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  #1  
Old 10-07-2002, 06:42 PM
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Help Forged pistons/rods

Howdy ya'll, I got another question for you engine wizards out there. I am researching piston/rod combos and am definitly going the forged route, but need advice on which metal to use. 2 types I'm referring to are steel and aluminum. Here are my specs:

440...030 over
stock forged crank
gear drive with Crane roller cam, 1.6 roller rocks, and roller lifters
Edelbrocks rail type EFI
INDY aluminum heads..440-1
Vortech/Paxton centri.s-charger

These are the basics. I wanna keep the comp ratio 9.5:1. It will be an 80/20 car. 80% street and 20% drag and road racing. Should I go the forged aluminum route or with forged steel. I would like to know the benefits for both b/c money will not matter. Just don't suggest a titanium/magnesium setup ok you smart asses out there!! Thanks for all your help and be cool people!!


J-440
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  #2  
Old 10-07-2002, 11:30 PM
451Mopar 451Mopar is offline
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Aluminum forged pistons.
Rods would depend on how often you plan to replace them.
Good aftermarket forged steel rods should be fine and last a long time.
Aluminum rods will save some weight and can absorb some shock, but they stretch more and have a shorter fatigue life so you will have to replace them more often.
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Old 10-07-2002, 11:37 PM
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Forged steel pistons??

I've never heard of that, man.
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  #4  
Old 10-08-2002, 07:52 PM
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Thanks 451, sure as hell do not want to be tearing into my motor every year just to change rods.
DAVE!! Dave's not here!! Yeah man its my 1st engine buildup. Hell I thought there were two types of pistons. Forged aluminum and steel, guess I was wrong. So I guess cast pistons would be made of what then? I wanna get this right the 1st time that's why I'm asking you guys. Thanks for yer help.
Dave, you get the good stuff from Kentucky or what?


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  #5  
Old 10-08-2002, 10:45 PM
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"cast" pistons are made of cast aluminum

"forged" pistons are made of forged aluminum

Early engines(ie flathead vintage) had cast iron pistons. They're not used in modern applications. They're just too damn heavy.

Most modern engines have forged steel connecting rods as stock, but some have cast iron. Big caddy motors have cast rods, hence the reason why they don't get used in performance applications, they just fly apart.

Ask all the questions you want. that's why this board is here. As soon as someone thinks they know every thing they stop learning.

By the way...we grow our own up here
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  #6  
Old 10-09-2002, 01:04 AM
451Mopar 451Mopar is offline
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That's a pretty killer setup for your first engine buildup!
Are you working with a performance machine shop?
It sounds like your building a $10,000+ engine that could produce over 900 HP?
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  #7  
Old 10-09-2002, 06:41 PM
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Thumbs down aluminum rods

aluminum rods are great for race only and a high maintiance engine.
And even then should only be used after doing a lot of research.
They are not as forgiving as steel rods.
Should you drop one it will have to be sent back to the manufacture to be reconditoined.
That is only one example .
Good luck with your prodject.
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  #8  
Old 10-10-2002, 09:13 PM
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451, yeah dude, I've already figured the motor will set me back about 10 grand plus another 25G's for bodywork, chassis setup, interior and paint. This is my dream car and I'll be keeping her forever so money won't be a problem. It's a #'s matching 68 Charger with the 440. Bringing it back to all original is not my style, I want something original. As far as a machine shop goes, the guys are very reputable. They build a lot of race motors down here.
Thanks again Dave, you guys have helped me out on what I want for the short block. I appreciate every little bit of info I can get my hands on.


J-440
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  #9  
Old 10-26-2002, 04:36 PM
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J-440,

I can really sympathize with you on what you're doing to your charger. I've got a 72 RR that I'm (slowly but surely) restoring--but not for originality. I want it to be fast and loud!

You're doing a smart thing by asking around before you dive into your project. I'm stupid and compulsive, on the other hand, and I bought lots of nice parts w/o thinking of the drawbacks or what applications they'd be more appropriate for.

And so I ended up with aluminum rods for a car that I plan on putting on the street now and then. I found out later that they'll expand a lot quicker than steel rods.

So here's my question while we're all talking about aluminum rods. Since I've already got them, would it be stupid to buy steel ones now or should I just put the aluminum rods in and just expect to tear the engine apart in a little while?

How quickly will the aluminum rods expand (if the car is barely driven on the road how soon will they need to be taken out) and what can it do to an engine if the rods are all stretched and they're not replaced?

One other drawback, I heard that if I do get steel rods my crank will have to be rebalanced because it was set up for the lighter rods. Is this true?

Thanks all.
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  #10  
Old 10-27-2002, 03:42 AM
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Default Re: aluminum rods

.?$.?i]Originally posted by dirty dan [/i]
aluminum rods are great for race only and a high maintiance engine.
And even then should only be used after doing a lot of research.
They are not as forgiving as steel rods.
Should you drop one it will have to be sent back to the manufacture to be reconditoined.
That is only one example .
Good luck with your prodject.
[/QUOTE]

This man is completely correct if you asked me. As to how long they will last, it depends on what kind of conditions they are subjected to. Top Fuel NHRA guys get one pass out of them. I have heard of these being run in short ovals, but couldn't tell you how long they live in one of them--my guess would be about 250 laps. From what I have heard, a good rule of thumb is to get them resized every time you are ready to change the oil--this means race only! (that is unless you like pulling a street driven motor down about every other weekend) Aluminum rods are generally used by professional teams using multiple engines. Their intended purpose is to absorb the extreme shock to the crankshaft in an extremely high output engine making in excess of 1000 horsepower when using a roots supercharger/nitromethane combination. My advice (this is just my preference in rods) is to invest in a set of forged H-beams. Oliver is just about top of the line, but Eagle makes a damn good set that is more reasonably priced. This is arguably the absolute strongest rod design available, and though they are heavy, they will be much more suitable for an engine that sees even marginal street activity. Engine teardowns would be much less frequent, and rod resizings can be done at a local machine shop when necessary. As to the rebalancing, this should be done whenever anything on the rotating assembly is swapped out for a heavier or lighter product, or has been modified from stock form (beamed connecting rods, milled pistons, etc.), though it is advisable to do this on any performance buildup.
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  #11  
Old 10-27-2002, 08:26 PM
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wow

Yo deadhorse, I heard that re-balancing an engine is around 2 to 4 grand and usually done for race only use. Don't they completely disassemble your motor to do that? Also, since the stock comp ratio in a 68 440 block was 10.25:1 would I still need to balance my motor since I am only going 9:5.1? Preciate the input guys, have a good one.



J-440
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Old 10-27-2002, 08:47 PM
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Ballancing is a really good idea at time of rebuild. Especially if going to forged pistons. The machine shop doing the rebuild should be able to do it. If not, I would question whether I wanted them to rebuild my motor or not.

The cost isn't very much. $200 dollars comes to mind, but I don't remember for sure.

Definately a lot less than 2-4 grand. Leaves you some dough for accessories.
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  #13  
Old 10-27-2002, 10:00 PM
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Quote:
Originally posted by J-440
Yo deadhorse, I heard that re-balancing an engine is around 2 to 4 grand and usually done for race only use. Don't they completely disassemble your motor to do that? Also, since the stock comp ratio in a 68 440 block was 10.25:1 would I still need to balance my motor since I am only going 9:5.1? Preciate the input guys, have a good one.
J-440
Compression ratio does not affect engine balancing. When someone has their engine "balanced", the weight of the counterweight is brought to equal the weight on the other side of the main journal. For instance, if you had a piston/rod combo that weighed 1300g as stock, and you went to one that weighed 1100g, the opposing counterweight would be heavier than the crankpin connecting rod and piston combo. In this instance, material would be removed from the counterweight to "balance" the weights on each side of the main journal. This is done before engine assembly by weighing each piston/rod combo and attaching dummy weights that are equal to the weight of the piston/rod combo in each respective position. The crank is then placed in a special fixture and spun. The computerized fixture can detect imbalance in each counterweight and the heavy or light spot in each counterweight is detected using a similar device to a timing light. Weight is added or removed accordingly. As to the cost, $200-300 sounds about right. For 2-4 grand, you can have one built, blueprinted and balanced by a professional engine builder.
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  #14  
Old 10-28-2002, 11:54 AM
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Default dead hores is right

Dead horse is right on target.
The only thing I would add to that is this.
It Is allways good to balance the engine.(always)
Even if your are only doing a stock rebuild it`s a good idea.
Mopar performance says the factory ballance is suficent for a certain amount of hp.(I don`t recall the #)
Just so you know, if your expectting a large performance gain from ballanceing your engine .
You are in for a disapointment.
I supose now your wondering( Why Ballance)
Well here`s the reason its a good idea.
The benifit to ballanceing is in longevity for your engine.
It will lessen the vibritions and lighten the load on the bearing
by evening out the load across the entire cranck.
And so on and so on.
The end result is your engine will live longer.
Especially on High rpm aplications.
Ihope this helps
Dan
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Old 10-28-2002, 03:00 PM
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How about the H-beam rods that some of the other places are making. SCAT is one of them. They come in a LOT cheaper than Eagle. I have been looking at these for my 360(408) build. There are a couple of vendors that sell on eBay carrying Mopar H-beam rods for anywhere from $325 - $399 a set. Anyone know if they are legit pieces or if they're junk?
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  #16  
Old 10-29-2002, 12:01 AM
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Default rods

Iam not formiliure with them .
But I wouldn`t skimp when it comes to rods.
I would go with the egale rods or some thing none to be of equal quality.
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Old 10-29-2002, 01:27 AM
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Scat makes a pretty decent connecting rod, but I would rather pay the extra $150 for the Eagles because they are a pretty established name and I know for a fact that they are some of the strongest on the market. If you asked me, they are about the best deal for the money--you usually get what you pay for. If you research it, you will find more H-beam connecting rod makes than you care to think about. As far as brands, Crower & Oliver are some of the best, but expect to give some part of your body for them. Hughes and Scat also make H-beams, but I know for a fact that Hughes' are made of billet steel--this sounds fancy, but a forged rod is stronger due to the fact that there is no interruption in grain flow within the metal. Billet rods are machined out of a piece of steel stock--forged rods are stamped by a large die, and the stamping die is more expensive and less versatile than a cnc machine. Increased production cost adds up to a more expensive product, and that is why the Eagles cost more. I recommended them because I personally feel that they are the best balance between cost and brute strength.
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Old 10-29-2002, 08:36 PM
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Getting back to balancing a motor. Would they only balance the short block and how would they do it? I think just about everybody uses Eagle rods on this board. Its all I ever hear about so I'll definitly try some as well.


J-440
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Old 10-30-2002, 12:18 AM
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When you go to get your engine balanced, all you are really balancing is the reciprocating assy. You have to your engine completely apart to do this. When you get ready, take your crank, rods, pistons and wristpins to the machine shop, just tell your machinist to balance them, and he will balance them as per the procedure I mentioned earlier. Also, while your stuff is there, you can take your block to him, and have him blueprint the crankshaft bore, crankshaft, and connecting rods. This consists of measuring all of the running clearances down to the ten-thousandth of an inch to ensure that they are in spec, while checking for out of round, taper, flaws, etc. If you are not too familiar with engines, many machine shops will balance and fully blueprint them for you and build them while they are at it. Expect to pay for it though.
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Old 10-30-2002, 12:26 AM
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P.S.--If you are using a crank from an externally balanced motor such as a 360 or a late model 440, you will need the harmonic balancer and flywheel, or something to mock the butterfly weight on it, as these engines don't have big enough counterweights on the crank to balance themselves internally. This can be foregone when using a lighter conrod/piston combo, though I couldn't tell you exactly how much lighter you will have to go.
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