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PostPosted: Mon Dec 11, 2006 11:19 am 
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I'm in the middle of trying to make a decision what rods to stick in my new motor I'm building this winter. Almost everyone running a nitrous motor at this level uses Aluminum rods, GRP, MGP, etc. Very few use steel.

The aluminum rod advocates all say that they absorb the shock of nitrous, that one I say is BS in my opinion. I have a hard time believing that they could absorb or soften that blow any amount that would be measurable or make that much of a difference. There are some benefits that I see such as:

Lighter reciprocating weight
Less side loading on the piston (due to less weight)
Lower cost (as compared to steel billet)

But the big drawback is faster fatique than steel. You hear recommendations of not making more than 50-100 passes on a set.

Steel rods on the other hand don't have the fatigue issue but have the drawbacks of higher weight. Are aluminum rods a "monkey see, monkey do thing""? Anyone aware of specific tests on the dyno or track that proved they were either faster or made more power?

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PostPosted: Tue Dec 12, 2006 1:56 am 
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I had a stroker small block that came with aluminum rods. I made WAY more passes than recommended. After several seasons the block was worn, and it was at max bore to start. As I didn't want to hassle with grinding the new block or buy new rods, I swapped over to steel. I reused everything after freshening but the rods and block. I didn't like it because it took longer to get the rpm's up, and it just didn't 'feel' right. I pulled it back down and put another set of aluminum rods in it. JOY!

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PostPosted: Tue Dec 12, 2006 10:10 am 
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Location: Wichita, KS    "It's OK - They're only tires..."
i have heard and read the same stories john. but from my experience on the healthy sbc (a little over 1000hp) steel seem to work well. of course using top of the line rod bolts. my steel pieces are probably 75-100 grams heavier than a similar heavy duty aluminum piece depending on the brands.
i really have not had any rod problems.


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PostPosted: Tue Dec 12, 2006 8:02 pm 
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Location: Wentworth MO
John we use steel rods and put 400Hp shot out of the hole with very good luck. We did hurt the bearings in the 588 but can't say with certainty what the problem was. Not much help sorry!!!

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PostPosted: Wed Dec 13, 2006 12:18 am 
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Location: Moore OK.
there can be up to 6oz per rodx8= 3 lbs of rotating weight saved with greater mass than steel = more strenght. the real reason, is alum has greater elasticity, spelling dosen't count by it's nature the alum is more forgiving than steel they will handle higher shock loads due to more mass to displace the load but it is the shock. high nitrous loads that are placed instantly and removed off on off on that kills the steel rod. think of a turbo mtr like the 3.8 have you seen the rod in that!! looks like it was rejected for any use but they live.. the turbo dosen't shock like nitrous...i have spoke to 2 of the top engine shops in tex and Ok both stated as long as you are under 1000. total hp steel is fine over 1000 with more than 25% power adder alum is recomended. one of the guys at the tex shop laughed when i asked him about the 200-250 run freshen up, he stated that at that level 1000+25% the motor needs more than rods by that time. :roll:

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 Post subject: aluminum rods
PostPosted: Wed Dec 13, 2006 8:54 pm 
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Location: Colonial Beach VA If I am not at home or the track then I am probably at HOOTERS
some friends of mine several years ago built a crazy buick 455 stroker not sure of the c.i but it was over 500 from what i know it is one of a kind. I dont know who the crank mfg was but it was stroked and had bbc rod journals.I know they had the longest rod for a bbc you could buy at the time in it {15 yrs ago} but they were childs&albert aluminum and they were told by all means no"instant warm ups" the motor had to opp. temp before it could be revved over 2000 rpm this may have been b.s. or maybe technology was not as good then as now. however the motor was never dynoed to get any h.p. readings but it ran 6.0s {1/8th} in a 3300# truck and sounded ungodly. they never sprayed it before the truck was destroyed :cry: i suppose these were fast times for being so long ago.

tporter it may interest you to know it was a chevy luv they had it in the guy who tubbed it added about 800# of steel he didnt need to need less to say it was a bumper dragger

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PostPosted: Thu Dec 14, 2006 9:19 pm 
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John my buddy switched from steel to alum in his blown alky motor when he went from 8.8:1 to 11:1 they told him the same thing about the rod absorbing some of the "pressure" .Theres only a handfull of runs on the motor so we dont know how long they will last but he does use a heater on the oilpan before he starts it.I dont know what brand he has.


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PostPosted: Thu Dec 14, 2006 9:20 pm 
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I meant the brand of rods not the heater.


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PostPosted: Mon Dec 18, 2006 12:30 am 
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another thing to consider is that if you have a failure the aluminum rods are much more forgiving on other parts, when you lose a steel rod it tends to take out the block, cam, crank etc. also lighter weight of aluminum means less wear on the cylinder walls and pistons.

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PostPosted: Mon Dec 18, 2006 12:33 am 
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also yes you must get the oil temp up to operating temp before putting any loads on the engine.

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PostPosted: Mon Dec 18, 2006 6:58 am 
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I think I finally deceided on aluminum rods, Moose said I wouldn't be able to outrun Sutton unless I got them soooo...

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PostPosted: Mon Dec 18, 2006 7:02 am 
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:lol:

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 Post subject: aluminum rods
PostPosted: Mon Dec 18, 2006 4:44 pm 
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Location: Colonial Beach VA If I am not at home or the track then I am probably at HOOTERS
tporter what year is your luv?

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70 Nova SS bracket / t.n.t car.
(Yes REAL SS 396 DISCS 12B0LT ETC)

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PostPosted: Tue Dec 19, 2006 2:15 pm 
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I said that John????? Must have been when we were talking about how many cubic inches my moto was. LMAO!!!!!!!!!!!!!!!!




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PostPosted: Sun Jan 07, 2007 12:47 pm 
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Location: Raleigh NC
John you made the right choice because they do absorb shock of detonation and someone above stated that they took out there brgs but wasnt sure why. Well the steel rod wont give at all and then the Brgs take the load and then the crank.

You may get away with it up to 400 and those that do have there tune dead on but anything above 400 you will thank youself later.

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