Benefits of 4-port water bypass on a SBC?

[ChopperScott]

As mentioned before, flow rate at high rpm's, with a mechanical water pump, could have adverse effects. The coolant is flowing too fast to efficiently transfer heat. Reduction pulleys, or an electric water pump, are beneficial in this situation.

I'm not sure I follow this theory.
I think with the excessive high engine RPM, the water pump falls out of its efficiency range, it cavitates, and doesn't move the coolant, it just rips it apart.
That's why you gain back cooling on high rpm engines by gearing the pump down to its designed operating rpm range.

Yes. That would definitely be one of the adverse effects once rpm exceeds the capacity of the pump.

[Robban 54]

With a higher flow, you also get the advantage of lower temperature difference between inlet and outlet. That is, less difference front to back, block to cylinder head.

[frnkeore]

Higher flow, also means more HP lose. Not a lot but, every little bit counts. Look what OEM's have done with oil pumps lately.

[af2]

I have a hard time picturing how pulling additional water from the back of the head is a bad thing. Water comes in the front of the block and heads back and up. I'm not sure what the passages are like in the head but I'd assume it's a long route from the back of the head all the way to the front to get to the water outlet portion of the intake. It also seems like the rear of the head would get the hottest water after traveling passed all the cylinder walls to move upward through the head and then back towards the front.

I'm picturing the holes in the deck as a manifold of sorts flowing water upward into the head. If you pull from the front and rear of the intake would the middle of the deck/head not become the farthest distance to the outlet rather than the back of the heads? Seems like that would cut the max water travel distance (within the head) in half.

Oy vey, it isn't about water flow at that point, it is about removing an air pocket. Shite, back in the day we used to tap the top of the block for plugs with holes and that wasn't truly for flow

The only reason I also have done this for ever. Last year My uncle rebuilt his blown 331 and it always ran hot. Ran 4an hoses to the front and now it gets 180 in the summer instead of 240+. Don't get stuck on flow!!

[Geoff2]

Of course it shows a lower temp!!! Coolant, still relatively cool, that should passed through the hottest part of the engine, the heads, picking up heat, gets routed direct to the temp sensor.

And it IS all about the flow!

[Geoff2]

This is the coolant flow description in the 1967 Pontiac manual. For 6 cyl engines, but procedure is the same for 8s & other brands.

" The water pump discharges coolant into the jacket chamber between the front face of the block....Coolant then flows through the block towards the rear, passing through two large cast openings into the cyl head to cool the valve seats & forward to the front of the head. Coolant then flows through the coolant outlet...

[Robban 54]

It is not so difficult to choose between a little unnecessarily high flow and waste some horsepower and too little flow and overheating.

[AA Performance]

Of course it shows a lower temp!!! Coolant, still relatively cool, that should passed through the hottest part of the engine, the heads, picking up heat, gets routed direct to the temp sensor.

And it IS all about the flow!

Pretty easy to understand, don't you think? Pressure has a bearing on cooling which not been mentioned at all. Electric pumps don't have as much pressure as good mechanical pumps. And there is a big difference in mechanical pumps. Why would anyone want to take waterflow away from an engine with those bypass lines as that is all they do and yet many can't see it. You would be way better off tapping into your water pump and run lines to the back of the intake with cooler water.

[frnkeore]

" The water pump discharges coolant into the jacket chamber between the front face of the block....Coolant then flows through the block towards the rear, passing through two large cast openings into the cyl head to cool the valve seats & forward to the front of the head. Coolant then flows through the coolant outlet...

This doesn't address the water that goes past the large openings and on to the rear of the block.

The water that passes those larger openings, is getting hotter as it goes, correct?

The water that enters the front and goes into the head, before getting to the larger holes and then to water outlet, is cooler, right? It has lost it's usefulness at that early point and the rear water is still be heated and over used, right?

If you have one inlet and one outlet, the water, as a whole, can only flow one direction. If there are more than one outlet, it can flow two directions or more, after entering.

I would think the most even water flow, would be to manifold the water to the two expansion plug holes, in the block and take it out, at the front and back of the intake.

For a more standard application, a biased head gasket, with more flow to the rear, might be good, with the extra water to the head, between the exhaust ports, as shown.

The old Ford flathead, did that, in the '49-'53 years, with the actual head and not just the gasket.

[leahymtsps]

Let's face it 55 Chevy had no clue how much power would be extracted from this engine design. If
they had, who thinks they would have still stuck 2 exhaust valves together in the middle of a head?
RT seems to be the only one who understands bypassing water at the rear can be and is beneficial but
requires other work in the flow path. It's not as simple as drill and tap a cpl. holes and hook up a pair of
hoses.
One has to also look at the inlet flow as the hottest part of this engine design is certainly not at the rear.
Running water from front past the hottest spot to cool rear is certainly not the best idea.
Certain deck passageway sizes might have to be altered.
As far as high hp -rpm endurance engines look at valley trays where the water passageways are connected
rear to front and side to side at front and rear equalizing pressure - volume at the 4 corners.
Sorry for being vague not much of a typier.

Tom

[In-Tech]

Shoot, the original question was about a SBC and 4 port at the intake manifold.
The answer in most situations is to provide a steam pocket relief at the rear of the intake. To aid more is to feed the center of the head below the exhaust ports with fresh from the water pump.
As noted by others, this is finished off with data acquisition of temperatures at multiple places so you can regulate pressures and/or restrict of said flow to maintain.

If you take a few moments to think and look at a design that wasn't meant to do what we do in racing, idea come to mind :}

[xxdabroxx]

Looking at this headgasket, it seems that cometic is biasing more water flow to the center of the head. But they aren't side specific so no flow bias front to rear is available or built into the design.

headgasket.jpg

If you look at a sbc head, you can touch your fingers together through the deck surface and the water outlet hole at the front or rear of the head. Water from the front upper portion of the deck has a very short path to thermostat housing portion of the intake fresh from the water pump. Although metered through a hole in the gasket.

Why would it not make more sense to have water removed equally from the front and the rear of the head if water infiltration from the deck surface to the cylinder head is biased to the center of the engine?

[cjperformance]

Looking at this headgasket, it seems that cometic is biasing more water flow to the center of the head. But they aren't side specific so no flow bias front to rear is available or built into the design.

headgasket.jpg

If you look at a sbc head, you can touch your fingers together through the deck surface and the water outlet hole at the front or rear of the head. Water from the front upper portion of the deck has a very short path to thermostat housing portion of the intake fresh from the water pump. Although metered through a hole in the gasket.

Why would it not make more sense to have water removed equally from the front and the rear of the head if water infiltration from the deck surface to the cylinder head is biased to the center of the engine?

With this type of parallel coolant flow pattern removing coolant from either end of the head makes perfect sense.
With a series flow coolant pattern removing coolant at both ends is not correct although in many cases a small steam relief does help.

[cjperformance]

Looking at this headgasket, it seems that cometic is biasing more water flow to the center of the head. But they aren't side specific so no flow bias front to rear is available or built into the design.

headgasket.jpg

If you look at a sbc head, you can touch your fingers together through the deck surface and the water outlet hole at the front or rear of the head. Water from the front upper portion of the deck has a very short path to thermostat housing portion of the intake fresh from the water pump. Although metered through a hole in the gasket.

Why would it not make more sense to have water removed equally from the front and the rear of the head if water infiltration from the deck surface to the cylinder head is biased to the center of the engine?

With this type of parallel coolant flow pattern removing coolant from either end of the head makes perfect sense.
With a series flow coolant pattern removing coolant at both ends is not correct although in many cases a small steam relief does help.

This is the coolant flow description in the 1967 Pontiac manual. For 6 cyl engines, but procedure is the same for 8s & other brands.

" The water pump discharges coolant into the jacket chamber between the front face of the block....Coolant then flows through the block towards the rear, passing through two large cast openings into the cyl head to cool the valve seats & forward to the front of the head. Coolant then flows through the coolant outlet...

Keep in mind that this pontiac series flow description is not relevant to the parallel flow as used in the SBC in question.

[xxdabroxx]

I picture what's going on under the deck of a SBC similar to a log style exhaust manifold but backwards. In through one hole and out through the many ports in the deck. The head gasket is like a metering block of sorts and depending on the head gasket the bulk of the coolant flows up the middle. This high flow in the middle would likely fight the flow from the rear to the front in my opinion. Fluids generally take the path of least resistance. (I'm no fluid engineer though)