Cooling Difference in Aluminum heads?

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Howard1784

Howard1784

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What cooling temp. differences did you experience when switching from iron heads to aluminum heads??
 
The combustion chamber will cool faster with Aluminum heads regardless of what thermostat you are running. Aluminum dissipates heat very well.
 
Then with aluminum heads, run a 15-1 Comp ratio and fuel it with alcohol. The thermostat may never open, LOLOLOLOLOL
 
MY aluminum heads seem to take a couple of minutes longer to warm up in the morning. But once up to temp the stat sets the minimum, and the ability of the cooling system to shed heat, sets the max.
The aluminum sucks heat out of the chambers and delivers it to the cooling system, as well as to the underhood area, as well as into the exhaust. Because it it extracts heat so well, you pretty much have to bump up the compression to keep up with iron heads. If you don't the effective C/R takes a dump and performance suffers. The heat is what makes the power. The more heat,the more power, until you get into detonation or something melts,lol. Heat is the secret.
I run 205*F at the stat-house,all the time.Some adventurous types run even hotter.Modern EFI engines run 220 or a bit more. That's partly how those NA teensey 2.5/3.3 engines pull 3200 pound cars around reasonably well.
When running al heads Data seems to indicate that the DCR should be run at least a half point higher, than with iron, and some fellows are pushing over 9.3Dcr in their well executed combos. I run 8.9Dcr on 87E10. That's 10.9 Scr. I can run 36* power timing at 3400, but the engine performs just as well (by seat of the pants) on 32* so I compromised and have run 32/34 since 1999.
She does like a lot of cruise timing tho. I have experimented with up to 60*@2200. Typically I run 44/56 on flat hard pavement.(dial-back timing device)
That's another nice thing about Al heads with a tight Q (mine is .034), it's hard to find detonation on a typical 360 or smaller engine. Well maybe not if you get greedy with timing below 3000,lol.
 
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I was pondering what I may encounter. I put eddy s on my 380 h.p. crate motor with comp rollers. No cr ratio gaskets added. Gasket matched. Ported. M1 intake ported and runners cleanup up etc.

All new experience with me.

Engine masters boasted a 92 hp gain with
Light h eadwork on their 360.
 
Howard1784 said:
I was pondering what I may encounter. I put eddy s on my 380 h.p. crate motor with comp rollers. No cr ratio gaskets added. Gasket matched. Ported. M1 intake ported and runners cleanup up etc.

All new experience with me.

Engine masters boasted a 92 hp gain with
Light h eadwork on their 360.
Click to expand...
Moving pushrod holes in the head (w2 style) and fully porting with oversize valves is not what most would consider "light head work"
 
AJ,,,,,,do you have an idea what your timing curve looks like, I'm messing with my FITech timing control and I feel it should be higher but I'm a little leary to put too much in there. It's a .030 over 340, .039 quench with AL Eddy RPM's, 222/226 @ .050, .540/.555 lift, 10.1 CR, 9.35 DCR on 91
AJ/FormS said:
MY aluminum heads seem to take a couple of minutes longer to warm up in the morning. But once up to temp the stat sets the minimum, and the ability of the cooling system to shed heat, sets the max.
The aluminum sucks heat out of the chambers and delivers it to the cooling system, as well as to the underhood area, as well as into the exhaust. Because it it extracts heat so well, you pretty much have to bump up the compression to keep up with iron heads. If you don't the effective C/R takes a dump and performance suffers. The heat is what makes the power. The more heat,the more power, until you get into detonation or something melts,lol. Heat is the secret.
I run 205*F at the stat-house,all the time.Some adventurous types run even hotter.Modern EFI engines run 220 or a bit more. That's partly how those NA teensey 2.5/3.3 engines pull 3200 pound cars around reasonably well.
When running al heads Data seems to indicate that the DCR should be run at least a half point higher, than with iron, and some fellows are pushing over 9.3Dcr in their well executed combos. I run 8.9Dcr on 87E10. That's 10.9 Scr. I can run 36* power timing at 3400, but the engine performs just as well (by seat of the pants) on 32* so I compromised and have run 32/34 since 1999.
She does like a lot of cruise timing tho. I have experimented with up to 60*@2200. Typically I run 44/56 on flat hard pavement.(dial-back timing device)
That's another nice thing about Al heads with a tight Q (mine is .034), it's hard to find detonation on a typical 360 or smaller engine. Well maybe not if you get greedy with timing below 3000,lol.
Click to expand...
 
LJ67barracuda340 said:
AJ,,,,,,do you have an idea what your timing curve looks like, I'm messing with my FITech timing control and I feel it should be higher but I'm a little leary to put too much in there. It's a .030 over 340, .039 quench with AL Eddy RPM's, 222/226 @ .050, .540/.555 lift, 10.1 CR, 9.35 DCR on 91
Click to expand...
Are you sure about the 9.35 DCR?
That does not compute with a 10.0 Scr
I'm guessing that's a typo and the Dcr is really 8.35?
I grossed your 222@050 up to 262/110 advertised and ran the numbers with 10.0 Scr, and I get 8.38@170 psi; so I'm guessing 8.35 is correct.
Ok having got that outta the way, I ran a cam like that in my 367 for two years, with aluminum heads. I loved that cam. In my 367 it made monster torque and I was able to squeeze 32mpgs out of it, cruising with the equivalent of a 1.97rear gear. Yeah so that cam was for me a perfect street cam. It power-peaked at about 5200 for me.Because it was down on power compared to a much bigger cam, I ran it with an A833OD and a GVOD behind that; so my splits were really tight. This allowed the engine to stay on the pipe from-IDK maybe idle to 110 mph,lol.
Ok I tell you this cuz the chassis loading was very light, the engine never had to pull hard in the detonation zone from stall to about 3600rpm. This is key; the lighter the load, the easier it is to stay outta detonation.
Furthermore I ran at a minimum coolant temp of 205*F. This makes it easier to find detonation, than say at 180 or 165.
Further more I run a 3.58 stroke,vs your 3.31. My pistons dwell at the top longer than yours, again inviting detonation.
I'm telling you these things cuz, you need to know that, and so my engine will have different timing requirements from idle to 3600ish, than your 340.

So now,with EFI, the door is wide open, on account of there is no T-port sync to deal with. The power timing will be the same or very similar to mine as all hi-compression SBMs run about the same; namely 36* with iron heads and 32/34 with aluminum and tight Q,like yours. I felt no difference between 36 and 32, so most of the time I run 32* . So that is step 1.
Idle timing with Efi can be whatever you want it to be from as little as 12* with that cam (mine ran 12*), to as much as perhaps 22* or wherever the starter complains about it. That is step 2.
If you have a stick car with hiway gears, I suggest starting on the low end of the scale. If 3.73s or better, then on the hi-side. With 3.55s or 3.23s I suggest 16*.
If you have an automatic, it goes according to the stall-speed; the higher it is, the more timing you can run, cuz the engine is only lightly loaded and spends waaay less time in the detonation zone,below 3600.And again 4.30s will drive the revs up much faster than 2.76s,lol.

So a typical combo used with a 222 cam, will be an auto with 3.23s and a 2400TC.And I'll assume it to be in a 3400# chassis. With this,I expect it to idle at 650 in gear/750in N/P. I would start out at maybe 16* at idle. I would then bring timing in starting at about 1000 rpm, at the rate of .75*/100rpm until you hit about 29.5* total@2800rpm. From there I would slow it down to .6*/100 until all 32/34 are in, somewhere after 3400rpm. This curve will probably let you burn 87E10 without detonation.

But if you're ok burning slow-gas 91,
then you can start off sooner at a higher number and finish sooner also at a higher number. In this case you can start at say 900rpm with 18/20, and slam 16 more in by 3000, for a total of 32/34, with a straight "curve"of .75* per 100rpm.
So that takes care of the power timing

Now as to VA, or equivalent. I found my 367 power curve loved plenty of timing at PT and higher vacuum readings. For instance at 2800rpm, the car was doing 33mph in second (3.55s)and the power timing,as mentioned was 28*. I installed a 22* VA can and so the total at 2800 was 50* and the engine liked that. Then at 65mph in double OD the rpms were 1600ish. The power timing here was just about 17* with 22 more in the can for a total of 39*. I didn't think this was enough. I had earlier installed a dial-back timing device that was able to change the timing from the driver's seat ,up to 15 degrees. So I began experimenting with more timing. The potential total now was 39+15=54*. I had installed the DB device with the adjuster knob in the center allowing changes of 7.5* advance and 7.5* retard. Well she liked all 7.5*,for a total of 46.5. Running this combo up to 75/80 mph, the total cruise timing became about 51/53. Then I leaned out the low-speed circuit. And leaned it out some more, and eventually that combo pulled 32 mpgUS at 75 mpg/1900 rpm.
So, what I'm saying is with a stick-car, a carb and a common dizzy, it is my opinion that starting with less is more. 14* of base timing and 20 in the dizzy and 22 in the VA and the DB gizmo, got me to where the engine wanted to be. And it burned 87E10 with 10.9Scr/8.9Dcr. The slight loss of torque at the lower rpms was never noticed (remember it's a stick car with a 10.97 starter gear), and mostly it has enough power to spin 295s to 50/60 mph,anyway.
If I would'a had an A/T I would just slammed 4* more into her, topping out at 34@2800 and called it done.

PS if you have a stick, driving at very low speeds can become an exercise in clutch-slipping. If you retard the timing from about 75 rpm below the normal idle rpm, and set the rate of decay at about 12*/100rpm, it takes most of the jumpiness out. My 367 will pull itself at 550rpm with just 6* of advance. With 3.55s and a 3.09 low gear, this works out to about 4mph, a fast walk.That's with a fat 750DP, and a 230/110 cam.
BTW, the DB device is an awesome tuning aid.

I'm not sure I've been any help, just remember; the lighter the loading, the less likely the engine is to detonate, and every combo is different.
 
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[WOW,, dude that's a lot of info to digest,,,THANKS,,,I'll work on that.
More info on my unit,, 5 speed close ratio stick, 2.66 first, .68 5th, 3.23 rear, intake closes @ 37 abc, my math at Wallace Racing gives me DCR of 9.41 with a 10.1 CR. Just did United Engine & Machine calculator and I got 8.738 DCR, base timing 10*, idle timing 22*. Engine starts at 10 and computer adds 12* for 22* after start, dizzy is locked out.
since I posted I bumped the timing up to these figures and it seems to like it. Even at idle at full temp 190+ the tail pipes are dripping a lot of water, running much cleaner. Driving in traffic I see 213*. Yes your info is helping with a direction ,,thanks.


QUOTE="AJ/FormS, post: 1971720186, member: 33537"]Are you sure about the 9.35 DCR?
That does not compute with a 10.0 Scr
I'm guessing that's a typo and the Dcr is really 8.35?
I grossed your 222@050 up to 262/110 advertised and ran the numbers with 10.0 Scr, and I get 8.38@170 psi; so I'm guessing 8.35 is correct.
Ok having got that outta the way, I ran a cam like that in my 367 for two years, with aluminum heads. I loved that cam. In my 367 it made monster torque and I was able to squeeze 32mpgs out of it, cruising with the equivalent of a 1.97rear gear. Yeah so that cam was for me a perfect street cam. It power-peaked at about 5200 for me.Because it was down on power compared to a much bigger cam, I ran it with an A833OD and a GVOD behind that; so my splits were really tight. This allowed the engine to stay on the pipe from-IDK maybe idle to 110 mph,lol.
Ok I tell you this cuz the chassis loading was very light, the engine never had to pull hard in the detonation zone from stall to about 3600rpm. This is key; the lighter the load, the easier it is to stay outta detonation.
Furthermore I ran at a minimum coolant temp of 205*F. This makes it easier to find detonation, than say at 180 or 165.
Further more I run a 3.58 stroke,vs your 3.31. My pistons dwell at the top longer than yours, again inviting detonation.
I'm telling you these things cuz, you need to know that, and so my engine will have different timing requirements from idle to 3600ish, than your 340.

So now,with EFI, the door is wide open, on account of there is no T-port sync to deal with. The power timing will be the same or very similar to mine as all hi-compression SBMs run about the same; namely 36* with iron heads and 32/34 with aluminum and tight Q,like yours. I felt no difference between 36 and 32, so most of the time I run 32* . So that is step 1.
Idle timing with Efi can be whatever you want it to be from as little as 12* with that cam (mine ran 12*), to as much as perhaps 22* or wherever the starter complains about it. That is step 2.
If you have a stick car with hiway gears, I suggest starting on the low end of the scale. If 3.73s or better, then on the hi-side. With 3.55s or 3.23s I suggest 16*.
If you have an automatic, it goes according to the stall-speed; the higher it is, the more timing you can run, cuz the engine is only lightly loaded and spends waaay less time in the detonation zone,below 3600.And again 4.30s will drive the revs up much faster than 2.76s,lol.

So a typical combo used with a 222 cam, will be an auto with 3.23s and a 2400TC.And I'll assume it to be in a 3400# chassis. With this,I expect it to idle at 650 in gear/750in N/P. I would start out at maybe 16* at idle. I would then bring timing in starting at about 1000 rpm, at the rate of .75*/100rpm until you hit about 29.5* total@2800rpm. From there I would slow it down to .6*/100 until all 32/34 are in, somewhere after 3400rpm. This curve will probably let you burn 87E10 without detonation.

But if you're ok burning slow-gas 91,
then you can start off sooner at a higher number and finish sooner also at a higher number. In this case you can start at say 900rpm with 18/20, and slam 16 more in by 3000, for a total of 32/34, with a straight "curve"of .75* per 100rpm.
So that takes care of the power timing

Now as to VA, or equivalent. I found my 367 power curve loved plenty of timing at PT and higher vacuum readings. For instance at 2800rpm, the car was doing 33mph in second (3.55s)and the power timing,as mentioned was 28*. I installed a 22* VA can and so the total at 2800 was 50* and the engine liked that. Then at 65mph in double OD the rpms were 1600ish. The power timing here was just about 17* with 22 more in the can for a total of 39*. I didn't think this was enough. I had earlier installed a dial-back timing device that was able to change the timing from the driver's seat ,up to 15 degrees. So I began experimenting with more timing. The potential total now was 39+15=54*. I had installed the DB device with the adjuster knob in the center allowing changes of 7.5* advance and 7.5* retard. Well she liked all 7.5*,for a total of 46.5. Running this combo up to 75/80 mph, the total cruise timing became about 51/53. Then I leaned out the low-speed circuit. And leaned it out some more, and eventually that combo pulled 32 mpgUS at 75 mpg/1900 rpm.
So, what I'm saying is with a stick-car, a carb and a common dizzy, it is my opinion that starting with less is more. 14* of base timing and 20 in the dizzy and 22 in the VA and the DB gizmo, got me to where the engine wanted to be. And it burned 87E10 with 10.9Scr/8.9Dcr. The slight loss of torque at the lower rpms was never noticed (remember it's a stick car with a 10.97 starter gear), and mostly it has enough power to spin 295s to 50/60 mph,anyway.
If I would'a had an A/T I would just slammed 4* more into her, topping out at 34@2800 and called it done.

PS if you have a stick, driving at very low speeds can become an exercise in clutch-slipping. If you retard the timing from about 75 rpm below the normal idle rpm, and set the rate of decay at about 12*/100rpm, it takes most of the jumpiness out. My 367 will pull itself at 550rpm with just 6* of advance. With 3.55s and a 3.09 low gear, this works out to about 4mph, a fast walk.That's with a fat 750DP, and a 230/110 cam.
BTW, the DB device is an awesome tuning aid.

I'm not sure I've been any help, just remember; the lighter the loading, the less likely the engine is to detonate, and every combo is different. [/QUOTE]
 
LJ67barracuda340 said:
intake closes @ 37 abc,
Click to expand...
No it doesn't; that is the .050 tappet lift number. In other words the valve is still open; .050 times the rocker ratio, less that portion lost to pushrod angularity.I could guess the valve is still open close to.067 with 1.5 stamped arms. You cannot start building compression until the valve is right on the seat. Fully closed.
 
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LJ67barracuda340 said:
base timing 10*, idle timing 22*. Engine starts at 10 and computer adds 12* for 22* after start, dizzy is locked out.
Click to expand...
This is all chinese to me.
The base timing is the same as initial timing, and it better be the same as idle-timing.
But if you have a computer controlling the timing, well then I don't like your numbers, and you failed to mention the" all-in" power-timing and when it occurs and what you are doing for VA.
The all-in power-timing needs to be in the 32/34 degree range., and
It needs to be all-in by 3400 to as early as 3000,and
a streeter IMO, HAS to have a working and well tuned VA.

I don't know where you got the idea that a 2.66 low 5-speed is a close ratio tranny, cuz it's not,(unless it was compared to another wider ratio tranny in the same manufacturers line-up), but none-the less; a 5-speed with a 2.66 low and 3.23s and a .68OD is also messed up.
My combo didn't come alive until I hit nearly 11/1 starter gear. For you, that would be 11/2.66=4.10s and the hiway gear would be 4.10 x .68=2.79s, just about perfect. For optimum forward motion with a 222 cam,your shift rpm will be about 5800rpm, perhaps a little less.
If you are running something like these ratios; 2.66-1.91-1.39-1.00-.68od, then the splits are about 71/72%. Theses work great with that 222* cam, dropping the Rs to about 4200 on the shift, just a little above the torque peak.
Of course the 3.23s will work, if a bit lazy outta the gate. And cruising 65=1800 ain't bad, and again the 222 cam will pull a hiway gear down to about 1500, so if hiway cruising is your thing, then the 3.23s gotta stay.
But, for optimum fuel-mileage, the cruise timing at 1800 will need to get up around 45 to 50 degrees perhaps even more.Then you can lean the heck out of the low-speed circuit and target fuel mileage in the mid 20s,mpg.

To recap
Idle timing about 14(with a stick),
power-timing of 32/34*(aluminum heads).
All-in by 3400 to 3000
VA of 22*, in ASAP
Minimum gear for performance, of 3.73 , 3.91s preferred
With the 3.91s, and all in no sooner than 3400,you will probably find that it will run fine full load-WOTon 87E10(mine always has). In all cases, it will be happy with 87 on the hiway.
Now, I'll tell you a secret;
The 3.91s will get you shift rpm at 45mph with 27" tires.Whereas with 3.23s,this will not occur until 54 mph,9 mph later. That means you just put down all your horsepower 9 mph sooner, and so the average power put down during the timespan it took, will have been much closer to the peak horsepower that the engine is capable of producing. In other words this is the quick way.
And now you are set up to pull second gear, which will hit 60 at 5600, just after peak power,perfect. Whereas with the 3.23s you will hit 60 at 4600, barely past peak torque, and fully 800rpm too soon.
If these things matter to you.
 
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