Supercharged Camira..

Craig and Adam\’s attempt at adding an SC12 to a JE Camira wagon

Preliminary Home Dyno Testing

Posted by superchargedcamira on September 7, 2008

Hi all,

Spent some time playing around with the inductive pickup the other day, trying to figure out how to get a cleaner signal. After numerous tests in different configurations we came up with a setup that appeared to work quite well. Basically what we wanted was a wave form with the nicest signal per pulse, and the least amount of noise or interference the rest of the time. Suprisingly the best results came from actually turning the inductive pickup the other way around. They come with an arrow on them which is supposed to point to the distributor (from memory anyway), but we found that turning it around so the arrow pointed to the spark plug gave a far cleaner signal. We also found that keeping the pickup in the middle of the lead so it was as far away from the spark plug and distributor as possible also resulted in less noise. Another modification to the pickup was to earth it to the car instead of the recording device. We still kept the resistor and capacitor in circuit as this helped smooth the signal.

So in summary, the best results from the inductive pickup required the following
1. Arrow on pickup to point towards spark plug rather than distributor
2. Pickup to be located in the middle of the spark lead, longer leads are better to use.
3. Earth the pickup to the battery terminal earth or chassis earth rather than the recording device.
4. A recording device that can actually record at a decent sample rate! (the higher the better)

Point 4 refers to a discovery we made during the preliminary testing, which you may notice in the dyno graphs provided at the end of this post. What we didnt realise was that the voice recorder we bought ages ago to record these runs does not actually sample at a high enough bitrate to give an accurate reading in the homedyno software. To our suprise the record was only rated for 19200bps, which translates to 2.4khz. The minimum we should really be working with is 11khz. A laptop can record at up to 48khz. This lack of resolution becomes noticable in the higher rev ranges when the graph becomes more ‘jumpy’ than it should. This is purely down to the lack of resolution, which can result in the hp and torque figures not being as accurate as they should be. So for now we will have to go back to a laptop for our next recordings, however i have found that there are some portable voice recorders that can record at 128kpbs which is at the 16khz mark, so should be suitable for this purpose.

We ran a preliminary dyno test on the camira with the supercharger on and off which presented us with some interesting results.

Original Test (Jun 2006): 1 bar (factory akfl rom) – 87hp @ 4900 rpm, 93 lb/ft @ 4900 rpm
New Test 1: 2 bar rom, supercharger off – 65hp @ 5200 rpm, 84 lb/ft @ 3700 rpm
New Test 2: 2 bar rom, supercharger on – 112hp @ 6000 rpm, 120 lb/ft @ 3900 rpm

The first thing we noticed was that the 2 bar rom tuning with the supercharger off was actually a fair way down on power compared to our original dyno runs we did in 2006 at the start of this project. As you can see, the original akfl rom was producing 87hp and 93 lb/ft, whereas the 2bar rom is only producing 65hp and 84 lb/ft. This indicates that our tuning for 2 bar is nowhere near as good as it should be. While it does drive ok, it does feel quite unresponsive when you put your foot down. In contrast, with the supercharger on its producing around the 112hp mark, a whopping 72% hp increase between SC on and off. That power difference is certainly noticable, the car really comes alive when you turn the SC on. However when you compare the SC power with the original power from the akfl rom, its a 28% power increase.

So what does that tell us.. well basically it appears that we need to look at tuning the lower map areas better for when the supercharger is off, as we should be able to get that same 87hp with the SC off.  We also need to perform some more tuning to see if we can eek some more power out of the supercharged mapping.

Another thing to remember though, was that the original factory akfl rom was always a better (read more powerful, better tuned) rom that the amxy rom we used as the base for the 2 bar conversion. While we would very much have liked to start from the akfl base, we didnt have the required ECU map to be able to modify the components we required.

Whether or not we can get more power out of the tuning, its still brings a huge grin to our faces everytime we put our foot down and listen to that supercharger scream. Hopefully we can get some video up soon to demonstrate.

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5 Responses to “Preliminary Home Dyno Testing”

  1. Fishsoup2003 said

    Hi Adam & Craig,
    An interesting post, I’m sure glad your doing all this pioneering work, saves me doing it later. Very interesting note about your modified amxy map being well below the original akfl when not running supercharged, it shows how useful homedyno can be as well. Have you done a homedyno run with the original akfl map with all your supercharger piping installed (current setup) but with the supercharger off and the 1bar Map sensor refitted? This would be a true baseline.

    Good point also about digital voice recorders sampling frequency. I just looked at the specs for my Sony ICD-P520 and its 6.8kHz max. As there is one pulse per 2 rpm for a spark plug lead I guess that gives an absolute max. rpm able to be measured of 2 X 6.8 = 13.6kHz (13600rpm) which should provide plenty of margin? Phew!

    I tried a while ago to get the homedyno software but the link was, and still is, dead.
    http://www.charm.net/~mchaney/homedyno/homedyno.htm
    Do you have any idea where to get this software?
    Cheers and good luck.

  2. Hey,

    I would very much like to be able to run the original akfl with the 1bar sensor to get an accurate baseline, however we no longer have the same injectors in the engine, so it wouldnt run properly anymore. However, i think the ECU file for the akfl does contain the injector constant, so we could always modify it to make an akfl rom to run with the bigger injectors and then try and do a baseline run. We will have to give that a try.

    I just looked up some more info on the voice records. I have a Sony ICD-P320, whereas you said you’ve got the P520 model. I did a quick google of both models and according to the sony uk website..
    P520 Frequency level (Hz) = 220 – 3400
    P520 Sampling frequency LP mode (kHz) = 220 – 3400 <— typo on website??

    P320 Frequency level (Hz) = 260-6800 Hz
    P320 Sampling frequency LP mode (kHz) = 8.0

    So according to the website, my P320 model should be a higher quality. However i was finding that it didnt seem to be high enough. That sony uk website also gave me different figures than what i found the other day. I will have to do some test comparisons with the laptop to see what sampling rate we really require for an accurate measurement.

    I also had a look for the home dyno site the other day only to find the links are dead. Perhaps they no longer want to support it so have shut the site down. I did a quick good and found another site that seems to be starting up that looks like they do pretty much the same thing.. these guys sell the hardware too though as well. Check out http://www.ontrackdigital.com/
    Another thing you could try is to email the Home Dyno guy at mchaney@charm.net and see if hes still doing anything with it.

  3. Fishsoup2003 said

    Hi Adam & Craig,
    I downloaded some manuals for the Sony ICD-P320 and ICD-P520 and it looks like they both have the same sampling frequency of 6800Hz in high quality mode. The Sony website specifications, both UK and US are misleading and full of errors.

    You mentioned that you planned to record direct to your laptop, if the results at higher rpm’s are still erratic then the Camira may be suffering from ignition system breakdown when under boost at high rpm’s. Many people who turbo their engines need to put in more powerful coils as more electrical power is required to produce a satisfactory spark for richer mixtures and also for higher cylinder pressures.

    Home Dyno looks to be no more, the email address mchaney@charm.net has also dropped off its perch. OnTracks Digital Dyno at US$149 must be sold by relatives of Bill Gates, no thanks. There’s also a free but very old (Win95) program called Street Dyno, I’ve downloaded version 0.6.0 but I haven’t checked if its any good. It can be found here: http://www.drivewerks.com/tech/street_dyno.htm

  4. matthew said

    hey im doin a camira up as well, just wondering if you now or have a spare sc12 supercharger,

  5. Craig said

    Hey Mathew,

    Not sure if you’ve noticed, but our supercharged beast is now up for sale. Thats obviously got the supercharger, all the pipework, custom mounts, pulleys etc. Dont know if that would be an option for you.

    Cheers,
    Craig

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