Aluminum Rods Vs. Steel Rods
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Aluminum Rods Vs. Steel Rods
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?
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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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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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.
i really have not had any rod problems.
- sunsation540
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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.
make a plan and stick to it !!
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aluminum rods
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 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
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
74 chevy luv 355 sbc bracket car
70 Nova SS bracket / t.n.t car.
(Yes REAL SS 396 DISCS 12B0LT ETC)
WANTED DEAD OR ALIVE 68-74 NOVAS
TOO MUCH IS NOT ENOUGH!!!!!!!!!!!!!!!!
70 Nova SS bracket / t.n.t car.
(Yes REAL SS 396 DISCS 12B0LT ETC)
WANTED DEAD OR ALIVE 68-74 NOVAS
TOO MUCH IS NOT ENOUGH!!!!!!!!!!!!!!!!
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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- jones_performance
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- John_Heard
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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...
My 1971 X275 Nova | Facebook
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aluminum rods
tporter what year is your luv?
74 chevy luv 355 sbc bracket car
70 Nova SS bracket / t.n.t car.
(Yes REAL SS 396 DISCS 12B0LT ETC)
WANTED DEAD OR ALIVE 68-74 NOVAS
TOO MUCH IS NOT ENOUGH!!!!!!!!!!!!!!!!
70 Nova SS bracket / t.n.t car.
(Yes REAL SS 396 DISCS 12B0LT ETC)
WANTED DEAD OR ALIVE 68-74 NOVAS
TOO MUCH IS NOT ENOUGH!!!!!!!!!!!!!!!!
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.
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.
Johnny B.
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