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Discussion Starter #1
First, YES I searched!
I know that the bolt patterns can be made to be the same if they arent already(stock tt block has dohc. callmebryan put sohc on tt block, therefore dohc fits on sohc block).
I know a new timing belt is required, and massaging the firewall will be also be needed.

My questions which havent been answerd are:

I believe that the timing gear(which was rear bank cam driven on the vr4's) needs to me moved(or possibly elimated)?

With the vr4 heads and the stock 10:1cr pistons, will I have valve clearance or would pistons designed for the NA or TT dohc motor be needed?

Will the stock ecu be able to run it? (even if that means tricking it) Or would I need either a standalone (which means Im not doing this) or a 3000gt sl (non turbo dohc motor) ecu?

Thank you

P.S. If you think I may be overlooking something else, please go ahead and bring it up. If you're going to tell me I'm an idiot for thinking about doing this please don't post. If you're going to tell me this isn't a good idea, please provide specific reasons why.
 

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First, YES I searched!
I know that the bolt patterns can be made to be the same if they arent already(stock tt block has dohc. callmebryan put sohc on tt block, therefore dohc fits on sohc block).
I know a new timing belt is required, and massaging the firewall will be also be needed.

My questions which havent been answerd are:

I believe that the timing gear(which was rear bank cam driven on the vr4's) needs to me moved(or possibly elimated)?

With the vr4 heads and the stock 10:1cr pistons, will I have valve clearance or would pistons designed for the NA or TT dohc motor be needed?

Will the stock ecu be able to run it? (even if that means tricking it) Or would I need either a standalone (which means Im not doing this) or a 3000gt sl (non turbo dohc motor) ecu?

Thank you

P.S. If you think I may be overlooking something else, please go ahead and bring it up. If you're going to tell me I'm an idiot for thinking about doing this please don't post. If you're going to tell me this isn't a good idea, please provide specific reasons why.
This isn't a bash. Just sell your car and buy a 94+ VR4 that needs some work.
 

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i dont believe you'd have any trouble with the ecu since the heads are mechanically driven and not managed by the ecu. I think the only reason people havent done this is because of clearance issues. The firewall def needs modified and the hood would probably need cut and molded over the cam gears on the front bank. <---im not sure about that. only speculating though.
 

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that is not the point. most of us are trying to get what we can out our eclipse. I probably could have bought 2 VR4s with the amout that my 3g cost me. nj-spyder- good looking out. never caught that. Sounds like an awesome idea.
 

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Discussion Starter #5
In order:
I've always wanted a VR4 the problem is a VR4 that needs work-needs a lot of work(my neighbor is kicking himself for going this route) and the VR4's that don't need work usually cost an arm and a leg.

Thanks skinny. Worst comes to worst, I'll have that second generation hood hump-just on the other side lol

slvrblt, you got the idea.
Thanks guys
 

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I'm a 4 cylinder guy so I don't know as much about the GT's but was curious if any one has actually done this head swap, sounds pretty interesting.
 

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i dont believe you'd have any trouble with the ecu since the heads are mechanically driven and not managed by the ecu. I think the only reason people havent done this is because of clearance issues. The firewall def needs modified and the hood would probably need cut and molded over the cam gears on the front bank. <---im not sure about that. only speculating though.
I'd imagine the hood clearance wouldn't be too big of an issue, since a 6g74 fits no problem, and they have a taller deck height. The DOHC heads aren't that much bigger to interfere in the top or front, but the rear would be quite a challenge, especially keeping heat away from the A/C lines that are right in that area. If you could "Redesign" one of the header kits out there to bend tighter on the rear bank, you just might be able to pull it off. It would be one hell of an interesting write-up though.


edit: I just realized that the DOHC heads do not have provisions for a distributor. If you were to go that route, you would need to go standalone and figure out a form of ignition control. I highly recommend adapting Ford's EDIS-6 system to the engine. It just needs a 36-1 ring on the crank pulley, and a VR sensor to run.
 

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Discussion Starter #8 (Edited)
Yea, Hardline I just figured that out last night by looking at the manual...I'm trying to figure out a way around a standalone because I don't have the money for one. As far as ac lines go, I'm not worried. Worst comes to worst I'll just have them re-routed. I know there are aftermarket ignitions out there that can convert from distibutor to non distributor, but again theres cost. So, hopefully I'll be able to figure something out that wont cost me an arm and a leg. Luckily, the dohc heads already have a cam angle sensor on them so converting shouldnt be too difficult.
 

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I'm trying to figure out a way around a standalone because I don't have the money for one.
If you can't afford $1500 for a standalone, should you really be messing around with trying a swap that has never been completed before on your daily driver?

You have to realize that the major problem of trying to retain the stock ECU in a situation like this is that it's expecting a certain pulse for each revolution of the engine for the CAS built into the distributor. I've pulled apart the CAS from a VR4 and the pickup is completely different and will send a signal that your stock ECU will not understand.
 

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.I'm trying to figure out a way around a standalone because I don't have the money for one............ but again theres cost........... So, hopefully I'll be able to figure something out.......... converting shouldnt be too difficult.

Do what everyone else here is doing,SDS or the 6g74 swap. It will be cheaper, much easier and you can go drive with no worries.

Let the guys that DO have the money, time and know how do all the one off customs jobs that could end up not working in the end. What will you make out of the DOHC anyway over pooping out your SOHC???

Unless you want to pose at the car show cruise scene with a DOHC motor I say forget it.
 

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Discussion Starter #11
Ok Pharm, then the only other thing I can think of is modifying the vr4 heads to accept our distributor and sensors but that sounds like it wouldnt be fun(I have a full metalshop at my disposal so thats not the issue). So unless I can figure out how to swap our head's stuff into the vr4 heads, this isn't going to happen because of the ignition issues.

GSX, SDS will be more expensive and the 74 swap, unless I get lucky with an engine that doesn't need any tlc, would be more expensive as well. (I can get a nice set of vr4 heads for 250 and then I would need a timing belt for another 70 or so). What do I expect to gain? Heads that flow a ton better(flow more air than the cylinders can at 100% VE because of larger valves, ports, and more aggressive cams) and a valvetrain that can take 8k rpm (which I wouldnt get out of the 74).
So unless something incredible happens this just wont work (for me).
Thanks everybody
 

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Ok Pharm, then the only other thing I can think of is modifying the vr4 heads to accept our distributor and sensors but that sounds like it wouldnt be fun(I have a full metalshop at my disposal so thats not the issue). So unless I can figure out how to swap our head's stuff into the vr4 heads, this isn't going to happen because of the ignition issues.

GSX, SDS will be more expensive and the 74 swap, unless I get lucky with an engine that doesn't need any tlc, would be more expensive as well. (I can get a nice set of vr4 heads for 250 and then I would need a timing belt for another 70 or so). What do I expect to gain? Heads that flow a ton better(flow more air than the cylinders can at 100% VE because of larger valves, ports, and more aggressive cams) and a valvetrain that can take 8k rpm (which I wouldnt get out of the 74).
So unless something incredible happens this just wont work (for me).
Thanks everybody
ummm....i think your making it out to be simpler than it is. If it was as simple as youve put it, everyone would have done it, but thats just common sense. seeing as you dont have enough money for a new ecu i would just stick with i/h/e setup. honestly "re-routing" the ac lines isnt fun or easy or cheap and niether will all the other variables involved in this "head swap" be. save yourself a "HEAD" ache and just call it a night man.:rofl:....o and no offense i admire your unique sense of ambition!
 

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Good luck with project......btw if you are able to do all this to a your car then a vr4 that needed work wouldnt cost you much if your know what your doing (which seems like you do).
 

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Do what everyone else here is doing,SDS or the 6g74 swap. It will be cheaper, much easier and you can go drive with no worries.
What will you make out of the DOHC anyway over pooping out your SOHC???
That's is it in a nutshell. How much do you expect to gain from the conversion? If you want to do it to be unique, that is fine. Turbo, SDS, 6g74 swaps has been found to be that path of least resistance... relatively speaking.
 

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To take to car shows and and cruise nights and show off I think it is really cool. For trying to make power and come in under budget I say go with what you know will work.

I am married, just bought a house and wanting kids. I am a mechanic for a living and I would not even try something like this. I want what is quick, easy, cheap, proven and going to get me on the road between work and home as fast and fun as possible without having to wrench on it all the time.

Some guys like working on there cars and some guys like driving them. I like driving unless I am getting paid handsomely.
 
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