Aluminum heads

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yellow rose said:
My question is...even if the head rejects heat quicker, does the medium used for coolant accept heat any quicker, or does the coolant not know (or care) what they head material is?
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Nope

The answer is the head can only reject heat as fast as the coolant allows.
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Largely true. If anything, think of the metal as a electrical conductor. How many ohms (resistance) in each one? If the head material is slow to move heat, then it will loose against the higher flowing, heat removing energy transfer metal.

I think the difference in the metals are realized in extreme environments more so than what goes on and talked about here.
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rumblefish360 said:
Nope


Largely true. If anything, think of the metal as a electrical conductor. How many ohms (resistance) in each one? If the head material is slow to move heat, then it will loose against the higher flowing, heat removing energy transfer metal.

I think the difference in the metals are realized in extreme environments more so than what goes on and talked about here.
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I can't totally disagree, but every time I've tested for pump gas CR and the tune was correct the head didn't matter.

When I've seen a CR issue the detonation usually occurs at tip in or under a rolling load when throttle opening is low.

At that point, any increase in temperature from detonation is so quick that any materiel I can think of can't transfer the heat quick enough to have any affect.


That's my thoughts. You can't control detonation with head material because unless the heat transfer is quick enough to make a difference it won't matter.

Why Jpar is having run on issues I can't say. Usually it's because the throttle is too far open, but with the TR he shouldn't be anywhere near open enough on the throttle to cause run on.

The only other thing I can think of for Jpar is a spark plug that's too hot.
 
Jpar, what’s your octane rating on the fuel being used?
 
@yellow rose

Now on the reverse, let’s say our iron headed 8.0-1 engine has the most bitchin cooling system. Is it possible to have an engine run to cool? What if, the engine never gets above 80*’s in temp. Never mind the impossibility.
 
YR, I don't believe your 11.1 engine will maintain 160 degrees on a 100 degree day with 4.56 gears. I'm sorry I don't buy it.
and it wouldn't do it with an aluminum head either. compression creates heat.
I do believe you are able to run 11.1 on pump gas without detonating, but you would not with a 1-1.5 compression increase even with an aluminum head.
The heat has increased in the combustion chamber with the added compression. lol
 
RustyRatRod said:
Compression ratio and cylinder pressure are both results from mechanical features. Aluminum or cast iron has nothing to do with either, as long as the chambers are the same volume. The only positive attribute aluminum has on combustion is, the quicker heat dissipation, which does allow for more compression, but only through the more effective heat dissipation. The physical compression or cylinder pressure is unchanged from cast iron to aluminum all other things being equal. A compression test would surely be the proof there.
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Let's a tackle things one at a time. The above would be true IF there was no heat transfer between the cylinder components and the compressing mixture. This would be called an adiabatic process (with no external heat transfer to/from the gases), but the reality is that there is substantial heat transfer to the gases during the compression stroke. Most of this is from the cylinder head. If there is a hotter material (AL or iron), and equal heat transfer coefficient (the resistance to heat flow across change in materials) then the hotter material will obviously heat the compressing gases more. If there is more heat input to the gases, then the pressure WILL be higher. There is no avoiding this.... it is a laws 'of physics' thing, expressed in the Ideal Gas law..... PV = nRT. If T goes up then P HAS to go up too.

If there is doubt of the effect of added heat causing increased pressure, then let's look at something that we all pretty well accept: quench. Quench is the rapid movement of the compressed gases across a cooler surface (typically the piston). It lowers the tendency to detonate by lowering the gas temps.... and thus the pressure. So if you believe in quench (and I think pretty much everyone here does), then the belief that more heat into the compressed mixture raises pressure (and raises the tendency to detonate) automatically goes hand in hand with that. They are 2 sides of the same coin, so to speak.

So now we are really only left with the question of whether AL and iron transfer the same heat into the compressing mixture or not. That leads to 2 questions that effect that:
  • whether or not the heads run at different temps
  • AND the heat transfer coefficient between the gases and the head
 
nm9stheham said:
Let's a tackle things one at a time. The above would be true IF there was no heat transfer between the cylinder components and the compressing mixture. This would be called an adiabatic process (with no external heat transfer to/from the gases), but the reality is that there is substantial heat transfer to the gases during the compression stroke. Most of this is from the cylinder head. If there is a hotter material (AL or iron), and equal heat transfer coefficient (the resistance to heat flow across change in materials) then the hotter material will obviously heat the compressing gases more. If there is more heat input to the gases, then the pressure WILL be higher. There is no avoiding this.... it is a laws 'of physics' thing, expressed in the Ideal Gas law..... PV = nRT. If T goes up then P HAS to go up too.

If there is doubt of the effect of added heat causing increased pressure, then let's look at something that we all pretty well accept: quench. Quench is the rapid movement of the compressed gases across a cooler surface (typically the piston). It lowers the tendency to detonate by lowering the gas temps.... and thus the pressure. So if you believe in quench (and I think pretty much everyone here does), then the belief that more heat into the compressed mixture raises pressure (and raises the tendency to detonate) automatically goes hand in hand with that. They are 2 sides of the same coin, so to speak.

So now we are really only left with the question of whether AL and iron transfer the same heat into the compressing mixture or not. That leads to 2 questions that effect that:
  • whether or not the heads run at different temps
  • AND the heat transfer coefficient between the gases and the head
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ok.
 
Let's look at heat transfer coefficient from the chamber into the head material first. As I understand it, it is mostly due to the surface characteristics. A rougher surface will generally tend to transfer heat better across a material interface. But at the same time, polished chambers have long been done as aids to limit detonation. I think that the theory behind polishing the chambers is that you get rid of tiny hot spots in the chamber surface that could be instigators of detonation.

I really don't have a great feel for whether chamber polishing is better or not.

But I don't have any good reason to believe that the same surface finish over AL or iron is going to change anything between the 2. So, at this point, I will put AL and iron heads as being equal as for heat transfer at the surface. So that leaves us just with actual head temps as being the difference maker, if any. That part is going to take more explaining.
 
rumblefish360 said:
Jpar, what’s your octane rating on the fuel being used?
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I swear the last time yr made a plug recommendation it was hotter plugs LOL
I think he'd love to see me chasing my tail...
(I'm going to need more than a picture of a rusty r-block on the floor and a no-show...)
The summer I tried just running straight 92 non ethanol from the pump. As soon as the race gas send out I was starting to get some run on when I shut it off. So now for every 4 gallons of 92 I put in one gallon of 110 Sunoco. About 95.5 - 96?
 
According to Hughes I should drop 1 to 1 1/2 points of compression with my aluminum heads so I should be great?..
 
j par said:
According to Hughes I should drop 1 to 1 1/2 points of compression with my aluminum heads so I should be great?..
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No, according to Hughes, you need to up the compression 1-1.5 points to make use of the aluminum head and not lose power. lol
 
fishmens67 said:
No, according to Hughes, you need to up the compression 1-1.5 points to make use of the aluminum head and not lose power. lol
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They're delusional. In no way shape fashion or form will you LOSE power going from iron to aluminum if all things are equal. Ain't happenin.
 
rumblefish360 said:
@yellow rose

Now on the reverse, let’s say our iron headed 8.0-1 engine has the most bitchin cooling system. Is it possible to have an engine run to cool? What if, the engine never gets above 80*’s in temp. Never mind the impossibility.
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Yes, you can go too cool. I opted for 170 degrees but anything colder than that, and the heater didn't work too good. If I was only driving the car during the spring and summer I could live with that. But I drive year round so I need a heater. I've driven the car in the temp was in the mid teens!!! And that's with a Strip Dominator. No icing either. That was thanksgiving 2013. Damn cold. But a nice drive as it was sunny and clear as a bell.
 
fishmens67 said:
YR, I don't believe your 11.1 engine will maintain 160 degrees on a 100 degree day with 4.56 gears. I'm sorry I don't buy it.
and it wouldn't do it with an aluminum head either. compression creates heat.
I do believe you are able to run 11.1 on pump gas without detonating, but you would not with a 1-1.5 compression increase even with an aluminum head.
The heat has increased in the combustion chamber with the added compression. lol
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I can get it to run cooler that that. How do I know? I tested it. And sent the written results to Evans so they could see it. I should have taken a video but they just wanted me to do a test.

Like I said...my original intent was block the bypass and not run a thermostat. IIRC, on a hundred degree day at road speed I could barely get 140 out of it. It would creep up at stop lights but never got over 190 just sitting there.

So I was forced to run a thermostat, just to get some temp and them to control the temp.

My cooling system was thoroughly researched long before I bought my first parts. I'm currently running the pump 6% over and if I could find 10% over pulleys I'd do I in a New York second.

My next engine (if everything goes as planned and right now, the old ball and chain and my boy are trying to derail everything but I'm working on that) will be 12:1 on iron heads on pump gas. It's doable. I just need to spend some time doing the research first.

If the aluminum head theory is correct, I should be able to run 13.5:1 on pump gas with aluminum heads and even I don't have the balls to try that.
 
j par said:
I swear the last time yr made a plug recommendation it was hotter plugs LOL
I think he'd love to see me chasing my tail...
(I'm going to need more than a picture of a rusty r-block on the floor and a no-show...)
The summer I tried just running straight 92 non ethanol from the pump. As soon as the race gas send out I was starting to get some run on when I shut it off. So now for every 4 gallons of 92 I put in one gallon of 110 Sunoco. About 95.5 - 96?
Click to expand...



The last plug picture you posted that I remember was pretty rich. I don't think I said you needed a hotter plug. If I did, find the link and the picture and let me see it.

Like I said, I doubt with a TR you have the idle screws too far in.
 
There was a guy over on The Hamb years ago that had an early Hemi that was 13.5:1 and ran on pump gas. But that's a Hemi head. A bit different animal.
 
nm9stheham said:
Let's a tackle things one at a time. The above would be true IF there was no heat transfer between the cylinder components and the compressing mixture. This would be called an adiabatic process (with no external heat transfer to/from the gases), but the reality is that there is substantial heat transfer to the gases during the compression stroke. Most of this is from the cylinder head. If there is a hotter material (AL or iron), and equal heat transfer coefficient (the resistance to heat flow across change in materials) then the hotter material will obviously heat the compressing gases more. If there is more heat input to the gases, then the pressure WILL be higher. There is no avoiding this.... it is a laws 'of physics' thing, expressed in the Ideal Gas law..... PV = nRT. If T goes up then P HAS to go up too.

If there is doubt of the effect of added heat causing increased pressure, then let's look at something that we all pretty well accept: quench. Quench is the rapid movement of the compressed gases across a cooler surface (typically the piston). It lowers the tendency to detonate by lowering the gas temps.... and thus the pressure. So if you believe in quench (and I think pretty much everyone here does), then the belief that more heat into the compressed mixture raises pressure (and raises the tendency to detonate) automatically goes hand in hand with that. They are 2 sides of the same coin, so to speak.

So now we are really only left with the question of whether AL and iron transfer the same heat into the compressing mixture or not. That leads to 2 questions that effect that:
  • whether or not the heads run at different temps
  • AND the heat transfer coefficient between the gases and the head
Click to expand...


You need to add in the fact that at any given RPM/load the heads BOTH have the same temp. It's that simple. Again, the rate of heat increase and rate of heat rejection would have to be so great as to not overcome the increase in temperature.


And I'm not sure quench is the be all do all end all either.

I'm running in the .058-.060 quench range right now and I'm running full timing. I can take the quench down to .040 and go from 11.08:1 to 11.25:1 and maybe I'll play with it later. I'd need shorter pushrods for sure.

When quench became popular, it was when Chevrolet had the most shitball chambers on the planet. Even the closed chamber BBC head was a pinging nightmare. When they used what is now the preferred chamber (essentially and open chamber type) they make more power and are much less sensitive to detonation.
 
j par said:
I swear the last time yr made a plug recommendation it was hotter plugs LOL

The summer I tried just running straight 92 non ethanol from the pump. As soon as the race gas send out I was starting to get some run on when I shut it off. So now for every 4 gallons of 92 I put in one gallon of 110 Sunoco. About 95.5 - 96?
Click to expand...

LMAO, a hotter plug would be silly.


j par said:
According to Hughes I should drop 1 to 1 1/2 points of compression with my aluminum heads so I should be great?..
Click to expand...

I don’t know what your ratio is now.
yellow rose said:
Yes, you can go too cool. I opted for 170 degrees but anything colder than that, and the heater didn't work too good. If I was only driving the car during the spring and summer I could live with that. But I drive year round so I need a heater. I've driven the car in the temp was in the mid teens!!! And that's with a Strip Dominator. No icing either. That was thanksgiving 2013. Damn cold. But a nice drive as it was sunny and clear as a bell.
Click to expand...

Screw the heater aspect. We’re talking straight up engine and power between things. An engine can run to cool r not hit enough, correct?

RustyRatRod said:
They're delusional. In no way shape fashion or form will you LOSE power going from iron to aluminum if all things are equal. Ain't happenin.
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Have you tried this with a 7.5-1 engine to start with?

yellow rose said:
My cooling system was thoroughly researched long before I bought my first parts. I'm currently running the pump 6% over and if I could find 10% over pulleys I'd do I in a New York second.
Click to expand...
Custom jollies can be made for a price I wouldn’t e willing to pay.

My next engine (if everything goes as planned and right now, the old ball and chain and my boy are trying to derail everything but I'm working on that) will be 12:1 on iron heads on pump gas. It's doable. I just need to spend some time doing the research first.

If the aluminum head theory is correct, I should be able to run 13.5:1 on pump gas with aluminum heads and even I don't have the balls to try that.
Click to expand...

Thats not an issue. It’s a matter of having enough or really not to much cylinder pressure for the limited octane. To that end, it would probably end up being a cam to large for the combo or at least to effectively take advantage of the cam properly.

The combo would more than likely under perform with the various concessions to be made than what would be best for the set up.

But that’s the EZ no brainer way out.

How I would do it today would be an interesting test and application of the various tech and advancement materials that have come out since I had to stop playing around and experimenting. Oh this would be a joy to throw money at like the US government.

Quench certainly is not an end all but just another building block in the house of power. Tighter the better. The issue to be aware of is of course piston to head contact and the control of the metals stretching and wobbling around should on use a short piston.

Once you have a known metal and it’s behavior under high stress and loads during the extremes of its linear motions, (The connecting rod) AKA, lack of stretch or its growth during the various loads and conditions, you can then move the slug closer to the head.

But now that I mention that word again....
let’s get back to the head metal use issue....

How cold is to cold to effectively make good use of an engine. Where is that point of it runs like Crap-Ola and will never improve?

Is it actually possible to make it worse by using something to make it run even more horrible?
 
rumblefish360 said:
LMAO, a hotter plug would be silly.




I don’t know what your ratio is now.
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Lol.. that's rich spend a bunch of time digging back through threads from earlier this summer to dispute plug sizes...
Stock 596 heads with 202 valves. .010 above deck icon forged with valve reliefs. 1008 gasket.. you tell me..
 
j par said:
Lol.. that's rich spend a bunch of time digging back through threads from earlier this summer to dispute plug sizes...
Stock 596 heads with 202 valves. .010 above deck icon forged with valve reliefs. 1008 gasket.. you tell me..
Click to expand...


Didn't you say you are 11:1? If so, I'd start with a C9YC and then take a look. If that's too hot then I'd...damn gotta get the book. BRB.
 
If the 9 is a bit on the hot side you can drop a half a range to the RC8YC and if that's still too hot you can go to the C65YC.

That's what I'd start with.
 
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