CR and pump gas question

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Fact.......Aluminum does transfer heat better.

What scientific tests have proven its quantitative effects in horsepower, combustion chamber cooling, detonation resistance. Some even claim it cools so much that you must increase the compression 1 full point to keep the same horsepower. Now, as I see it, there is an old mechanic's tale.
You aren't reading what I'm writing man. All I'm saying is aluminum transfers heat better and a cooler chamber is better. I don't know if aluminum transfers heat better enough to have a cooler chamber. I don't want to guess one way or another, because I don't know.

I'm going with aluminum heads because I need them to flow well, not because of any adaptability to CR increase. Everyone here seems to agree for the most part that I don't have to worry about detonation with 93 if my timing is on, so thanks for the info everyone. Learned a lot in this thread.
 
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Ok what the hell, I give this a try.
So we all know that atomized fuel will detonate at X temperature while at X pressure. I have no idea what the real numbers are. So if our mythical combo generates temperature and pressure that are very close to both of the x’s small environmental variances can cause detonation. Burr in the chamber ect. We have one with aluminum heads and a completely identical iron head. Aluminum transfers heat to the coolant quicker than iron. Heat is something, molecular movement, cold is just the absence or reduction of molecular motion. If heat is transferred from the chamber to the coolant faster with aluminum the chamber will be cooler. If the combo is close enough to the x’s that the difference in chamber temperature matters, well there you go. If it sheds heat quicker you can put more in it before the aluminum gets to the x’s. HOWEVER, there is no such thing as two identical heads. One aluminum, one iron. Chasing unicorns! An aluminum head will take more compression than an identical iron head. It just physics...............but wait is that a UNICORN!
 
These people were not testing for detonation resistance specifically, but the results are interesting....................

Comparing Aluminum And Iron Cylinder Heads - Car Craft Magazine

Iron vs. Alloy Engine Heads - Tech Article - Chevy High Performance Magazine


I read the bottom link. I has seen it before. There is a 7cc difference in the port volume, with the iron head being smaller. When the ports start getting that big, 7cc is a pretty big difference.

I'd love to see both heads on a flow bench.
 
You aren't reading what I'm writing man. All I'm saying is aluminum transfers heat better and a cooler chamber is better. I don't know if aluminum transfers heat better enough to have a cooler chamber. I don't want to guess one way or another, because I don't know.

I'm going with aluminum heads because I need them to flow well, not because of any adaptability to CR increase. Everyone here seems to agree for the most part that I don't have to worry about detonation with 93 if my timing is on, so thanks for the info everyone. Learned a lot in this thread.


I'll say it again, using aluminum heads because you think it's going to help with detonation is just not true.

Head materiel is at the BOTTOM of the list of concerns for detonation.
 
I wonder how much the improved chamber shape and quench of the Eddie heads over stock open chamber irons come into play as far as CR is concerned
As mentioned earlier there are no comparisons of identical heads in both mediums.
 
I wonder how much the improved chamber shape and quench of the Eddie heads over stock open chamber irons come into play as far as CR is concerned
As mentioned earlier there are no comparisons of identical heads in both mediums.


I'll tell you a simple metric I use to determine combustion chamber efficiency.

How much total timing does it take when your have your **** correct.

Not the clowns who run a plug two ranges too hot, then drown the plug with fuel to cool it. Not the goons who don't think before they build and don't have enough gear, converter and a cam they picked out of a book.

I'm talking about a correctly assembled combination.

Any early SBC head with its horrible plug location that doesn't run on 42 total has an issue. And that's a quench chamber head.

A conventional BBC needs 38-40 total or something else is wrong. It has quench.

BBM has a head with garbage plug location. It needs 38-40 total. Doesn't matter if the head has quench or not.

A SBM, which has a plug location about as good as you can get for a conventional wedge will run with 35-36 total or something is wrong. That is a head without quench.

A Hemi, which doesn't have quench will normally run ar 32-34 total.

My point is plug location is much more important that quench or chamber shape.
 
You aren't reading what I'm writing man.........
I hear ya....I was feeling the same way, that it why I ducked out of this discussion early on. The science is sound, but its just not worth explaining to folks that are set in their ways.

Apparently this topic is the same as talking about the correct pinion angle over on Moparts (generates 1052 pages of comments in 1 hour).:lol:
 
I'll tell you a simple metric I use to determine combustion chamber efficiency.

How much total timing does it take when your have your **** correct.

Not the clowns who run a plug two ranges too hot, then drown the plug with fuel to cool it. Not the goons who don't think before they build and don't have enough gear, converter and a cam they picked out of a book.

I'm talking about a correctly assembled combination.

Any early SBC head with its horrible plug location that doesn't run on 42 total has an issue. And that's a quench chamber head.

A conventional BBC needs 38-40 total or something else is wrong. It has quench.

BBM has a head with garbage plug location. It needs 38-40 total. Doesn't matter if the head has quench or not.

A SBM, which has a plug location about as good as you can get for a conventional wedge will run with 35-36 total or something is wrong. That is a head without quench.

A Hemi, which doesn't have quench will normally run ar 32-34 total.

My point is plug location is much more important that quench or chamber shape.

My point is ...are people ignoring variables such as chamber shape , quench and surface finish etc and jumping to the conclusion that it is the alloy that allows them more compression than their old head/build .???

I have no opinion on the efficiencies of Eddy heads .
 
yr
those late 302-308 and the EQ heads typically take less timing
The 440's I built with closed chamber heads and either FT or dished pistons took less timing than open chambers
413-426 with domed pistons and closed chamber (Max Wedge style) took a lot of timing- less with a "fire slot" they ran better with the domes "massaged" even with less Cr
I agree it's all about the newer combustion chamber shapes
an addendum to my previous open chamber post- open chamber can have less shrouding- can flow better at higher lifts- good turbulence at higher rpms
btw 361/413 truck takes less timing than passenger car- for those not familiar it has FE Ford style plug locations (or SBM)
 
My point is ...are people ignoring variables such as chamber shape , quench and surface finish etc and jumping to the conclusion that it is the alloy that allows them more compression than their old head/build .???

I have no opinion on the efficiencies of Eddy heads .


Yes, they are. That's exactly what they are doing.

I may, just maybe pull the heads off my junk and make it 11.25:1 just for giggles.

The next engine will be a 386 CID W2 deal and it will be 12:1 on pump gas. On iron heads.

Unless I die first. Which is always possible.
 
yr
those late 302-308 and the EQ heads typically take less timing
The 440's I built with closed chamber heads and either FT or dished pistons took less timing than open chambers
413-426 with domed pistons and closed chamber (Max Wedge style) took a lot of timing- less with a "fire slot" they ran better with the domes "massaged" even with less Cr
I agree it's all about the newer combustion chamber shapes
an addendum to my previous open chamber post- open chamber can have less shrouding- can flow better at higher lifts- good turbulence at higher rpms
btw 361/413 truck takes less timing than passenger car- for those not familiar it has FE Ford style plug locations (or SBM)


How much less? I mean a degree or two can be in the light. I don't particularly care for that chamber, or the W5 chamber. In fact, I hate the W5 chamber. It is a PITA to get the flow back up, the kids stink if you get the high flow numbers up where they should be and to get them back will make you say curse words.
 
Yes, they are. That's exactly what they are doing.

I may, just maybe pull the heads off my junk and make it 11.25:1 just for giggles.

The next engine will be a 386 CID W2 deal and it will be 12:1 on pump gas. On iron heads.

Unless I die first. Which is always possible.

I hope you are right about this.
My current build came out with more compression than I intended . Close to 11...
Race close chamber W2s , Polished chambers , .029 Quench . 246/250 @ .050 108 roller cam.
 
I hope you are right about this.
My current build came out with more compression than I intended . Close to 11...
Race close chamber W2s , Polished chambers , .029 Quench . 246/250 @ .050 108 roller cam.


You'll be fine. You could probably have gone a bit higher yet. But you are plenty safe.
 
I keep a reserve of Sunuco 110 on hand just for good measure.
I am also running a Daytona systems CD1 ignition so I can map my ign curve precisely.
 
The science is sound, but its just not worth explaining to folks that are set in their ways.
I wouldn't think that IQ52 is set in his ways... at all.
He probably knows more about engines and this very subject than a good deal of the members here... together.
 
There certainly is a lot of experience out there that says that AL head material IS an aid to fighting detonation. And I notice one post that says it is on the bottom of the list of detonation fighters (but not off the list), which is plausible to me. I am going to continue to run with the commonly accepted idea that AL is an aid to fighting detonation until I can find some research that nixes that idea. That last research article I referenced above, that gives evidence of slowed combustion with mixture heating, would support that. (I'll try to find that article in the next few days but if anyone cares to look back through similar threads here, I linked it before in a similar discussion in the subforum. No one appears to have taken that up when I posted it before....)
 
Don't ya hate when a thread goes a page or 2 sideways with an argument finally dwindling to "more heat slows combustion"
Too much fuel slows combustion as well when there isn't enough air density.
Cold air=denser air =more power with the right mount of fuel. What happens to fuel molecules when they get hot or are compressed, the separation and joining of oxygen begins and it lights off...and sustaining the heat to continue the next combustion.

No one has shown me that aluminum heads are a benefit in any way other than lighter weight and usually easier to fix/weld up.
 
Don't ya hate when a thread goes a page or 2 sideways with an argument finally dwindling to "more heat slows combustion"
Too much fuel slows combustion as well when there isn't enough air density.
Cold air=denser air =more power with the right mount of fuel. What happens to fuel molecules when they get hot or are compressed, the separation and joining of oxygen begins and it lights off...and sustaining the heat to continue the next combustion.

No one has shown me that aluminum heads are a benefit in any way other than lighter weight and usually easier to fix/weld up.
Must agree, I have seen no internal combustion engine tests that would indicate otherwise.
 
I'll tell you a simple metric I use to determine combustion chamber efficiency.

How much total timing does it take when your have your **** correct.

Not the clowns who run a plug two ranges too hot, then drown the plug with fuel to cool it. Not the goons who don't think before they build and don't have enough gear, converter and a cam they picked out of a book.

I'm talking about a correctly assembled combination.

Any early SBC head with its horrible plug location that doesn't run on 42 total has an issue. And that's a quench chamber head.

A conventional BBC needs 38-40 total or something else is wrong. It has quench.

BBM has a head with garbage plug location. It needs 38-40 total. Doesn't matter if the head has quench or not.

A SBM, which has a plug location about as good as you can get for a conventional wedge will run with 35-36 total or something is wrong. That is a head without quench.

A Hemi, which doesn't have quench will normally run ar 32-34 total.

My point is plug location is much more important that quench or chamber shape.

I knew u were a pretty sharp guy , but ur full of **** when u say a hemi doesn`t have quench ! Its on the tapered sides of the tops--------
 
On hemis we ran the piston close to the sides of the chamber and at the tops
single plug are different than dual plug
you need to leave room around the plugs
if you go big bore you can do circular quench all the way around at the deck
helped in round d round where you got down to lower revs
high rpm not so much as there is plenty of turbulance
did not do it back then but I'd try coatings now and longer rods and lighter pistons
the short deck motors ran better but I never ran a shorter deck than a stock 400 with conversion heads and 426 crank RB hemi rods but that gives a hint to the theory
 
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