I got this problem twice today.
When im creating a engine and set a determined compression ratio, after save the engine and load it the compression have to be reduced losing power and torque.
pics and engine file:
3.0L RBRev0.lua (79.2 KB)
3.0L RBRev0.lua (79.2 KB)
anyone? 
This is rather weird indeed. So you make an engine, test run it, get your stats, save it, then exit, then revise it and things have changed?
No, nothing changes. But the engine cant run anymore. The first image is when I save the engine and return to my engine list. The second is when I load to revise it.
I like to build powerful engines as you can see. I try to reach the maximum that the engines can offer. But that problem is fooling me since the last updates 
I cannot seem to reproduce the problem. Can you give me a more detailed list of what you do to get there? Or maybe even record a video of it if you have the means to?
ok, ill build another one and write all steps
This can take some time
OK. on This steps ill build a twin turbo R8 V8 engine.
1 set engine type, displacement (doesnt seem to affect, the problem occurs anyways)
2 Billet steel crank, i beam titanium conrods and forged pistons
3 set valve type (the type have no effect. In the end the problem is the same for all)
4 Head material I use Cast Iron (i dont know if this is normal, but using Cast Iron the engine gets a bit more power and torque than the other materials)
5 Set compression to 9.0:1 (average compression when use turbo)
6 Set cam profile to 90 (average setting for most engines)
7 Set VVT and VVL (doesnt affect. The problem seems to occur for any type)
8 Set aspiration type (The problem seems to occur only when use turbo)
9 Set the bearing type (I only use ball bearing)
10 Set the bigger (or better ) intercooler
11 Set turbine and compressor size (doesnt seem to affect. The problem occur on any size of each other) But i always set the compressor to the maximum avaiable and the turbine a few mm smaller than the compressor. On this i set the compressor to 67.4 (maximum) and the turbine to 66mm.
12 Set Air Ratio to maximum (1.40)
13 Set Boost to Maximum (3 bar/44.1 PSI)
14 Direct Fuel injectiom, throttle per cylinder and race intake.
15 Fuel type Super unleaded 98
16 Set Fuel Mixture to 10.0:1
17 Set ignition Timing to 100
18 Set RPM limit to 8500 (average limit for high when I use turbo)
19 Set short cast (only avaible if use turbo)
20 Set dual exhaust (if avaiable)
21 No bypass valves
22 Set exhaust diameter to 5.50" (average size for best power and torque results)
23 None catalytic, None Mufflers
All quality was set to maximum on each section
This is the result (no problems ocurred)
Now ill make a fine tune for better results and write all steps again.
This can take some more time.
4.2L R8Rev0.lua (73.4 KB)
im a bit out of time, so ill resume:
just a few adjustments on turbo sizes, exhaust, boost and cam profiles the compression miraculously is able to get increased from 8.9:1 to 9.7:1 and the engine works fine. But after save and close to revise it again the engine cant run anymore. It says the compression need to be reduced.
Here it is
4.2L R8Rev1.lua (73.5 KB)
It is this step I’m interested in:
“just a few adjustments on turbo sizes, exhaust, boost and cam profiles the compression miraculously is able to get increased from 8.9:1 to 9.7:1 and the engine works fine. But after save and close to revise it again the engine cant run anymore. It says the compression need to be reduced.”
Changes to “turbo sizes, exhaust, boost and cam profile” should have a huge effect on which RON rating you are getting, especially for high-performance turbo setups, there is no miracle in that per se.
The only thing that seems out of the ordinary in your description is that the saving doesn’t work.
Did you rerun the engine test before saving the modified version of the engine and it worked just fine? I cannot reproduce any saving problem here currently, and I’m using your engine.
there is no problem to save.
But after save and close the revision, when you click to revise the engine again its like the compression doesnt fit anymore.
Did you test the the second engine I uploaded?
[quote=“Bullets”]im a bit out of time, so ill resume:
just a few adjustments on turbo sizes, exhaust, boost and cam profiles the compression miraculously is able to get increased from 8.9:1 to 9.7:1 and the engine works fine. But after save and close to revise it again the engine cant run anymore. It says the compression need to be reduced.
Here it is[/quote]
Well you say “a few” - can you post the exact details to it? I suspect a bug in the Saving Mechanic where a small change in turbine or compressor size is being stepped up or down to get it saved. We had that a long time ago where the bore and stroke sometimes were off by 0.1mm after saving.
(IF you can reproduce it -> Make a small video on youtube and we may can spot the problem way easier)
Yes I did test the second engine as well, the only problem I can really see is that the engine manager doesn’t show the correct stats for it. I couldn’t reproduce getting the game to save an engine which shows the wrong stats in the engine manager though, using your engine as a basis.
No. Nothing change after save. I already made that test.
The problem is when I am making some changes, miracously the compression get able to be highly increased (in this case from 8.9:1 to 9.7:1) and after save and close the designer, the compression doesnt fit anymore.
The first image is after save the engine and close the designer. Look at the power and torque. Its normal, like none problems on it.
The second is after I click to revise the engine. The compression doesnt fit anymore.
The game “accept” that compression rate but when I close and open the designer to revise the engine again the game “refuse” it.
In both images you have a 0.0 MTBF, that means that BOTH engines fail, not just the second one.
If you try to replicate the AUDI R8 4.2, the max rpm on the real engine is 8700.
[quote=“RobtheFiend”]In both images you have a 0.0 MTBF, that means that BOTH engines fail, not just the second one.
If you try to replicate the AUDI R8 4.2, the max rpm on the real engine is 8700.[/quote]
I dont care about MTBF. Im just exploring the limits and technics. 0 MTBF or not, the engine runs and show results anyways.
I’m close to found the source of the problem. I think its related to the Exhaust diameter and cam profile.
I have discovered how the bug appears.
it seems it only affects turbo engines. you build and tweak everything and when saving the engine something breaks. the problem only surfaces after you modify something again, usualy AR ratio or boost or put the engine in one of your cars. if you reload the engine in sandbox mode, nothing happens.
LE: it also happens when you test it againg right after saving.
Yeah i forgot that detail about this problem affect only turbo engines.
Today I made another test: I loaded a 4 cyl engine and after enlarge the exhaust diameter in 1" the “miracle enabled”.
I tried to reproduce again but it doesnt work. I got fooled again
Thank you very much for the video! This showed what actually happens 
We’ll get on fixing this for the next update.