Aluminum block Versus iron; HP diff?
#1595449
03/19/14 05:22 PM
03/19/14 05:22 PM
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Joined: Jan 2003
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Frostbitefalls MN (Rocky&Bullw...
gregsdart
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I thought I would bring this up again to see what has been learned in the last couple of years, or there abouts. In years past, some said the aluminum blocks cost some power, roughly 40 on a 900 hp build. I am curious if the info has changed!
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Aluminum block Versus iron; HP diff?
[Re: Airwoofer]
#1595452
03/19/14 06:29 PM
03/19/14 06:29 PM
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Joined: Apr 2005
Posts: 2,128
Salt Lake City
camastomcat
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Joined: Apr 2005
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Salt Lake City
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Quote:
Is that from the cylinders not staying round?
I don't think that's a problem any more.
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Re: Aluminum block Versus iron; HP diff?
[Re: camastomcat]
#1595453
03/19/14 09:48 PM
03/19/14 09:48 PM
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Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
MRMOPAR622
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Sweet Home Alabama
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I would say if you lost any it would be 10-15 hp at the most,these newer blocks are much better.And you will lose 100 lbs off the front end.Go with Indy or KB which ever you prefer.
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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Re: Aluminum block Versus iron; HP diff?
[Re: camastomcat]
#1595456
03/20/14 12:00 PM
03/20/14 12:00 PM
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Joined: Feb 2014
Posts: 655
Huntsville, AL
Airwoofer
mopar
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mopar
Joined: Feb 2014
Posts: 655
Huntsville, AL
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Quote:
Quote:
Is that from the cylinders not staying round?
I don't think that's a problem any more.
What changed? The KB block in my car went from unfilled to filled somewhere along the way.
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Re: Aluminum block Versus iron; HP diff?
[Re: cudaman1969]
#1595457
03/20/14 12:08 PM
03/20/14 12:08 PM
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Joined: Jan 2003
Posts: 16,928
NC
440Jim
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Quote:
I would think it would be not retaining the heat in the cylinder and head. My Indy engine would lose a tenth leaving at 160 instead of 200 degrees. IMO
I guess that makes getting heat in the engine even more important for those running alcohol.
One other difference is the thermal growth effect on cam/valve lash. With Aluminum heads on an iron block I was using ~0.005" tighter cold lash to get the hot lash correct. I have heard a lot more when running both aluminum heads and block. Any experience? 0.015" ?
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Re: Aluminum block Versus iron; HP diff?
[Re: 440Jim]
#1595458
03/20/14 12:16 PM
03/20/14 12:16 PM
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Joined: Dec 2004
Posts: 298
Shelton, Ct.
572_HEMI_Cuda
enthusiast
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enthusiast
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Shelton, Ct.
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Quote:
Quote:
I would think it would be not retaining the heat in the cylinder and head. My Indy engine would lose a tenth leaving at 160 instead of 200 degrees. IMO
I guess that makes getting heat in the engine even more important for those running alcohol.
One other difference is the thermal growth effect on cam/valve lash. With Aluminum heads on an iron block I was using ~0.005" tighter cold lash to get the hot lash correct. I have heard a lot more when running both aluminum heads and block. Any experience? 0.015" ?
zero lash cold...
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Re: Aluminum block Versus iron; HP diff?
[Re: 572_HEMI_Cuda]
#1595459
03/20/14 12:27 PM
03/20/14 12:27 PM
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Joined: Mar 2006
Posts: 9,910
Eighty Four, PA
B G Racing
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Posts: 9,910
Eighty Four, PA
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Quote:
Quote:
Quote:
I would think it would be not retaining the heat in the cylinder and head. My Indy engine would lose a tenth leaving at 160 instead of 200 degrees. IMO
I guess that makes getting heat in the engine even more important for those running alcohol.
One other difference is the thermal growth effect on cam/valve lash. With Aluminum heads on an iron block I was using ~0.005" tighter cold lash to get the hot lash correct. I have heard a lot more when running both aluminum heads and block. Any experience? 0.015" ?
zero lash cold...
All aluminium engines can grow .015+-.We usually will not set them any tighter than .005 for a cold startup,then check them hot(operating temp)to see what the expansion rate opened to.  
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Re: Aluminum block Versus iron; HP diff?
[Re: 572_HEMI_Cuda]
#1595460
03/20/14 12:28 PM
03/20/14 12:28 PM
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Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
MRMOPAR622
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Sweet Home Alabama
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I found that on my all aluminum engines using Jesel rockers from cold to hot the lash grows .008.With Aluminum heads & steel block from cold to hot .004.Both Big Block Mopar & Big Block Chevy.I have heard of others having more,and have checked mine close to make sure they were gapped right.
On all of my engines they have run best between 160-180 degrees.
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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Re: Aluminum block Versus iron; HP diff?
[Re: MRMOPAR622]
#1595461
03/20/14 12:51 PM
03/20/14 12:51 PM
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Joined: Jan 2003
Posts: 19,373
Las Vegas
Al_Alguire
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Las Vegas
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My KB B1 deal I se about .015" growth. Lash on my cam is .016 and while I cannot get a feeler gauge in it due to the fact it is about as thick as tin foil there is a bot of lash cold. Can also tell you it pick up when the oil gets hotter. Cannot put a number on it, as in a 50 degree difference equals .01 but it does pick up. So I try to keep it as steady as possible. However when late in rounds and going the round robin style we usually get I just know I will be fast.
AS for the question at hand about HP loss. IMO these days it is negligible at best. I think ANY loss is offset up better cooling and less weight. With the 16 volt system I can have the water temp down to nothing from 180 in a matter of a couple of minutes. My car has never really seen over 180 either, even with it's smallish sirocco style radiator/
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: Aluminum block Versus iron; HP diff?
[Re: Al_Alguire]
#1595462
03/21/14 09:42 AM
03/21/14 09:42 AM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
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Left Coast
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Quote:
My KB B1 deal I se about .015" growth. Lash on my cam is .016 and while I cannot get a feeler gauge in it due to the fact it is about as thick as tin foil there is a bot of lash cold. Can also tell you it pick up when the oil gets hotter. Cannot put a number on it, as in a 50 degree difference equals .01 but it does pick up. So I try to keep it as steady as possible. However when late in rounds and going the round robin style we usually get I just know I will be fast.
AS for the question at hand about HP loss. IMO these days it is negligible at best. I think ANY loss is offset up better cooling and less weight. With the 16 volt system I can have the water temp down to nothing from 180 in a matter of a couple of minutes. My car has never really seen over 180 either, even with it's smallish sirocco style radiator/
The only power loss from an aluminum block is from cylinder wall distortion or incorrect valve lash. The activity that creates torque does not escape through the aluminum...as you kind of just said.
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Re: Aluminum block Versus iron; HP diff?
[Re: BobR]
#1595463
03/21/14 11:36 AM
03/21/14 11:36 AM
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Joined: Jan 2003
Posts: 10,010
Frostbitefalls MN (Rocky&Bullw...
gregsdart
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Sounds like it would be a perfect fit for my deal, I always warm and heat soak to 210 then stage at 190.
On the lash, it would also depend on rocker ratio used, If I see it correctly. A 1.5 rocker with .010 true block and head growth would show .015 at the valve, a 1.7 rocker .017
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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The higher the RPM(above 7000) the more loss 
