Kooldino

That's only true when you're talking about the air INSIDE the tubo housing itself.

Where you measure it, at the intake mani, will read the only number that really matters.

AvatarQAZ

Assuming there is no air leakage from the turbo to the mani, the system (turbo to intake) should normalize and be relatively close just outside the housing as it is right outside the intake. Granted, on paper, it works out that way. But in real life, there is going to be some back pressure and some fluctuation from point A to point B. But not so much as to really cause anything noticeable. Must be a closed system. Wastegate will take care of the rest.

1975yellowBSPz

THIS THREAD IS WORTHLESS WITHOUT PICS

DYNO SHEETS PLEASE!!!!!!!!!!

Just kidding. I was just suprised no one else said it, being the unpatient lot that is on this board.


bw

Richard Paul

iTrader: (5)

Wait a minuite I must have come in late. I never said anything about the size of the turbo. The compressor in my equations doesn't know anything or have a size. I'm only pointing out that the number of moles depends on the efficency.

Next if the tubes are smaller the air just speeds up. The same will go through unless your talking grossly small. You want to keep the speed up in the tract to a certain point.
Also when it goes through a smaller tube and speed goes up the pressure goes DOWN. This is known a Bernoulli's theorem. This is the reason venturi's work.

So go back to the experiments and it proves why you can get a false impresion as to what you have in the way of mass. Simply put, temp makes the moles run faster thus hitting the walls harder showing more pressure but there are no more moles.

Remember 2mc. Mass x twice the speed. Force.

Captain Amazing

It is Jan 21, You guys back from the dyno yet?

ranger4277

RP, This line made me laugh.

bw, I love the car in your avatar... have any more floating about?

dmp

I understand, Tiger ( ).

Looks like the car is losing 31??% thru the drivetrain, or we aren't starting with 238hp. The post you are quoting I used 15% - which SHOULD be about right for a rwd sports car. (Miatas, for example, are 'around' 15%). I can't believe the rx8 would be TWICE that.

I used 180whp. why? 180 x .75 - 240hp.

180whp + 40% = 250whp....180whp + 50%= 270whp. Frankly, I'd be thrilled if the car makes 230-235 w/ the GReddy kit....but since we don't have a baseline, we can only 'assume' whatever gains it shows.

My hidden agenda is this: 8psi on a motor rated at 164hp = 250whp. 8psi on a motor rated at 238hp, with a similiar-sized turbo SHOULD be quite a bit MORE....because as so many of you have stated, 'displacement doesn't matter'.

JoeMamma

^^^^^ What he said!!! ^^^^^^

(...and wait for the dyno numbers, of course....IMPATIENTLY, I might add...)

rotarygod

So if displacement is what really matters, what if we had a 450 cu. in. engine that only deveoped 200 hp for whatever reason. (I know it sounds like a waste but bear with me). If we had perfect efficiency meaning absolutely no temperature change at exactly 14.7 psi which also meant that we'd have exactly twice the air as at ambient (this is all for reference sake so don't get technical), we should theoretically have 400 hp. How would displacement factor in? Obviously the example assumes 100% efficiency and is purely fictional but the deciding factor seems to be the initial horsepower at ambient temperatures and pressures and not engine size. Displacement doesn't matter. Sorry. Initial horsepower along with a combination of airflow and efficiency (note I didn't state at what pressure!) and frictional losses will determine power output.

Kooldino

Probably the latter.

15% sounds a tad optimistic, but a lot more reaslistic than 31%

Right. Plus, we know jack about the dyno he's running on, and that's a big variable in itself.

You have to compare WHP to WHP, not CHP to CHP. And you'd have to comprare both cars on the same dyno on the same day.

Besides, while a KL might claim 164chp, it probably puts 140 or so to the wheels.

Kooldino

My point exactly.

Xyntax

I know the numbers, but I'm not gonna tell because of legal matters... sound familiar?
:D :D :D :D :D

37.06%

globi

I don't disagree with what you just said, but airflow (massflow) is a function of pressure, temperature, displacement, rpm and volumetric efficiency. (That's why you didn't state at what pressure.)

StealthTL

iTrader: (1)

243 hp,
at the wheels,
289 at the crank,
on a Dynojet brand dyno.

My guess is as good as anyone's. :D

S

twospoons_

Just thought about it, we never had any flow / fluid theory in physics. That is kinda strange isn't it. Oh well, time to do some reading. Thanks for the info.

So, pressure drops with velocity also. Meaning that a high flowing big turbo actually creates less pressure?

I think my brain finally re-booted.

RX-Nut

And if we're not satisified with the numbers we get from THE DUO, we'll start to question the accuracy of the dynos. I mean, wasn't the RX-8 was considered a bad dyno test car without FI (due to a **** PCM and finicky ABS/DSC/TCS blah blah)... wont it be a bad test car with FI?

AvatarQAZ

Ok, honestly... MazdaManiac, Philodox... you have built us up to a climax. The story is NOW at its apex. The suspense is killer... the commercial break, is over.

GIVE UP THE NUMBERS!!! WE WANT DYNO!!!! :D VIDEO!!! PICTURES!!! AIIEEEEE

JoeMamma

Heh-heh...he said "apex"....

(sorry...I'm impatient and trolling for the numbers, too)

philodox

Okay guys! After 400 miles and 8 hours I am finally back at home. It was quite an eventful day today at Altered Atmosphere. Some members of the forum tried to get the scoop ahead of everyone else by pulling out a dirty little trick and calling my cell phone.. I won't mention any names *cough Polak cough*.. But he was misinformed by the media Here are the results


Jon's Car: 240.4 rwhp. Torque is a big fat ???????? because their dyno wouldn't read it properly.

Jeffs Car: 225 I think.. hopefuly he stops by to let you guys know.

Now, I did dyno my car before I put the turbo on. I had 174.44rwhp pre turbo and now I have 240.4rwhp with the turbo. For those of you that aren't mathematically inclined, that's a gain of 65.96rwhp coming from 7psi of boost. Not bad for a stock tune at all. I am very confident that when I tune the air/fuel I can squeeze another 25hp at the wheels. Eventually, I will tune for 9psi.

sorry for no torque numbers guys, call Altered Atmosphere and bitch at them for not being able how to get a proper RPM reading from a rotary engine Now your thoughts?

MazdaManiac

iTrader: (3)

Well, the dyno session went well, though it was a bit more expensive for me than I planned - I ended up being strapped down for three hours. Money well spent, though.

We had one fairly significant glitch and that is with the tach signal on the DynoJet. For some reason, it was unable to read our RPM ater 5500 RPM or so. Because of that, we couldn't get any torque plots because the machine would stop reading torque after it lost the ignition signal. It did, however, continue to record HP, but it needed to be plotted against wheel speed instead of RPM as most of us are acostomed.
This glitch was on both of our vehicles, so it isn't a failed component or the result of any particular combination of aftermarket parts since our cars are different in that respect.

First, Jon was hooked up and ran several base runs that were all within a hair of each other, so I think it is fair to say his graph is representative of the power he is producing. His results can be found just above this post in the thread.

After I got strapped in, we spent the better part of the next 3 hours tuning. My A/Fs were bumpy - mostly over-rich except for this lean spot right at 5100 RPM that I am still trying to tune completely out. The other issue was my boost.
I came to the dyno fearful of over-boosting since that had occured on some of my street-tuning runs. Last night, I pulled my wastegate actuator, cut it open and milled the spring down so that it would open at a significantly lower pressure. The problem is, I still don't understand how the PRofec modulates boost. I kept increasing the duty cycle to no avail. The result was I was trapped at 6 PSI, though I have been preparing for 9 PSI.
I guess I'll go back once I learn how to program the PRofec correctly.

Peak HP was 225 HP. I don't have a torque figure for the above-referenced reasons.

Vaillant

So, you have a peak hp number, but no plot? I was curious to see how linear the boost is and how well the GReddy maps are working.

Still, 240 hp is great! Congrats!

~ Matt

brillo

Jeff, looks like your not running to rich from what I can see, mostly all above 12. Is that what you were aiming for? Look's like the Greddy kit is performing as advertised.

Oh, and congrats guys

Vaillant

Another thought...if you have the mph, you can figure out the RPM and then, using the 5252 (is that it?) factor, you can get the torque, right? Anyone want to play with Excel? I'd do it, but I'm still at work...

~ Matt

philodox

Guys, I don't have a scanner to scan the dyno sheet it. So I'm trying to use my digital camera to photograph the pages.

Dynorun.007 is in 4th gear
Dynorun.008 is in 3rd gear

Sorry for the poor quality of the pics, but the graphs are faint even in person. Enjoy!

-Jon

Richard Paul

iTrader: (5)

If you have the engine running perfectly in tune the rotary will make about 7 BHP for every pound of air/min. A piston engine will make 10. No tears boys I learned this the very hard way.
Now it doesn't know how you made it eat that much air. If you forced it in at high pressure and high temp or lower press at lower press. It is the mass flow. Now it is easier to get the heavyer air in as it is displacing less volume. Also it lessens the thermal load on things plus helps detonation.

If you use a small tube or a big tube it doesn't know. It has nothing to do with the size of the turbo.
It has nothing to do with the displacement of the engine. What you are getting at is that a bigger engine will swallow more air thus have less resistance. Good point if that is what you ment. Manifold pressure is just the resistance to the airflow.

We took my blower off my dyno just as it was including pulleys, carbs and ducts. On my engine it was making 7psi. When we put it on the engine at someone elses dyno it made 10 psi. Their engine just didn't flow as much air. Proven by the fact that my engine made a lot more power with less boost. Their engine made less power before and after supercharging. The SC or turbo can't cover up all ills.

RG, I'm a little disappointed with the volume of you post, need some more mass.
Maybe you can explain it better then my little lab experiments did. But I can't see how, that is as plain as I can show it. I think these are smart guys saying the same thing, no?

In the famous words of Paul Newman "what we have here is a failure to comunicate"