6 bolt swap, water plumbing conundrum

[spyderdrifter]

First off, I am curious about what follows, but this post is also for reference for others. I have read through some other posts in regard to this, but nothing has been fully clearified.


I know MANY of you in this community have done the 6 bolt swap in some variation. This is now my second DSM to have the swap done, but it’s the first one I’ve started on my own. My last Eclipse had it done prior to me buying the car, so I only learned about what was already there, and not all the research type stuff. This time, as I’ve mentioned in other various posts, I’m doing it all myself, and learning more about it at the same time. However, I’m starting to have an issue with all the available info regarding this. Everywhere I’ve read that provides a list of parts required, or optional, states that a 1g main water pipe, 1g thermostat housing, & 1g lower radiator hose are required for this swap…

Such as Magnus Motor Sports:
https://docs.google.com/viewer?a=v&...Kt_wVn&sig=AHIEtbQQBwTcYCSRtq3ApdiDkDR7KpauYg

Road Race Engineering:
6 Bolt Motor Install Into a 2G Eclipse

Now that I’ve looked even closer at this link for RRE, I noticed it does mention the use of the 2g plumbing, but the others list 1g plumbing only.

I thought about this a little while ago when I was out in the garage tinkering with my setup. I put my 2g head on, and installed all the 2g plumbing. Everything works! Anyone have an idea why 1g plumbing is listed as required? I can see it being required for a 1g head, but not for a 2g head. Here are some pics…

From the front:

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Here you can clearly see the modified engine mount and 6 bolt water pump, with the 2g pipe in the back:

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It all works fine:

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Anyone can run the VIN to see it really is a 6 bolt, with 2g plumbing:

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Does this setup HAVE to have the 1g plumbing? If so, why? I used to think it was required based on the water pump, but clearly the 2g plumbing works with it just fine.

 

[19Eclipse90]

The main reason is this: with a 2G head and 2G plumbing on a 1G block, you lack a coolant feed for the turbo if you are also using a water-cooled oil cooler.

Edit: And to add, with a 1G head, the 2G thermostat housing will not bolt up, forcing the use of 1G plumbing anyway.

The 2G turbo is fed coolant from the block, directly, rather than from the thermostat housing like a 1G. See: http://www.dsmtuners.com/forums/newbie-forum/385767-2g-block-coolant-line.html.

Here's thinking a little further ahead. Even if you decide to use the water-cooled oil cooler feed on a 2G thermostat housing for the turbo instead, then you have to deal with closing off the water-cooled oil cooler return to the 2G main water pipe.

One way or another, using only 2G equipment and nothing more, you'll be missing something somewhere to have a closed system.

 

[spyderdrifter]

That all sounds good, I forgot about the 2g block feeding the coolant from the block

However, what if I set up the coolant feed and drain as this? Have one of the red circled spots being the feed, and the blue being the return? Can it be done this way if I use the 6 bolt external oil cooler instead of the ring type one that feeds from the blue area?


(on a side note, I really appreciate the info you've been providing me lately. been very helpful and recommended the info as such for you)

 

[19Eclipse90]

However, what if I set up the coolant feed and drain as this? Have one of the red circled spots being the feed, and the blue being the return? Can it be done this way if I use the 6 bolt external oil cooler instead of the ring type one that feeds from the blue area?

The lower red circle and the blue circle are both originally returns.

Upper red = feed for oil cooler
Lower red = return for turbo
Blue = return for oil cooler

Anyway you slice it, there is one port that will need to be capped/sealed/plugged/welded/whatever. Yes, that has been done before. Feed the turbo from the upper red (B below), return to the lower red and seal the blue.

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[spyderdrifter]

Sounds like a plan. I'm mocking it all up right now. Thanks again.

Well here's what I mocked up, not the exact turbo or water lines I'll be using... just for demonstration.

 

[19Eclipse90]

Seal the oil cooler return and that would do the trick. A bit unsightly, but functional.

So the perk to the '91-'94 turbo setups is that all the components have the adequate number of feeds and returns to bolt up and go. The '90 would be trivial as well if you had all the right parts for a '90 setup. I'm sure the idea to say 1G plumbing is required came from the fact that it can all become a bit of a headache when parts are mixed and matched with things which they aren't exactly compatible. As well, it allows the engine to maintain all original functionality in turbo and oil cooling.

 

[spyderdrifter]

I'm gonna have the oil cooler return welded to alleviate any possibility of leaks. It is unsightly, I agree, but hopefully that'll change after I order the parts I want for it. Some might think I have a problem with hooking up the 1g plumbing, but I don't. I just prefer the 2g setup since I've had all 2g cars. Plus the 1g t-stat housing I have has a bunch of hookups all over it that I didn't have a clue about until I read through one of your links. But I'd rather keep the 2g parts for ease of connection to the 2g harness. The 1g perks are definitely there, but I always seem to try the more less used way.

 

[19Eclipse90]

The 1G thermostat housings can be cleaned up really nicely, especially in a 2G. Here's an example of what can be done: http://www.dsmtuners.com/forums/custom-fabrication/437231-nt-thermostat-housing.html.

But certainly nothing wrong sticking with what you know and are comfortable with. Good luck with getting it going!

 

[spyderdrifter]

Thanks, should be up and running in less than a month. That housing looks pretty damn good. I'm still keeping all the parts I'm not using for this build. Purhaps I'll use it for my race engine build, once I get around to it.