Benefits of 4-port water bypass on a SBC?

[ChopperScott]

Hello there. Does anyone have any solid data concerning the benefits of using a 4-port water bypass on a small block chevy manifold? Does it help equalize cylinder temperature? Release steam pockets? Drag race or circle track use? What is your experience?

For example, here is my 434 with an Edelbrock 2892 SVII with the rear ports plumbed to under the thermostat...

4-port water bypass.JPG

[ProPower engines]

If you are using a std. coolant flow pattern it will get rid of steam pockets from the hot spots in the rear of the heads/block.
We use that same thing on circle track engine all the time with std or reverse cooling same affect.

[RW TECH]

Contrary to popular belief, you will get nothing out of that unless you rework the water passages on the decks to make water flow up the exhaust side of the head and center of the inboard side with plugs or restrictions on the rest of the inboard holes, then across the head towards the intake side and center of intake side towards each end, then out.

This is a very general description so don't consider it as an absolute recipie, but the bottom line is it requires more than fittings and hoses to make that scheme actually work.

Some will say they saw lower water temps with aux plumbing and they should, since cool water from the back of the heads is short circuited to bypass the heads altogether, instead of cooling them, and instead is plumbed into the area where the water temp gauge sensor is usually mounted. If they put the temp sensor in the middle of the heads they would probably see higher temps with the aux plumbing, unless the coolant passages are also modified.

For drag racing none of this is going to be worth your while, especially with electric pumps that have high flow ratings with no head pressure that wind up only flowing about 8-10 GPM once they're on an engine & pushing water through coolant holes and head gasket restrictions (no jacket pressure to stop localized boiling)
.

[Bob Hollinshead]

Rw tech, the electric water pumps are no good? The Menziere I just bought is rated at 55gpm I think

[BOOT]

I've pulled the intake and seen bone dry pockets on the rear ports into the head a few inches.

I like to use smaller lines than most(4an) and put them above the T-stat. Also I plug the block bypass so the smaller lines are the new bypass, think the two small lines equal just about the same area with maybe an 1/8" hole in the T-stat or w/o I did the math awhile back.

edit: FYI C4 TPI corvettes have a small line from the rear and the intake has a crossover to connect those rear coolant ports.

[ProPower engines]

I've pulled the intake and seen bone dry pockets on the rear ports into the head a few inches.

edit: FYI C4 TPI corvettes have a small line from the rear and the intake has a crossover to connect those rear coolant ports.

They are reverse cooled are they not?? The later later Camaro and F bird are with the LT1 type engine.They also use coolant lines from the rear of the heads.
I know we have tuned the water temps on sprint car cooling systems by varying the hose sizes from the rear of the intake to maintain a constant stable operating temps.

Most engines use restricted water passages to direct cooling to the center exhaust etc. but going from a #8 to #6 then a #4 line from the rear will make the difference between running 120 degrees to 185 degrees depending on time of year up here.

[Geoff2]

What RW tech said.

Of course the temp gauge is going to read cooler because the coolant that would have passed through the head picking up heat now gets sent srouted to the temp sender location & reads a cool temp. Meanwhile, the chambers are cooking because they are not getting the coolant flow they were designed to get.
The factory engineers were not idiots!

[ProPower engines]

What RW tech said.

Of course the temp gauge is going to read cooler because the coolant that would have passed through the head picking up heat now gets sent srouted to the temp sender location & reads a cool temp. Meanwhile, the chambers are cooking because they are not getting the coolant flow they were designed to get.
The factory engineers were not idiots!

That is if you are reading the temp in the end of the intake where the stat is located.
Also how the water is distributed through out the block.

[RevTheory]

I'm gather here that simply routing the rear coolant ports through the heater core in a street application thinking you're helping the rear cylinders may not be doing the engine any favors.

Am I tracking correctly?

[BOOT]

They are reverse cooled are they not?? The later later Camaro and F bird are with the LT1 type engine.They also use coolant lines from the rear of the heads.
I know we have tuned the water temps on sprint car cooling systems by varying the hose sizes from the rear of the intake to maintain a constant stable operating temps.

Most engines use restricted water passages to direct cooling to the center exhaust etc. but going from a #8 to #6 then a #4 line from the rear will make the difference between running 120 degrees to 185 degrees depending on time of year up here.

Nope TPI is regular gen1 SBC not gen2 LT1 reverse cooling.

It's a small line and in my research back at the time, think I came across some of the older C1 or C2 SBC Corvettes that also had a small rear port line. I know the C4 did cause I have one.

[RW TECH]

Rw tech, the electric water pumps are no good? The Menziere I just bought is rated at 55gpm I think

Put it on an engine with a flow meter in the outlet hose and you'll see about 10 gpm or so.

55 gpm is the flow rating with no head pressure against it.

[RW TECH]

I'm gather here that simply routing the rear coolant ports through the heater core in a street application thinking you're helping the rear cylinders may not be doing the engine any favors.

Am I tracking correctly?

Yes

[ChopperScott]

I've accumulated a few photos of various set-ups utilizing the rear ports...

SBCWP1.jpeg

SBCWP2.jpeg

[ChopperScott]

SBCWP3.jpeg

SBCWP4.jpeg

[ChopperScott]

SBCWP5.jpeg

SBCWP6.jpeg