Is building a 7 bolt really worthless?

[twinkiemobile]

Hello,

I just had a couple of questions that some people maybe able to answer.

1.) If i was to build the 7bolt currently in my 95 GSX would I be making the wrong decision?
2.) If i was to build the 7 bolt, can i transffer the internals i.e. pistons and rods to the 6 bolt?(Although i have read that the 7 bolt rods are not as thick as 6 bolt rods)
3.) My car currently has 87xxx miles on it and is still running very strong. Would changing out the pistons and rods soon increase the chance of me getting CW?
4.) If i were to do a 6 bolt swap, i heard i would need the splicing wire(something from RRE) and 1 different mount? is there anything else? can someone give me a link to a clear write up. Thanks.
5.) Lastly, Who has a built 7 bolt motor that makes somewhere around 400+whp?

Thanks,
- Jose

 

[MrPikolo]

Hello,

I just had a couple of questions that some people maybe able to answer.

1.) If i was to build the 7bolt currently in my 95 GSX would I be making the wrong decision?
2.) If i was to build the 7 bolt, can i transffer the internals i.e. pistons and rods to the 6 bolt?(Although i have read that the 7 bolt rods are not as thick as 6 bolt rods)
3.) My car currently has 87xxx miles on it and is still running very strong. Would changing out the pistons and rods soon increase the chance of me getting CW?
4.) If i were to do a 6 bolt swap, i heard i would need the splicing wire(something from RRE) and 1 different mount? is there anything else? can someone give me a link to a clear write up. Thanks.
5.) Lastly, Who has a built 7 bolt motor that makes somewhere around 400+whp?

Thanks,
- Jose

Your 7 bolt should be able to handle 400+ whp without any problems. The 7 bolt rods are weaker in stock form than the 6 bolts, but people have still gotten over 500 whp on the 7 bolt stock bottom ends.

Building up a 7 bolt isn't a bad decison. There are many people that have built up their 7 bolt motor. But unless your goals are pretty insane, you won't need to.

 

[96whgsx]

Internals are not swappable between 6 and 7 bolt motors. You can use the 2g pistons on 1g rods with machining.

 

[ian7321]

well yes you can build a 7 bolt but before you even think about buying bottom end parts you are going to have to have someon if you dont know how inspect the crank and measure the side to side, there is a certain factory distance and if that has been increased then wait a month measure again if it is more than you will probably have to scrap the project.

 

[TargeT]

11.91 @ 114.4 with a 75 shot of n20 & 50,000 miles of abuse,, the stock 7 bolt is FINE for even the above average "user"

 

[gaddis]

This car is running a built 7-bolt. http://www.tappauto.com/project.cfm?ProjectID=1

 

[mean_green_98]

the most ive seen was on a FRESHLY rebuilt to 100% factory stock, was 583whp, that was on a straight T3. the cars from illinois, and he had alot of stuff done to it at AMS. Although, i did hear the next weeked at the track, it did blow a pistion. Building a 7 bolt is not a wast of time, most people done even see 400hp with there cars. you should have no problem. Im in the middle of building a 2.4 stroker 7 bolt. im shooting for at least 600 awhp. I wont have to worrie about crank walk though, im running an automatic*

 

[Mike000]

the most ive seen was on a FRESHLY rebuilt to 100% factory stock, was 583whp, that was on a straight T3. the cars from illinois, and he had alot of stuff done to it at AMS. Although, i did hear the next weeked at the track, it did blow a pistion. Building a 7 bolt is not a wast of time, most people done even see 400hp with there cars. you should have no problem. Im in the middle of building a 2.4 stroker 7 bolt. im shooting for at least 600 awhp. I wont have to worrie about crank walk though, im running an automatic*

I seriously doubt it will happen to you, but I have heard of automatics walking.

 

[Boost Junkie]

This car is running a built 7-bolt. http://www.tappauto.com/project.cfm?ProjectID=1

Not according to their site:
"Engine: Tapp Auto custom spec 2.4 liter"

 

[Syndicate13]

Not according to their site:
"Engine: Tapp Auto custom spec 2.4 liter"

And how do you know it's not a 7 bolt? I will be runing a built 7 bolt here very soon so we'll see how things hold out.

 

[Limegrntaln]

I wouldnt risk rebuilding a 7 bolt, 2.0 liter that is. I have done them before and they were line bored and done by a reputable DSM machine shop, still walked in under 900 miles. its just asking for trouble.

If Tapp has a 2.4 liter (4G64) in that car, its not a 4G63, unless its got a 100MM crank and a huge bore. I have never seen nor heard of a 4G64 walking and its a 7 bolt from the 95-99 non turbo motors. the 4g64 is a TOTALLY DIFFERENT "mold" block and crank arent anything like the 4G63.

These are safer 7 bolt motors to rebuild, not all 7 bolt motors are trash. but the only ones I would rebuild is the 4G64 and the 92-94 7 bolt 4G63. The 2G block and crank 7 bolt turbo motors suck..

They make a 6 and a 7 bolt 2.4 liter, more than likely tapps motor is a g4cs 6 bolt 2.4 liter. which isnt prone to walking. and like I said neither is the 7 bolt 2.4 liter 4G64.

This is just my opinion

 

[biglady112]

Limegrntaln, you couldn't be further from wrong. Sorry but 7 bolts can very well be built and hold the power like a 6 bolt. ANY motor can crank walk. 2JZ's have been known to do it quite a bit. H and B series hondas do a lot from me recent research. So can big ol american V8's.

My friends daughter's 97 talon puts down 450awhp. She traps over 120mph here at 5800ft above sea level. Another gentleman locally here in colorado puts down over 600AWHP on his 98 eclipse. That is a seven bolt too. You have to take the proper precautions and have a good motor to start with. That is the key. I have seen a few locally that began to walk, the rebuilt as a preventative move. All are still on the road today. They were just further out than they were from the factory.

So twinkiemobile, with that said you can make you decision. There is a crank dowel alignment kit that is a must when building eithe a 6 or 7 bolt. But, in my opinion leave it until it breaks. You would be very surprised how well the stock motor holds up. Lets say that me and a friend both trap 115(him) and 125+(me) on the stock motor. My car is not in my signiature. Its my girlfriends and I am not ready for it to be known about yet. They above mentioned friend is on a 50 trim, I have the good old SCM61.

Steve

 

[gaddis]

Not according to their site:
"Engine: Tapp Auto custom spec 2.4 liter"

Yes, it is a 7-bolt 2.4l 4G64.

 

[Limegrntaln]

Thanks for the reply Steve, Im glad I put "just my opinion at the bottom" if you read some of my other posts elsewhere, I clearly state that ANY motor can crankwalk. again this is just my opinion. Ive seen 19 7 bolt 2G motors walk, and I would and another half dozen or so walk shortly after they were rebuild, by BJs Or Jackson and other reputable DSM builders. I (myself) would never put a 4g63 7 bolt in anything.

"There is a crank dowel alignment kit that is a must when building eithe a 6 or 7 bolt. But, in my opinion leave it until it breaks"

Im not here to argue with anyone or flame anyone, but if I have to sit around and wait for a motor to break then I probably dont want to build it in the first place.

I know Hal out there in Colorado, hes got a 2G and I know he doesnt have a 7 bolt 2G motor in that car. Im sure people have had success with it. I just wouldnt build another one. let 100 more people post behind me, 90% of people wont build a 7 bolt 4G63

again just my opinion.

 

[ltho98]

Limegrntaln, you couldn't be further from wrong. Sorry but 7 bolts can very well be built and hold the power like a 6 bolt. ANY motor can crank walk. 2JZ's have been known to do it quite a bit. H and B series hondas do a lot from me recent research. So can big ol american V8's.

Never in my life have I ever seen a honda motor crankwalk--- ever. B series, H series, K series, D series.. never. They'll rod knock before they crankwalk.

Never ever seen a 2JZ crankwalk either but I have seen a 7MGTE once.

In anycase, building a 7 bolt isn't a bad idea. The 7 bolt crank is not nitrided which makes it weaker than a 6 bolt. Even so, 7 bolts can withstand gobs of power. If you just do rods and pistons it should be able to handle as much power as you will probably want to make out of it-- 500-600hp. Just be sure to bypass your clutch switch to help preserve the life of those thrust bearings and the motor will break something else before it crankwalks.

 

[Syndicate13]

Never in my life have I ever seen a honda motor crankwalk--- ever. B series, H series, K series, D series.. never. They'll rod knock before they crankwalk.

Never ever seen a 2JZ crankwalk either but I have seen a 7MGTE once.

In anycase, building a 7 bolt isn't a bad idea. The 7 bolt crank is not nitrided which makes it weaker than a 6 bolt. Even so, 7 bolts can withstand gobs of power. If you just do rods and pistons it should be able to handle as much power as you will probably want to make out of it-- 500-600hp. Just be sure to bypass your clutch switch to help preserve the life of those thrust bearings and the motor will break something else before it crankwalks.

You are one of the very few people who I have found that know this fact. Here is a viewpoint on this subject from a local guy who has many years of experience building DSM's.

Posted: Mon Mar 14, 2005 2:02 pm Post subject: 7 bolts and crankwalk, 6 bolt swaps

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I am 100% sure I have discovered why 7 bolts are more likely to crank walk than a 6 bolt. The 7 bolt cranks are soft. They were not nitrided from the factory like 6 bolts. First I observed cranks left outside . 7 bolts rusted overnite. 6 bolts take months to rust. Then i discovered the file test. Take a small round file and try to cut in the journals. The file pretty much bounces off the 6 bolts. The 7 cuts like butter.

7 bolt blocks do not tolerate any kind of detonation or low oil pressure because of this. So that is why everyone is ditching them for the more durable 6 bolts. But is this a good idea?

The 7 bolt is superior design in many ways.
The block girdle is far superior design, adds tremendous stiffness to the main caps. The crank is 5 lbs lighter and more oil dynamic. It slices throughthe oil better. The block also comes with a splash pan so the crank doesn't have to slice through so much oil. The journlas are ten percent smaller for slightly less friction. The block IS designed to make more HP.

So where is the future? 7 bolts. All you have to do is nitride the cranks during a build up and you will have a superior block with the same durabilty.

Doing 6 bolt swaps is a pain in the arse. And there are problems. Mitsu no longer sells the 93-94 CAS. The cars will run on the earlier 1G sensors but it triggers a misfire code and is a royal pain in the arse resetting the ecu all the time. They also dont sell the 6 bolt oil bracket any longer. In short its getting difficult to find the 6 bolt parts needed to do swaps.

Unfornately nitriding is not as cheap as I hoped. It cost arond 275 after shipped two ways. Still seems like the way to go if you ask me.

 

[liquordrunk]

11.91 @ 114.4 with a 75 shot of n20 & 50,000 miles of abuse,, the stock 7 bolt is FINE for even the above average "user"

hahah tha aint gonna last long Jim mckeone runs 11.5 with his 7 bolt with fpgreen

 

[Big Woo]

Hello,

I just had a couple of questions that some people maybe able to answer.

1.) If i was to build the 7bolt currently in my 95 GSX would I be making the wrong decision?
2.) If i was to build the 7 bolt, can i transfer the internals i.e. pistons and rods to the 6 bolt?(Although i have read that the 7 bolt rods are not as thick as 6 bolt rods)
3.) My car currently has 87xxx miles on it and is still running very strong. Would changing out the pistons and rods soon increase the chance of me getting CW?
4.) If i were to do a 6 bolt swap, i heard i would need the splicing wire(something from RRE) and 1 different mount? is there anything else? can someone give me a link to a clear write up. Thanks.
5.) Lastly, Who has a built 7 bolt motor that makes somewhere around 400+whp?


1: No, if done correctly, you should have no problems with the 2G 7-bolt motor.
(However if you believe in the Magnus theory of crankwalk, you may want to plug the oil squirter's, or if you are unsure about this your could use a 1G 7-bolt block, with the 1G style oil squirter's in place)

2: No the 6-bolt crank and rods will not work in the 7-bolt block. depending on what pistons you are using, and what you end up doing for rods, you may be able to have your pistons wrist pins resized allowing them to be used, or you may be able to have a custom set of rods made, or reworked. It all depends on which way you are trying to If memory serves me here the 1G motors use a 21mm wrist pin and the 2G motors use a 22mm wrist pin. I have had custom rods made before for this purpose, but I happen to live in the town where Oliver rods are manufactured. Your best bet is to just buy the correct parts, for your chosen path, that way you will not end up with bastard pieces, and back yourself into a corner parts wise a few years from now.

3: No, again if you subscribe to the Magnus theory of crankwalk, plug the oil squirter's, or move to the 1G 7-bolt block. The 7-bolt motors do have narrower bearings, but they also have a lighter rotating assembly, therefore they have less rotating and reciprocating weight to accelerate and decelerate.

4: To connect the 1G CAS to the 2G CAS and crankshaft position sensor all you need is some wire, and patients. Your best bet here is to use the 1990 CAS as it come with a pigtail of wire already attached. You can find the wiring schematic at either RRE's site or at the Magnus site. Additionally you can cut the 2g cam and crank sensor plugs off from their respective 2G sensors and hard wire them onto the 1G CAS pigtail for a completely plug in application.

5: I have built several, and there is a list of others out there who have done it as well.

 

[Matts95TSiAWD]

you can run 7 bolts fine with a larger main bearing and rob bearings.
otherwise forget it

not to mention the smaller oil squirters arent that great either... im doing a 6bolt swap right now.

 

[SOURCE1064]

I'm doing it right now. I haven't been on the board in a while. I've had problems with my mechanic moving shops a few times but it looks like it might be done for the DSM Shootout in Ohio.

 

[1fast97gsx]

Building a 7 bolt is perfectly fine. I have done it and probably would do it again if it was the cheapest thing for me to do. I had some oil consumption problems due to improper machining on my old 7 bolt and had a lot of piston slap. There was no increased crank endplay at all and it had 5000 miles on it with a 2600. When I pulled the motor to do a rebuild a 6 bolt block and crank fell into my hands. I had to replace the pistons on the 7 bolt due to all the scuff marks and remachine the block for a larger piston again, so I said screw it and built the 6 bolt up which in the end cost the same. Don't be afraid to build the 7 bolt just do it all right the first time.

 

[drivemusicnow]

what would a list of "neccesary" modifications(machine work) be when rebuilding a 1g 7bolt

1gs already have the 'better' oil squirters, however using Marco/Magnus logic, I may be better off closing them off anyway.

what is this "clutch switch" thing, and what does bypassing it do?

Is nitriding the crank worth it in the general publics eyes? and who can do this process?

Basically I like the motor I have, however when rebuildling it i want to remove any risk i can... that makes sense dollar wise.

 

[Pezking]

I know it's a bit off-topic, but do only build engines walk or can stock/slightly modded engines walk, too ? Must a block be replaced if it has crankwalk or can it be rebuild ?

 

[SOURCE1064]

Stock, improperly built or what Mitsubishi love to blame an upgraded clutchs especially the popular ACT 2600 clutch kit are all victims.

 

[UNDERDOG]

I know it's a bit off-topic, but do only build engines walk or can stock/slightly modded engines walk, too ? Must a block be replaced if it has crankwalk or can it be rebuild ?

There is absolutely no need to build 7-bolt`s at all. Go to junk yard and pull a 6 bolt shortblock out of non-turbo eclipse or talon, get some rods and pistons off of 1g turbo car (on Ebay all day long for $50 a set), order new bearings and buy rings at local Autozone, and micropolish your 6-bolt non-turbo crank, hone the block, slap it together and you are good to go. Ignorant people might say something about lack of squirter on NT`s, but they are absolutely not need. Changing your oil cooling system to 1990 oil cooler and upgrading the stock oil cooler to any bigger one (also available on Ebay) will make up the difference.