15.6 psi boost)
Pressure in plenum: ~15.6 psi (1.1 kg/cm2 on GReddy gauge)
Pressure after turbo: ~17 psi (assumes a 1.4 psi loss in IC system)

IC efficiency: ~75%
Overall pressure ratio: ~ 2.3
Overall density ratio: ~2.2

I really need to do more tests at different ambient tests, at different boost levels, and to place a temp probe from my DMM in the engine bay to monitor air temp near the air filter to get more meaningful results.

Any ballpark figures on the efficiency (or inefficiency) of the stock intercoolers?


Clint

[twospoons]

well i've still been giving this some thought... and ran across this:

http://www.ls1tech.com/forums/showthread.php?t=202724

check out the calcs in post #2... how accurate is that info??? is 1075*F (combustion temp) really the "accepted detonation threshold"???

[Jeff Lucius]

IMHO, you can safely ignore that entire thread.

First "effective" CR is a mathematical construction that has little real usefulness in evaluating or predicting engine performance. Ignore it.

Second, detonation is not determined or prevented by IAT (at plenum) but by a variety of conditions in the cylinder (see links on the Tech Page at my web site). IAT is just one aggravating or mitigating factor.

1075ºF (assuming that is the same as 1075*F ) is not a "combustion temp". It is way too high to be an IAT and way too low to be a good EGT at WOT. Actual combustion temps will always be in the range of 2000ºC to 2500ºC (3600ºF to 4500ºF). Now it could be the temp of the spark plug electrodes, but that would be near the bottom of the ideal operating temp range.

One thing we do know is that when spark plug electrode temps, or any part or location inside the cylinder, is maintaining a temp above ~1050ºC (~1920ºF) between combustion events that autoignition or detonation is likely to occur.

In short, and as always, be skeptical of what you read on the internet. Just because a person is sophisticated enough to have a computer, internet connection, and can type doesn't mean they know squat.

[Jeff Lucius]

Originally Posted by cbatters

Any ballpark figures on the efficiency (or inefficiency) of the stock intercoolers?

Clint

Not from me. Since I've had my car, the factory ICs were in it (while it ran) for only 2 months (1997). We installed the "Alamo" ICs (and 15Gs) with the engine rebuild.

[cbatters]

Originally Posted by Jeff Lucius

Not from me. Since I've had my car, the factory ICs were in it (while it ran) for only 2 months (1997). We installed the "Alamo" ICs (and 15Gs) with the engine rebuild.

thx

[wraith]

So Jeff, 130 degrees is what you saw on a 75 degree day after the upgraded intercooler? I guess we can assume, the perfect reduction in temp would put it at 75 degrees, and since the Alamos are likely the biggest sidemount available, we really cant expect any better then this from an air air intercooler unless it was front mounted and huge? Had anyone measured the temps after a FMIC? I need to do this. I am curious where the DSM sidemounts compare on a similar temp day. Its rediculous how much companies charge for a small digital clock with memory and a couple quick acting thermocouples. This how contraption should not cost more then $150 and thats being generous. After seeing all the places where one could use a datalogger, those $200 PLCs with (a dozen input/outputs) software seem like a really good deal.

Sam