2G High Power 7 bolt Crank Recommendation (experience builders welcome)

[DSMReviver]

I have been getting mix answers on what crank to go with for my four-digit horsepower project. I have done a lot of reading on this forum and have talked to the builders but nobody seems to have a definite answer on what to use. Some people have told me stock crank is the way to go but others have told me stock crank cranks at the journals on high power levels. Others have told me Eagle crank can be used but some say to go billet. Billet is around 1400 dollars just for the crank and for that money you could spend it on a nice set of pistons and rods combo.

For anyone out there with real-world experience what has worked for you? What are you using for your 1000hp 7bolt build?

 

[DSMReviver]

Anyone?

 

[Gandalf]

Billet isn't necessarily stronger. Personally, I wouldn't waste the money based on research. I haven't broken into the 4 digets yet, but also havent seen someone in the 4 digets break a forged crank either. I choose Manley cranks for my builds.

 

[SasaniFab]

Anyone?

The factory crank can handle that power. How often have you heard of a crank snapping in half? The great thing about owning a 7 bolt is you have many many options as far as purchasing a crank. The real question is do you really intend on making 1000hp? The crank is the least of your concern.

 

[streetraceboi]

I second what he said ^^^^^

 

[mikEclipse99]

I can speak from experience here. I have had the same 7 bolt 100mm eagle crank(2.3L) in my car for 10 years now. It has been through hell and back including 60k miles. Not a single scratch on it when I freshened up the bottom end last year. Now I am not 1000hp but close to 700 on pump. I don't fear anything happening to the crank but more so the rods. Whenever this bottom end decides to let go I will be going back with a stock crank.

 

[DSMReviver]

Billet isn't necessarily stronger. Personally, I wouldn't waste the money based on research. I haven't broken into the 4 digets yet, but also havent seen someone in the 4 digets break a forged crank either. I choose Manley cranks for my builds.

Boostin told me they don't use stock 7 bolt crank for 900- above level. They see micro cranking at that level. JAM said on one of their posts that they don't recommend stock crank above 900. They both come to the same conclusion from their own experience. Magnus said to go billet. JAM said to go Eagle crank. Boostin said billet.

 

[DSMReviver]

The factory crank can handle that power. How often have you heard of a crank snapping in half? The great thing about owning a 7 bolt is you have many many options as far as purchasing a crank. The real question is do you really intend on making 1000hp? The crank is the least of your concern.

Boostin said on stock 7 bolt cranks they start to see microfracture at that power level. That is why they don't recommend stock 7 bolt crank for their high power builds. Now, 6 bolt crank, on the other hand, is much beefier and nitrided from the factory and supposedly better material. 6 bolt crank is good for 1000hp and up. I have the fuel, head, supporting mods, and a dog box transmission to handle the power so I figured why not.

 

[DSMReviver]

I can speak from experience here. I have had the same 7 bolt 100mm eagle crank(2.3L) in my car for 10 years now. It has been through hell and back including 60k miles. Not a single scratch on it when I freshened up the bottom end last year. Now I am not 1000hp but close to 700 on pump. I don't fear anything happening to the crank but more so the rods. Whenever this bottom end decides to let go I will be going back with a stock crank.

Eagle crank is what I can't find a definite answer on.

JAM said they are okay for 900hp on their other post. But 1000? not so sure. Now @Mark L who has the blue 1g talon pushed the 94mm Eagles to 1000whp on his drag car but not sure about the longevity. Will it suffer the same microfracture fate as the factory 7 bolt cranks? Or is it truly stronger and will last? If I can make it to 20-30K street miles and occasional 1000hp track events that would be alright with me.

 

[Twizted99GSX]

Eagle 100mm crank here and its fine when I refreshed everything nothing needed to be done to it.. I polished it to be sure but nothing major needed done an it seen some beating. just my 2.

 

[DSMReviver]

Eagle 100mm crank here and its fine when I refreshed everything nothing needed to be done to it.. I polished it to be sure but nothing major needed done an it seen some beating. just my 2.

I am leaning towards Eagle 88mm 7 bolt crank and cryo treat it for good measure.

 

[bastarddsm]

Here's a little tid bit on billet vs forged.
First think about the little kids breaking boards in karate, they break them along the grain, not across it.

Now picture a nice log, and you machine it into a billet crank. A billet wood crank, but still a billet crank. Think about how the grain is, think about how it will break, and how easy it will break with the grain.

Now picture a log that grew into the shape of a crank on it's own. That's kinda like a forging. Think about how the grain follows the shape of the crank, instead of being straight with big sections cut out of it. think about how this crank would break.

Now, metal isn't wood and they have different properties. BUT there is definitely a grain structure in metal, and it is definitely similar to a log when machined from a billet.

Maybe it doesn't matter, but it's something to think about.

My friend has a duramax powered pull truck. It's 1800+hp and 2500ft*lbs. A stock forged crank lasted them and others with similar setups one season. When they take it apart to freshen the engine it will be cracked, but still in one piece. The last few years my buddies have been running a winberg billet crank. It's cracked worse, and last year it flat out broke, halfway through the season. I think this year they have a callies forged piece. We'll see how it lasts.

 

[95REGF150]

Ya I always laugh when people get off on certain things being billet without thinking about how all that means is it was hogged out of a single piece of material on the CNC.

Billet is usually never an advantage for non uniform shapes like crankshafts. Its place for these pieces is in prototyping and low production runs that do not have enough quantity to be produced economically by the proper means (forging or casting) with less waste.

Now that doesn't mean a billet piece can't be as strong as a forged piece of the same material. But certainly not at the same external dimensions. For all the reasons Bastard mentioned you have to beef up a billet piece in the areas of stress concentration where a forged piece would not have to be. And I am sure that is what billet crank manufacturers do. But still that is why our factory cranks can take so much in comparison.

We should all be thankful the factory peices arn't just cast nodular like so many of the domestic V-8 cranks. Snap right at the rod journal with the same amount of power a lot of you guys are getting easily out of a 2.0

 

[SasaniFab]

The reality is nothing with 2 liters over 1000hp is reliable. The good news is the 7 bolts have alot more support than the 6 bolt in this department. As of right now we are stuck with eagle and the billet magnus crank. If I HAD to buy a crank other than oem If probably go with the manley turbo tuff crank and rods as an assembly. Those rods are bullet proof, id imagine those cranks are also very strong. Like i said , for 1000hp the crank is the least of your concern.

 

[donniekak]

Here's a little tid bit on billet vs forged.
First think about the little kids breaking boards in karate, they break them along the grain, not across it.

Now picture a nice log, and you machine it into a billet crank. A billet wood crank, but still a billet crank. Think about how the grain is, think about how it will break, and how easy it will break with the grain.

Now picture a log that grew into the shape of a crank on it's own. That's kinda like a forging. Think about how the grain follows the shape of the crank, instead of being straight with big sections cut out of it. think about how this crank would break.

Now, metal isn't wood and they have different properties. BUT there is definitely a grain structure in metal, and it is definitely similar to a log when machined from a billet.

Maybe it doesn't matter, but it's something to think about.

My friend has a duramax powered pull truck. It's 1800+hp and 2500ft*lbs. A stock forged crank lasted them and others with similar setups one season. When they take it apart to freshen the engine it will be cracked, but still in one piece. The last few years my buddies have been running a winberg billet crank. It's cracked worse, and last year it flat out broke, halfway through the season. I think this year they have a callies forged piece. We'll see how it lasts.

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