Airfeed related page for MembersPage/MarcellGal/EngineSwap
Since the project reverted to an NA setup because of a space conflict between air conditioner and turbo, the airfeed is very simple.
When I first started the engine (without air filter box), it had a loud shhh sound like a gas turbine sucking air, so next task was to bolt the factory airbox (air-filter) on.
The tube that I could buy fast sucks, not smooth inside, so restricts airflow badly (appr. 10kPa=10% at high power), and a bit loud too. When I replaced with smoother tube, it became nicer.
TODO
- Take pics
- take out some ducttape (and replace with other materials :-)
Idle air
I have a (4-pin) bipolar stepper with 46 Ohm windings. Connections:
- A-B
- D-C
From [any bipolar driving cheetsheet]
I concluded that 0-1 and 2-3 must be driven a half period away from each other. So I need either
- 3,1,2,0 (=0xD8) (just checked: this is what mik has)
- 3,0,2,1 (=0xC9) (this is what anti-miks have in a world made of anti-material). Actually this was the right direction for my setup, because connection to my 4 stepper pins succeeded like A,B,D,C for historical reasons.
I played a bit with mdi.. (force iac position)
- mdi0e 780RPM
- mdi0f..mdi14 allows the idle controller to maintain 830 RPM with -8..+4 degrees ignition advance (on warm engine).
The stepper valve opening is huge.
I ended up setting the iac reference positions higher than necessary for the target RPM (at the relavant temp), so iac PID integral is normally negative. At the same time, I set very low iac_integral_limit_dec (=06). This only makes sense with iac_ki value and stepper parameters, so copy the idea, not the actual value. This makes it almost impossible for the engine to overshoot badly in the negative direction (=> stall).
When we first started the engine, we accidentally had iac_conf=0x18 (somehow mix-matched this variable from Dave's config instead of mik's) instead of 0x1e so stepper iac was disabled. The iac was approximately halfway, enough for 5000 RPM idle. The idle was regulated by overrun fuelcut=1100 RPM and overrun fuelresume=900 but it was terrible to drive, because
- very bad for the drivetrain when hitting overrun fuelcut every second
- the WideBand ego correction cannot work when the overrun fuelcut activates (because fuel is cut and it goes lean, obviously).
- also I had to add some throttle (not much, since iac_tps_thres was set _very_ low) to make the engine leave overrun fuelcut, but than it was a bit too powerful to start nicely.
I'm glad that I found the stupid hiding stepper-enable bit2 finally. iac_conf line in global.h needs some attention (~copypaste from iac.h)
Brake booster connection from plenum - done
Strange enough, the one-way valve for the brake booster vacuum accumulator had a small hole besides the large one. I have no idea what that is good for, but it was sucking air with an audible noise, so I had to use duct tape, which is very common on my engine anyway :-)
TODO: take a photo of the plastic bottle that is responsible for sucking cold air from before the air conditioner radiator.
MAT
I found most important signals and sensors, but MAT is hiding - surprising. Maybe the engine was originally MAF-only ? In worst case I apply a small NTC (from WebShop) with some epoxy (done so).
PCV system
Carter gas recirculate into the intake (before the compressor if engine is charged), or let it leave the engine through a filter into the free air
Variable intake reservoir connection on plenum. Separate reservoir for variable intake, not shared with brakes.
Already tuned VE with WideBand with actuator in default (highRPM, short runner) setting. The direction was first found in theory that there is an internal gear that inverts rotation. This was verified on the dyno, very smooth torque at upto almost redline.
I have the reservoir and valve (looks like a BoostControl valve, consumes 285mA at 12V and room temp) for it.
DONE
- mount the vacuum accumulator and small valve on the firewall
- connect air (vacuum)
- connect electronically
- verify valve operation (mdhc0 mdh40)
- activate the solenoid from 1000..3000 RPM if MAP > 80kPa
- correct j[] table for the small VE change
- TODO: verify with logs (with WideBand and ego correction, of course)
It seems that the extra torque is less than 10% (probably 6..10%, no precise measurements yet). It's noticable, definitely torque improvement is not as significant as the power improvement that came from replacing airbox-throttle bad tube with a nice tube of smooth interior (done at the same time).
EGR
Sort out the EGR. The EGR pipe is the 15mm metallic pipe that goes from under the variable intake actuation (pic3) to post-throttle. Yes, it looks like the head has a small passage for exhaust, on the output end of the intake side.
Water injection
Not as big benefit on NA as on a turbo engine, but still good for cooling: slightly more ignition advance allowed (for slightly more torque) at max load at low and mid-rpm where the ignition advance increase gives more torque.
Note: on an NA engine, at most loadsites we work near the top of the sine-like ignadv=>torque curve, so more ignition advance does not yield more torque, just increases risk of detonation.
A washer-pump with a home-made mister placed between air-filter and throttle should do it. I have to measure flowrate.
found some info that might be of intrest to you, research papers and implementation details: http://not2fast.wryday.com/thermo/water_injection/ - DB
Air filter
- DONE: factory filter for now
- might make a custom airbox later ... [see pics] shows I can choose to mount either the old airbox or (apparently have the space to) make a new one (for higher flow Champion 501 filter), if I measure too much pressure drop across the old filter. Making the new airbox would start with cardboard, and harden with glass fiber + epoxy. The only stress on it is vibration (no significant pressure or vacuum).
Not implemented for now, just plain 45mm "manual" throttle.
The reason is the lack of big, fast valve.
Is the EGR valve usable ?
I found that the EGR valve is pretty big. is it slow for throttle ? It's probably to slow for dbw. I don't know if it's vaccum powered. It's electrically a solenoid, but internally maybe solenoid + vaccum. I didn't disasemble it. There is no vacuum tube feed. But it lives on the intake, it might accumulate some vacuum for itself. The current consumtion will most likely tell us which it is.
Dropped because no turbo
Charge cooler - air to air (also dropped)
- piping from compressor to cooler
- piping from cooler to throttle
- BOV bolton
- BOV vacuum connection from plenum
See also