Except as far as I remember turbos work differently in regards to back pressure. N/A gains power and economy from a more restrictive system where as turbos benefit from a more free flowing system. Unless I’m wrong in that.
Why talk when you can show results, just download my engine and try it!
Once more, I will once I’m out of work and at my computer, which will be about midnight gmt.
Here is my revision.
I changed it to Dual Overhead Cam, 5 valves per cylinder, and fiddled with the cam and timing. Came up with more power and a nicer curve for both HP and TQ. Should make a nice little engine. I will compare the two next in my test sedan.
Okay here’s my take, most efficient engine here at %32, turbo spools at 2700rpms and it’s got a nice flat torque delivery until the horsepower is peaked, gear shifts should not be a problem as they ought to drop you back to the top of the torque curve. Also with no quality sliders it’s quite quick and cheap to build.
Hades BRC type R ECORev16.lua (68 KB)
I think if I kept the fuel ratio at 14.7 instead of 14.5 i could havw gotten higher efficency but 2% equates to a few mpg. I opted for a bit higher power output but it seems out engines are similar.
Oh I thought eco was the important part, but if it’s power you want…
Hades BRC type R ECO MK2Rev16.lua (66.6 KB)
Isnt the point of a small car engine to be inexpensive, why run on higher octane fuel that cost as much as 30 cents more per gallon?
Check the units, it’s 91 ron, that’s regular gas, our 86.4
Lol, my bad. I still stand with my 35% fuel econ rating 
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Well, I’ve gone for the very cheap solution, just 125bhp, but if you want more power you probably shouldn’t be using a 1.2L engine
Dragawn your engine is amazing, i just think that it needs to rev more to have a better power band. i would like to have your lua if you agree… lol
Very good engines on this tread, i learned a few things and also about the exhaust size, it improves the engine a bit with this style of tuning, its just that on my original engine it made no change.
I revised the engine in the direction towards irkie’s engine to see if it gives better performance in the testing, and it is, 0.4 seconds faster 0-100 km\h and a and 0.07 litre more per 100 km with the gearing set for minimal fuel consumption for both engines. (the car is the compact sedan and the weight is 1200kg)
But for a compact saloon i think its getting a bit too expensive, even my original SOHC in my opinion. Dont forget that this engine competes with a 1.6L with 500 - 600 material cost.
About the iron cast engines, i think they are too heavy, those who weights 140kg moves the CG 2% forward and today i think all of the 1.2L engines in the real world moved to aluminium too.
Well my it was my trade-off to sacrifice some rev range in order to get better stats, but here you go 
:1.2L 20V DOHC Turbo ecoRev0.lua (62 KB)
Aha! your engine is getting stressed at 5800rpm, thats not good.
So the tuning methods iv learned from this tread:
-In turbo engines its better to have retarder ignition and higher compression
-The mixture should be even leaner then i thought
-Sometimes its better to have bigger exhaust on turbo engines
I still stick to my SOHC aluminium head and block though
Compression only goes so far before the gains start to fall off. Take any engine and max the timing to 100, then flip flop that scenario and go for the highest compression possible. You will find that the higher timing motor will get quite a bit more power and be more responsive. Extremes on both ends however are not good, and often finding a balance between the two is your best bet for a solid baseline, then adjust from there.
Also KD14 you made your engine 50cc larger, a small complaint but one that does effect the outcome nonetheless.