M20B20 + 525td turbo + MS1 v2.2

[level5]

Hi! I currently own a n/a m20b20 and would like to turbo it. I want to start slow, just fitting the turbo, intercooler, oil lines and bigger injectors.
I've been looking at different options and for me the best one right now seems to be a turbo from a 324td. Would it be safe to run for a while with the stock ECU (Motronic 1.3)? How much power could I expect from this setup (around 150kw would be nice)?
I plan on getting a Megasquirt in the future and also upgrading the turbo and probably swapping in an m20b25 but since this is my first ever turbo build, I think it would be best to start with the b20 and move on from there.

The car in this video is supposedly running the same setup with everything stock, just the turbo bolted on. https://www.youtube.com/watch?v=VO3SzGTP-k0

[mrsleeve]

turbo is going to be WAY too small. M21 is 2.5L that spins a touch over 1/2 the RPM of the M20b series gas engines. That turbo will be nothing more than an exhaust restriction and cause more issues than it worth, unless your happy with a 3500ish RPM red line. Your waste gate is going to wide open and your turbo is going to be surgeing like a MOfo with that set up

Stock tune I have no idea if your going to be safe, but adding boost IE air you going to have to add fuel or your going to be so lean its going to burn holes in pistion's. You can add a raising rate FPR, to get around that for low boost applications, but that said your going to need a way bigger turbo to start with if you want it to run right.

[varg]

For engine management I cannot ever recommend stock E30 stuff with a turbo. Even with a proper tune the stock EMS will hold you back.

I did a quick search and if what I found is correct the M21 turbo is fitted with a 50 trim T3 with a .36AR turbine housing. I'm familiar with these small Garrett turbos because they came on some Volvos and Saabs. The compressor itself isn't too small for your engine, and can definitely flow enough to improve upon the 129hp B20, but the turbine housing will be a restriction. With a .48AR turbine housing you won't have to worry about the restriction at all until the compressor is out of breath and just blowing hot air. A 45(or was it 43?) Trim T3 with a .48AR turbine housing was stock equipment on some Volvo 240 turbos and it was enough to reliably make over 150hp and 170lb ft with the 2.1L low compression B21ET/FT, and more if pushed. In ideal conditions 200hp should be possible with a 50 trim T3 compressor.

Intercooler is mandatory.

[cro_xt]

Well I just removed turbo from my m20b20.
My setup was
renewed engine
k03 out of golf 1.8t gti @0.5 bar
some wide bmw intercooler
malpassi adjustable fuel pressure regulator
m50b25 injectors
blow of valve for sound only
wideband o2 sensor with controler and display, put aside original one so i could see what is my air fuel mixture
stock motronic 1.3 ecu
AFM put before turbo
Standard compression ratio 8.9:1 (its fine roughly up to 0.9 bar with 91 octane fuel, or better)
I managed to get most stable engine with 0.5 bar. It ran worse with 1bar, no mater how i tried to adjust fuel. (standard ecu held back)
I made adapter myself for original exhaust manifolds to fit turbo + downpipe and rest of exhaust...


my experience? aside from great pull at beginning,a ton of lost nerves.
I could not adjust afm to get me the good a/f mixture...after i did adjust it the best i could, i could at last get gas pedal to floor and engine would accept it, but it was nothing exceptional at all. I did benefit mostly on lower rpm. and its day and night difference in power. but car ran really rough, really poor gas mileage, and lots of small problems... I was nowhere near your 150kw expected power figure. but yes, it felt at lower rpm's much more stronger. At touch of a pedal i could accelerate the best, which was weird, and even slight uphill at around 70kmh in 5th gear it would accelerate good, which now, bottom stock, is impossible at same place.

Yes it was fun, i can give you all the pics from my project, but unless you do it the right way, with standalone ecu, dont do it at all. Not worth it for daily car. Trust me :), i was stubborn too and i learned it the hard way... start gathering all the parts needed and do it proper way. This engine for sure has a lot of potential, and will be worth it if you do it all yourself, so its "cost-performance effective", but do it right.
I ended up taking it off, and now il save some more money for standalone ecu and few more things.
I was too looking at those same videos on youtube, and trust me, it does not work every time like that.

[level5]

Thanks for the information guys.
I got a great deal on a Megasquirt 1 v2.2 and will be using that. Also, my friend's 525tds died a couple of days ago and he might be parting it out. Would a turbo from an m51d25 be good for the m20b20? I can make the manifolds etc myself.

[Q5Quint]

the m51d25 had about 105kw stock, about 140hp with the turbo.

If you go to whichever favorite internet oracle you use and type in 'bmw m51d25 turbo size' you find out it has a mitsubishi td04-11g-4.

Now depending on your power goals you can do a flow map calculation for your engine size using some online stuff like here: http://www.lovehorsepower.com/joomla...d=35&Itemid=49

Then you take those numbers and plug them into the td04-11g-4 compressor map and see how off you are. I found a map for a 13 g which should flow a bit more than an 11... which should flow more than a 9g etc...



Now an m20b20 flows about 90kw/120hp stock, about 30 more than the turbo diesel did. At no boost and 5500rpm it flows about 175cfm. At 5500rpm and a mild 8psi of boost it should be flowing about 255cfm of air.

Looking at the 13g map, which is bigger than the 11g the bmw diesel came with... you are pretty much out of the efficiency range of that compressor at anything over 200cfm or 5psi of boost. If you put in the bigger m20b25 it will just be worse.

It will work, sure, so if it is free go for it, but it is not the right size at all.

I used a t3 super 60 with .63 ar on the exhaust housing and it seemed like a 'stock' feeling turbo on the b25 at just 8psi with room to grow to 20psi or so.





Modern turbos are much better, but it is hard to beat free!