Intake Question

[DNK]

Has anyone ever bypassed the water pipe that goes thru the manifold?
Not used it at all?

 

[eejay56]

Hey Don,
I've never tried it but the logic behind heating the fuel mixture escapes me. A colder eg: denser fuel mixture should lead to higher compression and more efficient combustion. That's why drag racers use a cool can in the fuel system.
P.S are you going to the Portland ABFM this year?

 

[poolboy]

I've seen it done by just going from point A to point B with a heater hose, Don.

 

[DNK]

What about just blocking it off at the thermo housing and blocking the other end too.

Hey Don,
...
P.S are you going to the Portland ABFM this year?

Still up in the air.
2 cars down, wife out of town the beginning of the week and the next week have to fly to Savannah to take the daughter to college.

 

[Darrell_Walker]

the next week have to fly to Savannah to take the daughter to college.

I'll be up your way doing that on Sunday (son is doing early fall start).

 

[Deleted member 8987]

Carb Icing. That's why V-8's had the exhaust ports that ran up under the carb, and a heat riser valve on one manifold. Air velocity, chill factor, you'll end up with a block of ice that can hold your throttles open, even kill the engine (or worse if the ice breaks loose and actually enters the combustion chamber). Until you move to a more temperate clime, leave it connected

 

[Gliderman8]

I've seen it done by just going from point A to point B with a heater hose, Don.

Ken-
Is there any advantage to rerouting the water line?
By doing so do it adversely effect intake mixture?

 

[DNK]

Carb Icing. That's why V-8's had the exhaust ports that ran up under the carb, and a heat riser valve on one manifold. Air velocity, chill factor, you'll end up with a block of ice that can hold your throttles open, even kill the engine (or worse if the ice breaks loose and actually enters the combustion chamber). Until you move to a more temperate clime, leave it connected

Dave, revise your thinking,
think FI

 

[lbcs_r_fun]

Has anyone ever bypassed the water pipe that goes thru the manifold?
Not used it at all?
/quote]

Just wondering why you would want to change this. Surely the engineers had a purpose for routing the coolant in this manner!

T

 

[poolboy]

I honestly don't know about the mixture, but I suspect not much if any, Elliot; it was just something I've seen a couple of times on other folk's cars.
If I were faced with the decision because of a leak or corrosion I would favor rerouting it for fear that the pressure might blow off or cause to leak whatever I used for a plug.

 

[70herald]

When I first got my car, the water path was bypassed since the steel pipe had totally rusted away. In hot weather it would be fine, but as if it were cooler it becomes difficult to warm the engine enough to get off of the choke.
My Toyota which is about 30+ years younger, Fuel injection etc. has a very similar heating pipe in the intake manifold.

 

[Brosky]

I would use it. It hurts nothing and it does get cold in your area of the country.

 

[Deleted member 8987]

Except, as Don points out, it's apparently going to be used for EFI.

 

[DNK]

I would use it. It hurts nothing and it does get cold in your area of the country.

Not when I drive
Brrrrr......

OK , will shut that idea down

Saw it on a MPI 6 while doing some web skimming

 

[swift6]

Don't think of it as just hot water running through, ie heating the manifold. Think of it as temperature stabilization of the manifold. Especially since the intake manifold sits right above the exhaust manifold. It does the same thing as coolant running through the rest of the engine. Will work equally well with FI. Even RG's triple manifolds have the coolant pipe.

 

[vivdownunder]

For the best of both worlds, insert a 1/2 turn tap into the coolant hose to the manifold. Switch off the hot supply in the summer months.

Definately good advice to leave the heat source for winter.

I've had carby spindles ice up on the TR3A, due to an extractor exhaust replacing the original cast exhaust manifold that heated the inlet manifold. Not good arriving at a small country town and the car keeps going at 60mph.

Viv

 

[sail]

Not good arriving at a small country town and the car keeps going at 60mph.Viv

Suppose you didn't stay long.

 

[poolboy]

Reminds me of :
https://www.youtube.com/watch?v=bYUrdMzbtUg

dMzbtUg" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

 

[HerronScott]

Hey Don,
I've never tried it but the logic behind heating the fuel mixture escapes me. A colder eg: denser fuel mixture should lead to higher compression and more efficient combustion. That's why drag racers use a cool can in the fuel system.
P.S are you going to the Portland ABFM this year?

I found the following as reasons for heating the intake manifold.

"Aid in the vaporization of the air-fuel mixture. To do this, provide the intake manifold a controlled system of heating. This system of heating must heat the mixture enough to aid in vaporization—without heating it to the point of reducing volumetric efficiency."

"<span style="font-weight: bold">Cold Air and a Warm Manifold </span>
Some of you might think a heated intake might be contradictory with a cool fresh air supply. It isn't. Cooler air supplied to the carb is better for power because it is denser. Once the cool air picks up fuel from the carb, some of it will vaporize and some of it will remain as tiny particles of liquid fuel. When the air stream makes a sharp turn from going straight down from the carb to horizontal in the plenum, some of the liquid fuel won't make the turn and will collect on the floor of the plenum. The liquid fuel will then work its way along the bottom of the intake manifold to the cylinders to end up in the crankcase. A hot spot on the plenum floor evaporates the liquid fuel so that the vaporized fuel can get to the cylinders for combustion. Cleaner oil and longer engine life would also be a benefit from intake manifold heat.

Keeping the heated air supply to the carburetor from the temperature-controlled air cleaner will help with fuel vaporization under cruising conditions. This device utilizes a hot air shroud around the exhaust manifold and a duct to lead warm air into the air cleaner. A thermostat in the air cleaner maintains (or attempts to maintain) a constant temperature to the carburetor. Although this type of air cleaner is probably more restrictive than a open element air cleaner, your gas mileage will probably be slightly higher with it. This type of air cleaner shuts off the hot air when the engine is accelerating (low manifold vacuum ~ 5" HG) and this is the time when the hot spot in the intake manifold is especially useful.

People sometimes read information and only pick out the parts that justify their point of view. Getting cold air into an engine should not be an end in itself. The true goal should really be to increase the horsepower of your engine or get better gas mileage or both. Unless you really need to pack your engine with as much cold air as possible, like if you are going for a land speed record or you are running a high revving engine on the drag strip, heat in the intake manifold will help your street-driven engine run better."


Scott

 

[Brosky]

I said earlier and still agree that it should stay. Back in the 60's we ran a coiled fuel line in an aluminum can with a petcock drain on the bottom to fill with ice to keep the fuel cold at the drag strip. We were running 450+ HP 442's and GTO's, some of which would pull the front wheels off of the ground. They got really hot in the summer and we needed to keep the fuel cold to prevent vapor lock.

That was pretty serious street racing in very hot and humid weather and we tried our best to improve upon the ram air affect of both cars in order to get more colder, denser air into the carbs.

And just like the TR6 trick in traffic, we kept the heater cores in the cars and used them to help cool down the water in the system as much as possible.

Sigh.........sometimes I really miss those days........