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Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

General engine tech -- Drag Racing to Circle Track

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NewbVetteGuy
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Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by NewbVetteGuy »

Yes, I've searched and I've read through a great many threads about improving engine cooling and cooling mods already.

What I don't have is a good answer to why just taking a head gasket and drilling out all the small holes bigger doesn't result in more coolant flow and therefore more engine cooling...


So why is this a bad idea/ counter-productive to the goals of engine cooling? (It is, right?)




My understanding is that the gasket, at least in an SBC is what meters the flow of coolant around the various parts of the block and heads. It seems to me that if you just start opening up holes bigger you're going to end up giving the cooling likely "short cuts" that it can take that will leave places like the rear cylinders with LESS coolant and more heat. (Temps get uneven.)



Adam
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by englertracing »

It is for distributing coolant flow evenly/ directing it to where it's needed most like exhaust side of head, siamesed exhaust ports need priority.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by PackardV8 »

Go for it!! What do those GM engineers know anyway.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by NewbVetteGuy »

englertracing wrote: Fri Aug 05, 2022 6:28 pm It is for distributing coolant flow evenly/ directing it to where it's needed most like exhaust side of head, siamesed exhaust ports need priority.
"But back in the 60s and 70s, when people just LEARNED BY DOING, they did this "and it worked"!"


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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by NewbVetteGuy »

PackardV8 wrote: Fri Aug 05, 2022 6:36 pm Go for it!! What do those GM engineers know anyway.
"Grumpy Jenkins showed that he had more smarts than a whole STACK of GM engineers!"

"The world of engineering achieved perfection with Grumpy Jenkins; it's only been downhill since then. Just think about how much further along internal combustion engines would be if he would've just lived forever."


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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by rebelrouser »

The thing about making modifications is you are the engineer. So how much time, money, testing equipment, design software, etc do you have access to? Engineers are not geniuses. My son is a pretty good engineer, and he asks a lot of questions when I ask for help with an issue, he does a lot of higher math calculations etc. and explains how his group would handle a problem. It is a process with several in a group. If you make changes just figure out how to measure your results.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by NewbVetteGuy »

englertracing wrote: Fri Aug 05, 2022 6:28 pm It is for distributing coolant flow evenly/ directing it to where it's needed most like exhaust side of head, siamesed exhaust ports need priority.
But just LOOK at how tiny those holes are on the intake side; how can that be good for cooling / flow?
cometic gasket drill.jpg
Next you'll be telling me that cooling jacket pressure in the head could actually be a GOOD thing!


Adam
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by BillK »

NewbVetteGuy wrote: Fri Aug 05, 2022 7:04 pm
But just LOOK at how tiny those holes are on the intake side; how can that be good for cooling / flow?
cometic gasket drill.jpg
Adam,

If you did a little bit of thinking about how the coolant flows through this engine you would see that making those holes bigger would not increase flow. The coolant in a traditional small block goes in the front, flows back through the block to the back then up into the cylinder head and back to the front and out to the radiator. The small holes are there to allow a limited amount of coolant flow up into the cylinder head at those spots, probably to avoid hot spots. If you opened those a lot they might bypass enough coolant up to the head that the back cylinder in the block might not get cooled enough.

By the way the holes in the Cometic gasket are no different than those in the stock gaskets which I am sure GM engineers spent a lot of time and money designing.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by RCJ »

You want to increase flow at the center exhaust ports.Plugging the tstat bypass and drilling a .125 hole in the tstatl will help somewhat.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by swampbuggy »

Adam, BillK stated the Facts very well and RCJ brings up a good point, the Hottest area is between the two center Exhaust ports, and plumbing water from the water pump to each Head or engine Block directly below the two ports is a good move . Mark H.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by Tom68 »

NewbVetteGuy wrote: Fri Aug 05, 2022 6:00 pm Yes, I've searched and I've read through a great many threads about improving engine cooling and cooling mods already.

What I don't have is a good answer to why just taking a head gasket and drilling out all the small holes bigger doesn't result in more coolant flow and therefore more engine cooling...


So why is this a bad idea/ counter-productive to the goals of engine cooling? (It is, right?)




My understanding is that the gasket, at least in an SBC is what meters the flow of coolant around the various parts of the block and heads. It seems to me that if you just start opening up holes bigger you're going to end up giving the cooling likely "short cuts" that it can take that will leave places like the rear cylinders with LESS coolant and more heat. (Temps get uneven.)



Adam
Yer, Chevrolet worked it out after several decades, that's how we got the reverse cooling system LT1.

Get enough capacity and air to keep the old girls around 180 degrees and you may not pass an emissions test but it'll go forever without needing crazy 24psi caps or anything stupid to stop steam pockets.

Pick your hole size and quantity.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by HQM383 »

You have to get your head around flow and think distribution.

https://www.felpro.com/technical/tecblo ... skets.html

Fun fact: coolant flow through a radiators core must go turbulent to ensure heat transfer from wall of tubes to the fins. Laminar flow would make for an inefficient radiator that compromises cooling.

It’s not always about our beloved term ‘flow’.
Tolerance doesn't have to mean accepting any stupid opinion but to counter and argue in a manner that leads to a healthy conclusion or increase in knowledge ...
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by englertracing »

NewbVetteGuy wrote: Fri Aug 05, 2022 6:45 pm
englertracing wrote: Fri Aug 05, 2022 6:28 pm It is for distributing coolant flow evenly/ directing it to where it's needed most like exhaust side of head, siamesed exhaust ports need priority.
"But back in the 60s and 70s, when people just LEARNED BY DOING, they did this "and it worked"!"


Adam
Yeah a friend of mine liked to tell me in the 60s some of the gaskets were wide open and they would use shim stock to block the holes in certain spots to better cool the rear cylinders.... so he literally did the opposite and achieved a reduction in temperature on the rear cylinders.

Doing it correctly would be a study involving a whole lot of thermocouples or rtds installed in a head that is setup like a block of swiss cheese.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by Geoff2 »

Early Pontiac V8 engines had reverse flow cooling. Changed to conventional cooling [ IN block, OUT heads ]. Not sure of the reason, but most likely because the more complex & costly RF cooling was little or no better than conventional cooling.
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Re: Drilling holes in head gaskets = more flow = lower temps: Change My Mind!

Post by JoePorting »

I wouldn't drill holes in the head gasket. I'd do the opposite and use the head gasket as a template to make sure all the water holes in the head gasket match the holes drilled in the head and block. Most SBC head gaskets have more holes in between the two exhaust ports on the exhaust side of the head. These are probably the most important holes since this is where most of the heat is. The holes are made small by the intake ports because they don't need cooling. This will force more water to the exhaust side of the head which needs most of the cooling. Many old SBC blocks will need to have a large 3/8" hole drilled in between the middle exhaust port where it is on the head gasket. Most after market heads and blocks shouldn't need any modifications as they usually have all the holes in the right places at the right sizes.
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