[Cliff R]

I certainly don't know all the "physics" involved here, but do not what happens on the user end with these things.

For about 90 percent of the folks who get involved with blocking crossovers it's a complete waste of time/funds, and will only prolong intake warm-up times and hurt engine efficiency.

Keep in mind the basics of the internal combustion engine N/A. Heat, fuel, and spark.

Heat is created by compressing a very lean mixture then adding a spark at the correct moment to achieve combustion. To do this we compress the volume of air/fuel above the piston past the intake valve closing point. The piston compresses the mixture, heats it up, and raises the LEL so we can ignite it.

In a wet flow system we rely on all the items involved with the intake system to effectively mix the fuel added to the air before it starts getting compressed. Things done to cool that mixture certainly don't help the process, and cold engine part take some of that fuel out of suspension and increase fuel demand to achieve the LEL.

Now, we're torn between wanting to induce a cool dense air charge which helps pack more air into the cylinders vs needing to raise the temperature of that charge high enough so that it needs the minimum amount of fuel added to it for maximum efficiency.

So the theory of having a cold intake to help things out pushes folks to block off the crossovers and take other steps to reduce the temperature of the incoming air charge.

The problem here is that you just can't get around the basic laws of physics with these things. Taking the heat away from the intake is a superficial benefit, and it disappears after heat soak and hot under hood temps go ahead and heat up all the parts of the intake tract anyhow.

Now the only point to argue or consider is how much lower the actual intake temperature is without the added heat from the exhaust, and if that lower temperature is beneficial at all to a street driven vehicle?

What I do here is not to worry about it, and we do NOT block off crossovers, nor do we eliminate the vacuum advance, nor do we run rich mixtures from the carburetor to compensate. I have found with my own vehicle, even when I was racing it couple of times a week, that it was best to run the engine FULLY heat soaked and up to FULL operating temperature, vs trying to run it cooler, or cool down any of the engine parts involved between rounds, etc.

Yep, I'm the guy you come up against in final rounds that can return immediately to staging when they start "hot-lapping" the field, and leave the engine idling in the staging lanes until we make the next run. 99.9 percent of the time my next opponent is frantically running around at his pit site trying to cool down the engine, running the cooling fans in staging, and having all his buddies push the car in the lanes until he's called to race it. I've even had folks beside me ask for more time, pack ice on the intake, hit it lightly with water from a bug sprayer, etc, all in vain, as that deal just has you all over the map when it comes to trying to reproduce the same ET/MPH from the last run...IMHO.

The cooling things down deal for the most part works fine early on, but in later rounds it becomes difficult, if not near impossible to get the engine back down to the same temperature that you achieved in earlier rounds, so you are going to be hard pressed to run your number.

So I'm giving up some secrets here, but at the same time showing how heat can be your friend with these things, on the street or at the track.......Cliff