which would you do?

[structured]

Assuming time and money are not that important, which of the following would you do?

1) eta bottom end, eta high compression pistons (10.2:1 or 11:1), 731 head ported to match "I" intake, oversized valves, aftermarket cam other related "I" parts.

2) eta bottom end, "I" block and pistons, 883 head, aftermarket cam, "I" intake and other related "I" parts.

3) complete "I" motor, aftermarket cam.


I want to do option 1 because it will have really high compression and will probably take well to camming.

Admittedly, I don't really know what I am talking about, but I've secured a space to work and have a mechanic/friend who wants to help.

[5KWattson]

you want really high compression? boost the bitch=)

[miles318]

Just do an s52 or m30 swap, or boost, or both. your first option sounds good too

[structured]

you want really high compression? boost the bitch=)

Just do an s52 or m30 swap, or boost, or both. your first option sounds good too

Thanks guys, but both of these arguments have been brought up in every other thread about M20 modification. /jk

My reasoning for not doing a swap is that I don't want or have the ability to have my car out of commission for a long period of time. I am just going to build a new motor then drop it in, all the while continuing to drive my car.

As for turbo; I would have to rebuild my motor either way because mine is burning both oil and coolant after 230k miles. I don't want to deal with a turbo and everything else that is involved on top of that.

[TrentW]

Thanks guys, but both of these arguments have been brought up in every other thread about M20 modification. /jk

My reasoning for not doing a swap is that I don't want or have the ability to have my car out of commission for a long period of time. I am just going to build a new motor then drop it in, all the while continuing to drive my car.

As for turbo; I would have to rebuild my motor either way because mine is burning both oil and coolant after 230k miles. I don't want to deal with a turbo and everything else that is involved on top of that.

I agree. Going between your Option 2 or 3 right now. What are you working from as a base engine?

[structured]

I agree. Going between your Option 2 or 3 right now. What are you working from as a base engine?

i am going to build an engine seperate from the one in my car, so i can start with whatever i want. if i do option # 1, i would get an eta motor and rebuild with new high comp. pistons and a 731 head.

[jmc1590]

Assuming that "time & money" are not issues in the decision, and the fact that you want to build it then swap it, I would recommend #1, with a couple of changes.

Get the 885 "i" head to begin with. Already has the larger valves and flows better than a stock 731. Use the money you save from un-needed headwork to buy a set of custom high-compression pistons, possibly even oversized (85mm or 86mm). The only argument not to change the pistons would be if you managed to find a euro eta block with the high-comp pistons intact. (And I'd still want to remove them for inspection.)

If I understand your option #2 (eta bottom end, "i" head & electronics),it is very easy to accomplish, especially with the block still installed. If you have all the needed parts on hand when you start, it can be finished in a weekend. (Minimal downtime.)

[structured]

Get the 885 "i" head to begin with. Already has the larger valves and flows better than a stock 731. Use the money you save from un-needed headwork to buy a set of custom high-compression pistons, possibly even oversized (85mm or 86mm). The only argument not to change the pistons would be if you managed to find a euro eta block with the high-comp pistons intact. (And I'd still want to remove them for inspection.)

This option would give a similar result to my option #1, but would almost definitely be more expensive. I guess that's my fault for saying that money doesn't matter...

If I did do this, would I just want a complete "I" motor with custom pistons and an eta crank?

[structured]

Also, where can one find new old stock Mahle pistons? ie. the high comp. ones from early euro models. I've seen a few for sale that were new in box and I'm wondering if they were just hoarded from the 80's or if they are still available.

[jmc1590]

Have you already started collecting parts? Have you priced out a complete 731 head, and found one available? Remember to figure in machine work to port and over-size the valves. The euro high-comp pistons will probably cost somewhere in the neighborhood of $1200 new. (MobileTradition has them listed, part # 11251287039.) Considering you still need to purchase a long block, your expenditures will start to climb rapidly.

An "i" 885 head should cost around $250 (or much less if you shop around.) Custom pistons, between $850 and $1100, matched to the head. If you decide to go with the "i" block you already have most of the parts except the crank. If you go with the eta block, you may wish to go with "i" rods.

I guess the question that comes to mind is roughly how much do you plan on budgeting for the swap? That will help with accurate recommendations for your situation.

[structured]

Have you already started collecting parts? Have you priced out a complete 731 head, and found one available? Remember to figure in machine work to port and over-size the valves. The euro high-comp pistons will probably cost somewhere in the neighborhood of $1200 new. (MobileTradition has them listed, part # 11251287039.) Considering you still need to purchase a long block, your expenditures will start to climb rapidly.

An "i" 885 head should cost around $250 (or much less if you shop around.) Custom pistons, between $850 and $1100, matched to the head. If you decide to go with the "i" block you already have most of the parts except the crank. If you go with the eta block, you may wish to go with "i" rods.

I guess the question that comes to mind is roughly how much do you plan on budgeting for the swap? That will help with accurate recommendations for your situation.

All good points.

I have already found two 731 heads for $200 shipped, one of which was ported already.

There were also two different sets of high comp euro pistons (used) and another (new) that sold relatively cheaply. $200-$500, I think.

The most that I would look to spend on the 731 head would be about $1000. I've priced it out and I think that it's possible. If I did go with the "i" block/piston/885 head setup, the head would be much cheaper (read: already has 2 valve springs and bigger valves) but the custom pistons would get pricey fast.

I guess that if I could find high compression pistons for the 885 head that were about $800, the option that you outlined might be the best.

[TrentW]

Have you checked Metric Mechanic for custom pistons? I just checked their site, but the info on parts and prices is down for construction right now.

[structured]

Have you checked Metric Mechanic for custom pistons? I just checked their site, but the info on parts and prices is down for construction right now.

MM is generally quite expensive. If I were to buy from them, I would probably just buy one of their built heads. It would probably be more economical than buying their parts individually.

[TrentW]

MM is generally quite expensive. If I were to buy from them, I would probably just buy one of their built heads. It would probably be more economical than buying their parts individually.

What I thought.

[lennon]

whats the difference in swapping in a 24v motor as compared to swapping in this custom m20 project motor? youll spend far less time and money refreshing a 24v than you will building a frankenstein m20. the swapping itself will take the same amount of time, and youll have more and better power. either way, you have PM about 11:1 pistons.