99 7 bolt ???

Posted by Djbaldhead, Jun 14, 2017

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  1. Djbaldhead

    Djbaldhead Probationary Member

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    Sorry. Didn't know where to put this post as I have limited access as of right now to the site.

    So I've been doing research before I buy my first dsm. I'm wanting to do the 6 bolt because from what I'm reading it will hold up better to the power that id like to have.

    Now I've come across a couple of disccusions (not sure if they were on this site) saying that the 7 bolts out of the 98-99 2g were less prone to the boogy man known as crankwalk. Is this true? If it is then what's the factor? Depending on the answers I might come to stand still on which motor I want
     

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  2. TurboTesh

    TurboTesh Proven Member

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    The late 98 and 99 motors have a "split-thrust bearing design" and some minor oiling change, which from what ive seen, does infact prevent crankwalk. (Search why crankwalk occurs) The crankwalk scare is a bit overrated, but ive seen it in person. Onset typically occurs on 95-97 7bolts when a heavy pressure plate is used in manual cars. Autos walk less often.
    That being said, i own 2 99 gsx's :p
     
    My DSM:
    1999 Mitsubishi Eclipse GSX

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  3. 91talonts1

    91talonts1 Proven Member

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    The later 7 bolts have a revised thrust bearing. I can't tell you the exact differences, but it's discussed in quite a few threads on here.
     
    My DSM:
    1997 Eagle Talon TSi AWD

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  4. Djbaldhead

    Djbaldhead Probationary Member

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    So are these motors better at holding higher Hp, than the other 7 bolts? Or even hold power better than a 6 bolt? Or does the higher compression on a 7 bolt ruin high hp all together?
     
  5. TurboTesh

    TurboTesh Proven Member

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    7 bolts have better exhaust manifolds, intakes, MAF, and a few other things. My understanding is the 7 bolt has stronger pistons, but weaker rods. Both are good to 400+ hp with a headgasket and studs.

    All year 7 bolts are the same potential i believe.
     
    My DSM:
    1999 Mitsubishi Eclipse GSX

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  6. 91talonts1

    91talonts1 Proven Member

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    7 bolts can hold plenty of power, they have been high 9s stock as far as I know. The early ones just have problems with wearing the thrust bearing out prematurely.
    The 6 bolts have larger head studs, and larger rod mains.
    The 2g compression is a non issue. Most 6 bolt builds run at least 8.5:1, and the 2g piston is a common upgrade for 6 bolts anyway.
     
    My DSM:
    1997 Eagle Talon TSi AWD

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  7. Djbaldhead

    Djbaldhead Probationary Member

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    So how can you tell if you have a 98-99 motor? Is there anything on the block/head indicating that its a 98-99. Also I see they use a different ecu, since the one these year models use is tune friendly I'm assuming it is better?

    Thought I had my build figured out.. guess not LOL
     
  8. Tyeler18

    Tyeler18 Proven Member

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    Don't get too hyped over crankwalk. Its no where near as hyped as people make it out to be. And actually by design, the 98/99 split thrust 7 bolt is better in almost every way than the 6 bolt aside from overall strength. If you plan on building the engine a split thrust would be great, as the rods are the weakest point. A forged bottom end would get rid of them at that point. It's essentially a mirrored version of the evo 8 bottom end as far as design goes.

    You're going to have to pop the pan to determine if it's split thrust or not. The 98/99 Ecu are normally flashable. "Better" is a matter of opinion however. Lots of people pull the flashable Ecu out and put the 95 Ecu in with dsmlink. The flashable Ecu aren't as user friendly and don't have quite the features link does, however, an Evo ecu swap is pretty simple and would net you the same/better capabilities than link, cheaper cost, but still not as user friendly.
     
    My DSM:
    1990 Eagle Talon TSi AWD

    Road Race Build

    GT30   manual
    1998 Mitsubishi Eclipse GSX

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  9. Djbaldhead

    Djbaldhead Probationary Member

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    Hmmm so now my mind is racing on what to do LOL. Now that I've actually got to talk to you guys who are knowledgeable about these cars I'm thinking about this 7 bolt.

    So first question is, how hard is it to find a true 98/99 motor and are there people selling them claiming to be 98/99 and actually not? Second question is are the 2 blocks designed differently or can you simply just buy the split thrust and put it in an older model? And if this is possible is the split thrust the ONLY thing separating the 98/99 from being superior to the older models?

    Sorry for being super newby about this, but I'd like to get this right the first go around and not get aggervated and end up selling it half way through the build
     
  10. ZACH 99 GST

    ZACH 99 GST Probationary Member

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    This is what I did. I needed a motor and the one I got happened to be a 6 bolt. I freshened it up with higher quality parts: bearings, bolts, studs, head gasket, timing belt, etc. I then put the 2g Pistons in the 6 bolt with a 2g head and now I have a Frankenstein motor that can handle anything I'll be able to throw at it.
     
    My DSM:
    1999 Mitsubishi Eclipse GST

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    14b   manual
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  11. Djbaldhead

    Djbaldhead Probationary Member

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    Building a Frankenstein motor is definitely not what I want to for do building this motor for the first time. I'm just trying to find the right platform for the power that I want
     
  12. pauleyman

    pauleyman DSM Wiseman

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    Frankenstein isnt a big deal, many parts interchange. It sounds like youre already overthinking this.
    Buy a well maintained car, learn, do maintenance, drive. I wouldn't even modify at all at first.
    I'm going to interject some heavy opinion here. If you do not have very good mechanical skills and a reasonable budget a modified DSM is not for you. These cars require knowledge and a healthy enough budget to fix what goes wrong when it goes wrong especially if you plan to daily drive the car. Personally I have 25 years of experience with these things and I continue to daily Drive mine. However I also have enough budget to drop nearly anything I want on the car when necessary and I also have a spare motor and transmission if the need arises and the ability to just get another car should the need arise. This is not necessary for everybody but keep in mind how old the cars are and what you may be planning to do and the fact that driving a car hard can break stuff. The problem I see with most dsm's over the last 20 years is that people assume that if the car is running properly and shifting properly it is ok. That is not necessarily true especially when it comes to Transmissions. At this point the cars are so old it would be reasonable to check certain things out while doing maintenance or modifications however many people do not. Consequently dsm's have a reputation for being unreliable which in my opinion is also not true. This post is not meant to sway you from buying a DSM rather to educate you in the errors that people have made over the years. I've personally seen so many failures and so many people give up simply because they didn't know what they were doing.
     
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    1997 Eagle Talon TSi AWD

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  13. mitsumike0

    mitsumike0 Proven Member

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    It's a little more difficult to find a split thrust bearing motor. However I have one sitting in my garage that I purchased from DACOWGOD. He actually has a long block in good shape as we speak. I personally refuse to ever go 6 bolt so I will be sticking with the 7 bolt motor.
     
    My DSM:
    1997 Mitsubishi Eclipse GSX

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  14. TurboTesh

    TurboTesh Proven Member

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    You have to be patient and find someone like me who is parting out a good shape 127k mile 99 gsx (no title :( ). 99 part-outs are less popular, as cars from that year are usually worth investing in to keep running. (last year made, and arguably the best)
    Also, you can usually tell the difference between motor years based on CAS and CPS locations/wiring. A search will fill you in on that should you need to go down that route.

    I would agree with pauleyman and say just find the lowest mileage car you can with little or no rust, and the least amount of modifactions possible and just use whatever engine it comes with. Getting a reliable and well-maintained car is the hardest part. Hell, even my clean 99 has issues I deal with regularily, and that was near stock when I bought it at 105k miles. Find something close to what you want, and then from there... nearly everything is interchangeable between 2gs and you can make it how you want.
     
    My DSM:
    1999 Mitsubishi Eclipse GSX

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  15. turbosax2

    turbosax2 Moderator

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    Check the VIN stamped on the block. The tenth character is W for 1998 or X for 1999.
     
    Last edited: Jun 15, 2017
    My DSM:
    1999 Mitsubishi Eclipse GSX

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  16. ZACH 99 GST

    ZACH 99 GST Probationary Member

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    I think the "Frankenstein" threw you off. I was just giving an alternative. It's not like I was trying put coyote pistons in it. It's just a fresh 6 bolt with stronger pistons. Believe it or not that combo can hold plenty of power. Unless you plan on something crazy like 600whp+, a well taken care of stock motor will surprise you. Now there is nothing wrong with a fully built 6 bolt or 7 bolt. I would've built mine just for the sake of mind if I had the cash to.
     
    My DSM:
    1999 Mitsubishi Eclipse GST

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  17. Spideydsm99

    Spideydsm99 Proven Member

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    I just want to chime in on the 7 bolt reliability part. I have a 99 spyder gst with the original engine and it's currently sitting at 231k never had issues out of it. Just keep up with maintenance and it will be good to go. Yes it is the original split thrust engine too.
     
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    1997

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  18. Chaotic Deconstruct

    Chaotic Deconstruct Supporting VIP

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    Crossville, Tennessee
    My 98 GSX is a split thrust block and has 226k, all stock, miles on it currently. Runs great with no issues. Even so, I would probably wager that my car is out of spec in regards to crank walk. Probably not a significant amount, but after that mileage the wear is there I'd guess.

    I have seen both 6 bolts and 7 bolts walk. My best guess is insufficient oiling of the main bearings. Add a heavy clutch setup, improper torquing during assembly, or factory parts just slightly out of spec and it makes it that much more likely.

    The 6 bolts just appear more resistant than the 7 bolts, maybe because of the nitrided crank, but I'm not sure. I know the oiling systems differ on the blocks and many feel that could also help the 6 bolts survive longer.
     
    My DSM:
    1998 Mitsubishi Eclipse GSX

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  19. Djbaldhead

    Djbaldhead Probationary Member

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    Thank you for that Turbosax.

    And pauleyman I completely understand your point but I'd rather go through a headache achieving a goal that I want, than getting aggervated from something I don't want. I'm asking these questions to gain knowledge like you have on these cars so I don't make a mistake on building something that's not meant for what I want.

    As for a Frankenstein swap that's not something I'm gonna go after until I can fully understand this car. I've done them and seen them done on Honda's and it's a nightmare guessing game and that's even knowing what your doing.

    You guys have been more than helpful, already going to look at she'll this coming weekend. Might end up being a "fathers day" present
     
  20. pauleyman

    pauleyman DSM Wiseman

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    For what it's worth I drive a 97 which does not have the split thrust bearing. I am not concerned about modding this car. It currently has 118,000 original miles.
     
    My DSM:
    1997 Eagle Talon TSi AWD

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  21. pauleyman

    pauleyman DSM Wiseman

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    I have seen too many people improperly set up their cars and likely cause the issues and not be a design flaw of the car itself.
     
    My DSM:
    1997 Eagle Talon TSi AWD

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  22. Djbaldhead

    Djbaldhead Probationary Member

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    The shell I'm going to look at is a 98 has 175k miles on it and the guy says it's the original tranny and motor but it's currently out of the car with a blown head gasket (from what he says). Wants $500 for the shell and $750 for all together. Good deal?
     
  23. Spideydsm99

    Spideydsm99 Proven Member

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    I'd pop the pan off since it's already out of the car and inspect it. And also check under the oil cap and see if there's any sign of a blown headgasket.
    If it's a clean shell and theres no holes in the block I'd say it's still worth 700$
     
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    1997

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  24. TurboTesh

    TurboTesh Proven Member

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    Check for strut tower rust and rust in front of the rear tire. FWD or AWD?
     
    My DSM:
    1999 Mitsubishi Eclipse GSX

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  25. Chaotic Deconstruct

    Chaotic Deconstruct Supporting VIP

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    I see running GSX's pop up from $3-4K quite frequently. I cant imagine what a $750, motor out shell would even look like. I can imagine it's very rough. If it wasn't a GSX I wouldn't even advise looking at it, as I have owned both, and would never buy another GST due to endless wheel hop.

    It could be a great deal and everything may work out great, but as I've gotten older I tend to find that project life is much easier starting with a complete car that runs and drives. Without knowing the condition of the other driveline parts, suspension, etc, your $750 project may very well cost you more than just starting with a $3k car to begin with. On top of the big parts, an incomplete car can be the biggest headache because of the littlest of things. DSM's aren't 69 Camaro where there is an endless literature and aftermarket support that produces every OE washer, nut, bolt, or custom piece imaginable.
     
    My DSM:
    1998 Mitsubishi Eclipse GSX

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