my fault , i didn't notice this is the diesel chat.
well in theory the turbo lag is lower if the pressure difference between the pressure of the air going into the intake and the pressure of the compressed air (ie before and after the turbo) is smaller. So theoretically, in order to have 0 turbo lag you need higher pressure before the turbo and lower pressure after , but of course this is not practical.
This concept is similar to the thermal efficiency of an engine which is related to the temperature difference of the cold and hot sources (it's actually a ratio)
To reiterate, the higher the pressure after the turbo , the longer it will take for the turbo to spool up. So from this point of view, dump valves are beneficial.
You are right , i should have referred to it as spool up time exclusively instead of turbo lag. Indeed , spool up time is not the same as turbo lag, but it's one of the reasons for it.
As for how to increase pressure without a throttle plate, i thought that the rate at which pressure is relieved into the cylinders was too low, but at a second thought that's just improbable.
Btw is there an overlap in the opening of the intake and exhaust valves in a diesel engine?
Like i said you are probably right but from what I can gather it should help stop the boost going back though the air filter and back though the turbo which isn't good
It cannot go back through the air filter because there's no throttle in a diesel engine.
DIESEL ENGINES DO NOT HAVE THROTTLES :amazed::amazed::amazed::amazed:
Look. Whatever you've heard or seen, the bottom line is diesels have no need or use for dump valves.
Also, dump valves and wastegates are completely unrelated. If you think they are, you have some very basic reading to do on understanding how turbochargers, wastegates and the like work.
whats scavenging?
it also helps trapped exhaust gasses in the cylinder mix with the air/fuel mixture
That's pointless - exhaust gases need to go south, whether via a turbine or not. You don't want them remaining in the combustion chambers.
Diesel engines do not have throttles - there's nothing to dump.
there will always be a small quantity of exhaust gases in the cylinder that won't flush no matter how you tune your exhaust manifold/ports and the best you can do is to make sure that they mix properly with the air/fuel otherwise you won't get a good combustion.
Would it not be the same amount of mix going in, just that it was combusting better, due to no co, which dosnt burn.
So. From what your saying is i dont need a dv. Cool, i wont waste the rhino.
Back to scavenging. I was always under the immpression that the idea of valve overlap, was more geared towards getting the exhaust out of the pot, then getting extra fuel air mix in.
Would it not be the same amount of mix going in, just that it was combusting better, due to no co, which dosnt burn.