Well i've done exactly this experiment on both my gturbo and eclipse turbo. Gate setup has a massive effect on EMP:IMP even though the boost pressure remains the same. If you think the sole purpose of the wastegate is to only control boost pressure then you are seriously missing out.
The 2H/12H-T/1HZ/1HD-T/1HD-FT Gturbo Alternative Tech Thread (3 Viewers)
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Opening the gate and maintaining boost is only possible with an increase in engine rpm.
What you claim violates several laws of physics. The wastegates only function is to control boost.
Agree to disagree with you on that one. I guess if that's all you believe it's there to control then nothing I say can make you see the truth.
Perhaps look at how they work. The sole input they have is a boost pressure hose.
I'll have to disagree with you on that fact too. There's also the the input from EMP at the other end on the gate itself which can easily be overlooked.
That's not a signal input and the spring inside is sized to keep the wastegate shut against normal EMP.
It most certainly is if your set it up with the correct spring to keep EMP exactly where you want. But if all you want to use the gate for is to control boost then I guess you wouldn't count it as an input.
Using a sprung wastegate so it blows open means the turbo drops boost in many bad situations. It's a terrible idea which is why no manufacturer does that. Only hack tuners.
Accelerate from cold. Big reduction in boost. RPM climbs, big reduction in boost.
Both situations give you smoke and high EGT. Not to mention risking melting pistons.
There is no benefit at all. In fact it's a terrible idea. EMP is not the goal. Air flow through the engine is. Boost provides that air-flow.
Well I get zero of those issues you have suggested and I have found nothing but benefits. Boost doesn't really tell you exactly how much air is going through your engine either. For example two different setups, one taking into consideration EMP, could both have 20psi on their boost gauge but one will be flowing a lot more air through the engine than the other. Using boost only as an indicator of how much airflow you have is a really flawed way of thinking.
AussieHJCruza
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Um, I don't think this stacks up... Admittedly I don't know a lot about this side of physics, but:
Boost = essentially a measure of restriction. Pressure = P = F/A - unless area changes then force must change.
If nothing else changes, less boost has to equal less airflow.
The only ways you can affect EMP vs Boost is by turbine sizing and turbine/compressor efficiency. The good turbo makers are all over that and have been for ever.
Wastegating has zero influence on those. It cannot change the turbine map at all. It can only bypass exhaust flow around the turbine.
Pretty much correct. The restriction in this case is higher EMP therefore with the same boost it flows less air.
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How does EMP influence intake airflow? Are you saying that higher EMP is likely to lead to a lower VE?
Pretty clear we have different views on the subject @Dougal but that's fine. It's conversations like this that might trigger some people to carry out their own testing to find out. I know that's how I become interested in this stuff and learnt how you can alter EMP:IMP via different gate setups and still keep the same target boost pressure.
That's how it works. Higher EMP vs IMP means more retained exhaust in the cylinder on each stroke. The differences have to be huge to have an effect.
Except you cannot alter EMP:IMP via different gate setups. The gate setups cannot an do not alter the turbine maps or performance at all. Your experiment has issues.
So your saying same turbine same engine, same compressor, same everything you can change emp by " tuning" your Wastegate? You like to make claims and not explain them. I'd have to say you should explain yourself. If you don't explain yourself then you have no credibility here.
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Yep, this seems obvious now I think about it again, but I would doubt unless drive pressure was very high proportionally, the difference would be anything significant.
That's exactly the case. The differences have to be huge.
@gerg I have explained myself, I've told you what I did and how it was affected. Not my problem you couldn't get the same results with your own testing. Couldn't care less of your opinion about my credibility, I just don't like to take anything as gospel and need to find out stuff myself which is exactly what I have done. I've done more than enough testing now to come to my own conclusion that the wastegate has a much bigger role to play than just solely controlling boost pressure. EMP control to me is just what I prefer to focus on, some people choose to only focus on boost which is fine. Not everyone wants the exact same setup which is why it's good to hear differing views on subjects like this.
You may need to read what is written by others to not mis-represent their arguments.
