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

 

[10's or bust]

You can use his pistons with your rods...that's actually the stronger and more ideal setup

 

[dimon2000]

can I use his rods too or I can only use his pistons and my rods?
I will try to post some pics I think that would make it easier to understand. My rods look thiker and stronger. His look thiner but machined better from what I can see plus I know that the 7 bolt engine can take more power, so i guess the piston and rods should be better than mine. I'm really new to this so any help will be great.
thanks for you time

 

[BenGSX]

can I use his rods too or I can only use his pistons and my rods?
I will try to post some pics I think that would make it easier to understand. My rods look thiker and stronger. His look thiner but machined better from what I can see plus I know that the 7 bolt engine can take more power, so i guess the piston and rods should be better than mine. I'm really new to this so any help will be great.
thanks for you time

Backwards.. The 6 bolt engine can handle more power stock..

The 6 bolt rods will have to be machined at the small end to narrow them to fit in the 7 bolt piston.

7 bolt rods are about as strong as chicken bones..

As seen here..

You must be logged in to view this image or video.

 

[synthetek]

Was your friends talon a 1g or 2g? The prefered setup is to use 2g 7 bolt pistons (which are higher compression) with the 6 bolt rods (which are stonger) but the 6 bolt rods will need to be machined to accept the 2g pistons. You can not use 7 bolt rods in a 6 bolt. If your friends talon was a 1g 7 bolt then you should just use your pistons (or get some 2g pistons) & rods, if it was a 2g you should use your 6 bolt rods & his pistons.

 

[dimon2000]

my friends talon was a 1993 1g. I was sure his would work because it looks the same as mine wow didnt know that. Plus i thought the 7 bolt is a stronger engine anyways thanks alot guys for the help. I have another question. My engine over heated and worped the head thats why i'm kind of rebuilding the engine and while i'm at it decided to make it better. anyways i have his 7 bolt head which looks the same as mine (just like the pistons haha). his for some reason has 2 extra holes in it and mine doesnt, and my bloke doesnt have them either,but the original headgasket did I guess for an option. So I was wondering if I can use his 7 bolt head on my 6 bolt block?
thanks again

 

[JayRolla]

If you match up a 7 bolt crank and a 6 bolt crank you will notice the 7 bolt crank is a little beefier. When using oem parts the 6 bolt rods are way stronger. When building a stroker the 7 bolt crank is a better candidate than the 6 bolt crank.

 

[dimon2000]

hey
well I guess I solved the piston and rod problem so thanks for that. Now what about the 6 bolt,7 bolt head difference? because i want to use the 7 bolt head on the 6 bolt block. and it seems the 7 bolt head has 2 more cooling holes or oil holes than my other one? and my block doesnt have these extra holes.

 

[JayRolla]

Im not possitive but I think you need to drill the holes out to make it work. Also I thought I heard someone say the bolt holes are larger and need to be drilled and tapped to work. Im not positive though.

 

[Zex4g63]

7 bolt rods are about as strong as chicken bones..

I'll have to disagree. People find a way to blow up stock 6 and 7 bolts all the time. Blown motors are usally caused by operator error. And based on that pic, it looks like a piston failed, not the rod.

 

[dimon2000]

so over all can i use 7 bolt pistons/rods on my 6 bolt engine?
can i use the 7 bolt head on my 6 bolt block?
is there any benifits in using the 7 bolt pistons/rods or just put my original ones back?
and what should i do about the 2 extra holes i have in the 7 bolt head?

 

[synthetek]

No, read my post above, you can not use the 7 bolt rods on your 6 bolt, you can use the pistons but since they are from a 1g there is no benefit, if they were 2g pistons they would be higher compression. you should just use your rods and pistons unless they are damaged. You can use the 7 bolt head but the holes where the head bolts to the block will have to be drilled to accept the head bolts. The head gasket should block those 2 extra holes.

 

[dimon2000]

thanks guys for all the help now i'm going to start putting it together

 

[JayRolla]

I'll have to disagree. People find a way to blow up stock 6 and 7 bolts all the time. Blown motors are usally caused by operator error. And based on that pic, it looks like a piston failed, not the rod.

The 6 bolt rods are way stronger, thats why they call them the big 1g rods. But you are right usually motor failure is due to a bad buiid, tune or something along those lines.

 

[BenGSX]

I'll have to disagree. People find a way to blow up stock 6 and 7 bolts all the time. Blown motors are usally caused by operator error. And based on that pic, it looks like a piston failed, not the rod.

Yah.. I just like the picture

Piston melted..

My buddy sold his 2g and the kid who bought it cranked the boost way way up as he was leaving and blew the motor 1 block away..


BUT.. The 1g big rods are MUCH stronger than the 2g's.. Its the difference between running 400ish wheel horse on the bottom end and not worrying about it.. or constantly waiting for the sound of a rod to punch through the back of your block when you go WOT.

Not to mention bearing surface area..

 

[McFox]

Ok before you start to yell, yes I do know the 6 bolt is stronger than the 7 bolt is.

My question however is what about rebuilds. I'm wondering if the block itself is stronger, and not just the internals. If I plan to replace everything (rods, pistons, bearings, yada yada) does it matter which block I get? Hope that makes sense to someone out there.

 

[bling5tatus]

Man, you're trying to start a religous war aren't you. Crankwalk is only on a small percentage of 7 bolts, don't go believing everything you read. As far as the blocks are concerned, I'm sure they're nearly the same, and I wouldn't worry about which is "stronger" than the other. I would get a 6 bolt, but that's just my opinion.

 

[jbramble2]

Here's some good reading for ya.


http://www.magnusmotorsports.com/tech/crankwalk.htm

 

[Dsmboy1991]

You say you are going to replace everything "(rods, pistons, bearings, yada yada)" but what car is it going to go into? The car in your profile is NA 2g (with turbo) which has the 420A. If you are looking to put a 4g63T into that you have alot of work ahead of you, and not just engine...drivetrain as well. But to answer your question, 6 bolts have been known to hold up to more abuse. If you are looking to build a 7 bolt I would recommend the split thurst version from late 98 to 99. For these has better oil flow and put less strain on the crank bearings. Therefore lessing the chance of crank walk.

As for the blocks themselves very little difference besides the internals however the cranks are not interchangeable. If you want 6 bolt crank you need 6 bolt block same with 7. Any other questions let me know.



Jon Nye

 

[MelloEclipse]

Here's some good reading for ya.


http://www.magnusmotorsports.com/tech/crankwalk.htm

that was some good reading right there! *gives my 97 gst an evil eye...*

 

[McFox]

I'm sorry I started that discussion on crankwalk. Thats not what I was trying to say.

I know the 6 bolt's internals are much stronger and hold more than the 7 bolt. I was just wondering about the core block, if there was a difference. But dsmboy answered, thanks.

As for about my car, the engine would go into a gsx or gst, whichever I end up buying.

 

[JayRolla]

My mechanic has been building dsm's for years. He highly reccomends if you build a stroker to build a 7 bolt. He has had some cranks fail on a 6 bolt stroker. Showed me the weak point on the crank and showed me the 7 bolt crank. Its a lot beefier. If your building a 2.0l he reccomends a 6 bolt for high rev.

 

[mhuffman]

My mechanic has been building dsm's for years. He highly reccomends if you build a stroker to build a 7 bolt. He has had some cranks fail on a 6 bolt stroker. Showed me the weak point on the crank and showed me the 7 bolt crank. Its a lot beefier. If your building a 2.0l he reccomends a 6 bolt for high rev.

I thought the 6 bolt had heavier components, and that the seven bolt had lighter components shared with the evo at the time, so it would be better suited to higher rpm?

 

[JayRolla]

I thought the 6 bolt had heavier components, and that the seven bolt had lighter components shared with the evo at the time, so it would be better suited to higher rpm?

The 7 bolt has lighter rods and thats about it. The crank is a little heavier. When building a stroker you use all new forged internals so the weak parts are now gone.

 

[98GSt_4life]

The 7 bolt has lighter rods and thats about it. The crank is a little heavier. When building a stroker you use all new forged internals so the weak parts are now gone.

the crank in a 7 bolt is actually much lighter than the 6 bolt. i have one of each right next to me, and the 6 bolt crank has alot more material on it.

 

[JayRolla]

the crank in a 7 bolt is actually much lighter than the 6 bolt. i have one of each right next to me, and the 6 bolt crank has alot more material on it.

Wierd because when he compared them the 7 bolt seemed to have way more material. He showed me the spot where the 6 bolt is prone to breaking and then showed me the 7 bolt. It had more material in that area. Maybe its just that spot that is heavier.