7 bolt crankshaft strength

[96eclipseawd]

I'm replaceing my stock 7 bolt crank because I dont want to have it ground down, and I've already purchased new std. acl race bearings. My question is, are the replacement stock cranks that aren't OEM as strong as stock OEM cranks? Does anyone know how strong the stock 7 bolt cranks are?

 

[hediki12]

crank shafts are pretty hard 2 brake i doubt u will make enough power 2 brake it. but umm for a 7bolt motor general rule is 400 ish whp... and a 6bolt 500ish whp before you need to upgrade the internals...

 

[Cesar]

they're forged. as strong as they get...kind of.

avoid detonation, aka knock. even the toughest parts can't stand too much abuse for long.

 

[96eclipseawd]

400 wont be strong enough. We aer looking for 500 to the ground. I guess I need to look for an Eagle crank. Thx for the responses.

 

[tkelly27]

No, the stock crank can hold in excess of 1000hp, 6 or 7 bolt. EVO's have basically the same crank as the 7 bolt, and there are stock crank evos well beyond 1000hp. I would even run a ground stock crank @ 500whp, but some people will tell you not to. The nitriding process goes well beyond whatever they take off, and a crank can be re-nitrided. If anything, the extra amount off could be added to the fillet radii and make it even stronger.

Off the top of my head, the highest hp 7 bolt I know of is twicks69, he is running a stock 2.3 7 bolt crank
View Profile: twicks69 - DSMtuners.com

When they say the internals must be upgraded, they mean the rods and the pistons. The limits for the block and the crank are yet to be reached that I know of. Reading through tuners for 2 years now I've never seen a "I cracked the block" or "broken crank" unless they were doing something stupid. From what I've heard, the only real benefit to an eagle crank is more accurate machining from the factory, and that they are available in stroked versions of 6 and 7 bolt, so there is no junkyard hunting necessary.

 

[96eclipseawd]

Ok, thats what I was hoping to hear. So will an aftermarket stock crank from an online company be as strong as the mitsu oem crank? I found a brand new 7bolt crank for 200 online. So if it can hold 500, i'll just get it. I don't want to have mine ground down, because I've already bought new std. size acl race rod/main bearings. This is the one i found on ebay, it's 190 shipped. New Eclipse Talon Laser 2.0L Crankshaft 93-99 7 bolt:eBay Motors (item 150347491665 end time May-30-09 07:34:57 PDT) . He has a few of them.

 

[tkelly27]

I can't say if an OEM one off of ebay will, but one from the junkyard will.

The 500whp E316g did it on a stock 7 bolt bottom end. Takes a hell of a tune to do it on those rods, pistons, and turbo, but the crank is not the limiting factor.

 

[96eclipseawd]

I have scat rods and race acl's, but haven't bought the pistons yet. The new OEM one I found was as much as an Eagle. Slowboy has a topline new crank for 450, but I dont know how strong they are. Anyone know?

 

[twicks69]

I would trust OEM Mitsubishi anyday over Scat, Eagle or Topline.

I have seen quality issues with the Eagle and Topline cranks, and I wouldn't use them if I had the choice of a Mitsubishi OEM crank.

As well, Eagle rods are a good choice for a cost-effective and reliable rod.

They lasted 3+ years in my car putting down ~1000HP at the crank without issues, and I never had a problem with the rods or rod bolts themselves. I would recommend that if you are going to be running very high rpms (over 8000rpm on a 2.3L or over 9000rpm on a 2.0L), and high boost (over 35psi) that you check and replace the rod bearings every 20,000-30,000 miles because they will tend to get pounded out from the really high boost and high rpm abuse. It is just standard procedure on any high-performance engine to check rod and main bearings more regularly.

Scat rods are nearly identical to the Eagle rods, but I have not tested them to know what their capabilities are, or their quality.

Good luck with your buildup!

 

[bigf4]

If you go with aluminum rods you can forget about the bearings. Since aluminum rods take more of the stress than your standard forged metal rod.

 

[Blak Pearl]

I dont trust the top line cranks..OEM is the way to go..I've seen cars at 600 to 750hp on the stock cranks..if your gonna want more than that down the road i would go with the eagle crank. The Scat rods i dont like because i blew up 2 sets of those at 517hp 412tq.

 

[joe sobo]

i also am in the market for a cheap crank, and the ones on ebay are horrible . i used one before that was oem. they are NOT oem. i broke one with a pte 60 trim turbo at30 psi.i forget which one but there is a supporting vendor on here that i just talked to on the phone last week and for a non-reground crank that is polished and is within all specs, it was like 390.00 to your door. it was dsmgraveyard now that im thinking of it. the 7 bolt kit with bearing is 329.00. or if you want a un-cut, the crank is 399.00 plus 75 for bearings. but when i talked with him on the phone, they are awesome people, and i told him my concern on wanting a un-cut crank, they made me an awesome deal on the price . so call them and i beleive that the guys' name is austin is who will treat you like family

 

[96eclipzGsT]

It will crankwalk before it breaks.