Benefits of 4-port water bypass on a SBC?

[ChopperScott]

That's only part of the picture on a different head. The whole picture would include CFD of both the sbc block and heads together, with both standard and performance head gaskets, with and without the bypass.

https://youtu.be/QMH3RhCHgUQ

[SchmidtMotorWorks]

That's only part of the picture on a different head. The whole picture would include CFD of both the sbc block and heads together, with both standard and performance head gaskets, with and without the bypass.

https://youtu.be/QMH3RhCHgUQ

Yep, and it is more than enough information to answer your question.
I went against my better judgement and tried to be helpful.
I'll try to avoid making that mistake again.
And people wonder why those that have real knowledge and tools don't bother to post here much anymore.

Continue to believe what you wish were true, enjoy.

[SchmidtMotorWorks]

Isn't the pressure being higher a good thing. Anything I did that increased the boiling point seemed to be a positive. While keeping the Temps under control was a goal, the main thing was to stop the water from boiling and create hot pockets. Once the boiling steam pockets start forming the next thing you need to see is the checkered flag,other wise it's going to be an expensive night.

Yes, but the pressure is mostly only higher at the rear end of the head.

[RCJ]

Have you ever tried pulling water from the front of the head,toward the exhaust side.Smokey had recommended this in his book and I saw this on some Ford heads.

[SchmidtMotorWorks]

Have you ever tried pulling water from the front of the head,toward the exhaust side.Smokey had recommended this in his book and I saw this on some Ford heads.

No.
If I had a problem with cooling, I would improve the water jacket design.

[ChopperScott]

Yep, and it is more than enough information to answer your question.
I went against my better judgement and tried to be helpful.
I'll try to avoid making that mistake again.
And people wonder why those that have real knowledge and tools don't bother to post here much anymore.

Continue to believe what you wish were true, enjoy.

I'm sorry sir, but you're comparing a Cadillac 500 to a small block Chevy. At this point, I don't 'believe' anything. I haven't been convinced either way. No need to be offended.

[arlancam509]

.... given the choice between CFD and a Flow Bench, I'll take CFD every time.

while I agree with everything you are saying about the flow in the head and block regarding the main topic of this post, I am a bit shocked that you so firmly stand behind the CFD over the Flow Bench. I have spent the last 31 years of my life at a desk doing design, so I get where you are coming from.
I myself would much rather use CFD - I'm lazy! - and not the Flow Bench, but I also understand "GIGO" and that why is why I tend to like real world stuff and not the happy-go-lucky world of computer animations.

Back on topic, If I was looking at doing cooling of a v8 from scratch and had never seen one before, I would not have the ports in the head at the front of the block and head. I would push the fluid into the front of the head, make it flow to the rear, then down into the block, and back out the front. This is why I am having so much trouble understanding why we want to bypass the fluid flow in the front of the head as per all of the pictures being posted in this topic. What am I missing? What is the advantage?

[SchmidtMotorWorks]

while I agree with everything you are saying about the flow in the head and block regarding the main topic of this post, I am a bit shocked that you so firmly stand behind the CFD over the Flow Bench.

CFD is vastly more informative than a flow bench.

[NewbVetteGuy]

I came across some information that seems highly relevant to the discussion in this thread from Stewart Components.

Their take seems to be that in racing engines the primary reasons that external plumbing makes sense, is that with aftermarket aluminum heads with their thick decks, thick areas under the rocker bosses and holes, and large ports, it's the cooling passages that ultimately suffer and end-up wherever they end up.

They ultimately view the external lines as a way to make up for the lack for cooling passage surface area / volume in the heads.

"External Plumbing
Street-driven vehicles seldom need auxiliary plumbing or coolant lines. SBC race engines with aluminum cylinder heads usually require extensive external plumbing to address two design problems:

Aluminum heads have much smaller water jackets than cast-iron heads because the external dimensions are similar, but the ports are usually larger, the deck is thicker, and the material near the rocker stands is thicker, all leaving less area in the water jackets. This decreased internal area leaves less area in the water jackets.

The siamese center exhaust ports are a design compromise that presents additional problems when aluminum heads are used. The area near the center exhaust valves is thicker, thus allowing providing less surface area for cooling.
We recommend installing a pair of –10 AN lines that connect the rear of the aluminum cylinder heads to the thermostat housing crossover in the front. This step will help offset the smaller water jackets. A pair of -10AN lines connecting the pressure side of the water pump with the area in the center of the cylinder head (just below the exhaust ports) will offset the lack of surface area due to the extra material. "

https://www.stewartcomponents.com/index ... tion_id=13




Adam

[juuhanaa]

First i want to thank everyone for writing, good reading.

Now i was left thinking without an experience of building SBC with a modified GM 601 iron heads, 1.85 and 1.6 valves, NA and no power adders, daily-drivable, good idle and sometimes revved to 6750-7250rpm, or wot racing

Whether a blocking the heat cross over and having a better flowing/less restrictive exhaust is a sufficient modifications to avoid overheating the rear cylinders and prevent problems at center exhaust ports area, when the rear cylinders bypass line is blocked and no external plumbing from the exhaust ports although better for front cylinders cooling @ higher power?

The head gasket as a metering block is a interesting thought, but makes the gasket choice more difficult.



-juhana

[pamotorman]

must do something as GM 604 crate race engines use it or GM would not have installed it

[PRH]

The are no external lines in the pic of the engine, or any mention of them being used in the installation guide.

D3BF029A-CC39-4084-B44B-A3D852A567CF.png

[cjperformance]

Screenshot_20220622-111924_Chrome.jpg

Pretty visible here.
Anyhow, make your own judgement, if you dont like the lines dont run them, if you like the lines then run them! Simple

[Tom68]

Depends what heads your running I thought ? Also if in a boat with that end of the engine high enough to get air pockets.
Vortecs bulge out on the exhust side so I guess they have plenty of internal room for coolant flow.
If it's only to encourage flow to the back of the block, it's doing it at the expense of the heads.

[NewbVetteGuy]

Last one on this subject...

Stewart's "Competitor Comparison" page that includes their pump flow per RPM and flow vs. HP charts includes this note about their testing methodology:

"Conditions: 200° F, 20 PSI System Pressure at Pump Inlet, Restriction Equal to 20 PSI at 100 GPM, (full size hoses, no restrictors, 2 row single pass radiator, -12 AN lines from rear of heads)

-They even test with 12 AN lines from the rear of the heads to the thermostat, surely that helps total flow, even if the portion of the flow going through those 12 AN lines is only going through the lower block and the rear 2 cylinders. (If it helps flow, it slightly hurts pressure, though, doesn't it?)

https://www.stewartcomponents.com/index ... tion_id=15

Adam