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Been following this thread... I'm not caught up enough to fully understand pressure maps and turbo sizing, but all of this discussion has me hesitating to install an 8474 sitting on my bench.
Question for those who understand them better: will the predicted high(er) emap be an issue if I'm only shooting for 14-15 psi? I'm trying to decide if I should just install it or bite the bullet and pay the restocking and shipping fees swap it for an 8374.
Who's prediciting higher emap ? Whoever they are needs to talk to Borgwarner and tell them they don't know how turbos work ...lol
I agree..
I know at the power levels between 25 psi and 40 psi , according to the 9280/9180 compressor map that I posted up, there is only a small difference (6psi) at the 3.4 scale of the map and it's dead even at the anything higher.
So regardless of the 73mm enducer vs the 67nn enducer, the 9180/9280 are virtually a wash, basically dead even in EMAP. That means the too high in EGT argument for the rotary concerning the 9280 has ended. Unless an "expert" can show actual logs that show Borg's advertised compressor map is wrong.
But I predict all we will hear are crickets.
Btw, I'm not saying that a Bullseye S481 Batmowheel isn't a better option for 800hp seekers, obviously it is. But for 600+ (mustang dyno) power and a pretty quick spool, I say 9280.
Been following this thread... I'm not caught up enough to fully understand pressure maps and turbo sizing, but all of this discussion has me hesitating to install an 8474 sitting on my bench.
Question for those who understand them better: will the predicted high(er) emap be an issue if I'm only shooting for 14-15 psi? I'm trying to decide if I should just install it or bite the bullet and pay the restocking and shipping fees swap it for an 8374.
If you want to keep it in that power range, the 8374 is proven, and the spool will be slightly quicker.
I know at the power levels between 25 psi and 40 psi , according to the 9280/9180 compressor map that I posted up, there is only a small difference (6psi) at the lower end of the map and it's dead even at the 3.4 part of the map.
So regardless of the 73mm enducer vs the 67nn enducer, the 9180/9280 are virtually a wash, basically dead even in EMAP. That means the too high in EGT argument for the rotary concerning the 9280 has ended. Unless an "expert" can show actual logs that show Borg's advertised compressor map is wrong.
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I really don't understand how you came to that conclusion from the discussion we had ....... a 9% improvement in compressor efficiency at 3.4Pr and 90lbs/min makes the 9280 superior by a good margin. The crossover point where the 9280 rules looks to be somewhere around the 85lb mark.
I really don't understand how you came to that conclusion from the discussion we had ....... a 9% improvement in compressor efficiency at 3.4Pr and 90lbs/min makes the 9280 superior by a good margin. The crossover point where the 9280 rules looks to be somewhere around the 85lb mark.
That's why I originally stated "Unless I am reading the map wrong" as to the +9%
Even if I have the efficiency between the 2 turbos in reverse, knowing how the 9180 has been unanimously considered rotary acceptable , my argument was to the naysayers who have been promoting their "math" about the 9280 being NOT rotary acceptable.
So what you are saying now is that Turblown was correct about the 9280 being more efficient (after the crossover) vs the 9180.
9180 with a 1.45 rear will have 1:1 emap at 22-23psi on a bridgeport. On a semi PP that shows it is at 1:1 at less than 17-18psi. (this is based on datalogs I have on both cars)
You can probably do 25psi on a street port, but any engine with descent VE is going to get maxxed out very quickly. Of course you can go past 1:1 to some extent depending on the level of porting, I wouldn't be using the word efficient.
I don't get it. Aren't there people running even the smaller 8374 above 30psi? Why would you not be able to run a 9180 into 30psi range on a streetport?
9180 with a 1.45 rear will have 1:1 emap at 22-23psi on a bridgeport. On a semi PP that shows it is at 1:1 at less than 17-18psi. (this is based on datalogs I have on both cars)
You can probably do 25psi on a street port, but any engine with descent VE is going to get maxxed out very quickly. Of course you can go past 1:1 to some extent depending on the level of porting, I wouldn't be using the word efficient.
I've been told that a 1-1 emap is an unrealistic goal while making big power in a rotary.
There have been logs posted of smaller than 1.45 (1.15) rears showing absolutely no difference in emap on the 9180 vs going to a 1.45.
Not trying to disagree, but I was 98% sure I was going with a 9180 and followed nearly every build on here related to that turbo. I've since committed to the 9280.
There have been logs posted of smaller than 1.45 (1.15) rears showing absolutely no difference in emap on the 9180 vs going to a 1.45.
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This doesn't surprise me ... I've experienced a similar result on a different turbo . After some head scratching and more analysis I came to the conclusion ...yes emap was the same BUT mass airflow was higher for the larger housing at the same boost . So in effect EMAP stayed the same at same boost but power was higher . This is one of those results that can be very confusing unless you are monitoring lots of parameters and can fully analyse what happened.
So bigger exhausts housing, same boost, but higher mass flow and constant EMAP.
I get that you experienced it. But what causes this to happen?
There is less exhaust restriction which I would think would mean greater exhaust flow or lower pressure.
Is the constant value for emap because the engine is breathing better due to lower physical exhaust restriction, enabling it too take in more air volume and then emap remains constant and balancing out as a result?
Or is the emap actually a little different and not constant, but the variance associated with whatever the boost level was, was not big enough to drive a material change in EMAP? Meaning emap was just not sensitive enough at the boost level and the flow being put through the engine? I imagine a bigger turbo will be less sensitive to AR housing changes at sub 20-25psi boost and a small turbo will be really sensitive.
It's super hard to tell what each person is experiencing unless every scenario comes with a bunch of other data like the previous poster mentioned above.
Sorry to ask a totally **tard question, but is EMAP the technical term for exhaust backpressure vs MAP??
i did a search and i think thats what it meant but just after clarification in simple terms pls so i can understand all this jargon (dyslexic!!)
e85 with an EMAP crossover point between 6k and 7k RPM (I would suspect this to be lower, but we don't have a Turbine Efficiency map to correct percentages).
Just another way of seeing it, but notice how you MUST change the Turbine Expansion Ratio to match the turbine housing?
Food for thought. I'm going to say that MatchBot is flawed and this data is incorrect based on the Ideal Gas Law. I'll have a chat with them tomorrow.
I think the motor porting and manifold design and fuel are really the only things that need to be the same. Dyno really shouldn't matter either, but an EGT/EMAP log will tell all.
Again, I'd like to see the proof or even the math explained that the 9280 at less boost making the same measured power is producing more emap then the 9180 at the same power level.
This thread is a prime example of what happens when you have too many people who have no idea how it works making baseless assumptions rooted in personal bias or something they read on the internet.
Literally copied and pasted from a post I made 2-3 days ago on another thread countering this same factless hype pitch from Turblown:
Originally Posted by Skeese
I don't need turbo-to-turbo data to back up an understanding of the system design. For example if you consider the 9180 vs the 9280 where the hot side turbines are the same size and are talking about a turbo-to-turbo comparison on the same manifold, same motor, same exhaust its a fair known fact that the larger compressor will FLOW more air at the same pressure. So with both turbos at the same 15 PSI, the 9280 is pushing MORE air into the engine requiring MORE fuel to balance to the same target AFR. More air + more fuel in the same compression stroke is going to equal HIGHER cylinder/rotor-chamber pressure, which is where the additional power comes from between the two turbos at the same boost level. With cylinder/chamber pressures this high (100+ PSID before boost pressure), temperature is DIRECTLY related to pressure. The higher the pressure is...the higher the temperature driven up (please refer to Boyle's law: the pressure-volume law states that the volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant, PV=nRT) SO....we have gasses coming out that ARE hotter.
Now next is mass flow. With the larger compression flowing MORE air requiring MORE fuel... you have MORE combustion MASS and more exhaust flow with everything else the same. If that flow is going into the same manifold and turbo housing into the same turbo wheel you are going to have MORE mass inside the SAME hot side volume with the same restriction that you had with the turbo that had a smaller compressor, which is....pressure! Think...if you have a pipe and you push XXXX amount of air/exhaust into it to get it to say 18 PSID, what happens when you force MORE into the same pipe? Pressure goes up. If you don't add flow, pressure will go up.
Making things worse, the exhaust temps are higher from the higher cylinder pressure which only compounds the fact that you're putting more mass into the same volume by adding more HOT mass. All of which brings me to the point that adding compressor without adding turbine or volume and holding everything else the same WILL BY FACT bring up EGT and backpressure. You can't force more into something with the same size outlet and expect temps or pressures to go down...that just isn't how it works.
I'm not saying the 9280 is a bad turbo. I'm stating it will generate higher EGTs and more backpressure than the 9180, because it will.
Skeese
I do not understand what about that is so difficult to understand. It isnt a debatable opinion, its the LAW of how ideal gasses behave. But, if anyone would like to bet money against that I'm open to make that wager.
^Science wins again (Yea!)...the Ideal Gas Law rules supreme indeed. And then, if my reading comprehension is correct, the previous poster is simply curious if the EGTs/EMAPs are comparable at a lower boost target for the 9280 relative to the 9180. I.e., What lower boost difference for the 9280, if any, would achieve comparable power and or EGTs of a higher boosted 9180?
^Science wins again (Yea!)...the Ideal Gas Law rules supreme indeed. And then, if my reading comprehension is correct, the previous poster is simply curious if the EGTs/EMAPs are comparable at a lower boost target for the 9280 relative to the 9180. I.e., What lower boost difference for the 9280, if any, would achieve comparable power and or EGTs of a higher boosted 9180?
Then use the science on the compressor map, show us anywhere after the crossover where there will be excessive EMAP or even a choke point vs the overlaid 9180 map.
I'm not saying the 9280 is a bad turbo. I'm stating it will generate higher EGTs and more backpressure than the 9180, because it will
I just read your explanation and understand the maths/physics is correct BUT I disagree with that last statement . Reason being you have omitted to mention THE most important parameter in all this , and that is .............POWER!
As we know mass flow and power follow each-other so If you do a comparison at the same power level , at a point where the 9280 compressor is more efficient than the 9180 (say 90lbs/min) you will find the opposite result.
At the same power level (and while at over 85lbs/min) 9280 will need Less boost ,create less heat and have lower EMAP than the 9180.
It's the same maths/physics ...........just comparing apples with apples this time!
^Science wins again (Yea!)...the Ideal Gas Law rules supreme indeed. And then, if my reading comprehension is correct, the previous poster is simply curious if the EGTs/EMAPs are comparable at a lower boost target for the 9280 relative to the 9180. I.e., What lower boost difference for the 9280, if any, would achieve comparable power and or EGTs of a higher boosted 9180?
Our real data would come from Turbo Shaft Speed in which we see exactly on the compressor map these setups run. I'm amazed that Aaron Parker who's had turbo shaft speed for YEARS on a sponsored EFR car hasn't chimed in on this. I'll text him and see what's up. I want actual data...
I just read your explanation and understand the maths/physics is correct BUT I disagree with that last statement . Reason being you have omitted to mention THE most important parameter in all this , and that is .............POWER!
As we know mass flow and power follow each-other so If you do a comparison at the same power level , at a point where the 9280 compressor is more efficient than the 9180 (say 90lbs/min) you will find the opposite result.
At the same power level (and while at over 85lbs/min) 9280 will need Less boost ,create less heat and have lower EMAP than the 9180.
It's the same maths/physics ...........just comparing apples with apples this time!
This is the reason I chose 9280 at the power level we will be at. The compressor map shows it and trumps the so called "science" the high EMAP/mismatch compressor theories that are missinforming those who may be considering this turbo.
The compressor map shows it and trumps the so called "science" the high EMAP/mismatch compressor theories that are missinforming those who may be considering this turbo.
9180 with a 1.45 rear will have 1:1 emap at 22-23psi on a bridgeport. On a semi PP that shows it is at 1:1 at less than 17-18psi. (this is based on datalogs I have on both cars)
You can probably do 25psi on a street port, but any engine with descent VE is going to get maxxed out very quickly. Of course you can go past 1:1 to some extent depending on the level of porting, I wouldn't be using the word efficient.
10-08-19, 03:41 PM
