M20 types and part compatibility

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M20_fever
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Re: M20 types and part compatibility

Postby M20_fever » Fri Oct 30, 2015 1:50 pm

no, he's talking about the 731 casting off the 2.3L m20 on a 2.7L bottom end. Some people have had good results from it, but just like any other head swap it's going to take more than just bolting the head and a couple accessories on to see any real gains. For example, you will need to port match the 731 head to the b25 intake (don't use the 2.7 intake), and to make any noticeable power gains you'll need larger valves (the 885 valves stock are like 2mm larger). The 885 head has larger combustion chambers too. Unless you are looking to make a really high compression NA m20 stroker, and plan to put a lot of money into machine work, the 731 head just isn't worth it.

I guess the real question is what it your budget and goals for the engine?
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Re: M20 types and part compatibility

Postby symplej » Mon Nov 02, 2015 1:28 am

Well, I wasn't really looking to put serious power behind it, I was more or less just looking to get a little more kick for a more enjoyable DD with a smaller budget. My max amount.to spend would probably be around $600, I had already planned on around $400 for a new head and components if I shop cheap, but the opportunity came up for a $75 731 head and the guy I may get it from said that he just bolted it up to the b27 bottom end, put the B25 intake and ECU on and it worked out Fairly well.
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Re: M20 types and part compatibility

Postby M20_fever » Tue Nov 03, 2015 2:19 pm

That combo could work, but after buying the intake manifold and ECU (and wiring harness to go with it, and all the 'i' electronics, and 'i' trigger wheel) it's not going to be a budget swap. Plus, the 731 head won't take 7k redline of the b25 ECU for long, so you'd need a custom chip to drop the redline back to 5k, or be REAL careful because 5k comes quick and going past that with that combo is a hand grenade waiting to go off.

For your budget your much better off getting a good used 2.7L head, or get your head redone, and buying a good name brand chip for an eta. You will feel a noticeable difference in performance with just the chip on your current engine in good running condition.
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Re: M20 types and part compatibility

Postby symplej » Wed Nov 04, 2015 6:31 am

Fair point, thanks for the feedback!
It almost just seems more worth it just to go all out with the 885 head, so I may just wait and do that eventually. I completely forgot about chipping it actually. That needs done. I'll do some searching on a good chip and get a really nice clean head to put on there and call it a day. It would hold value better if it was all stock anyway, right? Not that it's worth a fortune, but my mother-in-law's land lord keeps asking if I want to sell it, I wasn't planning on it, but if value goes up by chance, that just gives me more of a reason to hold on to it.
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Re: M20 types and part compatibility

Postby M20_fever » Wed Nov 04, 2015 2:44 pm

Unless you plan to drop $5k+ into a fully built stroker with custom pistons the 885 head sucks on a stock 2.7L bottom end. For what you would spend you'd be better off buying a complete m20b25 and swapping it in with a chip. Running b25s can be had for few hundred bucks. Not long ago I would say just sell it and buy an 'i' car, but prices are getting stupid on these cars so if you have a solid rust free car to start with swapping in a b25, or even a 24v depending on your mechanical prowess may be the better choice.
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