MazdaManiac

iTrader: (3)

You are missing my point. (The whole point in general, methinks.)

Pressure tells you nothing.

Forget "stock". What difference does "stock" make, anyway? Is there some pixie dust involved? You take and RX-8 and put a turbo on it. Are you saying that a different intake air filter or something is gonna make 90 HP on a turbo car?

MY CAR made 230 HP at 9 PSI and then made 316 at 9 PSI with no other significant changes other than the actual turbo (and its resultant increase in efficiency).
Of course, one was flowing about 250 g/sec and the other was about 330 g/sec.
Same intake, same exhaust, same manifold, same downpipe, same cold-side plumbing, same intercooler, same midpipe and same injectors.

Brettus

iTrader: (2)

No - i'm talking more about porting or compression ratio changes

man that must have been a seriouslyy bad tune to only make 230 at 9psi . (A Greddy makes 250 at just over 5 psi )
I could probably do the same with my turbo if I shut off the SSV and aux ports .....


can you show us the dyno with actual boost profile attached of that 316 whp dyno ?

MazdaManiac

iTrader: (3)

Now, if you take a car with a properly sized turbo and every thing else kept exactly the same, you will see a correlative increase in power as you increase the boost.
But that is because you are increasing the flow by raising the pressure and the temperature rise will be nomalized.
If the car makes 200 HP at 5 PSI, it might make 300 HP at 9 PSI. But it probably wont make 450 HP at 13 PSI. Why? Because the flow wont go up in a linear fashion because of the change in compressor eff.
But you will be able to say "it made so and so power at so and so pounds boost" and try to establish a correlation.
But you will NOT be able to translate those power numbers to a different car, even if the mods are exactly the same.
However, if you say "it made so and so power at so and so pounds of flow", you will be able to establish a baseline for a different car, even if its mods are completely different!

Nope. Tune was essentially OK.
The GReddy in its absolutely stock form as a kit makes anywhere from 230 to 280 HP at 9 PSI.

Brettus

iTrader: (2)

Look - I fully understand how good flow can be as a means of determining power but until I see you post some real info on a properly tuned engine with all ports functioning and no other issues with the tune to disprove what I'm saying I'm sticking with the numbers I put up above .....

MazdaManiac

iTrader: (3)

And again, I think you are missing my point.

No one cares what you are sticking with. Believe what you want to believe.
Just don't go around proselytizing.
Its difficult enough to un-do all the misinformation out there that is spread by less "invested" people than yourself.

I don't do all this to convince you.

Brettus

iTrader: (2)

well - I only said that because the argument is going nowhere and you keep spouting out numbers without backing anything up ....

MazdaManiac

iTrader: (3)

No, YOU keep spouting numbers without any backup. All you have stated here are conclusions drawn from inferences made by observing your own car without correlating the data.
There is no "argument". You just don't understand what is going on and I am running out of way to explain it to you.

I've published all the data for this stuff in immense detail for the last 4 years.
I'm not doing your homework for you.
If you think my conclusions are unfounded because I don't have the data, then you are barking up the wrong tree.

This is just how it works. I didn't invent it - its just physics.
All I'm trying to do is put it out there in a way that is comprehensible and correlated to every car.
I'm not pursuing the "why" like you are. I already understand the why.

Brettus

iTrader: (2)

if you take a jaunt over to the Highest horsepower thread you will see where i'm making some of my observations . The rest comes from analysing all the dynos that people actually post on here as well as my own .

How is it that the greddy turbo (the smallest one used here) dyno follows almost exactly every other turbo (including the 3071 ) that runs the same psi . Right up until it runs out of puff and the boost drops away .

Brettus

iTrader: (2)

here ya go


your turn

olddragger

iTrader: (3)

uh----us pettit guys do make well over 300 to the wheels at 10psi? i dont know if that is relavate to the discussion?

I think I understand what MM is saying. Doesnt matter what the boost is--- sooner or later the engine design restricts the power output?
I also think I understand what Brettus is saying ---the lbs of boost required for certain hp numbers are ...... it would be understood that the boost or more correctly the volumn being provided to the engine can be used appropiatly
Am I getting this right?

Another ? I have --why does this engine after FI has been install need an intake with valves?

MazdaManiac

iTrader: (3)

So, what does that show?
That at some "approximate" amount of flow restriction, 4 different turbos on 4 different cars produced roughly similar flow throughput?
That is meaningless information. What are you going to do from that? You can't tune with it because you don't know the temp deltas or the actual flow mass. You can't make a meaningful comparison of what the potential is of those turbo's because, lacking the data I just mentioned, you don't know where they are in their efficiency band.
You can't judge price, ease of installation, kit quality or even appearance.
That chart tells you absolutely nothing.

Some of you do - some of you don't. It depends on the massive quantity of supporting mods you need to get there.
With some of the less efficient turbos, that is the case as well.




NO!

What is being explained is that the only datapoint that actually tells us anything about the potential and actual output of ANY given FI system is total system flow.
Boost is a totally meaningless metric.


Off-boost throttle response and part-throttle torque, which are two additional drivability concerns that are seemingly swept under the rug when you discuss FI around here.
Strangely enough, those are yet two more features that can only be documented with flow since manifold pressure tells you nothing directly about either.

olddragger

iTrader: (3)

I think my point wasnt understood in reference to when I said "Doesnt matter what the boost is.....". I was responding to your response to Bret's chart that said a certain psi level would = to a certain hp. I agreed that was not totally true.
An engine cannot have unlimited flow. So merely "upping the boost/psi" with hopes to gain more flow/power may not happen.
Volumn being equal then flow is the king.

Further on the staged intake. has anyone tried to tune with all ports open, just letting the TB limit the flow?
I understand that the staged intake on a na engine is really well done by Mazda but when we fi with a pump that can provide low/high rpm supply, couldnt the valves be eliminated and still maintain driveability?
I am all for power under the curve and throttle response, but I do like simple. Oh yea---cheap too

MazdaManiac

iTrader: (3)

Yes.

No, not really.
Start-up sucks and off-boost throttle response is sluggish.

olddragger

iTrader: (3)

ok, good to know.
OD

paulmasoner

iTrader: (1)

ok, i certainly cant provide any data here but think of it this way Brettus - if X pressure differential is required to sustain a given mass flow from one end of a steel pipe to the other... you could begin to tie some meaning to Xpsi of boost. But what happens, when you have ambient conditions, different sized pipe, bends in pipe, restrictions, etc involved? psi of boost becomes meaningless without a myriad of other information. but if you are just measuring mass flow, chemisty and physics can tell you precisely the energy output based on the fuel you direct the injectors to input under certain conditions.

i think i do understand your position, but i think you are looking with blinders on. this approach wont work as comparison when you begin looking at other motors, more complex systems, and wider range of turbo's.

There are 2 things that bother me though Brettus, what is it that makes proper MAF scaling hard? IMO from the small grasp I have, its not the harder part of tuning, but is an important one. And it sure isnt less accurate than measuring boost.... read other forums and see folks who have changed nothing in their systems but the gauges/controllers and seen 3, 4, even 5psi or more variance between.

the second thing is why bother trying to relate to the F&F mindset crowd? Far better thing to do would be force them to get educated

Brettus

iTrader: (2)

Actually - yes . That is exactly what it shows .
Meaningless ? I don't think so .
Have you thought about what effect an intercooler has in all this ? To a certain extent it cancels out the higher efficiency from a larger turbo . Obviously this would not go on forever because eventuially the IC would heat soak and temp would rise more on the lower efficiency turbo .
But for the duration of a dyno run the IC does it's job .

BTW ,I'm still waiting to see one single dyno that debunks my assertions .....

I can't even imagine why you brought this up - how is it relevant to the discussion ?

Brettus

iTrader: (2)

The ONLY comparison where what I'm saying works is when we measure PSI at the manifold for identical engines . Sure a larger turbo will supply denser air and more flow/ HP will come with that , but Is the delta temp really that much so as to skew the power the way MM is asserting . I have never seen any evidence to support that other than his constant insistence that "this is how it is" .

If someone says to me me "how come I'm running 10psi and only makeing 250whp" . I don't say "cuz your turbo is too small and that is how it is" . I start looking for what is wrong with the system . Maybe his SSV or aux. ports are not opening . Maybe his cat is blocked his tune is miles off or one of his rotors is fubar .Maybe it's just that his wastegate is blowing open and he only makes 10psi till 6000rpm after which boost drops markedly or even something as silliy as a guage that is reading wrong .There can be a number of reasons . But I'm not going to blame his small turbo because I know that if he makes the boost and everything else is right (which includes analysing MAF numbers), he will make the power .





Have you ever tried to do it ? It is certainly not easy , although anyone that can follow directions should get there in the end.


I agree , but can you ever see that happening - really ?

999miki

If IATs are similar(and as I understand, differences that we usually see can´t throw actual mass flow so much), both compressors are well in the efficiency range at this pressure ratio and turbines aren´t restriction, we should see very similar power.

If it was as simple as saying bigger turbo/more CFM/more power we should produce bazilion HP at zero boost, but I think it isn´t working in such way...

For example, very same compressor on very same engine with less restrictive exhaust side is going to produce more power at same boost and same RPMs.(if it was restriction at first place)

but also larger compressor/turbine isn´t going to produce any more power at given boost and RPMs than smaller turbo if smaller one isn´t restricted on the exhaust side and is well in efficiency...

All these changes have certain effect on IATs but huge effect on overall VE% of whole system through the RPM range, and that is what gives that huge increase in mass flow...

But thats just my understanding...

MazdaManiac

iTrader: (3)

I've lost patience with this because I just can't see what the point is.
Flow works. It ALWAYS works.
It doesn't care about anything else.
Boost ONLY works if you have exact, quantifiable data for every other aspect of the vehicle, and even then it wont translate. (And you can't get that data, anyway.)
Why bother?

zoom44

brettus

does boost tell you how much air you have?
does boost tell you how much fuel to inject?

because at that pressure your turbo is only flowing enough air to make 250whp. a different/larger/more efficient compressor would flow more air at that pressure allowing for more whp.

please stop. flow is king, boost is not

MazdaManiac

iTrader: (3)

What he will suggests is that you do - but by inference.

If I hold my glass under the water dispenser for 6 seconds, I get 12 oz of water.
That should mean not only do I get the exact same mass of water every time I hold that glass there for 6 seconds, but that I should, within a reasonable margin, get the exact same mass as long as I always hold the glass under the same model refrigerator's water dispenser, no matter who's house I'm in or what the local water pressure and temperature are.
And I should depend on this method despite the fact that I have at my disposal a calibrated glass that I can clearly use to measure the exact volume and a thermometer for the exact temperature.

Kane

iTrader: (1)

That actually is the point of this thread.

Brettus

iTrader: (2)

Dismiss boost as a valuable piece of information about a system and you severely inhibit your ability to trouble shoot any problems that there may be .


Finally you get it - Thankyou for conceeding the argument .









I kid

MazdaManiac

iTrader: (3)

Absolutely not. Boost tells you nothing and anything it offers as a "diagnostic" can be better accomplished with flow.

What "problems" did you have in mind to diagnose? Boost leak? Fluctuating boost? Fuel delivery? Poor driveability? Poor fuel economy? Low power? Smoke? Hard start? Slow throttle response? Stalling?
Every single one of those scenarios can be diagnosed with flow and boost tells you nothing about (unless your leak is so bad that the turbo under/over performs because of it).


So, the argument was "Why is flow superior in every conceivable way to pressure as a viable tuning parameter"?

Brettus

iTrader: (2)

how about something simple like low power .
Say your boost is 10psi at 7500rpm and your power is only 250whp . Do you really think that is normal and can be explained through turbo sizing ?
Hell no !!!!! Give me a freakin break .




So you look as mass flow and see it's say 270g/s . Seems about right for 250whp . But why is boost so high and power /MAF so low ?
I don't know about you but I can think of some very good explanations for this -none of which involve the turbo size .....



BTW my argument on here has never been that boost > flow as a tool . Just that Boost is a valuable tool and you should not ignore it .