>The only way to show for certain whether these spacers are actually doing
>what you think they are is to put a thermocouple (or other comparable
>instrument) out into the airstream in the intake (right at the manifold
>gasket) and measure air temperature under the same ambient conditions, with
>and without the spacer.
True, testing with a some sort of measuring device will probably give the
best results.
>At any reasonable engine speed, there are tens of liters per
>second moving through EACH intake passage; it's hard to imagine that this
>amount of air could be heated to any degree by the intake manifold.
>
The air flow through the intake passage at steady state (forgetting about
the flow pulses as the valves open and close) could be considered a control
volume. The energy rate balance for steady state control volumes states that
0=Qcv/m-Wcv/m+(h1-h2)+(v1-v2)/2+g(z1-z2). Where Qcv is the heat transfer
rate. The heat transer rate in the equation goes to zero if:
1. The surface area is to small for effective heat transfer
2. The temp difference between the cv and its surrounding is
so small that Qcv is ignored
3. The air flows so quickly that there isnt enough time for Qcv to
occur
4. The outer surface of the cv is well insulated
I dont know how much air flows through, but if there is enough then there
isnt enough time for heat transfer to occur aka #3. Correct me if im wrong,
i forgot some of my thermo. So why the added HP? Anyone else have ideas. His
website states hp gains.
Javier
got a B in thermo
>It's possible that this mod is doing something other than what you think it
>is. It'd take a much smarter guy than me (automotive-wise, anyways) to
>figure it out. I'd also want to see a thermodynamic explanation rather
>than
>hand-waving. Unfortunately I bagged thermo in favor of statics/dynamics.
>And I'm kicking myself right now.
>
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