using Thermal paste on cylinder to block connection

[first timer]

Hey guys, I am just thinking out loud right now, but was wondering if it wouldn't be a bad idea to get some of that thermal paste they use on computer heat sinks to help transfer the heat from the processor to the heat sink and use it on a bike motor.

Basically isn't the block a big heat sink? and the iron sleeves the processor so to speak. I know they are a tight fit but no matter what there is still a small air gap in places.

so if you removed the sleeves when you did a rebuild and coated them in some of this paste stuff then put them back in wouldn't that help dissipate the heat to the block better? which would give you better cooling?

here is some basic info on the stuff
http://en.wikipedia.org/wiki/Thermal_grease

And here is a mds sheet of one of the brands,
http://www.arcticsilver.com/PDF/ceramique_msds.pdf
Aluminum Oxide
Boron Nitride
Zinc Oxide
Proprietary Oil Blend Non-hazardous

It has a flash point of 600 degrees F, so that shouldn't be a problem.
The only other thing think I can think of is maybe some sort of oxidation would happen and that would either jeopardize the heat dissipation or lock the sleeves into the block.

I was also thinking if I used one of the metal based pastes you could use it in place of anti seize (which I have heard hinders heat displacement between spark plug and head) which would help displace the heat from the plug to the head.

Anyone got any ideas or anything to add. Hearing from some Mechanical engineers would be nice.

[Commodus]

Well, sleeve to cylinder is an interference fit, so there's not really room for anything, even paste.

Additionally, I don't think overheating is really an issue for stock GS engines?

[first timer]

who sez it is stock? i have a 11.2:1 1085 kit i was thinking about adding to my 1k. Overheat can be an issue with any air cooled motor especially in hot climates or in stop and go traffic. So anything you can do to encourage heat dissipation should be a plus.

It may be a interference fit but this paste is real real fine stuff and granted some of it will be scraped off but there still will be some that is left behind to fill micro voids.

like i said before i am just concerned about Galvanic corrosion occurring because of the paste. Other wise using the paste should not have any other negative side effects.

[AOD]

What's the maximum temperature the CPU thermal paste can be exposed to? (I didn't read the MSDS you posted yet).

I would assume CPU's run a bit cooler than an engine, so you may end up burning off all the thermal paste.

~Adam

[Billy Ricks]

You also run the risk of contaminating your oil as heat and expansion forces the paste out of the space between the liner and the block. Tolerances are already so close any benefit would be negligible. Aluminum already does a very good job of dissipating heat.

[renobruce]

And with a 1085 kit you don't need to remove the sleeves.

I'd just get an oil cooler.

[first timer]

What's the maximum temperature the CPU thermal paste can be exposed to? (I didn't read the MSDS you posted yet).

I would assume CPU's run a bit cooler than an engine, so you may end up burning off all the thermal paste.

~Adam

flash point is 600 degrees F

You also run the risk of contaminating your oil as heat and expansion forces the paste out of the space between the liner and the block. Tolerances are already so close any benefit would be negligible. Aluminum already does a very good job of dissipating heat.

Aluminum is, thats why they use it on cpu heat sinks. What ever would be squeezed out would be very little, it would be expensive to gob the stuff on. You could also run a few heat cycles changing the oil in between.

The press fit between a CPU heat sink and the cpu is a very tight fit as well, the paste just acts like a more efficient bridge to transfer heat into the aluminum from the iron sleeves. Basically i am just thinking of ways to remove the heat from the combustion area better. Which will help keep the pistons and all that fun stuff cooler as well.

And with a 1085 kit you don't need to remove the sleeves.

I'd just get an oil cooler.

i am running a oil cooler, but think of it this way, if you pasted the sleeves, painted the engine with black gun kote and ran a oil cooler, that would really start to add up in heat dissipation. and a cooler motor with tight tolerances is a better motor.

[Billy Ricks]

If your looking to cool combustion chamber temps using the paste is probably not going to have any effect at all. To that end you can use a top end oiler to get more oil across the top of the combustion chambers and if you can find room maybe blow a couple of case fans across the top of the head. The real heat is generated in the head, not the the block.

[Planecrazy]

If your looking to cool combustion chamber temps using the paste is probably not going to have any effect at all. To that end you can use a top end oiler to get more oil across the top of the combustion chambers and if you can find room maybe blow a couple of case fans across the top of the head. The real heat is generated in the head, not the the block.

I would agree with this, Ryan. What you're really talking about is a lot of $$ and effort to achieve a negligible return on heat dissipation. Frankly I don't think it's worth the time and expense to even bother.

Regards,

[Commodus]

Hmm, interference fit means that the cylinder liners are actually larger than the bores for them in the block. You get them in using temperature differences and a press, at least that's how I've seen it done. I don't build engines, I don't do it myself.

So I know it seems like paste is awfully little, but there's no room for it. Like, literally no room. Like, when you're using plasti-gage, you know how you have to clean the oil from the item? Like connecting rods for example? That's because the thickness of the oil is actually going to give you a false reading. This isn't a computer, that's not the kind of tolerances we're talking about here.

[Billy Ricks]

Hmm, interference fit means that the cylinder liners are actually larger than the bores for them in the block. You get them in using temperature differences and a press, at least that's how I've seen it done. I don't build engines, I don't do it myself.

So I know it seems like paste is awfully little, but there's no room for it. Like, literally no room. Like, when you're using plasti-gage, you know how you have to clean the oil from the item? Like connecting rods for example? That's because the thickness of the oil is actually going to give you a false reading. This isn't a computer, that's not the kind of tolerances we're talking about here.

The block does have to be heated to press liners in and out.

[Nerobro]

It's an interference fit... you can't get better than that. heat sink compund is there to fill the gaps. Between the liners and the block, there won't be any gaps. if there were.. the cylinder liners would creep out.

It's a good thought though. :-) Perhaps putting thermal paste on your copper headgasket might not be a bad idea...

[49er]

Hmm, interference fit means that the cylinder liners are actually larger than the bores for them in the block. You get them in using temperature differences and a press, at least that's how I've seen it done. I don't build engines, I don't do it myself.

So I know it seems like paste is awfully little, but there's no room for it. Like, literally no room. Like, when you're using plasti-gage, you know how you have to clean the oil from the item? Like connecting rods for example? That's because the thickness of the oil is actually going to give you a false reading. This isn't a computer, that's not the kind of tolerances we're talking about here.

How true. But all interference fits are not equal.
Most machinists who do reboring work will mark 2 felt pen references on each sleeve that transfer accross the top of the sleeve and the mating aluminium surfaces. This gives them visual confirmation that a sleeve hasn't rotated duting the boring process. There may be some validity to using this paste as a repair medium if a sleeve should move while being bored.
I guess if you do a re-sleeving job yourself, then the interference fits will all be perfect!!