explain theory of intake spacer

[phutch11]

Did you happen to study the effect of changing the emmisivity and/ or the convection coefficient of the material making up the tube?

It is probably down in the weeds, but I have always thougth that you could probably further lower intake charge temps by either polishing the intake runners or by coating the inside of them with a ceramic coating. Both would reduce the emissivity and convection coefficient of the intake to the air charge.

Power changes dramatically with intake charge temp. There are several calculators online that can show you the effect.

Good luck....

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[tmoss]

thermal coatings on the bottom and inside the runners would help keep the air charge cooler. Flat black bodies radiate heat the fastest, so a flat black coating outside the intake might help too.

 

[njoliver]

mustang5L5 I am just curious what R and D do you work at if you dont mind saying. I was just working for Honda and Acura R and D. They are very interesting jobs

 

[Mustang5L5]

I'm in the semi-conductor industry. Unfortunately it's not automotive related. We develop systems (or components) used by the major chip and flat panel display companies to manufacture their products. It's interesting work...but doesn't excite me too much really. Rather be designing vehicle systems.

It just so happened I had to design a component to a system to heat Nitrogen flowing over 50 SLPM up to over 200*C in a relatively small amount of space. I did it in such a simple manner too that I would confidently say a nice heat soaked intake manifold does have an affect on the air temp flowing inside..even at a high flow rate.

One thing i did observe makes me wish i had a graph handy to show. Basically what i saw is that if you idled at a low flow for a while and then increased quickly to high flow, you'd get a temp spike that would surge up and then come back down. Basically what that would possibly correlate to is that when you are in the staging lanes, you manifold would absorb a lot of heat and basically store it. When you get to the line and go WOT, the rush of air would produce a dramatic spike in air temp as the heat in the manifold transfers to the air rushing through the intake. So you'd shoot way up pretty quickly. After a certain amount of time, the temp will actually begin to drop after this initial surge. How much time depends on the mass of the manifold that was absorbing the heat. If could be halfway down the track...or 2-3 miles after going WOT..who knows.

If i were to really play around with this, i'd maybe suggest making the manifold out of a material with very low thermal conductivity and polish the inside to reduce heat transfer. Toss a nice spacer on to keep the manifold from heat soaking and i'd think that would be the best at preventing the air charge from spiking when you go from low flow to high flow immediately....or at least lessen the spike.

But we are overthinking this IMHO. I personally run a 3/8" spacer. I also have a Cobra intake, so no coolant lines in my intake. My EGR works too, but i'll tune that out one day.

 

[phutch11]

Why do you think that all modern performance cars use plastic intakes? Besides the light weight the thermal properties would be much better than aluminum.

Here's what I'm doing (or considering doing) on my new exploder intake to control intake heat.

#1 - Ditched the EGR system and coolant system on the EGR spacer. (I have a QH, so it's tuned out as well.)

#2 - Bought non-EGR intake gaskets to keep the hot gasses from the going into the lower manifold.

#3 - Took Tmoss' template for the PVC baffle and extended it up to the runner for the #5 cylinder - I used polished galvanized sheet steel to reflect the radiant energy back towards the block and to almost completely keep the hot oil off the bottom of the runners.

#4 - Installed a 180 degree thermostat.

-----Haven't done these yet---

#5 - I plan to polish the entire inside of the coolant crossover at the front of the intake. This should reduce the total surface area and should reduce the heat transfer from the coolant to the intake - if only ever so little. (If I had the money or the stuff to do it at home, I'd coat the insides of the crossover with a ceramic coating instead.)

#6 - After port matching the intake runners, I plan to go ahead and polish them as well. This should again, reduce surface area for convection and decrease the emissivity of radiant energy from the intake to the air charge.

Probably will be a lot of work for zero reward...but it keeps the mind busy, and lets me use that engineering degree for something.

Good luck....

 

[90mustangGT]

In layman terms, in automotive terms: One disadvantage of a Turbo over a Supercharger is that fact that a turbo due to being an exhaust component transfers significantly more heat to the air charge than a supercharger. Well... how long is that air inside that turbocharger? Split second, maybe? Then consider how long the air flows through an intercooler/aftercooler and how much it can be cooled. How long was it in there? A second or two at the most? Think of exhaust gas tempratures from the manifold and how much it drops by the time it exits the tailpipes. Now, isn't it more than reasonable that inside the manifold the same science would apply?

I never ran a spacer but when I bypassed the coolant lines to the EGR spacer and blocked the EGR (exhuast gasses) when I changed the intake gaskets I noticed a low end gain and especially a better throttle response. Ice on the intake between runs defiatly made a difference.

 

[FastStang91LX]

That is one thing I might do this summer....Put 2 dozen intake spacers in my ride, cut a big hole in the hood, and show up at a gathering. Awesome!

Better than driving around with that wing on, lol

 

[Mustang5L5]

Lol. That might look funny!

Put about 2 feet worth of spacers, cut a rectangular slot in the hood, close the hood and then bolt on the intake. Then just extend the vacuum lines and wiring up to the intake plenum and let the throttle body sit wide open.

Then you'd have the air blowing past the plenum to cool it off!


Downside is to open the hood, you'd have to unbolt the intake