crazy_hotrodder

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Interesting mod(see Pic) I came across on an ebay listing, thought I might see if someone on here had done this or knew why someone would do this.
What is the advantage of running cooling lines like what is in the picture from the front to the rear of a manifold?
The only other time I've seen this done is on a nostalgia drag rail running alcohol and no radiator.

With a thermostat housing, this has to be a full cooling system. Is it just to "burp" the rear of the heads? Would this mod interfere with coolant circulation?
Can someone who has experience with this mod give some input?

AlkyIROC

Coolant flows from the water pump, through the block and returns through the heads to exit at the front of the heads into the intake manifold and back to the rad through the thermostat.

Running extra coolant lines from the rear ports on the manifold straight to the thermostat housing allows some of the hot coolant from the block to bypass the heads. Hot coolant still travels through the heads but the circulation has changed.

The hot block coolant at the rear is flowing past the thermostat directly to the rad. The head coolant can't flow to the rad until the thermostat opens. This will allow constant circulation through the block but restrict circulation through the heads until the coolant temp is hot enough to open the thermostat.

With alcohol, an engine has a hard time building heat. Plumbing a system like that will keep the cylinders cool yet allow higher temperatures in the heads. You want head in the heads. It adds life to the valve train.

When I'm at the track, one of the things I do is to run up the engine before racing to get as much heat in it as possible then shut it off to allow the metal a chance to absorb all that heat. Especially the valve train.

sofakingdom

iTrader: (1)

Coolant flows out of the "legs" of the water pump; into the block; through "calibrated" holes (orifices, if you will) in the head gasket, designed to direct the correct amount of water to the places that get the most heat; through the heads; and out the FRONT coolant passages into the intake.

Both the "front" and "rear" passages from the heads to the intake, are DOWNSTREAM of the heads. In fact, the "rear" coolant passage on the "left" head is identical to the "front" passage on the "right" head, and vice-versa, since the heads themselves are identical.

Some engines will run hotter in the rear cyls, since water will take the shortest / least-resistance path, which will be across the front of the motor. Adding those lines in that situation is a "crutch" for a cooling system with an inadequate water pump; it somewhat equalizes flow through the back and the front parts of the engine.

Alky's comments are more specific to "series cooled" big blocks.

-AO-

Those rear coolant outlets really aren't needed. Even if coolant in the rear of the engine was a little hotter than the front, the oil would still keep the entire engine at roughly the same temp. Keep in mind oil drains from the heads to the pan and also acts as a way to cool the engine.

crazy_hotrodder

Thanks guys for the response, and info. I had to look up exactly what the differences are between series and parallel flow.

(To anyone interested in this subject, this is a reposted from a guide on big blocks on ebay, link at bottom-
"Coolant Routing Mk IV/Gen 5/Gen 6
There are two different ways that coolant can be routed through the engine: series flow and parallel flow. Both ways work just fine. There may be a slight preference for parallel flow, but it is not a big deal. Series flow has the water exiting the water pump, flowing through the block to the rear, it then transfers through the head gasket and into the cylinder head through two large passages on each cylinder bank at the rear of the block. The coolant then travels from the rear of the head, forward to the front of the head, into the intake manifold water passage and out past the thermostat and thermostat housing. The water cools the block first, then it cools the head. The coldest water (coming out of the water pump) is directly below the hottest water (having already picked up the heat of the block and the head) as the hot water transfers into the intake manifold. By contrast, parallel flow has the water exiting from the water pump into the block, where a portion "geysers" up into the head between the first and second cylinder, another portion "geysers" up to the head between the second and third cylinders, another portion geysers up to the head between the third and fourth cylinder, and the remainder transfers to the head at the rear of the block. The coolant temperature inside the engine is more even that way. The differences in coolant routing is having (or not having) the three additional coolant transfer holes in each block deck, and three matching holes in the head gasket. The heads have passages for either system, and are not different based on coolant flow. - Entire contents copyright (C) 2007, 2008 Camino3X2)


So the only reason to run the coolant lines from the back of the head to the front is to make a faster flow at the back of the head to increase cooling efficiency of the rear cylinders?

I am curious if this would be advantageous on the right(odd) side only on a very high performance street/strip motor. Especially in a forced induction setup.
Reasoning- If a motor has a traditional 5-7 firing order(less air/fuel charge available in the manifold for cylinder 7 after 5 has cycled), and the cooling around 7 is less than optimal at the back of the block, would the potentially lean'er cylinder benefit more from better cooling? Are there many failures due to cylinder 7 specific issues like this? Or is this just over speculative?

AlkyIROC

The only way to know how well a cylinder is working is to run 8 EGT sensors and/or 8 O2 sensors.

There's a lot of "old school" techniques still being used. Many of them do little to nothing. If you have serious overheating problems with your rear cylinders, there's probably a reason and those coolant hoses are just a patch repair. Even when I ran a SBC, I never needed a hose setup like that.

FRMULA88

Circle track cars have done this for decades... specificly SBCs with 18 degree heads. Smokey Yunick was a pioneer in this.

It helps to equalize temps between cylinders as a SBC always runs hotter on the back half. it is not a crutch or band aid it it way to increase coolant flow thru the heads to eliminante "hot spots.

Books have been devoted to this concept. Grumpy Jenkins ( RIP ) did this as well and wrote about the modification in his book.
That man forgot more about SBC than I will ever know.

Some water pumps actually come with the additional ports to add the plumbing to the heads.

I did it on my engine and no regrets.

FRMULA88

Here's a picture with the center ports plumbed.

The rears were done later and those go to a water neck spacer.


These coolant lines along with a hi-volume water pump help to keep the engine temp equalized across all 8 cylinders; especially at 3,5 4,6 where the exhaust valves face each other & also helps to regulate oil temp.

EGT temps (1 probe per cylinder) during the dyno pulls were indicative of how well this mod works.

crazy_hotrodder

You wouldn't happen to be able to scan and post the before and after egt data would you?
There often seems to be a lack of real info like this floating around the web. For instance, I didn't think about the exhaust valves being side by side, but it makes perfect sense.

Maybe I'm foolish, but it seems to me that the guys that make the most power are the guys that think of more of these little details, (and have plenty of money to burn). Money aside, detail for detail more = more. Look at guys like Smokey Yunick, Mickey Thompson, or even any of the winning engines in the Engine Masters Challenge. It's all in the details, and trying anything that might work to find the ones that do.
Anyways, enough of my rant. I just appreciate you guys posting, and would love to see anything you may have for data on what did or didn't work so well for you. I don't want your 'racer's edge,' well maybe what worked before that you don't use or see used by everyone now.
-Jake.

AlkyIROC

Bad choices for comparison and you forgot Victor Edelbrock in that list. Yes they were pioneers in making HP but they were also doing it when there was little to no aftermarket components to use. Modern performance parts can easily run circles around what they were doing with OEM stuff.

crazy_hotrodder

The capacity of an air pump is not controlled by who cast the alloy, but more who better understands it's flow characteristics.
I picked a couple names out of the blue, I didn't try and write an article.

The last engine that won The Engine Masters' Challenge, had a highly modified aftermarket intake with epoxy, phenolic, and wooden spacers, at both the intake port and the mating junction on a two piece intake manifold. This wasn't some kindergarten art project, but neither was anything competitive coming out of the late Sixties or Seventies. In this, I see the same ingenuity and creativity that I hear about from the early days. Aftermarket parts are great, but to say they are the end all to performance power potential is akin to agreeing with Charles Duell in 1899, "everything that can be invented has been invented." I prefer more of a Tesla approach, anything is possible with a little creativity.
The purpose of this posting was to find anyone that was more creative on here, that might want to share what they have found on there own, with someone that wants to know.

AbdulMaatin7

If they’re really not needed why would they be included in all head design..???

AbdulMaatin7

That’s right. I have a built 92 mustang 302 engine that I did this similar mod to. However what I did was run the lines from the rear coolant crossovers to the heater hose tap on top of the thermostat housing on a ford intake manifold. Then ran the other side to the tap for the temp sensor. I then blocked off the top outlet at the water pump and still used the bottom outlet for the heater core and ran the other heater hose to the thermostat housing where the short hose that ford uses would go. It works great and improved the performance and horsepower. Who knew...