HiFlite999

iTrader: (2)

For what it's worth, the fox calculator I referenced above, doesn't seem to function correctly. First enter, 100 psi on the 3 faces and 0 ft altitude. It gives a corrected value of 105.6 instead of the 103.9 that would come from the Renny correction factor. Second as one raises the altitude, the corrected value goes down, not up. In other words, if you measured 50 psi at 18000 feet, the corrected value (at sea level) should be about 100 psi, not 25 psi as it works now.

Something's amiss. It would be quite nice if TwistedRotors would bring up the website and give us the scoop himself.

Doing another series, and making the calculation "correctly", at least as I understand it right now, gives:

F: 114.0 110.4 106.4 psi ... avg: 110.3
R: 117.1 112.0 115.1 psi ... avg: 114.7

wcs

iTrader: (2)

Thanks for the update HiFlite

wcs

iTrader: (2)

Bump.
Finally got around to doing this .. and as I suspected it's out of spec.
I imagine I've been out of spec for the last 40,000 km's that's when I started noticing hot start issues.

Front at 191 rpm
70 67 67
Rear at 196 rpm
73 69 68

Normalized using the foxed.ca application
Front
88.70 84.90 84.90

Rear
91.26 86.26 85.01

Meh .. oh well .. time to get a new motor ordered/shipped while I turn up the bewst on this one!

Footman

iTrader: (2)

There's an ANdroid App called RX8 Compression, does the normalizing for you.. pretty neat.

Footman

iTrader: (2)

Like I said before, I bet so many people out there are running low-compression (under spec) engines without even realizing it... poor fuel economy... random hot starts.... no CEL, never stalls....

wcs

iTrader: (2)

Yah man thanks ... I do have that but truth be told I don't trust the numbers.
I tried entering a few numbers for other people on the site and I couldn't get it to reproduce the same results.

If I go by the results given by the Android app I'm really really really low ...

Here are the links (for other peeps) that I used

Foxed Calc
http://foxed.ca/index.php?page=rotarycalc

Android and iPhone Calc
https://www.rx8club.com/series-i-tech-garage-22/rx8-compression-calculator-android-226754/

Excel App
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-renesis-compression-adjustment-rating-excel-application-180043/

Charts ... yes charts all different it seems
https://www.rx8club.com/showpost.php...56&postcount=2

https://www.rx8club.com/showpost.php...77&postcount=6

https://www.rx8club.com/attachment.p...6&d=1266716801

Found this Mac version: I didn't try this one.
https://www.rx8club.com/series-i-do-yourself-forum-73/diy-renesis-rotary-compression-calculator-mac-osx-10-only-170925/

What I find confusing is why do we need to normalize to 250 rpm when we are clearly given graphs that trend from 200 rpm (150 rpm in one graph) to 300 rpm.
Why ******* bother with a graph if we also have to normalize to 250 rpm ... if this is the class its much easier to say ... Adjust for altitude and normalize your values to 250 rpm, here's the acceptable range. <full stop>

The graphs lead me to believe you do not need to normalize ... just compare your rpm value and psi on the graph and see if you fall in the acceptable range.
Especially as one of the graphs in not completely linear https://www.rx8club.com/attachment.p...6&d=1266716801

HiFlite999

iTrader: (2)

WRT, my post #376 above, the Foxed calc seems to have been changed since I posted and seems to give better results.

The twistedrotors site seems to still be semi-dead, however.

Footman

iTrader: (2)

The problem with the stupid *** chart is that it's not clear which lines the values point to. Alsoas HiFlite999 mentioned it's not a straight line, someone must have calculated the formula for the curve (hopefully they have done it properly) and used that to normalize the value.

The only reason we normalize is because instead of relying on a graph to figure it out, we are given AS A FACT, numerically what the compression pressure values should be at 250 rpm. We're simply scaling "your curve" to the 250 rpm value to draw a comparison. That's all. Mazda did not say what the compression value should be specifically at 300 rpm, but they did say what it should be at 250 rpm and we're going by that.


case in point, if I told you to look at the graph only, tell me what the compression value should be at precisely 287 rpm, would you know? The graph is so vague, it sucks at doing so... try finding where your value is at 287 rpm on the x-axis, and then try determining what the pressure value is on the y-axis from the graph.

The graph sucks period...

Footman

iTrader: (2)

I find the excel spreadsheet pretty good, and the android app is good too (allows various units)

wcs

iTrader: (2)

Using this link to convert psi to kpa http://www.sensorsone.co.uk/pressure...onversion.html

Front = 603.636 : 577.781 : 577.781 kpa

Rear = 621.011 : 587.020 : 578.470 kpa

Now compare these values to the 3 different graphs
1) https://www.rx8club.com/series-i-trouble-shooting-95/compression-test-intrepretation-help-please-229440/
Front rotor = Epic Fail : Epicest Fail : Epicest Fail
Rear rotor = Epic Fail : Epic Fail : Epicest Fail

2) https://www.rx8club.com/showpost.php...77&postcount=6
Front rotor = Pass : Fail : Fail
Rear Rotor = Pass : Just Failed : Fail

3) https://www.rx8club.com/attachment.p...6&d=1266716801
Front rotor = Bad Fail : Epic Fail : Epic Fail
Rear rotor = Fail : Epic Fail : Epic Fail


Clearly after normalizing to 250 and comparing to the three graphs there are different tolerances. I guess I have to hope RIWWP is as always doing an excellent job at his due diligence and his graph is the correct graph.


Now I'm off to try and makes sure the Normalized values are being calculated correctly.

EDIT ----- Had the Tolerances given to me by RIWWP

Compression pressure
(kPa {kgf/cm2, psi} [rpm])

Standard
830 {8.5, 120} [250 rpm]

Minimum
680 {6.9 , 98.6} [250 rpm]

Standard difference in chambers
Within 150 {1.5, 21.8}

Standard difference in rotors
Within 100 {1.0, 14.5}

wcs

iTrader: (2)

Excel Spread sheet results normalized to 250 rpm

Front 620.92 : 599.92 : 599.92 kpa
Rear 627.98 : 600.98 : 593.98 kpa

Android App (Note I've read the thread for this app and to me it's not clear what the input values should be and what the app is actually doing. Therefore entered non normalized raw psi numbers and converted to kpa for final results)

Front 484.081 : 463.397 : 463.397
Rear 504.627 : 477.048 : 470.153

Clearly the Android App doesn't work or is doing something different or I'm not entering the right data for the input requests.

So what other value could you enter, well the normalized value?

EDIT --------------------------
So I just compared the Android values to the Excel App and the Android values are exact same as the unadjusted kPa compression values in the Excel App. So clearly my version on ICS is not doing and normalizing to 250 rpm it is ONLY converting the PSI (my input value) to kpa

EDIT EDIT -------------------
I just re-entered the values this time using kpa as the input value and it gave me almost the same values as the Excel app .. actually a point or 2 higher. I believe the Android app is not converting PSI and Normalizing correctly (bug my just on ICS).

wcs

iTrader: (2)

LOL well said .. I get it now .. gollee u sure make learning phun footman

Footman

iTrader: (2)

you're cranking low eh? need new battery?

Footman

iTrader: (2)

Are you within warranty for new engine?

wcs

iTrader: (2)

Old style starter.

It's a brand new battery ... brand new as in bought it yesterday Red Top 34/78

EDIT ---
Actually the first time I did the compression test I had the opposite spark plug installed that lowered RPM to 180.
For these results I removed both plugs.

wcs

iTrader: (2)

LOL you're soooo funny.
2005 with 84,000 km's

I believe I am but who would take it.
I'm not even sure I could put it back to stock.

Footman

iTrader: (2)

WCS, I've seen the 3 different charts you posted and here are my thoughts.

Two of them don't mention what engine it's for, maybe the poster cut it off the picture, but regardless no mention of the fact that the chart is for the Renesis 13B. The same two charts show only 1 curve. Now is this curve the "brand new engine" curve (standard), or is it the mimimum cut off? No idea.

This leads me to think that the best chart is the one with the two curves showing standard and minimum. This same chart also clearly says 13B-MSP (Renesis engine)

https://www.rx8club.com/attachment.p...6&d=1266716801

This is also the same chart I have at home in the RX-8 Field Service Manual (FSM).

Also using this graph it's a little easier to see that at 250 rpm, the minimum acceptable compression is around 680 kPa

Footman

iTrader: (2)

What the? How come you use 34/78 RedTop? That makes the connectors far to reach.... how come you didn't take Group 35?

Footman

iTrader: (2)

Put it back to stock WCS, then get new engine... hurry before 2013!!! (8 year/160,000 km)

wcs

iTrader: (2)

Actually I wanted the 34R but it was on back order.
Dude, maybe you didn't know. I'm boosted, my battery has been relocated to the trunk. I could put a fork lift battery in there is I wanted lol.

I have all the parts except the exhaust manifold which I technically have but the O2 bunghole is fucked (no pun intended)

I've cut some sheet metal around the intake area and modified the lower air deflector around the radiator ...

I dunno maybe

wcs

iTrader: (2)

New numbers in after installing new upgraded starter.
Wow ... just wow ... car starts instantly even after hot I tried a off/on and it fired right up.
Unfortunately the numbers are not a lot better.

Using foxed.ca compression app, my altitude is 1500 ft
Raw Data ------
Front @ 320 rpm @ 178 F coolant temp
101, 100, 99 psi

Adjust for Sensor dead space 1.039 and altitude 1.0417
109.3, 108.23, 107.15

Rear @ 289 rpm @ 183 F coolant temp
100, 100, 95 psi

Adjust for Sensor and alt
108.23, 108.23, 102.82

Normalized ------ using Android app
Front = 91.34, 90.27, 89.19 psi

Rear = 97.87, 97.87, 92.46 psi

Next step --- ATF trick then re-test

fgerghet

Driving the RX-8 is never about the numbers, it's about the experience and the experience of driving it is the best selling point in favour of it. If you drive it and there is a heart beating in your chest, I believe you WILL buy it. The tragedy is that too many talk themselves out of even trying it because of the numbers.
I would also display a final average while still displaying the instantaneous data. The average would discard the first two and last two readings. The fact that the last data being displayed appears to include the rundown of the engine raises some questions regarding its ultimate accuracy.

wcs

iTrader: (2)

First thing, what does your first sentence have anything to with this thread?
Did I miss the post where someone was not buying an 8 because of numbers?

Second:
I think I understand what you mean. I don't know if or how to get the instant numbers from the TR-01v2.
The procedure has you cranking the engine for 5ish seconds so you are going to have a large set of data. So I'm guessing this device only displays the final average compression values of the 3 chambers <mmmmm>

Ok, so continuing on your suggestion if I can get the instant numbers it is the first and last number of the instant numbers I would discard (for each chamber) then average the remain data.

I will do some digging and see if I can get more out of this device. Anyone know what that usb cable does?

Would someone explain to me what rundown is?



Those are the instant numbers and the normalized values.

You want to average the compression value for all the chambers ...

Going with the

wcs

iTrader: (2)

First thing, what does your first sentence have anything to with this thread?
Did I miss the post where someone was not buying an 8 because of numbers?

Second:
I think I understand what you mean. I don't know if or how to get the instant numbers from the TR-01v2.
The procedure has you cranking the engine for 5ish seconds so you are going to have a large set of data. So I'm guessing this device only displays the final average compression values of the 3 chambers <mmmmm>

Ok, so continuing on your suggestion if I can get the instant numbers it is the first and last number of the instant numbers I would discard (for each chamber) then average the remain data.

I will do some digging and see if I can get more out of this device. Anyone know what that usb cable does?

Would someone explain to me what rundown is?

pfsantos

Reviving the thread since I'm thinking about getting this tester or something similar.

Background...so I remembered there was a r.e. tester on one of the lists, so I googled it. The twisted rotors site doesn't have a price, and not sure if the info is up to date. Now some time has elapsed, so I'm wondering if another version has come out?

Also wondering whether by now you can get some hardware and an app and wiring and have something work on a smartphone.

Anyone know?