aluminum rods yes or no?

[hotrodharley]

building my first blower engine and confused on what i should use.aluminum or steel rods.
eng. specs;
11.8 to 1 comp
736 lift rollor cam
12-71 alcohol blower[25% od]
enderle "big&ugly" alcohol injector hat
mallory super 3
brodix heads at flow shop now being done.
1;80 plantier power glide[trans brake]
4;30 rear gears
weight of car unkonown at this time

this car will be used part time race[for fun only]and showed[car shows and short cruises] when no money to race;
already have a set of "H" beam 4130 rods w/i-19 bolts;;should i sell my rods and go to aluminum rods or will my steel ones be good for how i'm using emgine?pro's and con's please

[bjuice]

if your gonna show it and Putt around with a track appearance some of the time..The Steel Rods will be Fine........if you were gonna be racing it and leaning on it.. the Aluminum Rods is the way to go....The Aluminum Rods will absorb a lot of shock that would be passed on to the bearings under race conditions.

with what you have i would stay with the steel rods imo

[hotrodharley]

if your gonna show it and Putt around with a track appearance some of the time..The Steel Rods will be Fine........if you were gonna be racing it and leaning on it.. the Aluminum Rods is the way to go....The Aluminum Rods will absorb a lot of shock that would be passed on to the bearings under race conditions.

with what you have i would stay with the steel rods imo

thanks bjuice..it will be 50% race and 50% show;;unless i get like racing it more[afriad that might happen]

[bjuice]

if your gonna show it and Putt around with a track appearance some of the time..The Steel Rods will be Fine........if you were gonna be racing it and leaning on it.. the Aluminum Rods is the way to go....The Aluminum Rods will absorb a lot of shock that would be passed on to the bearings under race conditions.

with what you have i would stay with the steel rods imo

thanks bjuice..it will be 50% race and 50% show;;unless i get like racing it more[afriad that might happen]

well even if you do more of the racing then crusing..the Steel Rods will still be alright..its not like you are gonna beat the bearings out of it instantly...the aluminum rods just help soften the Hit on the bearings and help with a little longer time period between rebuilds with serious racers having to go back into their engines Monthly/Weekly that run a full race schedule...i do not think the same rules apply to the hobbist that play around every now and then......again this is Just my opinion...if you remember i had a blown alcohol SBC that i ran crower steel Rods..cause i was just playing as yourself.

not trying to tell you what to do...but we see so many Hot Rod enthuesist trying to follow the Pro's tit for tat...and its just not practical...


Now if your Going to Run a full race schedule some where each week and push 30lbs of boost @8500 rpm each week thru that engine...you may want to consider Aluminum Rods...

[hotrodharley]

THANKS BJUICE;;I HIGHLY RESPECT YOUR OPIONS.YOU'VE BEEN AROUND THE BLOCK A FEW TIMES AND KNOW WHAT YOU ARE TALKING ABOUT..I WAS THINKING THE SAME BUT JUST WANTED THAT EXTRA OPION ON THAT I'M MAKEING RIGHT MOVE ON MY PARTS.
DON

[bjuice]

Well i appreciate that Hotord..i respect you as well My friend...and cannot wait to see that thang come to life...cause i am one of the few on here that knows how long and the work you have put into it..

Good luck and Happy Thanskgiving

[zipper06]

I agree with Juice on this one, i had steel rods in my 355" blown alcohol sm/blk when it melted down a piston land and cracked the blk., but now have alum rods for the new build to a 383" blown.

Also i hope you meant 4340 rods with L19's rather than 4130 with L19's?

Zip.

[hotrodharley]

I agree with Juice on this one, i had steel rods in my 355" blown alcohol sm/blk when it melted down a piston land and cracked the blk., but now have alum rods for the new build to a 383" blown.

Also i hope you meant 4340 rods with L19's rather than 4130 with L19's?

Zip.

Yes Zip;;4340 rods with the L19 bolts

[hotrodharley]

while we on the engine subject what kind of HP and TORQ do you think i'am looking at?

[russ67chevelle]

11.8 to 1 compression with a blower on top wow dude u got bigger nuts than i do!!! ive always heard ten to one is tops.... :shock:

[hotrodharley]

11.8 to 1 compression with a blower on top wow dude u got bigger nuts than i do!!! ive always heard ten to one is tops.... :shock:

running alcohol was told more comp for alcohol then for gas

[kwkracing]

11.8 to 1 compression with a blower on top wow dude u got bigger nuts than i do!!! ive always heard ten to one is tops.... Shocked

That is somewhat true for gas engines. 8-1, street 10-1 racing

Alky loves Compression and can keep the engine cool unlike gas

I have had steel rods hold up in blown alky sbc's but never in a bbc. You are going to have alot of hp and tq. Should be a exciting ride!!!!

One of my 468's i dynoed made 1320 hp and 12 somthing tq
12.5 to 1 , bb2x, 8-71 with a birdcatcher. if i remember right that was 12lbs of boost on alky. Didnt try and turn up any more on this engine.

[TheRabbit]

I agree with BJ that steel rods will be just fine. However, it's always been my experience that if I leave anything out of a motor I always end up adding it anyway. I learned a long time ago for me it's cheaper to go all out the first time. It saves me money in the long run. :wink: JMO

[DRTRCR22]

Hi guys, I just had to bring this thread back up to ask stupid questions about a current issue I have over running aluminum rods in a high revving dirt modified circle track engine.

I just aquired a very nice used SBC Hines balanced 355 rotating assembly including Eagle 3.48 steel crank, SRP high dome slugs, and real nice looking 5.7 aluminum rods. I don't know what brand they are but they sure look like very high dollar pieces. This nearly brand new assembly came out of a drag engine that the owner claims he only made a half dozen passes and now wants a bigger badder 434 instead.

I started putting my shortblock together yesterday when a very experienced circle track racing partner came over and saw what I was doing. He loudly and adamantly protested that under no circumstances should I ever run aluminum rods in a circle track race engine. When asked why he claims that aluminum rods are too soft and stretch at cycling high revs, causing pistons to hit the small chamber heads I run (World Products Sportsman II 64cc).

Is he correct...? I was planning on running this up to about 8000 rpm on a mechanical roller cam, on rough dirt tracks, and I wanted to take some of the 'shock' out of my rotating assembly. I would 'clay' the valve to piston dome clearance as usual to make sure I have plenty of stretch room. The block deck height is still at stock 9.025 I believe...? I could run a thicker head gasket if needed.

Please give me the Good, the Bad and the Ugly about aluminum rod use on other than drag engines...?

Thanks, Jim

[zipper06]

I'll weigh in on this one (please it's just my own opinion) I have too agree with your friend about the alum rods and circle track racing. Look at the stats, i would venture too say that not one NASCAR team uses alum rods. There is a reason for that, alum rods move around and don't have the durability of steel or TIT, rods. Drag racers use them in blown cars too soften the hit on the bearings and they rev quicker. but the down side is that they also cap walk, even with serrated or hollw dowel locators. Blown fuel or blown alcohol cars don't get much over 50 passes if that, before they junk the rods, on hard chargers. A normally asperated car can get mybe 400/500 passes in a drag car situation.
Now back to circle track racing every hard lap you make it would seem to me you cycle the engine 2 times, which would be like 2 hard passes at the drag strip, plus as seen in other post a lot of people kick the hard charging cars into nutural at the finish line, but every cycle on a round track engine you are using the engine for braking, putting extra stress on the rods, not normally done with a drag car.
You can buy Eagle or Scat "H" beam 5.7 rods for around $250.00, and in my opinion it would be a better/safer engine build.

JMO

Zip.

[TheYellaBrick]

I forwarded this issue to my brother for his opinion;

Hi Dwaine,

The only aluminum rod that I would recommend for this application is the Bill Miller forged rod for the 2.100" rod journal. Most aluminum rods are built .010" shorter than their steel counterparts to allow installation in common deck height blocks, like if your block was setup at 9.000" (typical SBC after square decking) you wouldn't have to resort to "thick" head gaskets. The piston to head quench pad clearance must be .055" (for this application) or more to allow for the stretch and thermal expansion. I have built engines for sprint cars and street cars with the Miller rods with a great deal of success, and of course drag engines - how about a 468cid BBC with a 8200 RPM shift point equipped with Miller rods that still was in operation after 450 passes? The "New" generation of aluminum rods are CNC carved out of billet flat stock (not forged) that does not have controlled grain flow around the big and small ends of the rod and doesn't have proper
grain flow in the beam area either. The CNC rods can be built by anybody with a CNC mill (I've even built titanium rods on my manual mill for bike engines), so there are some fair designs and some really poor designs out there, and they look so damn good because of the infatuation with smooth, totally machined aluminum - the looks are deceiving! Most of the CNC rods are very squared off and bulky, probably to overcome the design flaw of CNC machining flat stock. The original 7075 Manley rod is forged but not to the standards that I go by. Be aware that all of these rods have the thermal expansion related dimensional changes that effect clearances from cold start to hot operating conditions, the clearances of interest are the rod bearing clearance and pin clearance. The rod bearing on the Millers (and all that others that I've been around) have the rod bearing lower half dowel pinned (bearing is drilled with locating hole) to determine bearing location
fore and aft and to prevent rotation. The big end is fairly massive on any aluminum rod to achieve enough ultimate strength to prevent deformation and failure, this mass expands as a result of the large amount of molecules interacting - so this area grows quite abit, even at an oil temp of 240deg it increases the big end bore enough to allow the rod bearing to "float" in the bore. Upon teardown of a properly built engine you can witness the "bearing float" by inspecting the backside of the bearing - they get burnished by this movement. The engines still run and don't scatter even with this movement, I think its really pretty slight but worth mentioning in this discussion. I normally don't use aluminum rods unless the application will have peak power over about 8000 RPM, even this decision can be effected by component weight and other considerations. So, to answer this guys question, I wouldn't use any aluminum rod other than Bill Millers (which has the
name forged into the rod) for a circle track engine - if they're not Millers install quality steel rods.

Hope your Christmas was good, we had a great time with family,

Any questions on this topic, feel free to ask! Dennis B

[DRTRCR22]

WOW, thanks Zip and Dennis, lots of good information here, thanks!

Well, I guess I should have done my homework before purchasing this assembly, but I was excited to get it all for less than half what it cost new.
I went back and found my notes, and the seller claims they are Manley rods, but they are not marked so I have no way of proving that. They are scribed by the machinst when balanced, but that is all I noticed. Yes, they are the dowel pinned lower bearings, and they have the serrated seam caps. I did not get the original bearings with this and had to order new ones, so I have no idea what they looked like coming out, but the journals have no unusual wear or color or any other indications of a failure. My notes also clarify that the seller says he only made four (4) 1/8 mile passes with this assembly before deciding it wasn't enough for his Quick 8 car. Does anyone recognise these as Manley rods? The big ends are big enough I had to 'clearance' the block like I do for 383 stroker assemblies.
Well, since I already have the shortblock together, I guess I will either complete this engine as a drag motor and try to sell it, or save it for my 80 Z28 T-top restoration into a street romper. It should be ok for street strip use, huh? Thanks again for the help. Jim

http://i850.photobucket.com/albums/ab64/DRTRCR22/AluminumRodEagle35503.jpg

[oldandtired]

Dirt- Another idea. Most people think aluminum rods are a lot lighter than stel rods. In fact they are real close. You might weight the rod (total/big end/small end) and buy a steel rod to get balanced to your bob weight.

Manley Super 70 SBC 6.0 LJ rod weighs 580 grams
Eagle SIR I beam 6.0 bushed LJ rod weights 590 grams

While the SIR rod may be too weak for your application, it's just an example of what is out there.

Dave

[DRTRCR22]

Thanks Dave, I'll think about that. I am not desperate for this engine yet, as I have a couple others in build process too.
I always build at least two full race engines every winter before race season starts, because dirt race engines rarely last a whole season, so I will have a backup ready to drop in and not miss a weekend. I bought this assembly wih hopes it might last a whole season of 45 nights or so, but I might save this one as a backup for big special outlaw shows instead.
However, I am really considering just parking it under the bench to save for my street/drag project Z28 under construction now. The only reason I bought this rotating assembly was because I had a fresh race prepped .030 over 350 block on the stand ready to build, and the price was very good for what I got. However I will probably build my latest 400 core into a 406 for my backup engine, as I already have my Dart Little M 404 ready to rock and roll... $10k later... ouch..?
Thanks for the tip. Jim

[TheYellaBrick]

WOW, thanks Zip and Dennis, lots of good information here, thanks!

Well, I guess I should have done my homework before purchasing this assembly, but I was excited to get it all for less than half what it cost new.
I went back and found my notes, and the seller claims they are Manley rods, but they are not marked so I have no way of proving that. They are scribed by the machinst when balanced, but that is all I noticed. Yes, they are the dowel pinned lower bearings, and they have the serrated seam caps. I did not get the original bearings with this and had to order new ones, so I have no idea what they looked like coming out, but the journals have no unusual wear or color or any other indications of a failure. My notes also clarify that the seller says he only made four (4) 1/8 mile passes with this assembly before deciding it wasn't enough for his Quick 8 car. Does anyone recognise these as Manley rods? The big ends are big enough I had to 'clearance' the block like I do for 383 stroker assemblies.
Well, since I already have the shortblock together, I guess I will either complete this engine as a drag motor and try to sell it, or save it for my 80 Z28 T-top restoration into a street romper. It should be ok for street strip use, huh? Thanks again for the help. Jim

http://i850.photobucket.com/albums/ab64/DRTRCR22/AluminumRodEagle35503.jpg

And again an opinion from my brother;

Hi Dwaine,

They do not appear to be any Manley configuration that I've seen, the big end design isn't the Super 70 nor is it the forged version. And not Millers anyway, and there's a thousand different combo's that are and have been produced (for instance Manley has std, nitrous and lightweight versions of their Super 70). Looks like the guy has the right idea about selling it as a drag engine. The piston dome appears to have been making contact with the chamber wall, he may want to look at this for whatever combo he's building. Using them for a street application can be done, just don't expect anything regarding long life (regard the engine as a disposable unit), and clearance the block and chamber for .070 to .090" clearance in all directions!

Dave's mention that aluminum rods sometimes are not any lighter is exactly true. The alloy rods can be much lighter at the reciprocating end, but slightly heavier at the big end, also everybody has mentioned the shock absorbing qualities, which is the primary reason why which I chose these parts when building a high RPM engine (blown alky or nitro too). Another thing comes to mind, the crank should have the bob wiehgt stamped or scribed into the front counterwieght or it may be a job number instead
-just a thought.


Have a good new years! Bro Dennis

[DRTRCR22]

Hummmm... it looks like its starting to rain harder on my parade very minute...?
Yes I did notice the very light discoloration on the top of this one particular piston dome only, that appears it might have brushed contact with the head. I see no real damage other than that shadow. The top ring land is not distorted, and is equal uniform all the way around. That is the first thing I checked. The ring floats free with no bind whatsoever.
I assumed the original block the first owner had may have been cut to 9.005 or even flat deck of 9.00. When I installed these in my block I have at least .010 downhole piston top from deck surface, and would adjust gasket thickness after clay measuring head to valve pocket distance.
Yes, I did have to do extensive clearancing of the block, and even went further than I normally would, expecting I might have extra expansion movement of the aluminum rods. The entire assembly has extensive numbers and notes scribed all over each piece, but I forgot to write them down before I finalized the assembly and zipped it shut. I really don't want to tear it all back down just yet, but in light of everything revealed here I just might go ahead and part this assembly out to find some good steel rods instead so I can use this shortblock without worry something is not quite right...?
Anybody want to buy a good set of 5.7" aluminum rods...? :)
Thanks guys for all your advice and help... I appreciate it. Jim

[zipper06]

Hey Jim,

If were a betting person i would say they are GRP, billet rods, not forged.

See pic. below.

JMO

Zip.


http://img.photobucket.com/albums/v515/zipper2/14314892-153-NEW-GRP-Aluminum-Rods-.jpg

[DRTRCR22]

Ok... is that a good thing or a bad thing...? Pros and Cons...?

[zipper06]

GRP's are considered one of the best on the market, too the tune of about $850.00 plus or minus. I don't think they are as strong as BME's or Childs and Alberts, but they are a cut above Manleys for sure, lot's of people run them in normally asperatered engines.

JMO

Zip.

[DRTRCR22]

Ok, thanks Zip... that makes me feel a little better about my purchase.
Well... I have been wanting to get away from dirt racing and back to street romping/drag racing for quite a while now, so I will let this sit a while and mull it over before I make any rash decisions. dirt racing has just gotten SO expensive and complicated now days, it is not even fun any more... why do it if you can't enjoy it...?
The only trouble now is, that I have been away from drag racing SO long, I don't even know anything about it anymore. So, I may be back asking more dumb questions about your expertice as time goes on...
Thanks friends for your honest and respectable advice, I do appreciate it.
Jim

[promodjohn]

building my first blower engine and confused on what i should use.aluminum or steel rods.
eng. specs;
11.8 to 1 comp
736 lift rollor cam
12-71 alcohol blower[25% od]
enderle "big&ugly" alcohol injector hat
mallory super 3
brodix heads at flow shop now being done.
1;80 plantier power glide[trans brake]
4;30 rear gears
weight of car unkonown at this time

this car will be used part time race[for fun only]and showed[car shows and short cruises] when no money to race;
already have a set of "H" beam 4130 rods w/i-19 bolts;;should i sell my rods and go to aluminum rods or will my steel ones be good for how i'm using emgine?pro's and con's pleasetoo much compression for your set up,you may want to consider 8.5 or 9.0 to 1

[bjuice]

i run GRP'S in my 632ci Nos Motor....also had GRP's in My 572ci Alcohol Blown (1471 Littlefield) injected 23 t altered