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Thread: Odd results at rolling road today. Any thoughts please?

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    Odd results at rolling road today. Any thoughts please?

    Hey guys

    Myself and my bro went to the rolling road today. It was Wiltshire's garage in Wimpole, Cambs. On the A603.

    My bro's Ferrari 360 got exactly what it should have done in terms of power results, proving that the dyno is working ok. It registered 390Bhp@7500RPM as can be seen below.

    But my SIL80 got results that were clearly incorrect. This is the car spec:
    - Red top SR20DET with HKS2530@18Psi & 550cc Injectors & supporting mods.
    - Running NIStune with a fairly conservative map that I wrote, 11.5 AFR and 15 max timing.

    I was expecting about 280Bhp at the engine, but as can be seen below it recorded 392Bhp@6000RPM. This is obviously wrong. I tried explaining to the guy in charge that it was wrong, but he was having none of it. He was a nice guy, but in his 70's and I don't think he'd seen a jap car before.

    Things to note:

    1) the handbrake was definitely off, so no problems there.
    2) there are no problems in the drivetrain, no seized calipers, dodgy diffs etc, everything is moving well.
    3) I think the most important thing is that the machine is apparently set up for 5th gear, but I had to use 4th gear, otherwise I would have hit my 120mph limit from my map.

    So the only reason I can think for the inaccurate results is that the machine may have been expecting 5th gear, when I was actually using 4th gear.

    What do we think? I wonder if there is a way to calculate the correct powers from the gear ratios, from the figures below? Or do I have to just write this day off as a failure?

    Ferrari figures:


    Sil80 figures:


    Some more pics:







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    Banned sideways14a's Avatar
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    Any cams or owt like fancy exhaust manis?

    Suppose it could be the 4th/5th gear thing but 280 was aiming a bit low, wouldnt it be closer to 330 /340 easy?

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    Regards hardware, no it's all pretty stock. Cast iron manifold. Stock cams. Pic below.

    Regards the power, I really have no idea. I just assumed 280bhp because Horsham's Stage 2 SR20 chip claims about 280bhp, and my set up is more or less Horsham Stage 2.







    Here is my current map. Also some data from a recent road power run:




    (click to enlarge)

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    OK gear ratio's from Wkpedia:

    180Sx SR20DET

    3.321 1st
    1.902 2nd
    1.308 3rd
    1.000 4th
    0.759 5th
    4.083 Final
    Just got to figure out what to do with these now.

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    TMNT Kieran_E1's Avatar
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    i've read all the info you've posted and with regards to a solution all I can say is get a job doing what your brother does Ferrari

    Yes wrong gear will **** the results up

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    LOL stop inflating his ego please. It's already waaaaaaayyyyyy too big as it is.

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    Guest Kieran O'Quick's Avatar
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    392 x .759 = 297.5 must be too easy?

    Be interested to see the answer to this...

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    OK. My maths isn't really up to this. Any smart ppl please jump in

    So the power was measured in 4th gear which is a 1:1 ratio.

    I need to convert that into 5th gear which is 1:0.759

    So, as far as I can see, all you do is to take my max recorded power 392bhp, multiply be 0.759 and we get 296bhp. So the actual max power was 296.

    What do we think?

    EDIT - sorry 297.5 not 296
    Last edited by jont; 15-07-2014 at 18:55.

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    lol SNAP

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    If the above were correct. Then here would be the chart. Looks the right shape for an SR with a small turbo doesn't it?


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    Guest -ghost-'s Avatar
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    Needs to work harder and get a 458


    I'm not sure why but s13s are growing on me(but only with sr's)

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    LOL

    Here is my virtual dyno result from when I was mapping the car. I think the shape looks pretty similar.



    S13's are amazing.

    Mine is 1056Kg without fuel, and by the looks of things about 300Bhp with almost no lag. That's 285Bhp/Ton from a 5k car. Frigging awesome. Who needs Ferrari's.

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    Guest tokyo_black's Avatar
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    Quote Originally Posted by jont View Post
    Who needs Ferrari's.
    Ferraris make Ferrari noises But yeah the Sil80 did really well, the engine sounded lovely and smooth, effortless power. It will be a weapon on track - can't wait for Snetterton!
    Last edited by tokyo_black; 15-07-2014 at 19:24.

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    Banned sideways14a's Avatar
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    Isnt that puffer similar to a 28rs, if so then 550s a z32 afm and a good map is going to be well north of 280.

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    Correct me if I'm wrong but been to quite a few dyno's. And all of them using the gear with closest ratio to 1.0 so he was right to use 4th regardless of how the dyno was setup. There all configured to run on set gearing ratios

    I got a mate who owns a dyno and always happy to explain things etc can put you in touch if you want

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    Guest 59bhp's Avatar
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    to be fair ive only seen 360's make about 320-330 on dyno dynamics dynos so maybe it does over read and coincidentally just brought the 360 up to standard power :S

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    Quote Originally Posted by scotch_kris View Post
    Correct me if I'm wrong but been to quite a few dyno's. And all of them using the gear with closest ratio to 1.0 so he was right to use 4th regardless of how the dyno was setup. There all configured to run on set gearing ratios

    I got a mate who owns a dyno and always happy to explain things etc can put you in touch if you want
    If the operator said the dyno was set up for 5th does that mean it was expecting a ratio of say 0.7 - 0.8, so it would inflate the figures it produces otherwise it would under read? (bear in mind I have no knowledge of how a dyno is setup!).

    I also originally did the 392 x .759 calculation, but if the dyno was inflating by say 0.25 for a 0.75 ratio that would mean his final figure is actually 125% of the reading as it was run on 1:1.

    390/125*100 = 312bhp

    /end of guess!

    But it seems the car is sitting around 300 whatever way you look at it. Need to get it on another dyno.

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    Your calculations aren't a very accurate way of working it out im afraid but they give you a ball park figure. I think you can assume its somewhere between 290 and 310 which sounds about right. A 360 of that age shouldn't be making that power so I don't think that dyno is worth the ground its set in. Get to another approved dyno and see what you're really running. Unless "around 300" is enough for you. In which case enjoy the car. Must give the 360 a run for its money anyway!

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    Quote Originally Posted by pippin89 View Post
    Your calculations aren't a very accurate way of working it out im afraid but they give you a ball park figure. I think you can assume its somewhere between 290 and 310 which sounds about right. A 360 of that age shouldn't be making that power so I don't think that dyno is worth the ground its set in. Get to another approved dyno and see what you're really running. Unless "around 300" is enough for you. In which case enjoy the car. Must give the 360 a run for its money anyway!
    Oh yes of course, there are loads more factors that just a simple calculation, but we were just trying to get a best guess for Jon. 300 +/-10 seems to be the best guess until it gets on a decent dyno.

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    Yeah and for that purposes it gives you a good idea. Sounds like its where it should be considering the mods.

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