What about aluminum rods? How do they compare to billet and forged rods?

 

Well at least we can see what time it is and where your mind is .

 

alumnium rods are great....... for nitro burning funny cars.
You would only get about 100 miles out of them on the street.
They are strictly for track use.

 

Damn, Jared....I knew you were mad about me leaving you in the dust that one night, but do you have to go this far?

 

The question about aluminum is a great one to illustrate one of my points. It's light and strong. Also not very expensive compared to a "billet" stell rod. So why aren't they used in street cars? Poor fatigue resistance. The people who run them replace them after 50-100 runs. That's in the range of 15 minutes of WOT . Obviously, not a street item! But at ~150gms less weight than a steel rod, they are great for high rpm drag motors.

If you wanted to build a 1,000hp small block with a life cycle anywhere near a stocker, you would probably need a nice set of titanium rods. Stronger than steel, ~30% lighter, and only in the $4,000 range for a set!

I'm going overboard to make my point, so I guess I'll stop now.

Rich Krause

 

Yup, since my crank has to come out, this has always been a somewhat dream of mine (turbo lt1), figure now is the time. 1000 hp is a little unrealistic i guess, but this gives me a strong knowledge foundation to start on. More than likely it will end up in the 800 fwhp range. BTW, i want a rematch now that my cam is actually installed straight up instead of way retarded

 

This makes good sense to me. Yes it is a street driven car, and yes it sees a fair amount of track time. The nice thing about the turbo is ability to turn down the boost and HP on the street. Hopefully this will allow the engine to live quite a bit longer than it would seeing a sustained 1000hp

 

From what I hear, the fatique issue is just a wive's tale. The guy I talked to this weekend (Hot Rod Hawk, Michigan Section Moderator) said he knows someone who has been running a set for 5-6 years now. He said that you just have to let the engine warm properly before using it.

BTW, here is a link to his site.

I would like to hear a few more opinions or comments on the subject. Not trying to say anyone is dead wrong here, just repeating what I've heard

 

I have the advantage of having watched one of the most powerful LT1 blower engines ever built go together, and come apart for inspection. And that includes going from the 750HP to 850HP to 925HP to 1,125HP. I know what worked, and what didn't work. Oliver forged rods had a problem at the 850HP level. The replacement was a set of the Oliver billets. I immediately opted for the Oliver billets in my lowly 800HP nitrous motor. Seemed like cheap insurance.

Surprisingly, the stock straight 4-bolt main LT1 block held up very well. A very thorough examination (by the shop that built the engine, not me) of the bottom end of the LT1 block, before going to the 1,000+HP level showed that it had some features that were very similar to the "bowtie" block, and probably a bit more capable of handling higher HP loads than the traditional Gen 1 SBC stock block. The same block that was used for 1,125HP is being reused in an 1,100HP nitrous motor.

 

Been doing some searching for rods.

Whats the difference between a scat 4340 billet rod, and an oliver 4340 billet rod?

Also, are I beams a no no, and stick with the H beams only for high HP engines?

 

The difference is in the machining and where they keep the material. Both companies are trying to make there rods as strong as possible while keeping the weight to a minimum, and im sure both have slighty different opinions of where to keep the material in the rod for strength and where to take it out. Also the I-beam design is supposed to be a little better than the H-beam, so the I-beam will be fine. Also whats the difference in price for the billet and the forged olivers?

Unless you just have tons of extra money to blow on this short block no way would I spend the extra money for the billets, the best I would put in it would be the oliver forged I-beams that are more than capable of handling the job for a long long time.

On another thought, im not going to argue that the billet rods wouldn't be as strong as a forged rod. But in alot of well known and respected circles are going away from the billet cranks because the grain flow of the metal isn't as desirable or strong as a forged crank. So I don't know or have heard anything about the same being true for the rods. Just something to think about.

 

Well i have seen some billet I beams go for 500ish.

Oliver billet rods are almost 1300. There 4340 forged are about 700.

Really a VERY wide price range for rods that claim to be the same thing.

The one billet rods i saw claimed 1000hp capable at 8k rpm as long as the weight of the rest of the components didnt get out of hand. Those were only 650 or something, some off brand company

 

be careful my friend, it's easy for people to give you advice as to "what they would do" when it's not their motor. my old man use to warn against buying insurance from a salesman who didn't hold the same policy he sold. same can be said for taking advice on how to make a million dollars from a guy who only makes $30k a year. you catch my drift?

not to take anything from anyone here because alot of the advice given so far is right on. rich and injuneer are obviously in good standing with good engine builders. want to know what works, well one way is to pull the engine apart and see. injuneer's post says just that. granted, you can't afford to try it out, so you'll have to get parts that are dependable from the get go. when in doubt, use what you know is up to task. take advice from those who've been there (experience) or are intimate in the details of similar engines.

a 1000 hp turbo motor? what's the displacement? what's the typical duty of this engine going to be?
if this were a race only engine the answer would be a little easier. i don't agree with the suggestion that there's a move away from billet cranks. i'm in the "circle" so to speak and i just don't see that happening. looking at race engines and the torsion a crankshaft sees along with the inaccuracies this causes with valve events in relation to piston position etc., it just doesn't pan out. why would you even bother optimizing valve timing for an engine that will be inaccurate do to torsion in the crankshaft? that's why we run billet cranks in our race motors... it twists less, making for more accurate "timing" and that is horsepower. you could extend the same to billet camshafts with larger cores.

so on billet cranks... do you need one for your engine? probably not but i wouldn't skimp anywhere else up the ladder. if you inspect high hp engines much you'll see the same thing injuneer pointed out. weaker rods stretch more and they'll only stretch so far before they say "i've had enough". granted, this is still a street engine but a billet rod is still your best bet. i would steer clear of titanium and aluminum. titanium has it's place but force induction/ nitrous aint it. big cubed na engines turning lots of revs can really benefit from them, especially tall deck engines. aluminum can be run on the street but is it really worth the few grams of weight. i doubt you'd find a builder out there who would give his blessing (never mind a warantee) for an aluminum rod street engine. want light rods? stay with the forged i-beam designs like crower maxi-light, manley tour lite, etc.. they are great for na motors with short compression height lightweight pistons, pins and that deal.
for your build, there are two choices as i see it. you use the beefier i-beam rods like lunati pro-billet and oliver billet or you can opt for a slightly heavier h-beam rod like a carrillo, lae. they are proven performers and after putting as much money in a motor as you will have once this is said and done, the little extra here is well worth it.
as an engine builder, i always want to use the best components i can. i understand that there are guys out there making this power and running eagle h-beams, manley h-beams and the like. hey, it's your money but when your name is on the line, you tend to use a rod that you know is capable of the job without failure. and lets not give too much credit to the rod, cause bad machining will literally break the best of parts. it can also make the cheaper stuff last longer.

regards,
JB

 

Was going to be a .030 over 350, 3.75 stroke = 383. However some advised to try and keep the stock bore, or maybe .010 over instead to keep the block stronger.

Typical duty = will see race track at least 1x a week, at higher boost. Street driven the rest of the time at low boost (4psi or something small like that)

Very nice post BTW, so if it were your engine , would you go with an offbrand billet rod that claims 8k rpm and 1000hp capable, or with a oliver forged piece? Both are very similiar in price.

 

Not to try to steal Jeff's thunder, but I need to put in my $0.02 on this one. Stay away from any no-name/off-brand parts unless you are capable of independently evaluating their suitability for your use.

Rich Krause