Hx-40wii safe boost on stock compression

[Dylly]

Ok, my bad. Sorry Dylly, I was thinking that with a larger/more efficient turbo I could theoretically move more volume and mass. Here me out on this, so you know where I was/am coming from. Air compresses and I was figuring that with a given volume (6.5), the gmx could hypothetically push twice the air volume. And a larger volume could be realized
by a larger turbo pushing (again hypothetically), say three times the volume. Keeping in mind air compresses. What I don't know is at what point the air can no longer be compressed. That's where i was goin.

Owww, my head hurts now...

I know what youre saying. Bigger turbo equals higher attainable boost numbers which is correct if your engine can spin/ compress air with said turbo.... the gmx becomes a grenade where larger holsets are most efficient.

Also theorerically you could compress air infinitely high... turbo selection gets really tricky because of this.. you can make as much boost as you want as long as there is enough fuel to spool your selected turbo... and thats why we steer away from the gmx toward spexific models... i must thank the members for all their r&d with the tested turbos so far.

 

[littleboy]

Mass air flow is not volume????? Now i'm confused:???: Seems to me if i'm moving more mass i'm moving more volume..... :rolleyes5: With different compressor wheel design i can control how much boost versus volume we have . I can make more boost with no gain in flow or in can slightly lower boost and gain air flow volume. Boost pressure does not make power .....

 

[buddy]

It seems you dont understand chemistry. Volume is a physical size of something, not a quantity as it is used in some cases. And you arent even increasing mass flow over another turbo, unless you get the IATs lower.

Big difference between mass flow and volume flow. You cannot control boost verus volume, you can just control boost, air temp and demand (RPM and displacement). You have a general lack of understanding of the chemistry involved, but have benefited from general practices over the years, but not understood the overal design.

 

[Dylly]

Mass air flow is not volume????? Now i'm confused:???: Seems to me if i'm moving more mass i'm moving more volume.....

When talking these engines the volume is constant - its 6.5L or 395ci... No matter how much air you pump into it, the volume will never change. One thing to remember is that most people consider mass and weight the same thing, which they aren't, but they are closely related, and it makes explaining this easier just to consider mass=weight.

For example:
You have a 5 gallon pail, you fill that pail up with rocks - you now have a pail with mass of 50lbs but volume of 5 gallons.
Now add sand to the pail full of rocks, it now has a mass of 70lbs, volume still 5 gallons
Add water to the pail full of sand and rocks, now it has a mass of 85lbs, but the volume again is still 5 gallons.

So the cooler the air going into the engine, the more dense it is, the more mass you flow... Hot 130F air going into the engine would be like filling it with rocks, 80F air would be like filling it with rocks, sand, and water (with consideration to the above example)

 

[littleboy]

Lolz....... thanks for the entertainment. But it works for me so I'll keep running larger turbos so i can have more cfm moving through my engine so i can keep my pressure to a minimum!

 

[littleboy]

Air compresses ...... sand does not.

 

[buddy]

Lolz....... thanks for the entertainment. But it works for me so I'll keep running larger turbos so i can have more cfm moving through my engine so i can keep my pressure to a minimum!

We have been down this road with you before, and if you refuse to educate yourself, don't miseducate others, thats just irresponsible. Its almost as bad as telling people the Compression ratio, which is volume based, can be used to linearly calculate pressure. Again, not a 1 to 1 comparison.

 

[Dylly]

Air compresses ...... sand does not.

Congratulations on that one. I tried to dumb the concept down to a level that everyone might be able to understand. All 3 of those, rock, sand, and water are incompressible fluids, but obviously you missed the point.

Maybe listen to the little voice in your head that reads these threads: you might learn something

 

[littleboy]

We have been down this road with you before, and if you refuse to educate yourself, don't miseducate others, thats just irresponsible. Its almost as bad as telling people the Compression ratio, which is volume based, can be used to linearly calculate pressure. Again, not a 1 to 1 comparison.

I may not know all the fancy terminology for the politically correct wording but i do have seat and dyno experience to draw from! It's kinda funny how every time you get into arguments with folk who have experience but you can't back yourself up ..... you just have big fancy theories.

 

[Dylly]

I may not know all the fancy terminology for the politically correct wording but i do have seat and dyno experience to draw from! It's kinda funny how every time you get into arguments with folk who have experience but you can't back yourself up ..... you just have big fancy theories.

Just a heads up: That "Fancy Terminology" and "Big Fancy Theories" built every engine, every car, every building, EVERYTHING that is man made. They aren't theories, its physics LAW.. The laws of physics are constant, you can't break them. Period.

I would like to see your "seat and dyno experience" design and build an engine... I wish you luck.

 

[littleboy]

Go look on cumminsfevers latest thread... that's all i'll say for myself. He and i are brothers and work together.
Oh, can you spool an hx-55 turbo with a .29 plunger pump by 1500 rpm? Just sayin.....

 

[THEFERMANATOR]

Yes, MASS AIR FLOW, that is more mass, people just incorrectly apply the theories to volume (CFM is a volume flow). And its not voodoo that a larger turbo automatically means better mass flow. To increase mass air flow you need to increase boost or lower the air temp. If you do not lower the IAT, then you don't increase mass flow at the same boost. So the GMx at 8psi of boost and IAT of 150F will flow just as much mass as an HX40 at 8psi boost at 150F IAT. However, the at 15psi the GMx is already a heating element so IATs are typically higher so it doesnt flow as much mass as an HX40 or ATT at 15psi. That and improvements in exhaust flow also help the larger turbos, with very little to do with the intake air flow.

A mass air flow sensor measures teh volume of air passing through an orifice. You can change turbos on a DMAX and NOT change boost and see an INCREASE in airflow. Believe what you want, but I have seen it first hand in data logs. In a naturally aspirated engine yes an engine can only flow so much air at X amount of atmospheric pressure, but once you go artificially aspirated there are MANY factors that figure into airflow. So how does exhaust backpressure figure into your equation of any turbo regardless of size can only move X amount of airflow at Y amount of boost? Answer this one and maybe you will see teh BIG picture. I'm not saying you will see a HUGE change in airflow at the same amount of boost, but you CAN move more air at the same boost pressure in a artificially aspirated engine while maintaining the same boost and cylinder pressure by reducing exhaust pressure. Otherwise there would be no point in changing out to the ATT over a GM-8 as they would both be moving the same amount of air at teh same boost pressure so the gains would be negligeable..

 

[buddy]

You got that a bit wrong Ferminator. A mass air flow system may measure volume flow, but the system must use an IAT sensor to actually calculate mass air flow. In order to gain mass flow, you HAVE TO LOWER THE TEMPERATURE. So if X turbo is larger, it probably is a little more efficient at a specific pressure ratio and will contribute less heat to the intake air. This I have already stated about 3 times in this thread. In this respect a larger turbo does give you greater mass flow, IF you are in a higher efficiency area. This I have already stated multiple times. Yes, you do get more mass flow from a larger turbo under the right conditions, and the right conditions are typically high fuel rates and a loaded engine. And yes, the turbo itself will flow more CFM through it, not the engine, if the intake air is lower at a given boost value. This I have already stated.

You are not seeing the bigger picture. Reducing exhaust pressure frees horspower. It takes work to create exhaust backpressure, the piston has to push against it. So that is another type of gain for a turbo which I have already mentioned. With the 6.5 camshaft design, you can get slightly more air in the cylinder because the exhaust trapped is under less pressure, but its very small, only about 2%. With another turbo engine that has valve overlap and divided manifolds for scavenging it wouldn't make any CFM difference.

You have to understand these concepts to understand the best way to modify a powerplant. And also a bunch of other stuff.

So, take the lesson for the day, and at 15psi of boost and even more so at 20psi of boost, the ATT and HX40 have much superior efficiency (less thermal transfer to the intake air) than a GMx turbo. So yes, they do "flow" more air in that scenario, when the IATs are lower than compared to the GMx. The mass flow has increased through the engine, even though the engine volume flow never changed. The turbo took more ambiant air and made it into that same volume that went through the engine. So the turbo compressor had more CFM.

This is why air filters need to be rated at your turbos CFM and intercooler need to be rated for engine CFM. Two very differnt VOLUME ratings, because neither cares about how many Oxygen particles are in that volume of air that pass through it.

 

[THEFERMANATOR]

You got that a bit wrong Ferminator. A mass air flow system may measure volume flow, but the system must use an IAT sensor to actually calculate mass air flow. In order to gain mass flow, you HAVE TO LOWER THE TEMPERATURE. So if X turbo is larger, it probably is a little more efficient at a specific pressure ratio and will contribute less heat to the intake air. This I have already stated about 3 times in this thread. In this respect a larger turbo does give you greater mass flow, IF you are in a higher efficiency area. This I have already stated multiple times. Yes, you do get more mass flow from a larger turbo under the right conditions, and the right conditions are typically high fuel rates and a loaded engine. And yes, the turbo itself will flow more CFM through it, not the engine, if the intake air is lower at a given boost value. This I have already stated.

You are not seeing the bigger picture. Reducing exhaust pressure frees horspower. It takes work to create exhaust backpressure, the piston has to push against it. So that is another type of gain for a turbo which I have already mentioned. With the 6.5 camshaft design, you can get slightly more air in the cylinder because the exhaust trapped is under less pressure, but its very small, only about 2%. With another turbo engine that has valve overlap and divided manifolds for scavenging it wouldn't make any CFM difference.

You have to understand these concepts to understand the best way to modify a powerplant. And also a bunch of other stuff.

So, take the lesson for the day, and at 15psi of boost and even more so at 20psi of boost, the ATT and HX40 have much superior efficiency (less thermal transfer to the intake air) than a GMx turbo. So yes, they do "flow" more air in that scenario, when the IATs are lower than compared to the GMx. The mass flow has increased through the engine, even though the engine volume flow never changed. The turbo took more ambiant air and made it into that same volume that went through the engine. So the turbo compressor had more CFM.

This is why air filters need to be rated at your turbos CFM and intercooler need to be rated for engine CFM. Two very differnt VOLUME ratings, because neither cares about how many Oxygen particles are in that volume of air that pass through it.

You have your view of it, and honestly you contradict yourself in this thread. You state that pressure is pressure, yet now your throwing temperature into the equation. Also your over anylizing what a mass air flow sensor does. It is an air meter, plain and simple. Yes to get total airflow you have to throw in temperature to get density, but the statement has been made NUMEROUS times in this thread that X amount of pressure is Y amount of flow regardless of turbo which is 100% false. You hint at that now in this post though. There are so many variables that figure into CFM of flow, that to say that 15 pounds of boost with an ATT, HX40, or GM8 wil lall move the same amount of air is a completely bogus and misleading situation. I mention the MAF because it measures airflow BEFORE the turbo showing a true measure of airflow into the engine in a situation that I have witnessed. I was simply trying to point out that the equation to calculate total airflow is much deeper than simply boost, and 2 turbos at the same boost level CAN move different amounts of air.

 

[buddy]

Do i have to go quote myself. X amount of pressure is Y amount of flow at the same temperature. How many times have I said this? The point being, you have to lower the temperature to achieve any mass flow gains. I never said they were incapable of flowing differnt amounts of mass, just that its the same at the same temperature.

The engine CFM is essentially constant for a give RPM. That does not change ever. So that must be where you think I contradict myself.

A MAF system is an air mass meter, not an air volume meter. Because a computer needs to know the air mass to properly compenate for air to fuel ratio. Rather than just relying on exhaust O2 sensors.

 

[littleboy]

Buddy you have contradicted yourself so many times.... i believe you are a bit confused now....just sayen

 

[THEFERMANATOR]

Do i have to go quote myself. X amount of pressure is Y amount of flow at the same temperature. How many times have I said this? The point being, you have to lower the temperature to achieve any mass flow gains. I never said they were incapable of flowing differnt amounts of mass, just that its the same at the same temperature.

The engine CFM is essentially constant for a give RPM. That does not change ever. So that must be where you think I contradict myself.

A MAF system is an air mass meter, not an air volume meter. Because a computer needs to know the air mass to properly compenate for air to fuel ratio. Rather than just relying on exhaust O2 sensors.

Your not very clear to many of us as evidenced by the posts here in your conveying such is my point. You say in one part that at the same boost pressure that each turbo moves teh same amount of airflow, but then later on throw in intake air temps. I know trying to convey what your thinking over a forum can be difficult as I have a hard time doing so. My point is that you weren't evry clear in your conveying of this. You can agree or disagree with me, but had your true popint been clear to the rest of us we wouldn't have 3 pages of confusion trying to state it with all of the back and forth.

 

[THEFERMANATOR]

Buddy you have contradicted yourself so many times.... i believe you are a bit confused now....just sayen

I don't think he means to contradict himself, it's just that he has a thought in his head, and it is not being clearly conveyed through his typing.

 

[buddy]

Dylly was correct, the CFM is exactly the same through the engine at the same boost level. The mass flow is exactly the same at the same IAT. But because it is more efficient there are gains with larger turbos with lower IATs. The definition of efficiency is basically how much mass are you flowing compared to the same boost at ambiant temp. The higher the efficiency range you are in on the compressor map the less it will heat up the air, thus flowing more mass. But the CFM through the engine remains the same. There is a CFM difference at the inlet of the turbo depending on the IAT difference, but always equivalent through the engine cylinders, its a fixed volume pump.

So more air mass at 15psi of boost is the most appropriate way to describe it, because the GMx transfers more heat to the incoming air. volume and mass flow are entirely different.

First dang post of the topic, now who is confused? Go learn yourself to read better.

 

[nmb2]

boost is a measure of restriction at the engine, not a measure of flow from the compressor. Different chargers most certainly will flow different amounts of air at the same pressure ratios.

Post the compressor maps.