SNAFU; high performance 318is build that lives up to the name, Turbo M42 ➞ Turbo M20

[varg]

Good to see you up and running again.
Big difference from the M42 huh..?

Sure is. I'm glad to finally have an M20, the torque is nice and there's the peace of mind of a more durable engine.

How did you vac plum your solenoid? Middle barb on the solenoid to atmosphere?
It's something I've been putting off for a few months now due to not knowing how to tune the tables for it really. Looks good.

It's a single port wastegate actuator so middle to wastegate, lower to compressor housing, upper open. If you don't have boost creep to deal with, tuning the open loop table is easy, it's all trial and error, closed loop control has been a pain in both of my setups I never got it perfect with the M42, it would either oscillate, overshoot, or be slow to rise.

[ak-]

How did you vac plum your solenoid? Middle barb on the solenoid to atmosphere?
It's something I've been putting off for a few months now due to not knowing how to tune the tables for it really. Looks good.

[Good & Tight]

Good to see you up and running again.
Big difference from the M42 huh..?

[varg]

In sound not spirit John. At least they're hypothetical hondas with extra cylinders ;)

[ForcedFirebird]

Spec e30's aren't near as bad as the Spec Miatas. I dies a little inside when you compared us to Hondas :(

[varg]

I reinstalled my boost control solenoid and started tuning the closed loop boost control again this week. It's kind of a pain, but it's almost there. I'm currently running around 10psi of boost, and am turning it up another pound tomorrow. Though I've added a degree of advance here and there in boost, this tune is going to stay conservative as long as I have a stock head gasket. I don't trust it. I am very happy with my exhaust though, the second muffler I added a while back is still worth the loss of ground clearance, the car is quieter with the M20 than it was with the M42, and has a nice deep sound with little of the awful rasp that is present in so many loud M20 cars. If you haven't heard a field of spec E30 cars I'd describe the sound as like a flock of civics which have been blessed with two extra cylinders each, or many, many bees.



Another decent shot of my engine bay. I'm going to do a valve adjustment and clean the aluminum up a bit in the next couple of weeks. I really want to get rid of the yellowing on the intake manifold, I like the look of clean cast aluminum.

I have two busted HX40 compressor wheels that I think I have plans for now...

Can you clock your compressor housing to move the outlet?
Or what I'm really asking, is can you move the wg actuator around the turbo?

In my particular case it just wouldn't fit (the arm should extend straight to the valve) so I had to cut the arm and put it there, it's far from ideal but it's working so far. The bracket is also for a T3, not a T4, so it is only held on by one bolt. Some turbos don't allow this kind of re-positioning, the actuators are bolted to the front of the housing or otherwise affixed to a spot other than the bolts holding the housing on. In the case of some holsets the actuator bolts to a bracket that is cast into the compressor housing, those are a pain to clock and use.

[Northern]

I have two busted HX40 compressor wheels that I think I have plans for now...

Can you clock your compressor housing to move the outlet?
Or what I'm really asking, is can you move the wg actuator around the turbo?

[CorvallisBMW]

sick oil cap ornament

I noticed that too, I actually really dig it!

[varg]

I first was exposed to megasquirt around a decade ago, I'm pretty much self taught and have tuned many cars and built many units over the years. The tuning is the fun part, though I run into frustrating snags once in a while.

(edit)

[efficient]

Dang dude
I'm jealous that your already boosted. I been sitting on my turbo parts for a long time already. How did you learn how to use megasquirt?

[Dj Buttchug]

sick oil cap ornament

[2mAn]

boost is addictive... I have to stay away from it.

[varg]

I'm on the road again, tuning and enjoying the noticeable improvement in smoothness and sound of the M20.





It's really slow for now, but as I tune I will progressively turn up the boost. I will quickly make more power than I did with the M42, I'm guessing it will be faster at 13psi than the M42 was at 18psi based on a previous race against an M20 turbo car which I barely beat. All tuning will be conservative since I'm still using the stock head gasket, which I won't likely push past 15psi. Some day I'll O-ring it and put the big turbo on :up:

[varg]

A week ago the engine went in.



Since then I've been otherwise occupied with school but working steadily in the time I could find. I had to make a "custom" wastegate actuator arm because my wastegate actuator would not fit between the turbo and the fender well.



The clearance between the silicone coupler on my compressor outlet and the header is scarily small. I'm going to have to make a little sheet metal shield to keep the huge amount of radiant heat from the header off of it.



This is how it sits as of tonight.



All that's left now is to build the megasquirt adapter, expansion tank mount, heat shield, and some small odds and ends like filling the cooling system. It should be running this weekend and I'm stoked!

[MF DOOM]

There's no way I'd go from 18psi of boost to NA M20.