thanks for the comments guys. I need to work on better videos for you guys. I love how my car is still running an M20... I got a comment from a local guy who i saw on the highway in his e46 M3 coupe, and he asked, "what's under the hood?' and when I told him turbo M20, he said it sounded great.
The car seems to be running great. i took it on mountain drives about 3 of the last 4 weekends and I don't even have to shift out of 5th at 11,500 feet (atmospheric pressure of about 9 psi or about 66 kpa). I have been wondering about the strength of the M20 as well. It turns out the S54 has a larger bore and stroke than my engine with the same cylinder spacing and still has an 8000 rpm redline.
My engine has 86mm bore, 89.6 mm stroke, 135 mm rod, forged crank, pistons, rods, 206.2 mm deck height, 9.5:1 CR
S54b30 has 87mm bore, 91 mm stroke, 139 mm rod length, forged crank, 216.9mm deck height, 11.5:1 CR
The main difference is the height of the engine which allows the s54 to have longer rods which keep piston speed under control with the longer crank. Because of this, I have my current rev limiter set at 6000 rpm. This puts the piston speed somewhere around 58.8 FPS This is an equivalent piston speed to a stock m20 (75 mm stroke) spinning up to 7170 RPM. Outside of piston speed I don't really worry much about the engine but have been cautious to run too much timing or too much boost without knowing what I'm doing.
One thing I have done since the last post is I found a 3/8 NPT female bung and an 8" section of aluminum pipe that i could use to replace the AFM. With a GM IAT sensor I was able to remove the barn door and see how it changed the drivability of the car. One of the biggest differences was the instant response. It seems the barn door would be mostly shut on light throttle not allowing air through to the idle valve. Without it, there is less of an on/off bucking of the engine at light throttle positions. I had to use a blue silicone coupler to get it to work for now since the AFM inlet was 3", but I just ordered a black one to replace it. To connect the GM IAT, I had an old AFM that was junk that I took apart. I removed the male portion of the AFM connector and connected to the GM sensor to that so I could plug it directly in to the engine harness. I wrapped it in electrical tape to prevent corrosion and debris from damaging it, but I plan to rotatre the pipe upsidedown so the bung is on the bottom and the sensor and wiring is not visible.
It turns out the car is as fast as my brothers e39 540i/6.
And for the drive i took on Saturday I removed the heavy steamrollers form the picture above (17x7.5, 235/40/17, wt about 20+ lbs) and I put on this autocross setup (falken hanabi 15x7, 205/50/15, wt 12 lbs on RE-11a Bridgstones) but I ended up drving them in rain and snow at 9000+ ft. it is even faster and i managed over 25+ mpg.
And here is a video my brother took when I let him drive it about a month ago. 2nd gear, shifting at 4000 rpm, you can hear the wastegate dumping.
The car seems to be running great. i took it on mountain drives about 3 of the last 4 weekends and I don't even have to shift out of 5th at 11,500 feet (atmospheric pressure of about 9 psi or about 66 kpa). I have been wondering about the strength of the M20 as well. It turns out the S54 has a larger bore and stroke than my engine with the same cylinder spacing and still has an 8000 rpm redline.
My engine has 86mm bore, 89.6 mm stroke, 135 mm rod, forged crank, pistons, rods, 206.2 mm deck height, 9.5:1 CR
S54b30 has 87mm bore, 91 mm stroke, 139 mm rod length, forged crank, 216.9mm deck height, 11.5:1 CR
The main difference is the height of the engine which allows the s54 to have longer rods which keep piston speed under control with the longer crank. Because of this, I have my current rev limiter set at 6000 rpm. This puts the piston speed somewhere around 58.8 FPS This is an equivalent piston speed to a stock m20 (75 mm stroke) spinning up to 7170 RPM. Outside of piston speed I don't really worry much about the engine but have been cautious to run too much timing or too much boost without knowing what I'm doing.
One thing I have done since the last post is I found a 3/8 NPT female bung and an 8" section of aluminum pipe that i could use to replace the AFM. With a GM IAT sensor I was able to remove the barn door and see how it changed the drivability of the car. One of the biggest differences was the instant response. It seems the barn door would be mostly shut on light throttle not allowing air through to the idle valve. Without it, there is less of an on/off bucking of the engine at light throttle positions. I had to use a blue silicone coupler to get it to work for now since the AFM inlet was 3", but I just ordered a black one to replace it. To connect the GM IAT, I had an old AFM that was junk that I took apart. I removed the male portion of the AFM connector and connected to the GM sensor to that so I could plug it directly in to the engine harness. I wrapped it in electrical tape to prevent corrosion and debris from damaging it, but I plan to rotatre the pipe upsidedown so the bung is on the bottom and the sensor and wiring is not visible.
It turns out the car is as fast as my brothers e39 540i/6.
And for the drive i took on Saturday I removed the heavy steamrollers form the picture above (17x7.5, 235/40/17, wt about 20+ lbs) and I put on this autocross setup (falken hanabi 15x7, 205/50/15, wt 12 lbs on RE-11a Bridgstones) but I ended up drving them in rain and snow at 9000+ ft. it is even faster and i managed over 25+ mpg.
And here is a video my brother took when I let him drive it about a month ago. 2nd gear, shifting at 4000 rpm, you can hear the wastegate dumping.
My guy will have to fab up the driver floor jack area from scratch because I do not have a replacement section for that, but luckily that will all be covered by the rear early model iX fender flare. Assuming the repair gets done right, it should be looking good and i'll have the paint matched close enough. It will still look like a beater but if that fixed the rust i will be stoked.
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