6 dollars to lower your mat temp 20 degrees. - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 06-28-2010, 03:34 AM   #21
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Quote:
Originally Posted by NA6C-Guy View Post
**** doing a cheap or free mod to lower intake temps!!!
It's all about doing dem tyte type-r filters, right?
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Old 06-28-2010, 03:36 AM   #22
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**** yeah. I want a Weapon-R cold air intake, and I want to route it up through the hood. Maximum cool, true ram air... if I can trim down my budget by skipping out on the light weight pulley kit or ground kit, I might get a second and a Y-pipe and run two.
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Old 06-28-2010, 05:52 AM   #23
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Quote:
Originally Posted by lordrigamus View Post
Hahahaha, is that a speed limit sign?
Indeed.
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Old 06-28-2010, 07:51 AM   #24
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OK neo, I see your point.
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Old 06-28-2010, 10:03 AM   #25
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Let boost be at 6 psi. The temp gain with turbo is about 14/15F per psi, or about 90F.

On a 90F ambient day, ambient absolute would be 90 + 460 = 550F.
The charge temp absolute would be about 550 + another 90 from the turbo, which comes out to 640F

Density would degrade by 550/640 = .86

The pressure ratio at 6 psi is 1.41.

With the heat from the turbo, then the 141% more density from compression will be degraded by .86 x 1.41, or to about 1.21. Thus a huge chunk of the density/power was lost and the system is 90F closer to knock.

With a 90% efficient IC, .90 of the 90F temp rise will be taken out, or about 81F removed, thus leaving a net gain of 9F. This would leave a density loss of only 2% from the heat, or a net gain of 1.41 x .98 = 1.38, or an overall gain of 38% rather than the 21% without the intercooler.

This assumes the filter is in a position sourcing ambient air. Behind the radiator is one of the worst places, the temperate sourced from that area is going to be closer to 150-190F.

So, let's compare:

perfect conditions; 90F ambient + (90F turbo addition x 90% intercooler) + 460F = 559F
unideal conditions; 90F ambient + [(190F intake + 90F turbo addition) x 90% intercooler] + 460F = 575F

550/559 = 1% density loss or overall gain of 39.5%
550/575 = 4.3% density loss or overall gain 34.8%

So if you dynoed at 160rwhp with the filter behind the radiator, you have a potential of a 7.5rwhp gain if you simply moved the air filter to somewhere that would source ambient air.

something like that.
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Old 06-28-2010, 10:27 AM   #26
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precompressor density increase > intake mani density increase

EDIT: Technically the above is wrong, but was written in the sense that making increases in precompressor density is more worthwhile than post compressor increases, although you can more easily increase density post compressor due to the larger deltaT of the now compressed air.

A better way to put the above is: post compressor density increase = PR * precompressor increase for the same mod. /EDIT

This is especially true with smaller compressors, or will make a bigger difference to you. With a larger, efficient compressor you just turn up the boost...but in trying to eek every last little bit out of my tiny IHI I did everything I could to get the densest, coolest, highest pressure air into the compressor intake.

A given pressure ratio does not equate to an absolute mass flow rate. A 2.0 pressure ratio simply pressurizes the air to twice what it was at the intake. It does not care what the intake pressure or density was, it will operate as efficiently as it's flow map dictates at that pressure. What does change is the air mass. You can effectively "shift" your efficiency map by providing denser, or higher pressure air. This is how compound turbocharging works, and why the second compressor on such setups doesn't need a huge pressure ratio, just a high flow rate that is efficient for said pressure ratio.

The RHB5 was only efficient up to about 1.7 pressure ratio for the 1.6L, and blowing nothing but hot air after that. Coupled with a tiny intercooler on the original BEGi kit and I had to do what I could to direct cool, high pressure air to the intake.

Either way you're optimizing your setup. It amazes me that we can spend $200 for 5hp, but will scoff at the $6 solution that nets just as much gain, especially when it's one that makes life easier on both turbo and motor.

Last edited by gospeed81; 06-28-2010 at 10:47 AM.
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Old 06-28-2010, 01:02 PM   #27
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hmm. looks like your airfilter was located right where mine is. i'm suprised at the kind of temp loss that you experienced just by boxing it in. looks like i have another project to add to the list.
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Old 06-28-2010, 02:25 PM   #28
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Heat reflection and compartmentalization (******* huge word huh?) are amazing things.
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