I was talking about people in general, no one specific lol
The 2H/12H-T/1HZ/1HD-T/1HD-FT Gturbo Alternative Tech Thread
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And you take a pass on explaining it. Great. Good job.
Anytime mate.
Haha I've just seen your little quote you have underneath you name @gerg
You see things; and you say, 'Why?' But I dream things that never were; and I say, "Why not?"
I guess this applies to me in this case as you don't seem to be living up to it! I constantly think of crazy ideas and different approaches to certain things then try to test it all out to see if it works better than before. I'm really not sure what your agender is or your attitude towards other people posting their own opinions and results they have found. I didn't realise this is the Gerg and Dougal show and everyone else has to keep quiet if they don't agree or have differing views. I'm just putting out what I have found as it might be helpful to someone who might have an open mind about things.
Not that I need to prove anything to you but here are the three different springs I used on a recent test where I could run 18psi target pressure on all of them but they all produced a different EMP:IMP which was very clear in how they drove on the road. It doesn't take a big change either to start feeling the difference, this particular test was for EMP build during spool and you could really feel the difference going from 1.5:1 down to 1.2:1.
Haha I've just seen your little quote you have underneath you name @gerg
You see things; and you say, 'Why?' But I dream things that never were; and I say, "Why not?"
I guess this applies to me in this case as you don't seem to be living up to it! I constantly think of crazy ideas and different approaches to certain things then try to test it all out to see if it works better than before. I'm really not sure what your agender is or your attitude towards other people posting their own opinions and results they have found. I didn't realise this is the Gerg and Dougal show and everyone else has to keep quiet if they don't agree or have differing views. I'm just putting out what I have found as it might be helpful to someone who might have an open mind about things.
Not that I need to prove anything to you but here are the three different springs I used on a recent test where I could run 18psi target pressure on all of them but they all produced a different EMP:IMP which was very clear in how they drove on the road. It doesn't take a big change either to start feeling the difference, this particular test was for EMP build during spool and you could really feel the difference going from 1.5:1 down to 1.2:1.
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The problem with a turbo boost pressure reading is you’re not measuring the pressure inside the cylinder, instead you’re measuring at the turbo output (or maybe in the intake manifold)
If you CNC/port and polish a cylinder head and fit a larger camshaft it will obviously flow considerably better than standard. Therefore you would have a reduction in boost pressure (as measured at the turbo) but an increase in airflow.
Your statement would be correct if you were somehow able to measure the boost pressure inside the cylinder with the piston at the bottom of its stroke.
So essentially your formula needs to include volumetric efficiency
AussieHJCruza
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The problem with a turbo boost pressure reading is you’re not measuring the pressure inside the cylinder, instead you’re measuring at the turbo output (or maybe in the intake manifold)
If you CNC/port and polish a cylinder head and fit a larger camshaft it will obviously flow considerably better than standard. Therefore you would have a reduction in boost pressure (as measured at the turbo) but an increase in airflow.
Your statement would be correct if you were somehow able to measure the boost pressure inside the cylinder with the piston at the bottom of its stroke.
So essentially your formula needs to include volumetric efficiency
True, boost isn't measured in the cylinder and actual pressure of the intake charge would be likely different, but it's a constant that we all understand (More is always better
)I guess what I was trying to say was, if nothing else changes, ie intake mods, camshaft, etc, I can't see how, with boost as the only variable, lower boost pressure could equate to higher airflow, except a negligible difference based on EMP.
Interesting senario about head work, cam, etc tho - wouldn't a wastegated turbo still provide the same boost PSI if the intake flowed better, given boost pressure actuates the wastegate, not airflow. Volume of air increase but boost the same?
I'm out of my depth here...
I called you out and asked you to explain yourself. My apologies.
Well if everything is the same then partially correct however there is one other aspect to consider... heat.
Higher boost pressure might be at a higher temperature therefore less mass of oxygen compared to lower boost at lower temperature.
So depends what you mean by “air” and how you are measuring it (eg by weight or volume).
What you want is the most mass of oxygen molecules entering the engine.
Hence an intercooler will drop boost pressure (by dropping temperature) but the mass should remain the same
Edit - it’s also the reason why mass airflow sensors include an intake temperature sensor... so it can work out the mass of air flowing into the engine per second. (In a GM ls1 engine the ecu reports grams/second of oxygen)
Higher boost pressure might be at a higher temperature therefore less mass of oxygen compared to lower boost at lower temperature.
So depends what you mean by “air” and how you are measuring it (eg by weight or volume).
What you want is the most mass of oxygen molecules entering the engine.
Hence an intercooler will drop boost pressure (by dropping temperature) but the mass should remain the same
Edit - it’s also the reason why mass airflow sensors include an intake temperature sensor... so it can work out the mass of air flowing into the engine per second. (In a GM ls1 engine the ecu reports grams/second of oxygen)
The turbo would still make the same boost but you would increase VE and decrease pumping loses.
AussieHJCruza
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To quote Gale Banks, "Air Density is what matters"Well if everything is the same then partially correct however there is one other aspect to consider... heat.
Higher boost pressure might be at a higher temperature therefore less mass of oxygen compared to lower boost at lower temperature.
So depends what you mean by “air” and how you are measuring it (eg by weight or volume).
What you want is the most mass of oxygen molecules entering the engine.
Hence an intercooler will drop boost pressure (by dropping temperature) but the mass should remain the same
Edit - it’s also the reason why mass airflow sensors include an intake temperature sensor... so it can work out the mass of air flowing into the engine per second. (In a GM ls1 engine the ecu reports grams/second of oxygen)
As someone who works in the structural field, the way boost, air density, etc etc all work together is absolutely fascinating.
The problem with a turbo boost pressure reading is you’re not measuring the pressure inside the cylinder, instead you’re measuring at the turbo output (or maybe in the intake manifold)
If you CNC/port and polish a cylinder head and fit a larger camshaft it will obviously flow considerably better than standard. Therefore you would have a reduction in boost pressure (as measured at the turbo) but an increase in airflow.
Your statement would be correct if you were somehow able to measure the boost pressure inside the cylinder with the piston at the bottom of its stroke.
So essentially your formula needs to include volumetric efficiency
My turbo sizing all includes volumetric efficiency. But the way it works is the opposite to your example above. Fixing flow restrictions results in more air flow, faster spool to max boost and maintains max boost in more challenging conditions (altitude etc).
Because better intake flow gives you more exhaust flow to spool the turbo.
There is not ever a reduction in boost. Unless the wastegate setting has been manually changed to reduce boost. But no-one ever does that.
Indeed. Intake air density is everything. The only thing things that can increase intake density are boost and cooled boost.
I wasn’t referring to your example, more the point HJCruza was asking how reducing boost pressure could result in more airflow. Ignore turbo choice and waste gates and even engines for this matter... the simple fact is boost pressure doesn’t indicate how much air is flowing through a system. An engine with less restriction and a more efficient turbo compression (eg less heat) can deliver more oxygen modules at lower boost pressure than an inefficient turbo with a restrictive cylinder head that is making more boost.
All I was trying to point out is that more boost pressure doesn’t nessisarily mean more “airflow” in terms of grams of oxygen per second.
All I was trying to point out is that more boost pressure doesn’t nessisarily mean more “airflow” in terms of grams of oxygen per second.
mudgudgeon
Resident galah
Can you clarify this?
Are you suggesting two different set ups in this scenario as the same engine, same turbo, but different waste gate setup?
Both showing 20psi, but different flow through the intake? Different EMP?
Doesn't make sense to me.
An analogy that works for my brain is
picture a 1/2 garden hose (intake manifold, cylinders, exhaust manifold is all part of the hose)
Now pump 20litres per minute through the hose.
With an open end on the hose pressure in the hose is relatively low.
Put your thumb over the end of the hose (closed wastegate), if the flow rate stays the same at 20litres per minute, pressure in the hose has to go up because you're trying to squeeze the same amount of water through a smaller restriction at the outlet.
Opposite is true. If you have a restricted opening, and flow is constant as soon as you open up a restriction (wastegate) pressure has to drop, unless you increase the flow at the same time.
With a turbo, when the waste gate opens, drive pressure drops, turbo speed drops, volume of air pumped through the system drops.
This is true whether the wastegate opens because of boost signal at the actuator, or whether it opens because EMP has overcome the wastegate spring preload.
The only way that changes is by pumping in excess fuel to increase the amount of exhaust gas and gas temperature to create more drive energy.
At this point you have more fuel burn, and no increase in oxygen (your example has you still at 20psi). AFR goes to crap, with EGTs not far behind.
@KiwiDingo feel free to improve on my analogy
@Dougal @gerg feel free to tear apart my clumsy analogy. I know you guys have a better grip on the physics at play here than most
The combination of spring rate and preload is what keeps the wastegate shut. Your springs with less preload force are leaking during spoolup. This is reducing EMP but also reducing boost and turbo spool when the manifold is cold.
There is no magic here. You simply have a wastegate that can't keep itself shut to provide low end boost. That is a bad thing.
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The analogy of an engine being a restriction is one I really don't like. An engine is a fixed volume pump. Turn that pump faster and it pumps more air. Improve VE and it flows more air. Increase air density (with boost) and it pumps more air per turn.
It is not a pipe which simply flows more when bored out bigger.
The difference between say 85 and 95% VE is enormous as far as turbo response, spoolup and drivability goes. But no changes in VE can compete with a turbo cramming 2+ times as much air into the same space for power.
OEM's working to predefined power/torque limits are the only ones who will reduce boost if they can find a VE improvement and still meet all other targets. The rest of us tend to increase fuelling to match or leave it as reserve for altitude work.
Nothing bad about my setup. The wastegate opens exactly how I want it too. I don't see the point in forcing the gate to stay closed longer than it ideally should just for the sake of making boost slightly earlier at the expense of performance. I'll choose the setup that actually drives better and gains speed faster than one that just looks better on the boost gauge. Just another example of how boost really does mean very little to how a car actually drives on the road.
By venting EMP you are reducing boost, reducing intake density, reducing engine air flow, increasing smoke and EGT. All those things are bad for performance. You have less power with more diesel going out as smoke.
If you really want to improve performance by your methods. Disconnect the wastegate arm. Your EMP will be close to zero.
Nope wrong, I have more power, less smoke and a heap more airflow actually going through the engine. I think we have differing views on the definition of the word bad. I can reduce EMP and keep boost pressure exactly the same, not sure you why constantly keep trying to say I can't and also keep trying to explain to me how a turbo should or shouldn't work even though your keep forgetting the most important aspects.
I don't think you know how engines work. If they worked the way you think they do, we would have no turbos because EMP is bad.
No you cannot. Physics bro. EMP and EGT is the energy source for the boost.
Yep, I can. I don't need you to confirm this, I already know it to be true.
Indestructible 47
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The problem here is that you have provided absolutely no proof that what you say you can do, you can do. In theory and principles it won't work, so to prove it will post up some numbers.
