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Thread: Porsche 996 cup car

  1. #121
    Gas Turbine enthusiast da9jeff's Avatar
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    Quote Originally Posted by BLO 767 View Post
    Starting a Cup car in a residential garage is goals.

    Pressure relief valve? Surely that's max reading @ 150psi +. I have a similar wallet-draining-exy MoTeC OPG - does it need calibrating in the MoTeC?
    That's a good point, does it read zero with engine off and 30-40 while cranking?

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  2. #122
    Registered User spiller's Avatar
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    Hooked up mechanical gauge just then. Stone cold, the oil pressure was 110 psi and after approx 6-7 mins of idle it dropped down to 65 psi. Iím sure oil was not yet up to full operating temp but the water temps start to go up as no cooling fans so I didnít want to push it. Iíd imagine oil wouldnít have been much higher than 85 degrees whereas full operating conditions are 110 degrees.

    I gave it a few revs to 4K rpm and it went up to about 105 psi. Didnít rev any higher than that. Not sure when the pressure relief valve opens...



    So the motec reading is definitely wrong (not surprised). Thoughts on the readings from the mechanical gauge?

    This is an oil pressure map that a guy from France with a 997 cup sent me for reference.




    EDIT: went back and reved engine to a bit over 7K and the max reading on the mechanical gauge was 7.8bar which is similar to the pressure map above. I think Iím good to go.
    Last edited by spiller; 16-02-19 at 08:59 AM.

  3. #123
    Registered User BLO 767's Avatar
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    Yeah man, looks like that has established a few things:

    MoTeC OPG is clearly just reading max.

    Oil Pressure is indeed (there) & moving, and dynamically rising with revs.

    Oil Pressure is not showing anywhere near 150psi+ all the way up to 7k.

    Good to go.

    I'd much rather see a little more cold oil pressure, than the converse. As it'll warm more.

    You'd want to be worrying if it was dropping at anything over 2,500.

    Good luck tomorrow dude, vids!

  4. #124
    Registered User spiller's Avatar
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    Thanks man, Iím pleased it appears quite healthy as the map provided by the car above is on a very fresh motor. Will grab some in-car tomorrow, should be a good day with a couple of 991 cups and lambo GT3s coming out.

  5. #125
    Registered User Andy San's Avatar
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    Not sure what motec you have, but the sensor that's in the car doesn't look like what you'd usually use.
    Most motec stuff uses honeywell 0-5V output sensors which are 3 wire rather than the two on yours.

  6. #126
    Registered User lightyear's Avatar
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    A car like this makes a lot of sense. Be keen to see what running and maintenance costs work out to.
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  7. #127
    Registered User spiller's Avatar
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    Quote Originally Posted by Andy San View Post
    Not sure what motec you have, but the sensor that's in the car doesn't look like what you'd usually use.
    Most motec stuff uses honeywell 0-5V output sensors which are 3 wire rather than the two on yours.
    Itís a very early motec minidash, pre ADL1. They were adapted to talk to the Porsche Motorsport Ecu and so the car mostly uses Porsche sensors. Anything that was already there from the factory was left with others added in. For example, the air temp sensor is similar to the plug you are referring to as they didnít come from the factory that way.

    Quote Originally Posted by lightyear View Post
    A car like this makes a lot of sense. Be keen to see what running and maintenance costs work out to.
    Iíll try and be as transparent as possible in this thread. Theres a bit of a premium on some parts as theyíre hard to get or no longer available but there are thrifty ways to do certain consumables e.g. using aftermarket steel rotors from Porsche panemera on the rear and Porsche Cayenne on the front, rather than factory Porsche drilled rotors which crack and cost 7x more. Tyres are the worst part but Iíve been running used stuff thus far while getting to know the car.

  8. #128
    Gimme six Schlitzes Beavis's Avatar
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    I'd love to see a pic of the dash

  9. #129
    Registered User spiller's Avatar
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    ^^^ not the greatest pic but you can see the dash just to the right of the main instrument panel. It doesnít tell you anything in real time other than your current lap time, best lap and lap counter (provided you have a beacon set up trackside). I believe they can be configured to show other stuff such as gear and certain warnings but not as informative as the ADL2 dash. Iím not even sure my display can be re-configured as these were supplied via Porsche to the Carrera Cup teams and pretty sure they are locked. As far as real time goes, you only have the factory gauges in a 996 cup.
    Last edited by spiller; 16-02-19 at 01:25 PM.

  10. #130
    Registered User BLO 767's Avatar
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    Oh yeah, that's an MDD. Usually a Formula car dash, is what you see them as here in Oz.

    Interesting setup considering everything it logs.

  11. #131
    Registered User spiller's Avatar
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    Yesterday's Porsche club supersprint at Mallala is done and dusted. It was pretty hot yesterday, around 34 degrees but fortunately we had some cloud cover which kept the sun away for about half the day and it was not windy like it normally is out there. Still, I did not come prepared with ice/esky and my twelve 600ml waters went hot pretty quickly. They don't allow us to open garages for the Porsche sprints (or even the option pay for one) which is bullshit, so you are basically out in the sun all day. What's worse is the car is out in the sun all day too. This was the hottest conditions I have ever driven the car in. I'd estimate it was 55C+ in the car and it really got to me. Not so much being able to drive, but I really struggle to load the car back onto the trailer and pack everything up at the end of the day and it was all a bit of a blur. It was probably the first time in my life I've ever experienced genuine heat exhaustion - feeling or burning from inside out, nausea, goosebumps etc etc. Not cool! Next time I will take a big esky with plenty of ice and I think I need to invest in a portable shade to park under to keep the heat off the car.

    All of that aside, I went into the event looking forward to having a bit of fun and seeing how the car would perform. As discussed earlier in the thread, I've speculated as to the straight line speed of the car and questioned the mid-range performance as to whether it was acceptable as normal, or if there might be something holding it back. I have speed data from my old GT3 at Mallala so I was pretty keen to see how the cup car compared to this. I also wanted to see how the lap times would compare. Once again, I went out on old slicks but all being well, I would still expect the cup car to be 1.5-2 secs per lap quicker than the road GT3, all things considered.




    I decided to pull some wing out of the rear which I think was a good decision as aero does not play much of a role here and you want to maximise speed down the back straight. After a couple of sessions I got a feel for how the chassis was performing. The car was tending to understeer a bit and so when trying to drive around this, you would inevitably upset the rear end by turning in harder, and so it was a bit of a balancing act. Still, it was manageable and I felt I could drive around it. Keeping in mind I have not bothered to tune the set up of the car since the initial corner weighting and alignment for a couple of reasons: 1) because it's been a drawn out process of running the car to sort through little performance bugs and 2) as a result of point 1, I have not yet bothered to run fresh rubber and I feel that trying to set up the car based on feedback from old slicks will just have me running around in circles.

    Out on track, the most noticeable issue was again straight line performance. Particularly in 3rd and 4th gear where it seemed to take forever to rev out. There was a subtle sensation of a loss of HP through the mid range and then a kick in the pants from about 7400 rpm right to redline, as if the car suddenly got its legs back. I have felt this in earlier situations driving the car but at that time, the car was very new to me, so I wasn't sure what I should be expecting. Now that I am more aware of it, I feel it's either an issue with fueling, perhaps a dirty injector or fuel pump on the way out, or a faulty throttle position sensor (as discussed previously)...or both. Either way, I reckon it's robbing 40-50 hp at times and consequently my straight line speed, and thus lap time is a little lacking.

    My best time for the day was a 1:15.75 and my maximum speed was 195 km/h. Compare that to my road GT3 which bested 1:15.0 and ~210 km/h. I realise that track conditions can vary significantly from day to day, however there is no way a GT3 cup at 1150kg on slicks should be slower than a road GT3 at 1350kg on r-compound tyres with the same driver, old slicks or not.



    Looking at the motec data from my best lap, specifically the throttle position, once again it never goes above 92%. I have circled an area where you can see the speed climbing (as I am on the back straight at WOT), yet the throttle position drops off to about 67%. One some other laps it drops to as low as 45% in this part of the lap! Oddly though, there were other parts of the lap where I could feel that same sensation of power coming and going, yet the throttle data did not show it. Either way, i'm fairly confident a dodgy TPS is part of the issue.



    Despite all of this, I had fun hooning out on track and it was good to get back to Mallala for the first time in over 2 years. Not going to lie though, I am keen to just get this shit sorted so I can finally have a go in this thing at full tilt and see what it can do! I am thinking the next step from here is to get the TPS issue seen to and then throw it on the dyno to see what the curve/fuel/etc is doing. I do not want to go back to the track until it's fully sorted as it's a lot of time, effort and $$ to get out there and it's frustrating not being able to drive the car to it's full capability. The next Porsche event is at The Bend in May so that will be a good on to aim for.

    Unfortunately I did not get any gopro footage because I forgot to clear the SD card before the event and so it didn't record!
    Last edited by spiller; 18-02-19 at 04:02 PM.

  12. #132
    Gas Turbine enthusiast da9jeff's Avatar
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    Sounds like a successful day out despite the lap time (which is still bloody quick). Definitely head to bcf and invest $200 on a 3x6 pop up shelter.

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  13. #133
    Registered User BLO 767's Avatar
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    She cleans up alright, for sure! Such a smart looking car in blue + white.

    It wouldn't have liked the heat either. Cool suit + dry ice and anti freeze man? I reckon it's mandatory here in Aus, esp in a full steel race car.

    I think dyno time is invaluable in a car like this. Allows you to sort out all those issues without the need to go to a track with your full setup. Then when you know it's tested and proven you can focus on tuning the setup for the day at the track.

    I'll be honest in that I'm not educated enough to comprehend the MoTeC data and like yourself, I want to sit down with my tuner and get the basics down for that same reason. But FWIW I've checked some of my Comm logs and find the same bizarreness going on incl with throttle. Apparently - and don't quote me - but some of my research lead me to an understanding that the reading can also include or exclude the throttle plate. As the throttle is not on 0% once the car is running. It could be cracked 8% on idle (manifold plate), which is set to 0% (throttle at the pedal), and then it is 'opening' 92% further at the plate, which is actually 100% at the pedal and plate. Had all manner of in-between %'s too, so I re-mapped mine dozens of times resetting it to 0% and 100%. Then I ended up reverting back to what it was originally. And it seemed to actually show 0 - 100 properly for a while, and I believe still does.
    Wouldn't it be ironic if we both just had faulty TPS'!

  14. #134
    Registered User spiller's Avatar
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    Yep I reckon the 6x3 is a goer and lots of ice for cold water in future. Cool suit would be awesome but not sure I can justify the cost given only in the car for 15 mins at the time mostly. Health and shit though...

    Interesting points re: the throttle position Blake. That makes sense. Then again old data shows 101% so fuck knows! I don't really understand how the whole scaling thing in the motec relates to actual throttle position but it's going into the shop when I get a chance to check fuel pressure and throttle opening then I'll put it on the dyno.

  15. #135
    Registered User gmx's Avatar
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    The TPS might also be an angle measurement. A lot of Bosch/Valeo throttle bodies which I'd assume this has will read very similar (89 IIRC). Especially if it is a cable throttle. You definitely want to compare your data to others and knowledgable people.
    Is your foot flat when it drops to 45 or 67 as in thr graph etc? If these are DBW, could be an issue with the engine and the electric throttle closing the plate to save it. No obvious pinging, misfire etc? I'd get it on a dyno and have it figured out. Perhaps like you said, injectors flowed too.

  16. #136
    Registered User spiller's Avatar
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    No pinging that Iíve noticed. It occasionally misfires for a couple of minutes when cold but then smooths out and thereís only once been misfire/ignition break down when actually out on track (a couple of events ago) and it fixed itself and hasnít happened since. In retrospect, some of those 45/67% throttle measurements could have been me lifting slightly as the back straight has a kink in it, however the 67% lap was my fastest of the day and usually if you lift, itís very slight through the corner then back on the power for another 250m or so before the braking zone. The throttle data does not go back up though and drops to zero once I start down shifting. So, not a true reflection of what I was doing with the pedal. Also if the throttle was closing to save the engine, you would then think it would be opening again after 7400ish rpm when I started to feel full power come back, but the data doesnít show that. I would have thought the ECU would just pull timing if the fuel leans out as thatís a lot more aggressive and immediate protection than closing the throttle? This stuff is not my domain so Iím only guessing but itís interesting to speculate. Iím not overly worried as I reckon the car has been this way since I got it and Iíve only now driven it a couple of times without popping coolant hoses to realise that itís not right. Iíd imagine if it was dangerous to the motor it would be fucked by now as Iíve probably done 400 odd kms. The car otherwise is running well. If you hadnít driven a GT3 in anger before you probably wouldnít even notice as it still feels pretty rapid.

    The shop who works on it are running a car in Carrera Cup at the Adelaide 500 in a couple of weeks so it will go in to them after thatís finished and hopefully then weíll have a verdict.

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