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**nando** · 07-12-2021, 10:23 PM

I'm sure JE pistons can make you something, they've done lots of M20 pistons. The stock CR is fine for boost, but the stock pistons have weak ring lands and tend to break catastrophically.

To be honest, the bottom end - crank, rods, block - probably don't need a whole lot other than new bearings and assembly. If the parts are in good shape I'd just use them as-is. Focus on the tuning and reliability of external stuff.

Lots of people were boosting stock M20B25s back in the day with good results. I mean, basically all stock internals with a junkyard Holset HX35 and Megasquirt was hitting 350whp pretty reliably. But maybe not lasting forever.. I think your other plans for the head and block seem solid.

It's too bad E30tech.com is long dead, or we could just point you to some of the excellent threads there.. R3v was really never the best forum for boost/tuning. But a lot of those guys are still here. :)

**Mnav13** · 07-13-2021, 02:32 PM

nando alright thanks, yea i want to do a solid build, im the type i like doing it right first. I have heard good things from JE, i saw some discussion on gapless rings? what you think? Mahle rods? You tuned it urself? cause here in Miami idk anyone that tunes mega squirt and e30s

**zwill23** · 07-13-2021, 02:59 PM

You're not looking hard enough :) you're lucky to have an excellent M20 turbo tuner at WOT-tech near Miami - R3v resident ForcedFirebird.

Fwiw I just had my stock M20B25 w/head studs tuned this weekend and it made 304whp. It's my daily and only car again so we'll so how reliable M20 turbos really are, but it just did a 1000+ mile road trip without issue this weekend.

**Mnav13** · 07-13-2021, 03:24 PM

zwill23 i say him on another post from a few years ago but when i looked him up his website seems not e30 based anymore, idk guess i have to message him lol

**nando** · 07-13-2021, 03:25 PM

Yeah, definitely go talk to John / ForcedFirebird. I haven't personally used him for tuning, but he's done work for my car all the way in WA, we used to text all the time. :)

I tuned mine myself, there was a lot of resources though, especially on E30tech. I and many others posted a lot of detailed threads there, but they are unfortunately lost and I have no memory of most of what I did now. There is probably some good info still on MSextra.com, but I haven't looked there in years. I also have a wiring diagrams for MS2 and MS3 on the M20 here http://megasquirt.325ix.com/MS_to_Mo..._motronic.html and here http://megasquirt.325ix.com/MS_to_Mo...c%203.3.1.html - you'll probably see these copied all over the web now.

My car isn't turbo but really the only difference is the load axis goes a lot higher, and maybe you'll use closed loop boost control. WOT tuning for power is the easy part. It's making the car livable that's tough.. cold starts, hot starts, idle, throttle transitions, fuel economy. Takes an eternity. But it's worth it if you put in the work.

I originally had MS2, but I built my MS3 in 2011 right when it came out, and haven't touched the tune once since 2012. it runs perfectly - the only flaw I've really found is recently, due to literally the hottest weather in the history of the PNW, my intake was heat soaked (it was 116f or hotter!) and it was pulling fuel at idle, so it wanted to stall. It would be an easy fix if I got the laptop working I used to tune it, which died like 5 years ago, lol. I sold my MS2 setup to a forum member who as far as I know still uses it now.

We do have an alternative tuning/megasquirt forum. Some of the people from E30tech are here, and there are many others who know about this system. You don't really need MS3, MS2 is basically just as good - but I happen to like projects. There is even newer stuff like ArduinoEFI, DIYEfi, etc. but I'm not familiar with them. And of course overpriced retail systems that are often worse than the DIY stuff.

The M20 is a good platform for tuning/boosting, despite all the guys now that are only about the modern 2-ton M3s because they can get 700hp with a $50 tune. Even though the car cost $85,000 and breaks down more often than an old Yugo.

As far as stuff like rings etc, eh, I dunno. Maybe some people have good experiences, but almost every OEM still uses traditional rings. That shit hasn't changed in 40 years, aside from better materials and tighter tolerances. I'd talk to the guys at JE and see what they recommend, I build an engine once a decade or more, I don't have enough experience to really say either way.

**e30davie** · 07-13-2021, 03:51 PM

Megasquirt is good, i have an MS2 and its been running fine for years on a stocko m20b23, but i don't think its as budget friendly as it used to be when you compare the cost of an entry level haltech or link. Especially if you can get a second handy. the big limting factor I feel on the ms2 is lack of knock sensor input. Now of course for many years turbo engines have been tuned without knock sensor feed back, but most of the entry level ecus now include it - i think the "level 2" link ecu now includes a wide band 02 controller, which is a big advantage. You need to jump to the MS3 to get the knock sensor feature, and by then you are up in the $$$ range where mega squirt is no longer the budget option. Megasquirt has the advantage of having a plug and play option for the m20b25 which makes it easy. but on my engine i made a complete custom loom as i went for LS1 coils, IAT sensor in the airbox and a few other non standard bits, which is not that big of a deal - but is a project in itself.

**nando** · 07-13-2021, 04:24 PM

You could knock sensing to an MS pretty easy, there's plenty of extra I/O on MS2, and definitely on MS3/MS3x. But I don't know if it's really needed on an M20, unless you are tuning it to the bleeding edge of its life.

What's more important than the brand is the availability and support of a tuning community than the hardware itself. If you get a cheap, or even really expensive system, but can't make it work, it's completely useless.

**e30davie** · 07-13-2021, 05:01 PM

Yer you can add it, but you need more hardware to do it which is more cost and complexity (conditioning daughter boards or external conditioners). Which brings it closer to the cost of units that have it onboard already. 'nice to have' perhaps on an M20, but a good safety feature to have especially for DIY tuning i guess. Cant argue with the comment on support availability, though to a certain extent only applies if the intention is to get it tuned/worked on by others.

**digger** · 07-13-2021, 05:06 PM

A set of JE pistons as follows:
conventional total seal rings
OE offset dish dome (top end can do this)
9-9.5:1 cr
85mm bore
compression height to suit 135 molnar rods and 81 or 84mm stroke

**nando** · 07-13-2021, 05:19 PM

Originally posted by e30davie View Post

Yer you can add it, but you need more hardware to do it which is more cost and complexity (conditioning daughter boards or external conditioners). Which brings it closer to the cost of units that have it onboard already. 'nice to have' perhaps on an M20, but a good safety feature to have especially for DIY tuning i guess. Cant argue with the comment on support availability, though to a certain extent only applies if the intention is to get it tuned/worked on by others.

You can build pretty much any additional circuits with inexpensive parts. I guess to me, that's the point of a Megasquirt and DIY tuning. If you just want a black box with stuff already inside, yeah, it probably makes sense to get something with everything integrated. Although, I still don't think knock sensors are really needed for an M20. You're not going to let your mom drive it and put 87 octane in, right? :)

Support ability I think is important regardless if somebody else is tuning it or not. I think MS favors the DIY category more since lots of people familiar with the M20 are also familiar with MS, and they work well together. Maybe there are others that also have great communities - I don't really know, lol. I mentioned ArduinoEFI etc because I've seen them come up lately. They're probably awesome in their own right, but I mostly only mess with OE computers these days.

If you're paying for somebody else to tune it though, you'd better be sure that somebody nearby knows what they're doing with it. So maybe that means something like a Halltech, Link Holley, or a multitude of others. There's plenty of choices!

And honestly I don't really care what brand of computer somebody else runs either way. I'll probably never touch the tune on my MS3 again, unless there's an urgent need. I'm just saying, you want something that you can actually make work, and make it work reliably. People talked shit about Megasquirt, especially here, for years, that it was cheap, crappy, or it would not work or be reliable. But I think 14 years of solid running is proof enough for me. :)

**turbski** · 07-14-2021, 06:32 AM

Originally posted by zwill23 View Post

You're not looking hard enough :) you're lucky to have an excellent M20 turbo tuner at WOT-tech near Miami - R3v resident ForcedFirebird.

Fwiw I just had my stock M20B25 w/head studs tuned this weekend and it made 304whp. It's my daily and only car again so we'll so how reliable M20 turbos really are, but it just did a 1000+ mile road trip without issue this weekend.

how much boost? I ask only because I had my car tuned a few weeks back and made almost identical power.

**Mnav13** · 07-14-2021, 06:43 AM

Originally posted by digger View Post

A set of JE pistons as follows:
conventional total seal rings
OE offset dish dome (top end can do this)
9-9.5:1 cr
85mm bore
compression height to suit 135 molnar rods and 81 or 84mm stroke

I emailed steve at top end this what he reccomended what yall think?

"JE Forged Piston Set for Turbo use. 84.5mm x 8.8:1
Molnar 4340 Forged Rod Set with ARP Bolts
ARP Head Studs
Race Timing Belt"

He also put MLS but i said ill stick with stock since im o-ringing the block, talked to alot of people with m20s a few years ago and they swore by stock gasket and oring.

**Mnav13** · 07-14-2021, 06:44 AM

Originally posted by turbski View Post

how much boost? I ask only because I had my car tuned a few weeks back and made almost identical power.

What are you running? lol

**turbski** · 07-14-2021, 06:48 AM

Lol 10psi +- it's a 2.7l fresh rebuild. New pistons. Rebuilt holset wh1c.

Arp head studs and stock head gasket

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