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Discussion Starter #1
What's the pro's and con's on aluim.{SP} blocks over cast iron block's besides the weight difference?




Jim S
 

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steelcomp was here
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con--less horse power, expensive
pro--repairable, available in wide choice of deck heights and and bore centers
X2, but it seems that in a lightweight drag boat, the weight savings may be more significant then the HP loss.

Hey GN...is that nail gun CA legal?
 

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Highaboosta
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I've heard the HP disadvantage point before.
Does anyone have any data on how much of a % factor that would actually
be ?
 

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Precision Craft Marine
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We have always had a better handling, quicker accelerating boat with an aluminum block. Remember that drag boats do not ever have enough heat in the motors when we actually run the boat. Even with our totally enclosed cooling system, the difference between the iron block and the aluminum block is not much, but the extra weight is huge.
 

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I personally used a Bowtie block for a ProStock engine. 500 inch Pontiac Kinsler injector. All I changed was the block to a Merlin-Lite. Same "everything" except the rings were new. Same brand and style rings, just new. Same guy doing the machine work too. + 38 hp on the same dyno !!!

Gordy told me the same story, that I'd lose power ! I call BS !
 

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Same "everything" except the rings were new. Same brand and style rings, just new. Same guy doing the machine work too. + 38 hp on the same dyno !!!

Gordy told me the same story, that I'd lose power ! I call BS !
I am pretty sure new rings cannot make a difference. Hell, almost no reason to ever replace them anyway. :D
Wags
 

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steelcomp was here
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I personally used a Bowtie block for a ProStock engine. 500 inch Pontiac Kinsler injector. All I changed was the block to a Merlin-Lite. Same "everything" except the rings were new. Same brand and style rings, just new. Same guy doing the machine work too. + 38 hp on the same dyno !!!

Gordy told me the same story, that I'd lose power ! I call BS !
Couple of questions. Do you think an aluminum block can hold it's shape as well as an iron block? Do you think there's a reason NHRA Pro Stock engine builders will sacrafice more weight in an already iron block, because it'll make more power than something lighter?
This is an old debate, and it'll go on forever. Your example is more the exception than the rule, and I'd venture a guess that something changed during the rebuild, because while in some cases it may be a wash, there's no way an aluminum block is going to make 38 more HP on it's own, over a good iron block.
JMO.
 

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Highaboosta
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I personally used a Bowtie block for a ProStock engine. 500 inch Pontiac Kinsler injector. All I changed was the block to a Merlin-Lite. Same "everything" except the rings were new. Same brand and style rings, just new. Same guy doing the machine work too. + 38 hp on the same dyno !!!
Gordy told me the same story, that I'd lose power ! I call BS !
There's some solid results. Now that's settled.

Whenever I heard the old story about aluminum blocks not making the same HP as cast iron it was always from someone who didn't have one. ;)

I also heard that my aluminum block would be corroded down to dust after using it in a boat. I've got 9 seasons on my Arias aluminum block and it's still in great shape.
 

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steelcomp was here
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There's some solid results. Now that's settled.

Whenever I heard the old story about aluminum blocks not making the same HP as cast iron it was always from someone who didn't have one. ;)

I also heard that my aluminum block would be corroded down to dust after using it in a boat. I've got 9 seasons on my Arias aluminum block and it's still in great shape.
LOL...you go, unchained.:p
I don't have an alligator, but I know not to stick my hand in one's mouth.
 

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"The" masheenist
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Oh HERE WE GO AGAIN.......................
 

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Precision Craft Marine
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What Steelcomp is saying is true, an iron block will make more horsepower on a N/A engine, and that has been proven. The best way to decribe a boat, is it is like a truck going up a hill. The more weight you put in that truck, the slower it is going to get to the top. All drag boats work and handle better with aluminum blocks. The real problem with the chevy is the bore spacing. How can a cylinder that is 4.600 or larger stay round. They get too thin and move all over the place, making for a bad situation. So maybe it not the fact that the block is aluminum, but maybe the bore is to big for its own good. Lets face it, these engines are so outdated, when it comes to technoligy.They still have push rods!
 

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What Steelcomp is saying is true, an iron block will make more horsepower on a N/A engine, and that has been proven. The best way to decribe a boat, is it is like a truck going up a hill. The more weight you put in that truck, the slower it is going to get to the top. All drag boats work and handle better with aluminum blocks. The real problem with the chevy is the bore spacing. How can a cylinder that is 4.600 or larger stay round. They get too thin and move all over the place, making for a bad situation. So maybe it not the fact that the block is aluminum, but maybe the bore is to big for its own good. Lets face it, these engines are so outdated, when it comes to technoligy.They still have push rods!
You may have something there about the bore size. Consider that a commercial diesel block is humongous(sp?) for the bore size. A few hundred pounds is not a big deal there, but wear is paramount.
 

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Resident Ford Nut
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There's some solid results. Now that's settled.

Whenever I heard the old story about aluminum blocks not making the same HP as cast iron it was always from someone who didn't have one. ;)

I also heard that my aluminum block would be corroded down to dust after using it in a boat. I've got 9 seasons on my Arias aluminum block and it's still in great shape.
LOL...you go, unchained.:p
I don't have an alligator, but I know not to stick my hand in one's mouth.
Could any of the power gains listed in the other post have to do with block design and windage control ?

When this topic came up again I asked my friend Randy Walls (he builds his own engines both steel and alumi blocks) he said that the cast-iron block "should" make more because of the lack of distortion and growth. Aluminum engines will grow out of spec. The deck will change, the valve lash will change, P to V will change, internal clearances will change. Just more to account for in a precession engine, it can be factored for, but a Steel block will be more consistent. I would tend to agree that the block all by itself would add 38 hp. As I asked I wonder about windage control ?


Sleeper CP :D
 

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Precision Craft Marine
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Sleeper, I really think that there are too many variables to say what is really the reason for that 38 hp number. A dyno can not be 100% consistant, and neither is the weather outside that the engine runs on. Fuel is always an issue. We can tweek 20 hp, with screwing with fuels. Windage, oil, oil temp, you can keep going. The fact of the matter is, aluminum blocks are fricken exspensive, and the average guy is not going to pony up for a good NEW block in Iron or aluminum. Most boat guys cant afford a 1980 pro stock motor. With this being the case for most boat owners, weight is the easiest way to improve acceleration with anything. Pro stock motors do not use steel rods, but 3/4 of these boat guys still run steel rods. I always thought that the NHRA had a rule for the iron blocks, maybe I am wrong.
 

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Speedy Member
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Sleeper, I really think that there are too many variables to say what is really the reason for that 38 hp number. A dyno can not be 100% consistant, and neither is the weather outside that the engine runs on. Fuel is always an issue. We can tweek 20 hp, with screwing with fuels. Windage, oil, oil temp, you can keep going. The fact of the matter is, aluminum blocks are fricken exspensive, and the average guy is not going to pony up for a good NEW block in Iron or aluminum. Most boat guys cant afford a 1980 pro stock motor. With this being the case for most boat owners, weight is the easiest way to improve acceleration with anything. Pro stock motors do not use steel rods, but 3/4 of these boat guys still run steel rods. I always thought that the NHRA had a rule for the iron blocks, maybe I am wrong.
Joe, we are gonna put an aluminum block in the Blinger and will dyno it when its done. Should be a good comparison. Ill let you know when it goes on and you can come over if you want. Maybe sushi too!!
 

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Pro stock motors do not use steel rods, but 3/4 of these boat guys still run steel rods. .
When you run an Alumi block do you have to run Alumi rods too ? :)bulb

Sleeper CP :D
 
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