Moon Assad

Unless you pass 380 maf reading you dont need to rescale I guess.

joff

Okay, I'm sorry, but that sounds like intellectual obfuscation and utter B.S. I don't think anybody but yourself follows how that rationalization refutes any statements I've made in my last 2 posts. To recap: the points I've brought up are:

1) morkusyambo is not actually experiencing 411g/s of flow
2) boost *is* useful to predict flow on positive displacement superchargers.
3) turbo tuners have a more complicated job because boost does not predict flow as well because of several things unique to turbos on the renesis.
4) mucking with MAF calibration makes MAF less accurate.

I am NOT:
1) advocating a tuning method (A inaccurate MAF is fine as long as its precise)
2) trying to bash turbochargers (I own both a supercharged and turbod rotary)
3) stupid

You, however, took exception to a couple off-point theories I made about why I thought boost might not be predicting flow well in turbos. Maybe because you thought I was bashing turboes or you thought I was talking about you when I mentioned "turbo tuners bad at math"

You wanted to call me out with a $100 bet that I didn't have any basis for my off-topic statement about exhaust backpressure effecting intake flow. I showed you how exhaust backpressure can effect intake flow on a zero-overlap engine even though it had no relation to the current topic of morkusyambo's MAF reading.

You obviously think morkusyambo is actually seeing 411g/s -- how does your grand unified flow theory explain that? I'll give you $100 if you can explain how a slightly more aggressive timing/fuel tune can unlock 80-100g/s of real flow on a positive displacement supercharger. Don't you think if I thought superchargers are the best I would go along with this evidence that morkusyambo's blower is flowing way more air than many turbos are...

Do you not see the ridiculousness of this assertion? Have you ever seen the t-shirts some computer geeks wear with the text "2 + 2 = 5, for sufficiently high values of 2". http://www.thinkgeek.com/tshirts-app...encemath/60f5/ The above statement (and your whole argument style, for that matter) reminds of that shirt.

Ah, I see now why you got so defensive -- you have a reputation to uphold and a "flock" of little-people to educate and enlighten. Forgive my low post count newbie naieveity.

paulmasoner

iTrader: (1)

(disclaimer - i havent been following, just jumped in browsing and saw this)
sounds reasonable to me - IF you know other variables. 10psi at 70 degrees precompressor isnt the same flow as 10psi at 35 degrees precompressor(not being smart, i know you understand this, just saying)

they are inter-related, with the right supporting information you can use either one for most(all?) purposes. its just a matter of which one can be used more precisely and/or more conveniently. IMO mass flow is more convenient and precise as other variable are already accounted for

edit:
ehhh just read the rest/last of your post. OK i'll bite. show us the math that can explain the ridiculousness of that assertion. If you cant quantify a scientific claim, then its only a theory. so show us something tangible, logical, and repeatable that disproves what he's saying

Rotr8

iTrader: (2)

Good Stuff, keep up the info and keep down the tempers, learning as always

joff

The ridiculousness is that it says and predicts absolutely nothing. 10 psi of air not being equal to 10 psi of air is about as useless a comment as saying 100 lbs of potatoes is not equal to 100 lbs of potatoes. Theres nothing tangible or logical to refute in that statement.

paulmasoner

iTrader: (1)

point taken. although i am pretty sure the point of the statement was meant to be implied that flow/ppo2/whatever at 10psi is not consistent unless other variables(ie temp) are also consistent

Kane

iTrader: (1)

Paul got my point.

I am not attacking your SC vs Turbo assertations; nor saying that Mork is seeing an actual 411 g/s. What I AM attacking is the Pressure argument; because it is in fact an incorrect assertion. Pressure by itself means squat.

10 PSI <> 10 PSI for air because the PPO2 can differ by a very large amount. My $100 bet was in relation to pressure = power vs the flow = power.

Partial Pressure of Oxygen(PPO2) aka the molecules of oxygen available to be burned = Power; period and without equivocation when it comes to the airflow of a motor. Please read my posts a bit more carefully.

I can prove my assertion - now prove yours.


All that info is here on the site; but the address is harder for me to remember. But since we are on the point of my "flock" of little-people. (Which by the way would kick ***... I need minions.) I seek out people who know a hell of a lot more than me; since I can't gain any information otherwise. I also reference all of them accordingly, my reason is not financial as of yet - my reason is simply to de-mystify the whole tuning process to the best of my abiity. I am always on the lookout for people to shoot holes in my math; it just hasn't happened in a while; so if you have the goods please please please by all means let me know because I would love some more peer review.

Kane

iTrader: (1)

10 PSI of air = X molecules of oxygen = (What is the answer?)

10 PSI of air = Y molecules of oxygen = (What is the answer?)

Prove they are always the same and I will Paypal you $100 in the next 20 minutes.

swoope

iTrader: (5)

wow,

another drive by guy that knows it all here to help for as long as he or she gets attention..

btw, this has what to do with the pettit owners thread?

pm is a great thing. or start you own thread.

beers

Kane

iTrader: (1)

While some of this is off topic Swoope; the gist of it matters. Since Morks was trying to see WTF was up with his MAF reading. My point was with his intake being the same (so same MAF voltage for airflow) from his old and new tunes / runs... that his increased mass of air could be a result of temperature / elevation / timing / etc... and that the change from old to new is valid... even if the 400g/s is not 100% accurate.


And further - to scale the MAF to be accurate one simply needs to use the fuel volume and AFR to extrapolate the Air Flow.

Then I got worked up.... plus I am taking a law class right now - so that may have affected my mood -

swoope

iTrader: (5)

not really aimed at you. more the drive by..

great the world needs another fng lawyer!!

btw, talked with juan today. you know if you add a new un winged trunk lid. the pettit sc goes faster! sorry.

was keeping it on topic..

beers

Kane

iTrader: (1)

HEHE - Yeah if I ever take the bar - all you guys have my permission to beat my ***.

marsredr100

iTrader: (1)

Hey don’t give out my secrets. BTW I do have the formula to back it up but I’m having some issues with changes in gravitational pull and daily solar flares fluctuations.

joff

Since other necessary parameters are not defined in the setup to the question, you also can not prove X is not equal to Y without adding more parameters. Here's an analogy to highlight the absurdity of your question:

100 ft/lbs of torque = X kilowatts power?
100 ft/lbs of torque = Y kilowatts power?

I would need to define rpm to complete that question. You would need to define temperature (I assume volume we're talking about is 654cc). I previously stated "perfect intercooling" as an assumption in my first response to simplify the math. With perfect intercooling temperature is always exactly ambient and 10psi of atmosphere in a 655cc volume has the same mass of O2. If you want to bring up humidity here, just stop or I will bring up how ideal gas law starts to fall apart when you start accomodating the specific heats of the consistuent gases and their internal degrees of freedom and this whole discussion will devolve into trivia. If you think I do not understand ideal gas law, you have not seen any of my previous posts.

Anyway, this still has nothing to do with my position on any of the above points I already mentioned and which you have not refuted. I have never even mentioned PP02, power, or how it relates to pressure -- I only brought up how pressure tracks with flow on different FI. You are engaging in classic obfuscation of whats being debated and this is just another invocation of the straw-man logical fallacy. For those that don't know what that is, here's the recipe:
1) Person A has position X
2) Person B ignores X and presents position Y
3) Person B attacks position Y
4) Person B draws conclusion that position X is false/incorrect/flawed.

The above tactic is used incessantly on internet forums. Many fall for it -- those that pride themselves on recognizing reason, logic, and truth do not. A few here I think know when they're doing it (MM) and they do it for fun -- some, like Kane, may not even know he's doing it.

It seems you do not wish to engage productively in the discussion of my previous comments. Probably because you are unable to refute them. Unlike you, my comments were brought up in the discussion of a Pettit supercharger topic and I am a Pettit supercharger owner. You want to talk about pressure, power, temperature and PP02 for some reason. I simply knew why morkusyambo was seeing 411g/s so I posted.

Thanks for the fly-by yourself swoope -- way to add to the discussion absolutely nothing for absolutely no reason.

My last post was my only useless post to the topics of this thread because I used it to call you out to which you ignored. I apologize to thread readers for that off-topic comment and for this one. As an attempt to rescue this post and close this topic since its been beaten to death, I will bring up this new topic related to the Pettit supercharger:

The adiabatic efficiency number advantage of turbos has negligible real world advantage with proper intercooling when compared to twin-screws. I realize anybody that really cares about this math/physics crap is in the minority, but I did just run through some calculations for this is another thread: https://www.rx8club.com/series-i-major-horsepower-upgrades-93/water-methanol-injection-163536/page3/ There are plenty of advantages turbos have, but adiabatic efficiency is not a big deal on most RX8s.

morkusyambo

I noticed this was the second time you mentioned extrapolating the curve from 4.7 volts beyond. Question: Does it make a difference that the #s I am seeing are all below 4.69V??

Thanks for participating in this discussion publicly, as well as the encouragement.

-Yambo

morkusyambo

On a side note; I think it is good that Kane joined this discussion, because it has led to some discussion about things I am not familiar with. Having said that, since its my stupid posts that led to this, I ask that Joff and Kane not get personal(even if only intellectuals understand some of what they are saying) and stay in this discussion.

With everything that has been said up to this point(and my interpretation of it) I still don't know if what I am seeing is wrong or right.

-Yambo

Kane

iTrader: (1)

Thank you joff for proving my point (albeit combatively)...

Without other information; pressure is a useless measurement in comparing power and or airflow. Even with perfect intercooling (an assumption that kinda defeats the purpose of trying to get accurate info)... the final airflow information requires ambient temperature information. Not to mention our perfect intercooling will reduce pressure and increase density yada yada....

You argument that the flow not pressure statement = turbo toolbags who suck at math was what I called you out on; not anything related to turbo's vs. superchargers or any of that BS.... so if you want to call me out - stay on topic.

Once again; Flow is king (when I say flow I think PPO2; why cause it is all that really matters anyway; and I am a diver and explosives expert by trade...so it works for me).

I can say that (without any other information) 40 lb/min of air is always greater than 39 lb/min of air.... I need no more information. When you only look at PSI; you will always have to qualify that information. I am not sure how much more succinct I can be.



EDIT: Followed your link.
I see now where you are getting your adiabatic efficiency info.... not from me; and not from any of my posts... if you are trying to have multiple arguments online; please keep them straight.

Kane

iTrader: (1)

Is your MAF factory sized? Did anyone at Pettit scale it?

If your Volts are all lower than the factory scale... then someone would have to have scaled that bad boy I am pretty sure.

And pre / post the tuning work etc.... did you cahnge any of the intake set-up?

Brettus

iTrader: (2)

see what a shitstorm your maf readings started morkus - the internet is fun isn't it ?

joff

Pettit's MAF housing is stock diameter, so any voltage above 4.7V you see corresponds to some unknown MAF value greater than 365g/s and anything under that value corresponds to less than 365g/s. What I meant by "extrapolating the curve" was that it seems possible to add (e.g.) an arbitrary entry into the calibration for something like 4.8V = 400 g/s if you actually could flow that much, which we can't.

Please understand Yambo that neither Kane or I think what you're doing is wrong. You obviously have a tune that works and without even needing to understand the physics. We are just background noise in the shadow of your accomplishment. The only disputed issue here is whether whats being reported by OBD2 on your logs as g/s is still accurate to make other predictions and comparisons with.

Kane thought I was talking about him when I said "turbo tuners bad at math" and proceeded to get on a soapbox about pressure vs. flow. The misunderstanding was that I was merely poking fun at turbo guys that believe in some "magic pixie dust" coming out of turbos that they use to balance the math when their logs show them constant boost pressure and steady IATs with wildly varying flow. Instead of critically thinking and understanding the reason for this, they just predictably chant in unison: "its all about the flow, its all about the flow" and then manufacture some (wrong) rationale from the better adiabatic efficiency of the compressor wheel. I was never talking about Kane or any particular tuner -- I actually was thinking of somebody on rx7club.com when I wrote it.

Really -- if everybody here were less sensitive and points were brought up in slightly different ways, there would be no "drama" here as basically Kane and I have the same (I think) understanding of things.

Kane

iTrader: (1)

I am confused if Yambo is seeing 400g/sec reported by the PCM and it hasn't been scaled - then something is up....


As for me and Joff...I thought I was correcting a pretty common mistake (flow vs pressure and all that crap) and it turned into a physics lesson (some how efficiency came in for whatever reason....).

Obviously, I was being overly-sensitive...

But your still wrong joff

morkusyambo

I did scale the MAF, if scaling means changing the expected flow numbers based on voltage. I made those changes for two reasons: 1/The datalogs were showing the higher g/s #s up to 6k rpm than were programmed into the original scale. 2/I had to just to be able to drive the car above 6k rpm because the AFRs were leaning out from 11-something to 13-something at that point. Maybe they would have leaned out even more, but I allways lifted throttle before finding out. Also, I did not change any of the voltage #s. I have that ability with the AP, but have not tried it yet. My max g/s happens below 4.69V.

-Yambo

morkusyambo

I know, right?!? But you have to admit this has been much more civil than some of the shenanigans that have happened in the past

-Yambo

rotarenvy

I'm not trying to discredit yambos numbers since I think there are plenty of reasons he could reach them.
I logged some strange numbers out of my MAF yesterday. I converted back to NA to fit a new cooler and logger 226g/s @7200rpm and wasn't even at full throttle. that equates to a 135% load. the engine isn't even mapped past 125%. it beats hymee's base line na engine dyno numbers 1000rpm earlier and I know my motor isn't that strong. I'll have to try and do some more runs to see if I can replicate it.

Rote8

On the MAF reading;
Doesn't cold dense air read higher on the MAF?

Or am I just dense?