Quote:
Originally Posted by BTRobertson
No, that's not altogether true, though it depends mostly on the brand and type of intake. My Fujita F5 SRI made power throughout the powerband - low to high. I have dynos. The TBS adds a trivial amount of power, but the main benefit is that it prevents heat soak - this is answered below...
First things first - heat soak is bad all the way around. Yes, heat has to disperse from the block, but if heat soaks into the manifold and then into the intake, there's no water channels or any other method of heat dispersal in those places, so the engine compartment heats up and heat is never removed except by the air around it or coming in through the front of the car at higher speeds.
The intake manifold gasket is something one would consider when doing the spacer, which keeps the heat from soaking TOO much into the manifold. Now, I say too much because it doesn't 100% PREVENT heat soak from occurring, just keeps it from happening too much. The water/coolant system works harder to keep the heat away from the block as a result because less heat is soaking into the manifold, hence less heat is soaking into the intake.
The result is a cooler charge of air entering the manifold and then the combustion chamber = more power/torque across the RPM band. The consequence? Keeping heat where it's supposed to be - where the water/coolant system can get to it and disperse a lot more effectively than the air can. And again, not ALL the heat is at the block, just a bit more than usual because the heat soak is prevented. Trust me, keeping heat where it can be dispersed more effectively is probably the best policy - the IM and TB don't have cooling capabilities at all, so why would it best to have heat soaking into those metal components when they're not built for dispersal?
That's my two cents, anyway; an engineer may prove me wrong.
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Your explanation looks good to me!
One little tidbit that doesn't really matter to our application but I'll include anyway: Getting a cooler (more dense), more energetic (since more fuel is added to match the extra air) charge burning inside each cylinder produces a corresponding amount of extra heat. The cooling capacity of our engine is more than adequate to handle this small amount of extra heat but if you were to add a lot more air/fuel (i.e. turbocharge, etc.) you could bump up against this limit. I intend to find it this summer with a drive to Death Valley in early July (hottest time of year).
The reason the intake manifold doesn't make a lick of difference in dissipating excess heat is that it takes way too long for the heat to move into the manifold. Any signifigant rise in cylinder temps during a hard run would transfer to the coolant long before it had a chance to make it to the intake manifold.
Now, if you've shut down and want to cool off your engine enough to work on it and you've raised the hood and maybe put a box fan in front of it, the engine with the intake manifold gasket WOULD NOT dissipate the heat as quickly as the stock setup, meaning you'd have to drink an extra beer or two while you wait for it to cool down or you get drunk enough that you don't feel/care about getting burned.
