Should I turbo my M20?

[PEZ2]

And there in lies the answer I was using .0070 x bore due to my lack of turbo experience. I am usually working in the N/A gap ranges of .014/.017/.015.

Didn’t mean to steal the thread just looking to spread turbo info.

[ForcedFirebird]

And there in lies the answer I was using .0070 x bore due to my lack of turbo experience. I am usually working in the N/A gap ranges of .014/.017/.015.

Didn’t mean to steal the thread just looking to spread turbo info.

As long as the rings don't get hot enough and/or expand enough to touch and snap, or lift a land, then all is good.

Many people have made 500whp on an otherwise stock m20 with head studs (one of our shop clients included). It's all in how well the tuner tunes, and your selection of parts.

A lot of that "rule of thumb" info comes from domestic small blocks. From the factory, they have a much worse bore to gap ratio than our tiny 84mm slugs. I just rebuilt an ls1 at work (well, aluminum 5.3), the stock gap was .013" on 3.78" bore, I opened it to .021" for a supercharger app.

[decay]

my $.02

as others have said, the m20b25 is a low-compression engine; it's almost like BMW designed it for boost

if yours still has good compression across all 6 cyls, check out the cxracing turbo kit; they have a setup that goes from the exhaust ports on the head to the rear bumper for a little under $3k, so inside your budget

you'll need fuel injectors as well, the kit doesn't come with them; that kit runs half a bar out of the box so E36M injectors should work fine, just make sure you buy bosch; that'll support the power an m20 on a few pounds of boost should make

they used to be known for garbage parts, but they've improved over the years

you'll be fine with their half-bar wastegate on the stock 173 ecu as long as you haven't chipped it (ignition advance and turbos do not mix well)

if you someday get bored of that, 1bar tial wastegate and one of those megasquirt PNP ecus and another set of bigger injectors and take it to a tuner local to you who has a dyno

i may be a bit conservative with my approach to building and tuning than some others, but i like building reliable daily-driver cars so that's why

good luck with your project, mahdood, and do not forget suspension and brakes, there's better stuff in the factory parts bin

[Hoffbrohaus]

my $.02

you'll be fine with their half-bar wastegate on the stock 173 ecu as long as you haven't chipped it (ignition advance and turbos do not mix well)

What for real? you can run 7lb psi on a stock ECU? I never knew that. and yea compression is good.

So far I think I'm on board to do this, but the $3k budget will move up and a build thread will appear. But wow that CXracing kit, with catback for $2600 might be the way to go. If not I was thinking:

• Turbo, still researching - HX35 used and then rebuilt, or Precision, or Garrett GTX ($$$), with blanket
• RSI equal length header (maybe, saw something about boost creep)
• 44mm ext wastegate
• 50mm BOV
• 60lb injectors/fuel pump
• MSPNP
• good intercooler
• boost controller
• probably arp head studs
• clutch (maybe after I burn up the stock one)
• 3" custom exhaust
• Already have Innovate AFR gauge w/wide band 02
• Boost & oil temp/pressure gauge
• I want to replace my oil cooler, so Mishimoto or CSF

Any reason to upgrade the fuel rail? what about the stock coil?

[ForcedFirebird]

No, you can't use a stock chip, the timing is too far advanced. You can, however use a chip with pulled timing and a rising rate fuel regulator, but honestly it's easier just to get a plug and play.

I have tuned countless turbo m20's on the stock DME, though, it does work for up to about 36lb injectors. The AFM has to be in front of the turbo - just like the Porsche 944 that also used Mortronic.

A Turbonetics Super 60 is a good choice if you are aiming for 3-400whp.

I sell and have installed tons of RSI manifolds, Good & Tight is local to me. The guys with boost creep issues (and/or poor turbo selection) had the old 6-1 design with the wastegate far off to the side, the new design is a 6-2-1 and the gate is inline with the gas flow.

Stock coil is fine until you get to high boost, then a GMv6 triple pack wasted spark takes care of that.

You definitely want ARP studs, the m20 head is long and the stretch bolts suck.

Stock clutch will give out at about 200whp.

Stock rail is fine, although I prefer to use the early ones where the supply is near the firewall and return is out front. The late model rails have the supply and return both at the front. You will need to notch the black plastic fuel injector harness for the supply line.

If you are handy fabricating, you still will spend about $4k for the larger/quality quality parts, then you need all the tubing, hoses, fittings etc.

Manifold $850
ECU $850
Injectors $300
Turbo ~$1k
44mm gate $400
BOV $250
Intercooler $250
ARP $200

[decay]

What for real? you can run 7lb psi on a stock ECU? I never knew that. and yea compression is good.

it's been done. i wish e30tech were still around; i could point you at a bunch of "first time running boost" threads

to be clear, i wouldn't any more than that, but the combination of compression ratio and the rather conservative ignition maps in the 173 ecu will allow you to daily it without the knock sensor freaking out on you or holing your pistons with detonation. just DO NOT forget adding fuel; you want that innovate reading below 12:1 under boost and the stock injectors are a bit on the lean side

if you think your oil temps are high now, do that oil cooler and temp sensor before anything else. head studs aren't a bad idea either. at a target of half a bar, the stock ignition coil should be fine; same with the fuel rail. go above that and you might start losing spark under boost, but i wouldn't worry about it with the kind of conservative setup i'm suggesting here

[decay]

ForcedFirebird heheh i knew we were gonna butt heads here.

i was pricing out a bolt-on budget build as you requested, OP, but if you want to go nuts, listen to him

[ForcedFirebird]

^^^ It wasn't that simple. Larger injectors and playing with the AFM spring "works", but I have seen a LOT of lifted heads doing that. We used that method for the $2010 e30 that came in second place - and the head still lifted on the drag racing day (using the TCD chip). Remember, I was a heavy poster on e30t. :P

Even back when TCD was popular, he would include a chip with pulled timing. Even though m20 is pretty knock-resistant isn't going to be happy with 29°, even at .5 bar.

"Can" you do it? sure. Do some people get away with it? Sure, but that was a day when m20's were $100 because everyone wanted an m50. Today you can't find an 885 head core for much less than $500, and m20's easily fetch $1k.

[ForcedFirebird]

ForcedFirebird heheh i knew we were gonna butt heads here.

i was pricing out a bolt-on budget build as you requested, OP, but if you want to go nuts, listen to him

I've done super budget builds. Just replace all of the above with eBay parts, keeping the manifold, and you'll shave $2k.

I am actually installing a "kit" right now on an e24. Nothing fits, the charge pipes were just 2 45's, 2 90's and 2 straight pieces.

OP just mentioned price vs SC the m3, nothing about a kit.

In the past using eBay parts and 325td manifold flipped over, was all in for about $1200 - but - that was also ~15yr ago, so prices have changed a bit

[decay]

in fairness, i did ask OP whether he wanted to build a fun street car or a race car like your WW2 GRM special (that was an awesome car), because he presented budget as a concern.

maybe i'm one of the lucky few that got away with a street-racer sh*tb*x back in the day.

i'll amend; maybe MSPNP isn't the worst idea ever, but that and a visit to a tuner eats at least half the budget, so we're priced out...

[ForcedFirebird]

I've remote tuned many cars from the forums, on dynos, even. Currently $150 gets you in the door and $50/hr for the remote tuning. Usually doesn't take long since I have so many starter files for various combinations. Funny side story, member here is in Denver. After the first pull, I was scratching my head why we were only logging 70kpa.

Plus now for $50,TunerStudio has VE Analyze live that will fix up your VE tables, automatically, based on the commanded AFR. MS has come a long way. First one I got didn't have spark control - MS3PRO is super capable.

[decay]

I've remote tuned many cars from the forums, on dynos, even. Currently $150 gets you in the door and $50/hr for the remote tuning. Usually doesn't take long since I have so many starter files for various combinations. Funny side story, member here is in Denver. After the first pull, I was scratching my head why we were only logging 70kpa.

well yeah have you been to that city? there's no f*cking air up there, compared to the coastal states we live in. i picked up a caddy ATS to flip from copart and it wasn't happy until i filled it with 91 in utah and then gave it a tune-up with synth oil and the usual K&N air/oiil filter treatment.

[ghrays]

In today’s market, almost all E30s have at least some collectible value. Adding a turbocharger would not, in my opinion, add to that value.

[bangn]

3.5K wont get anything reliable. To do it properly you're going to need a fully programable ecu and a tuner that uses a dyno and not a road. You will need head studs, fuel pump, injectors, rising rate fuel pressure reg, wideband, upgraded coolant temp sensor, fuel and oil pressure sensor if you're to have any sort of engine protection. You CAN incorp a knock sensor for that added protection as well. You will need an uprated clutch, the stock one starts to slip at 240rwhp (around 7psi which is SLOW), an LSD of some sort. You will want to convert it from batch fuel to full sequential and run coil packs. A cam sensor kit will be required. Then of course your turbo, intercooler, manifold and exhaust system. Allow for an oil filter relocation depending on the manifold you end up using.

The motor will handle it for sure, I was pushing 23psi on a 350xxx km bottom end with an organic gasket and studs only for two years until I decided to build a 2.8. The clean tune dictates your reliability, and you need modernish engine management to get that.. I am running a gtx3071r and to be honest if I was to pick the turbo again, I would go a bit smaller, maybe a gtx2867. Just so the power band is usable instead of only being able to see power at WOT. Its either ON or OFF. You want a usable powerband so smaller is generally better in a street car.

it wont wreck the value, build the car for you not for someone else. Spend the money on the car you will keep otherwise its a waste but above all else do it correctly.

[downforce22]

In today’s market, almost all E30s have at least some collectible value. Adding a turbocharger would not, in my opinion, add to that value.

maybe some people don't only keep these cars for their collectible value

I am surprised by the number of people who do not perform the work themselves.

Maybe it is because I am an engineer and have done it already, but installing a turbo on an m20 is not hard. The information about how to do it is on here, on youtube, on e30techarchive. Maybe I just have been looking at these build threads for too many years and know the m20 well enough from having done it. I was surprised a guy I just talked to was willing to buy the kamotors $4k turbo kit, ship the car to reno to have kameron baker do it for him, and pay $6k for the install to increase an m20b25 from 168 hp to 300 hp for $12k.

If it were me, the experience of learning how the engine goes together and how each components works together was worth the expense of building my turbo car. I spent way more than the car is 'worth' but I consider that my education. The real question is what is the outcome you want? Since most e30s are second vehicles these days, does turboing the car and reducing certain aspects reduce or enhance the enjoyment of it for you? What happens when you blow a headgasket, get more speeding tickets, get worse fuel economy, or realize you could have bought a car with 250 horsepower for the same price as going to the effort to turbo it?

http://e30techarchive.com/ has a lot of answers

This thread is where I started back in 2010 and a turbo install back then is priced at $5,000 http://e30techarchive.com/showthread.php&t=74816.htm