Diesel has vacuum, should not

Diesel has no throttle butterfly, so there is no vacuum.

Easy fix would be to change diesel turbo compressor map to begin from 0 instead of -3.5 or where it is set now.

For example etk_intake_i4_diesel_turbo could then be:

Code:

//turbineRPM, pressure(PSI)
            [0,         0],
            [24000,     0],
            [60000,     9],
            [90000,     17],
            [150000,    21],
            [200000,    26],
            [250000,    32],

Really minor thing, but just something catches the eye, especially with the semi. Not sure if that would break something other then, but I set my semi ETK 476 turbo compressor map to start from 0.

For gasoline powered cars -3.5 or whatever negative is correct I believe.

 

But there is no vacuum in diesel, according to vacuum gauge it does not go below zero.

At low throttle below 1500rpm needle stays at same position as at idle, so I'm not sure how much turbo restricts there, exhaust is lot less at zero throttle at idle than low throttle at 1500rpm so if turbo would restrict it should show up in vacuum/boost gauge, but there was no change.

I guess that as there is no throttle butterfly, what goes in does come out with enough energy to keep turbo at or near 0 restriction for intake side?

That is at least how it was with Peugeot 306 turbo diesel that someone had to play with things like free flow air filter and stuff, don't ask...

 

Yeah, that thing has small turbo, tiny, really tiny so probably that is affecting it too.

When I try to think how those gas volumes and energies would go, how much air would go in, how much would go out, my brain starts to ache, but diesel is at full throttle all the time, only amount of fuel is adjusted, so there is more exhaust gases coming out, you can feel this from exhaust pipe tip too, also compression is higher which affects that.

It very quickly becomes quite complicated to try to think trough, but where as normal gasoline car has throttle butterfly shut, relative big turbo is not spinning much at all if at all. With diesel things certainly are different, but now we are talking about stuff that has about 0 effect to game play and that probably would require hours of research and air pressure dynamics calculations, which might be rather pointless

Diesels are not very typical tuning platforms, I guess data is bit less from that reason alone. Was it Audi that had TDI at LeMans? Surely someone has the data, but finding it :-/

If I find something about such, I send it to you, but it's indeed hard to find such.