Crankwalk potential on my setup

[thekyguy11]

Well, I am building a 96 turbo awd basically from scratch. I have not yet begun assembly, but here is the list of mods on the bottom end already done...

7bolt block (I know, shoulda done 6)
JE pistons
JE rings
Eagle rods
bored over .020
Federal Mogul bearings
micropolished crank
internals balanced
All the head mods and bolt-ons to go with it
(using GM blowthrough setup)

Now, I would like to see 500 ponies at the wheels, and I dont really plan to push it any further than that (even tho I know it will have potential to go MUCH higher). I also know that crankwalk has always been an issue in some these 7bolt motors, and obviously I want to avoid it.

Here is my question... Seeing that I have all brand new, and/or freshly machined parts, all top of the line (or close enough), can I run 500 whp reliably and not have to worry about crankwalk?

 

[pballernh]

The threat of crankwalk will always be there....it is with just about al engines. 7bolts happen to be more prone due to faulty design. You basically have a fresh engine but it still has the design flaw(s) in it. More power will most definately put more stress on all components and will most likely speed the crankwalk process along. Depending on the clutch you're using that may be a big one. You may never see crankwalk but the chances are definately more likely with your setup now.

 

[OverboostXS]

Its not soo much a design flaw there are many theories on why it occurs. they do have the incorrect bearings, also the oil squirter theory. 2 things that can be easily corrected while rebuilding your engine. I just finished my 7 bolt(shoulda done a 6) but i drilled and tapped out my squirters. Hopefully it lasts.

 

[DSMJim]

Guys who rebuild 7 bolts do anything and everything to keep them from crankwalking. Dowels for the bearing caps, ARP studs to keep them from stretching, crazy thrust bearings and coatings and all kinds of crazy shit and guess what. They still walk.

Honestly it's more like luck of the draw, if its gonna walk you can't stop it. Some guys rebuild the 7bolt and it's ok.

I was in your same situation and went with a 6 bolt just because I didn't wanna chance it and spend all that money for nothing if it went. For the small extra cost I simply could not justify playing with fire for a couple hundred bux extra for the block and mods needed to make it work properly.

 

[qtxdevilz]

after all ive been through with my crankwalked 95...all i have to say is good luck...

 

[gixrman]

I read on here awhile ago about one guy who changed his main bearings every 20K miles to hold off CW. Not a bad way to deal with it if your willing to drop the oil pan all the time. I have 108K on mine now and I think its starting to show signs, just might try that until I have my 2.4 built.

 

[thekyguy11]

Has anyone had any experience with overbore.com's solution? I was just reading about it yesterday and they claim to have come up with the solution. I still dont know what they do yet, but they said to me that they "do all the block corrections on 7 bolt motors." Havnt gotten a price quote yet, but I am considering that option.

O, and I am using an ACT 2600 clutch.

 

[pballernh]

There's no proven solution to fix crankwalk. There's no proven reason for why crankwalk happens, just many theories.

 

[thekyguy11]

ok, well apparently overbore.com only sells shortblocks with the "corrections" already done.

 

[waiting2bl33d]

the act 2600 isn't going to help at all switch to a centerforce dual friction trust me umm and about overbore.com he seems like a nice guy told me that if my 7 bolt that i was going to buy from him walked he'd build me a 6 bolt as long as i gave him the 7 bolt back might want to give him a call though. its worth it make your own decision about it he drives a gsx a fellow DSMer and maybe hes on to something w/ over sizing the bearing (i think thats what he does)

 

[DSMJim]

Why even bother? You can buy a 6 bolt bottom end so friggin cheap and not even worry about it. Still use your 7 bolt head so you don't have to do anything with respect to the swap. All that you have to do is shave one mount thats it. Big friggin deal.

Honestly for all the trouble you may get in to save what $200 for a block and crank? Thats like down shifting and wearing out your $500 clutch to save a set of $40 break pads, just doesn't make sense.

 

[OverboostXS]

6 bolts will be harder and harder to obtain for such cheap costs finding an alternative Via fixing crankwalk for good will open the door to more good 7 bolt blocks to be on the road again. Physically the 7 bolt has nothing wrong with it.

 

[Baron4406]

Magnus has the best theory on crankwalk in my opinion, the best advice in this thread is GET A 6 BOLT!!! If you must have your 7 bolt then follow their advice on ditching the stock oil squirters and upgrading to 1g oil squirters.

 

[thekyguy11]

1g oil squirters???? Woudn't I be better off just eliminating them, if anything?

 

[gixrman]

1g oil squirters???? Woudn't I be better off just eliminating them, if anything?

Very true, many builders just elimate them when going to forged pistons.

 

[BoostinAWD]

I like nos lasers theory that the blocks had weak nickel content cause mitsu was trying to cut costs because the high overhead from coming out with a complete new car 2G.

Basically he says bolting the head on causes the block to get bent out of true just a hair.
I would suggest you have him assemble your 7bolt or go through his assemble pattern with your builder. It requires the use of a torque plate while assembling the motor or simply installing the head before you crank down on the crank. Along with repeating that process several times to check where clearances are each time.

Its been like 2 years and I havent heard of any of his 7bolts walking yet.

Just thought you might want to know..

 

[thekyguy11]

Thank you BoostinAWD, that is the kind of advice that I have been waiting to hear. What you said does make sense, and I would really like to know where you got that information from, because I can assemble that way if it will reduce the probability of the crank walking.