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Benefits of 4-port water bypass on a SBC?

24312 Views 99 Replies 37 Participants Last post by  CmonHoss88
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...

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Or is it a red anodized cap for some wiring for the red box thing that is right there? Help a brother out.
Looks like the clutch line and bleader.
I can understand the need to do it on a big block (if you don't use a coolant bypass hose on the water pump-to-intake, the coolant has no where to go on those rear cylinders), but don't see an advantage on a small block that has an internal bypass cast into the block -maybe in some high endurance application, but still.......
Huh?
How does eliminating the bypass hose affect the rear cylinders.
The bypass serves too purposes:
  • helps engine to warm up quicker because some heated coolant is routed to the inlet side of the pump.
  • pressure relief in case the t'stat gets stuck in the closed position.
I can understand the need to do it on a big block (if you don't use a coolant bypass hose on the water pump-to-intake, the coolant has no where to go on those rear cylinders), but don't see an advantage on a small block that has an internal bypass cast into the block -maybe in some high endurance application, but still.......
Huh?
How does eliminating the bypass hose affect the rear cylinders.
The bypass serves too purposes:
  • helps engine to warm up quicker because some heated coolant is routed to the inlet side of the pump.
  • pressure relief in case the t'stat gets stuck in the closed position.
Also, not sure for all, but a Dart SBC block does not have bypass holes like an OEM sbc.
The elimination of the bypass is the reason 'drilled' thermostats made there appearance. Stewart Components, makers of high output race water pumps, eliminated the bypass in some of their pumps. To provide pressure relief in case of a stat that stuck closed, they recommended drilling three 3/16" holes in the stat.
Since then, people have drilled their stats even though the original bypass was still in place. All this achieves is a longer warm up time, more engine wear, & a hard time for the stat to regulate coolant temp.
Bleeds in the rear?!?
Think he was saying he does?
I like number 8 lines.Great handles to rip the intake off.Ford clowns should look into this on stock 390 garbage
Hey that's my 18 degree 406 , Lol . Hard to see in that pic , but these heads also have the line that goes to between the exhaust valves .Just below the breather in the pic . Its plumbed from the water pump , the AN fitting has about a 1" long brass line that extends to the exhaust valves .
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Hey that's my 18 degree 406 , Lol . Hard to see in that pic , but these heads also have the line that goes to between the exhaust valves .Just below the breather in the pic . Its plumbed from the water pump , the AN fitting has about a 1" long brass line that extends to the exhaust valves .
Brodix heads?
Pump gas? (web site states that)
Street/Strip use?
Any prior 406 engine/Brodix head cooling experiences?
Brodix heads?
Pump gas? (web site states that)
Street/Strip use?
Any prior 406 engine/Brodix head cooling experiences?
GM 363 head , i bought them used and they came with all the additional cooling lines . 12.5 -1 , street strip , A few 406's in my past , but this is the most radical i have built .
slightly different train of thought; we ran 3/8" hoses from the "elbows" on a 50 gpm block mounted BBC pump to the rear ports to push cool water into the back of the heads. Resulted in a ~10* drop in temperature at the front sending unit (simple logic of additional inlet water being pushed into the rear instead of coming up through the block first), but more importantly was able to add 1-2* of timing back into some cylinders that we had taken out to keep them from being too hot (600ci nitrous combo with 2500+ pph).

Our new combo we "dry decked" drilling/tapping all the holes in the deck surfaces. 55GPM Meziere radiator mounted pump with dual -16 lines run to the back of each head, a -6 line T'd to it running down to the bottom of the block, then -12 out the front of the heads and -6 out the front of the block all to a small tank, -16 from it back to the radiator. Theory being to flow most the cooling through the heads and just enough through the block to negate the chances of steam pockets and help it keep the heads happy. - few runs on it as of yet, but seems to work well
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Also, not sure for all, but a Dart SBC block does not have bypass holes like an OEM sbc.
The Vortec blocks don't have a bypass hole either.
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Huh?
How does eliminating the bypass hose affect the rear cylinders.
The bypass serves too purposes:
  • helps engine to warm up quicker because some heated coolant is routed to the inlet side of the pump.
  • pressure relief in case the t'stat gets stuck in the closed position.
Geoff,
One thing I wonder about is that the bypass hole remains active even when the thermostat opens and seems like a coolant flow bias for Cylinder #2. Cylinder #2 gets it's own "Always on" extra volume of cooling going straight up into the head and then on to the intake and out the thermostat.

Isn't the cylinder-to-cylinder flow more even with that bias closed off as with the Vortec blocks, Dart blocks, and with the Evans pump and thermostat holes? (It just feels like providing more coolant to cylinder #2 where it's not needed and stealing it away from everywhere else including the rear cylinders to me.)

-I'm starting to like the idea of plugging the bypass hole and drilling the thermostat for bypass...

Adam
Chopper Scott, if someone starts you a Kickstarter and buys you 8 temp sensors, you willing to drill some holes in your heads and start testing stuff?


I'd be willing to chip in one sensor worth... ;-)
(I'm with you on the desire for data, but I need holes in my heads like I need a hole in my head.)

Adam
Chopper Scott, if someone starts you a Kickstarter and buys you 8 temp sensors, you willing to drill some holes in your heads and start testing stuff?


I'd be willing to chip in one sensor worth... ;-)
(I'm with you on the desire for data, but I need holes in my heads like I need a hole in my head.)

Adam
Hey Adam. If I could afford holes in my head(s), I would. Unfortunately, I don’t have the resources at this point in time.
Here are some images of two CFD runs on a head I did recently, showing velocity, one with 1 outlet and one with 2.
The sectioned images are the same simulations, just sectioned to see the velocity inside the water flow.

The difference is not much where it matters along the Ex side of the head.


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If you are wondering why the rear opening flows more than the front one, it is because the pressure is higher at the rear of the head.
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