6 Bolt vs 7 Bolt

[Blackcrow64]

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. )

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.

[blk_srt]

Originally Posted by Blackcrow64

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.

[Talon69]

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

[blk_srt]

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

[Talon69]

Originally Posted by pr_ricer

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.

[blk_srt]

Originally Posted by Talon69

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 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.

[Blackcrow64]

Originally Posted by pr_ricer

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. Did I explain that correct Talon69?

[Talon69]

Originally Posted by pr_ricer

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.

[Blackcrow64]

Originally Posted by pr_ricer

My 2g head is ported 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.

[Talon69]

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.

[blk_srt]

Originally Posted by Blackcrow64

Thats why you get an aftermarket intake manifold too.

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

[Eagalicious]

I am lost.

[Blackcrow64]

Originally Posted by pr_ricer

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.



I think.

[blk_srt]

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/vbul...ght=1g+head+2g there is the link

[clipsekid99]

Ehhh where's Kevin when you need him? lol