6 Bolt vs 7 Bolt

Alrighty... I've been doing a lot of reading and have heard many opinions on this. From what I can tell, people have completely blown the whole "7 bolt is worthless" theory out of proportion. I have read how the 7 bolts are designed so much better but the only problem they have is the higher possibility of crankwalk. (I know all about that. :rolleyes: )

Anyways, I have been looking for the most common "fixes" for crankwalk. The biggest theory is the thrust bearing failure theory. I haven't heard of any other possible causes for crankwalk though. So heres what I'm thinking... If I decide to build a 7 bolt using clevite bearings and a synthetic oil, I should have no problems with crankwalk. The one thing I've been searching for is how many people have built their 7 bolts though and I can't seem to find vey many at all...

I guess what I really want in this thread is opinions on this very subject. It would be a lot easier to just keep my 7 bolt and build it and put it back in my car. But I fear spending thousands of dollars on a motor only to have it crankwalk again. I could go the 6 bolt route but then I would have to rewire my CAS and change a few other little things and I would probably have more money in that route than I would the 7 bolt...

Oh yeah, the compression ratio... Thats another thing that I wondered about. I have read that the 1g's have a compression of 165 and the 2g's are 190. With the lower compression you can run more boost before worrying about detonation, right? But, with higher compression (190) your turbo will spool quicker and be more efficient in its power building?... Another plus to the 2g's is the heads can be more efficient than 1g's if ported out?...

I just wanna make sure I cover everything on here with you guys before I start buying things. I would hate to do this wrong and have to redo anything... Thanks for any input I get on this. :)

Oh yeah, the compression ratio... Thats another thing that I wondered about. I have read that the 1g's have a compression of 165 and the 2g's are 190. With the lower compression you can run more boost before worrying about detonation, right? But, with higher compression (190) your turbo will spool quicker and be more efficient in its power building?... Another plus to the 2g's is the heads can be more efficient than 1g's if ported out?...


the 8.5: compression of the 2gs seem to be the basis for most turbo applications, low enough to run as much boost as you want but high enough for a decent low end. As far as the heads go, the 2g has a more efficent design but the 1g will flow more air. Its impossible to port a 2g out even to match a stock 1g so as far as the head I would go with a 1g no matter what. Oh and the cam/crank sensor, I dont see why you cant use your stock units.

The crankwalk is coming from inferior cranks. They are only hardened like 2 Thousandths thick. The thrust washers are actually chewing into the cranks.

Here check this out man, this guy goes threw a 6 hour hardening process on the crank. Call him he will be happy to talk to a future costumer, he knows his shit!!

http://www.overbore.com/

Just enter site and you will see 7 bolt crankwalk fix

What are we supposed to check out? To me it doesnt make any sense that the bearing would "chew" into the crank. I dont get how that would cause excessive end play

the 8.5: compression of the 2gs seem to be the basis for most turbo applications, low enough to run as much boost as you want but high enough for a decent low end. As far as the heads go, the 2g has a more efficent design but the 1g will flow more air. Its impossible to port a 2g out even to match a stock 1g so as far as the head I would go with a 1g no matter what. Oh and the cam/crank sensor, I dont see why you cant use your stock units.


I read online somewhere that if you can get your 2g head ported out it would kick the shit out of the 1g head. People have ported there 2g out. I will have to do some search to find link but if i can find it again i will post.

I read online somewhere that if you can get your 2g head ported out it would kick the shit out of the 1g head. People have ported there 2g out. I will have to do some search to find link but if i can find it again i will post.
My 2g head is ported:wink: I'm sure you can get a 2g head to flow better than a stock 1g head but it is impossible to get the runners on the 2g to match up to a stock 1g let alone a ported 1g so I think that a 1g would be a better option because with porting a 2g couldnt touch it.

What are we supposed to check out? To me it doesnt make any sense that the bearing would "chew" into the crank. I dont get how that would cause excessive end play
Think about it... When the clutch is pushing on the crank and the bearings are in place, the crank is actually putting pressure on the passenger side of the bearings... I'm sure with enough of that on cheaply manufactured cranks will cause the sharp edges of the bearings to start to wear into the crank and then the crank gets that little bit of play in it. So it wouldn't necessarily be thrust bearing failure, but cheap crank failure which would appear to be the result of bad bearings. :wink: Did I explain that correct Talon69?

What are we supposed to check out? To me it doesnt make any sense that the bearing would "chew" into the crank. I dont get how that would cause excessive end play

The bearings are harder than the crank, so when the bearing wears into the crank you get excessive end play. Call this guy that i listed in above. He is in big import magezines and he his also the #1 4g63 machine shop on the east coast. Just call him and talk to him i cannot sit here and vouch for him. I met him in person at a import show. He knows his shit.

My 2g head is ported:wink: I'm sure you can get a 2g head to flow better than a stock 1g head but it is impossible to get the runners on the 2g to match up to a stock 1g let alone a ported 1g so I think that a 1g would be a better option because with porting a 2g couldnt touch it.
Thats why you get an aftermarket intake manifold too. :wink:

When i took my engine apart i had some where in the crank. When i got my new bearings i measured them to the old ones. They were almost the same.
Im not saying i know what the cure is im just saying what this guy says about solving the prob.

Thats why you get an aftermarket intake manifold too. :wink:
What I'm saying is that if you compair the runners on the 2g head to the runners on the 1g head you will see that the 2h head has litterally half of the size runners as the 1g head has and there isnt enough material on the 2g head to port match the head to a 1g intake manifold. Here look at this http://www.vfaq.com/mods/1G-2G_intake.html that compairs them to each other

I am lost.:banghead:

What I'm saying is that if you compair the runners on the 2g head to the runners on the 1g head you will see that the 2h head has litterally half of the size runners as the 1g head has and there isnt enough material on the 2g head to port match the head to a 1g intake manifold. Here look at this http://www.vfaq.com/mods/1G-2G_intake.html that compairs them to each other
Yes I see how much different they are. But what you could do is port it out as much as possible and then get an aftermarket intake, cut off the flange, have the runners taper down some to match it and then make your own flange. The only advantage to having it taper slightly is that it'll speed up the air speed going into the head. Its a full proof plan. :wink:



I think. :uhoh:

I still really think that you could port out a 1g head to be WAY better than any 2g head you could get. I had a discussion with kevin about this a while back. http://www.automotiveforums.com/vbulletin/showthread.php?t=499641&highlight=1g+head+2g there is the link

Ehhh where's Kevin when you need him? lol

Ehhh where's Kevin when you need him? lol
For real... Keeeevin, come help us... Please?... :iceslolan

My brother is "building" his 7bolt. He had all the internals cryoed. I don't believe any of these "fixes" for cw, there is no one testing this in a lab, so i i do something and my crank doesn't walk who's to say it wasn't going to walk if i didn't do it? Thats why you have controls in experiments. I don't think any poor-ass dsmer has a lab to set up a couple hundred engines running different "theories" on each engine. I say go 6bolt. Honestly i think it's the best solution to crank walk.

so if you where to get an aftermarket crank will it help with the cw problem? Thats what i get from what all of you are saying.
http://www.slowboyracing.com/more.php?id=5413&;

so if you where to get an aftermarket crank will it help with the cw problem? Thats what i get from what all of you are saying.
http://www.slowboyracing.com/more.php?id=5413&;
In theory it should... I looked at that same crank on SBR and was wondering if that would be good enough to do the trick.

http://members.shaw.ca/costall/1000Q/answers-terms.htm#whatiscrankwalk
According to that crankwalk doesnt have anything to do with the crankshaft. I'm not trying to start another debate, I just want to show you guys that apparently there isnt any definate cause of crankwalk

A 'walking' crankshaft is a crankshaft that moves too much inside the engine. This is also known as excessive thrust bearing play. The movement is usually due to the crankshaft not fitting inside its bearings correctly. While not bad for the crankshaft, the movement can place excessive or uneven loads on the bearings, causing premature failures.

Many 2G owners have suffered from walking crankshafts. It appears that Mitsubishi built many 2G engines using defective crankshafts, which were machined out of specification and are thus capable of moving around too much inside the block. All 2G model years appear to be affected to some degree.

To fix this problem, Mitsubishi has designed several versions of matching crankshaft bearings. This allows the defective motor to retain the crankshaft, yet matches the bearings correctly so as to eliminate the excessive crankshaft movement. Matching the bearings in this manner is tricky and requires exact information about when the crankshaft was manufactured, which may be determined by color markings on the crankshaft itself. The 2G factory manual includes information on how to match crankshafts to bearings.
Right there it says "defective crankshafts" which cause "excessive or uneven loads on the bearings, causing premature failures."

It still points to the crankshaft as being the main cause for crankwalk. But it also says that Mitsubishi offers bearings that fit these cranks better. So now heres what I'm wondering... If we were to just buy Clevite bearings, it could still crankwalk because they would be fitted the same as OEM bearings would be on the crank. So not even an aftermarket crank would help in this situation... If it all follows correctly with this theory...

Would a 6 bolt crank and bearings fit into a 7 bolt block?

In the first paragraph is says that the crank doesnt fit in the bearings, which inst bad for the crank, but causes premature failure of the bearings

Yeah, but the only reason there is any movement at all is because the cranks are machined to the wrong size. Which it said they later released a bearing to better fit these cranks... I wanna know if the Clevite bearings follow the original OEM sized bearings or these redesigned OEM bearings... Either way though, my crank is probably scarred and will need machined and balanced but then none of the bearings will fit it properly. Thats the reason I wanna know if the 6 bolt cranks will fit cause I could just get an aftermarket 6 bolt crank and then match it up with some 6 bolt bearings if they will fit in the block. I can't find anywhere online though that tells me the sizes of these bearings or anything... It kinda sucks. lol

The crankshafts are not hardened to the correct thickness.

well if you dont mind waiting I could probably look up the specs tomorrow at work/school

well if you dont mind waiting I could probably look up the specs tomorrow at work/school
Yeah I don't mind... I'm not in any rush. lol I wanna make sure whichever route I take, I take it right.

Can you get the specs for the 6 bolt and 7 bolt cranks and bearings?

yeah, I have access to both mitchell and all data so Ill get them for you

I also want to build my 7 bolt. The only thing that is holding me back is the same as you... fear of the dreaded cw after $2000+ into the motor. I am not trying to highjack your thread or anything I am just glad someone else is in the same spot as I am lol.

Also I posted this before but, I have heard of cw being partly caused by aftermarket clutches. Supposedly the extra pressure they have helps cause cw.

I also want to build my 7 bolt. The only thing that is holding me back is the same as you... fear of the dreaded cw after $2000+ into the motor. I am not trying to highjack your thread or anything I am just glad someone else is in the same spot as I am lol.

Also I posted this before but, I have heard of cw being partly caused by aftermarket clutches. Supposedly the extra pressure they have helps cause cw.
It's cool, theres no way you can highjack this thread. It is open to all. :)

As for the clutches, yes they don't help it any. But, I think the reasoning in that is what Talon69 said, the cranks aren't hardened deep enough so they wear out too quick and then the bearings wear into the crank... From all I've read, it seems as if the bearings are a harder metal than the actual crank, which is no good to us. I'm thinking if we can find a harder crank and bearings that are softer than the crank but harder than oem bearings, and that fit better, then we should be able to do it...

Apparently Mitsubishi released a second version of their oem main bearings which fit these "defective cranks" better. If that is the case then there is hope for us. But then you run into people like me whose cranks are scarred and need to be machined. If I machine it and try to fit it with the v2 bearings then they won't fit any better than the v1 bearings after my machine work. So, pr_ricer is gonna get me the measurements from his school from all the cranks and bearings so I can figure up a solution... Hopefully. lol

don't know how I missed this thread....

there are several theories on what causes crankwalk. Personally I believe that mitsu had a defective mold when building the engines. If this is the case, there isn't any cure for crankwalk. Other theories like oil squirters etc. don't really make much sense to me. Otherwise they would all walk around the same time, but that's not the case. It doesn't really depend on how much you mod it or how hard you drive it, which helps me believe the mold theory.

Personally I think the "crank walk" fixes out there are completely BS. If a 7bolt is going to walk, it usually does before 100k, if my 7 bolt makes it past this, then I will probably never switch to a 6bolt, no point. The power differences for someone with my type of setup just are not that apparent.

don't know how I missed this thread....

there are several theories on what causes crankwalk. Personally I believe that mitsu had a defective mold when building the engines. If this is the case, there isn't any cure for crankwalk. Other theories like oil squirters etc. don't really make much sense to me. Otherwise they would all walk around the same time, but that's not the case. It doesn't really depend on how much you mod it or how hard you drive it, which helps me believe the mold theory.

Personally I think the "crank walk" fixes out there are completely BS. If a 7bolt is going to walk, it usually does before 100k, if my 7 bolt makes it past this, then I will probably never switch to a 6bolt, no point. The power differences for someone with my type of setup just are not that apparent.
See, I have wondered too about the molds being different but don't have any way to compare the two. Has anyone seen a comparison picture anywhere online for this? Also, mine walked at 105k miles which makes no sense to me if it is indeed the mold. See, I changed to a 2600 lb clutch at about 90k miles... So if it is indeed the crank theory then that would put it at about 15k miles on my motor with the new clutch. Its because of my situation that I am leaning towards the defective crank theory...

Just build a 6-bolt? You can pick up a block for like 200 bucks.

ok brain I got the specs for you. The 6 bolt crank main journal measures 2.44" and the 7 bolt spec is 2.441" so they seem interchangable to me

This THREAD should be CLOSED!!!! its getting in the bullshit with crankwalk to much. Like the other 50 threads on this lol It did not start out for crankwalk but it just will not die PLZ close

We are concerned about cw because that is the only thing holding us back from building our 7 bolts.

Okay so, the other day I pulled out the big ass packet of garage bills and such the person gave me when I bought the car. My car has 145K miles on it now. However, in the reciept for the "rebuild" it says the previous motor was actually swapped for a new one. The diagnosis says the motor just died and would not turn over(maybe... cw). This all happened around 101k miles. So, I am wondering if the person before me was smart enough to go with a 6 bolt or not. I have read that you can tell the difference between a 7 bolt and 6 bolt by checking the shape of the oil pan( http://www.vfaq.com/mods/early-late-engine.html ). I do not think the oil pans are interchangable so I will be doing this asap.

Oh and the interchangable crank idea sounds very interesting.

This THREAD should be CLOSED!!!! its getting in the bullshit with crankwalk to much. Like the other 50 threads on this lol It did not start out for crankwalk but it just will not die PLZ close
Why do you want this thread closed now? We are trying to get all the important technical aspects of crankwalk together so we can determine a possible solution to it... Shouldn't you also be wondering the same since your building your 7 bolt as well? :wink:

Look how close we are getting, pr_ricer has given us very specific info on the cranks main journal. We now know that the 6 bolt and 7 bolt cranks are possibly interchangeable... This may be the greatest thing everyone has overlooked. Perhaps all the 6 bolt swaps could have been avoided if its as simple as swapping out the cranks and bearings from that of a 6 bolt. It sure would make things a lot simpler with building a 2g. :)

If you want I could get all of the block specs tomorrow and see how they match up to

How do you know when your car is crankwalking. I mean what are the symptoms when your driving. Is it hard to find second gear when making a left turn, cause thats what I used to have and assumed it was crankwalking. When i got my engine rebuilt it fixed whatever problem that was except that now I fear it returning??

check the crankshaft end play

If you want I could get all of the block specs tomorrow and see how they match up to
That would be excellent. :)

One way or another, we will be the ones to solve this problem once and for all... Then I'll rock out with my monster 7 bolt. :smokin:

I say more power to you guys, if you can figure out a good solid solution to the 7-bolt problem. ;)

I personally will be rocking my 6-bolt. Hopefully I can make it to the track this summer so I can finally be dissapointed in how slow my car is going to run a 5000+ ft of elevation.

I don't think the cranks are interchangeable. Have you seen a comparison between the crank caps? Much much different. As i said before i don't think there is a way without a lot of testing to find a proven fix.