6 bolt vs. 7 bolt [merged] 6bolt 7bolt 6-bolt 7-bolt six bolt seven bolt

[asdfzxc]

All 6 bolt vs. 7 bolt threads are merged here.
How do I tell if I have a 6 bolt or a 7 bolt?
Will x part from a 6 bolt fit a 7 bolt?
Will x part from a 7 bolt fit a 6 bolt?
Which one is better?
How do I swap my x bolt for an x bolt?

What is the difference between 6-bolt and 7-bolt engines (aside from the obvious - 6 vs. 7 bolts connecting the flywheel )

Is there an advantage over either of the two engines?

Thanks,

-Mike

 

[snowborder714]

No, it's not.

 

[spadepro22]

No, it's not.

What I ment was as far as crankwalk sorry. My goal is no more than 350 to the wheels dd, so I still should be ok right with a 1g 7 bolt?

 

[snowborder714]

Yup, you'll be fine.

 

[spadepro22]

And if your building your block 6 or 7 bolt, does it really matter?

 

[snowborder714]

Not really. Tim Zimmer has put down some big numbers with a 7 bolt block. I do believe if you plan on building a 7 bolt, a lot of people recommend getting a 2gb one as it has the better thrust bearing (3 piece design, I believe).

 

[suprasalas]

whats the difference between the 6 bolt rods and the 7 bolt rods?? i know they say the 7 bolt is weaker but what is the difference in the mesurements of the small bore end the the big bore end??

 

[99gst_racer]

whats the difference between the 6 bolt rods and the 7 bolt rods?? i know they say the 7 bolt is weaker but what is the difference in the mesurements of the small bore end the the big bore end??

The big end has the same bore diameter on both. 7-bolt rods have a 1mm larger wrist pin though. The big difference is in the overall weights and the diameter of the "beam".

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[Jdbeast27]

Alright- I recently had a large issue with one of my rod bearings going out and I bought a 94' 7bolt engine to go into it. I plan to build a block on the side and the only performance difference I have heard about 7bolts vs. 6 bolt blocks are that the 6 bolts stock have stronger rods. With my 7 bolt block out of the original engine, I would be putting in aftermarket pistons, rods, crank, bearings, etc. So I wanted to know if I did that, would it be the same as building a 6 bolt considering all I have known the difference to be was stock internals which would be getting swapped anyway. Thanks!

 

[motomattx]

The big ports on the 1g head is desirable for drag racers, as is the larger head studs and the slim chances of crankwalk vs the 7 bolt, there are also it seems more aftermarket support for the 6 bolt in some ways.

 

[bling5tatus]

^^I wouldn't say the big ports are better until you're over a certain hp level. There are drag racers of many hp levels and I wouldn't expect to see any gains from using a 1g head until my engine was over the 800hp worth of airflow mark. Below that, I'm not sure why you'd sacrifice the larger power band..... so I do not agree that "it's better for drag racers" as a blanket statement.

I've crank walked a 6-bolt before. Further, if you want to talk about crank walk.... let's talk about EXACTLY what causes crank walk. I have a pretty good idea of what causes it, but I'm interested in hearing your thoughts since you brought it up as a weakness in this platform.

Head studs are as strong as the material and treatment processes they go through. I wouldn't doubt that a modern 11mm stud would have an issue holding the engine together under a lot of boost with a proper tune. 9% bigger isn't that much of a gain with 12mm studs. Serious racers would likely use a billet block anyway that can accommodate whatever size studs you want, or they'd go through the trouble of making a block handle whatever size studs they think it needs.

I'm not just trying to shit all over what you said, but I've seen issues in the past with people on this site (including some "wisemen") speaking authoritatively about things while simultaneously not being correct or considering the other angles to what they're saying. For instance, saying "6-bolt is better for drag racing" is kind of not a great thing to spread around when there are people that are potentially gullible and not as knowledgeable reading.

I've never ran a 7-bolt anything, but my race motor is a 2g 7-bolt.... and it's going to either be installed in a 1g awd chassis or my dodge colt if it doesn't sale on here. Before anyone goes keyboard cowboy and attempts to assert their "knowledge" about DSMs, I already know that a 2g engine won't just go into a 1g chassis. If I thought the 6-bolt engine was a better engine (which I have a plethora of spares for).... I'd be using that..... but I'm not going to.

 

[motomattx]

^^I wouldn't say the big ports are better until you're over a certain hp level. There are drag racers of many hp levels and I wouldn't expect to see any gains from using a 1g head until my engine was over the 800hp worth of airflow mark. Below that, I'm not sure why you'd sacrifice the larger power band..... so I do not agree that "it's better for drag racers" as a blanket statement.

I've crank walked a 6-bolt before. Further, if you want to talk about crank walk.... let's talk about EXACTLY what causes crank walk. I have a pretty good idea of what causes it, but I'm interested in hearing your thoughts since you brought it up as a weakness in this platform.

Head studs are as strong as the material and treatment processes they go through. I wouldn't doubt that a modern 11mm stud would have an issue holding the engine together under a lot of boost with a proper tune. 9% bigger isn't that much of a gain with 12mm studs. Serious racers would likely use a billet block anyway that can accommodate whatever size studs you want, or they'd go through the trouble of making a block handle whatever size studs they think it needs.

I'm not just trying to sh** all over what you said, but I've seen issues in the past with people on this site (including some "wisemen") speaking authoritatively about things while simultaneously not being correct or considering the other angles to what they're saying. For instance, saying "6-bolt is better for drag racing" is kind of not a great thing to spread around when there are people that are potentially gullible and not as knowledgeable reading.

I've never ran a 7-bolt anything, but my race motor is a 2g 7-bolt.... and it's going to either be installed in a 1g awd chassis or my dodge colt if it doesn't sale on here. Before anyone goes keyboard cowboy and attempts to assert their "knowledge" about DSMs, I already know that a 2g engine won't just go into a 1g chassis. If I thought the 6-bolt engine was a better engine (which I have a plethora of spares for).... I'd be using that..... but I'm not going to.

Which is why your defending the 7 bolt..."because its what I have" I am not going to re-hash decades of knowledge and facts about the 6 bolt vs 7 bolt engines, if you want to pretend that the 7 bolt doesn't have crankwalk issues and smaller lower flowing ports and smaller weaker rods and smaller weaker head studs , then there's no point in even going down that road with you, look if it makes you sleep better at night then thats what you can believe, decades of people racing the 4g63 has proven otherwise, believe what you want and nit pick whatever facts that you want, while its true that liars sometimes figure, its also true that figures never lie. Ive crankwalked a big block Chevy, that doesn't mean that they have a crankwalk problem like the 7 bolt 4g63, they are known for crankwalk for a reason, like it or not, they are weaker in several different areas, its not debatable 12mm studs are stronger than 11mm studs in the same material period, smaller rods are weaker than bigger rods of the same material period, smaller ports flow less than larger ports period like it or not.

There was obviously a problem with the 7 bolt 2g engine, Mitsubishi fixed it in the Evo, they know it was a problem because they knew how to fix it, the 2g 7 bolt was made in USA, something went wrong, my guess is a combination of things, including poor iron content in the blocks, not hardening the crankshafts properly and the 2g clutch pedal not self adjusting and causing pedal pressure to remain applied to the crankshaft, not allowing oil to enter the thrust face of the main "thrust" bearing, couple that with the lack of zinc in the motor oils in that time and manufacturers not hardening engine parts to make up for it and you have crankwalk, GM went through it with cam lobes getting wiped off due to lack of zinc in the oil during that time as well, they now harden the cams and or use roller lifters to make up for the loss of zinc. The clutch pedal alone isnt the only problem, plenty of guys install a 6 bolt and leave the clutch pedal setup alone and dont get crankwalk ever again, so its not the only problem or just a single problem, its a combination as I said, couple those with an aftermarket heavy clutch and forget it.

Notice also that I said the 6 bolt head is chosen for drag racing more often, I have flow benched both the 6 bolt and 7 bolt heads and the 6 bolt flows better, simple as that, as far as giving up a powerband for extra flow, I'm not entirely sure what kind of a broad power band you believe a drag racer is looking for but I'm fairly certain that any serious racer is looking for maximum power over drive-ability.

 

[bling5tatus]

Welp i only got through your first sentence and already see where you're 100% wrong. I get it, you have an axe to grind, but you sound like one of the old carburetor rednecks that says "it's just better, it's easier."

I think ti's funny how you're seriously going to sit here and argue with the engineering of a team of paid engineers at Mitsubishi about what is better or not. Crank walk isn't a thing anymore. The cars that were going to crank walk have already done it.

I have a single 2g 7 bolt motor and like 8 6-bolt 1g motors so "it's what I have" is you being full of balogna. I'll read the rest of your (likely bs) post when I get home from work.

 

[motomattx]

Another one of my buddy's car crankwalked two months ago, so they haven't all crankwalked by any means, argue with an engineering team at Mitsubishi? why do you think there are recalls? why do you think the 2g crankwalked yet the 6 bolt isn't known for it and the Evo isnt known for it? you seem to put blind faith in the engineers and its proven fatal in plenty of circumstances, (GM ignition switch recall that cost plenty of people their lives) (Takata airbag recall that cost plenty of people their lives), there is no arguement here with Mitsubishi engineers, as an engineering student myself, they were simply wrong on their calculations or expected real world use of their product, simple as that, mistakes are made, nobody's perfect...this doesn't mean that the 7 bolt was intentionally junk, it was accidentally junk instead, they rested on their laurels and it bit them in the a$$ thats all, they cheapened and lightened the 4g63 to save fuel for cafe standards and to keep it light for fuel economy and also made the engines with smaller fasteners and in the USA to simply save cash and maximize profits, very simple really just follow the money, the believed that they could make those changes and still have a stout engine and instead found out that they just found the limits of the materials and it cost them bundles in warranty money, they changed it back to better materials on the Evo and found other places to cut costs such as the cheap interior, no argueing with the engineers here, I'm smarter than that, I know what they did and why already!