Engine Design Guide: Part 5 - Turbo Tuning
Turbos in Automation currently aren’t fantastic right now. Currently, even in 2020, they are based on 80s tech and as such you can’t tune them like real turbos or make them spool as quickly as real turbos.
Turbos can massively increase power and fuel economy if setup right, which can be tricky if you don’t know the tricks.
This section will be kinda vague, since turbocharging is more and art than a science. Still, hopefully with this you’ll be on the right track.
Turbos unlock in 1975. Engines with two cylinder banks can only have two turbos, while inline engines currently only have single turbo options.
The more displacement per turbo, the quicker spooling the turbo will be. For single turbo engines this is pretty simple, but for twin turbo engines just half your displacement to get that. A 2L I4 and a 2L I6 will spool a turbo up in near enough the same time, so cylinder counts don’t really matter.
Although for this reason, boxer 4s are terrible for turbocharging since a 2L boxer 4 has 1L per turbo, less than an I3 at 86/86 bore/stroke.
Journal Bearing vs Ball Bearing
If you can, don’t use journal bearings. End of story. Ball bearings cut down on turbo lag so much, without really having any negatives anywhere else.
Intercooler
Use the Flowbench for this. You never want to have your intercooler be restricting power. Set it to whatever gives you the most power, and simply lower compression if you need to.
Starting off
Ignore the presets and move straight to manually adjusting. Lower compressor and turbine to their minimums, while setting AR to its highest. This sounds wrong, but is the best way to tune turbos.
Eco tunes
- Usually 0.5 bar of boost or lower. The advantage of lower boost is it lowers octane requirement which you can spend on increased compression, leaned out fuel mixture, to improve efficiency.
- Almost always minimum turbine size.
- If turbine is at minimum size, you can then start lowering AR from 1.4.
- Compressor will be quite small, sand might also be at minimum size.
- The compressor and turbine will be very restricted.
If you want numbers to aim for, on the flow bench aim for a compressor about 0.82-0.86 and a turbine at about 0.6-0.75. I wouldn’t stick to these numbers though, adjust for yourself and it’s likely that range won’t work best for your car.
Sporty tunes
- You’ll need somewhere between 0.7-1.2 bar, depending on how extreme the performance needed is and the fuel you’re using.
- Everything will be more free flowing, probably spooling between 3-4K RPM depending on displacement and number of turbos.
- AR at 1.4 no matter what.
Again, numbers probably aren’t set in stone but if you want some numbers to aim for a compressor about 0.75-0.85 and a turbine at about 0.86-0.92. These aren’t strict rules, but tend to work.
Quality
Quality can help spool up the turbo quicker. It doesn’t affect PU as much as other places, but significantly increases ET. It can also make your engine much more reliable if you have lots of boost. For the most part though turbo quality is pretty useless.