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I've read some letters in Drive in The Age over the past few months where writers say they've got benefits out of PULP by "tuning" their cars (various recent models) for it. Are there any current mainstream ECU controlled motors that can actually be "tuned" for different octane ratings and, if so, how? I thought anything with a crank angle sensor and/or no dizzy would prevent advancing the base timing. Apart from that there's nothing to fiddle with to "tune", but I'm still getting on top of 1988 technology so maybe later cars are different.
EA, there are aftermarket ECUs that are home-programmable. Wolf3D, SDS and MoTec are the first that come to my mind. For a minute, think what are the main differences between PULP and regular unleaded? The most striking one is the different optimim ignition timing. On EA-ED and EL Falcons they still have a distributor-in-block ignition system, so its easy enough to bump the timing 1 or 2 degrees. After that, its complicated a little. I believe that PULP requires a slightly different advance curve to perform at its best compared to ULP. And if youre using something slightly more viscous, such as Shell Optimax, then it will require a slightly richer mixture curve to compensate for the fuel's viscousity. All up, it is possible to tune for different mixtures.. You could get a hot chip programmed for you with your car on the dyno, but that could end up costing a fair bit..
Originally posted by discokin6 ........And if youre using something slightly more viscous, such as Shell Optimax, then it will require a slightly richer mixture curve to compensate for the fuel's viscousity.
On the issue of fuels such as Optimax, Syndergy 8000, and BP Ultimate, they are higher density fuels. Means more mass for the same volume.
So, consider fuel injectors which rely on pressure and regulate the fuel delivery by pulse length. When the fuel is injected it is burnt and the ECU sees a mixture reading at the O2 sensor, and also a MASS air flow into the engine. The result of using the denser fuel is that the fuel injector pulse length is now excessive (same VOLUME but more MASS) and so the fuel delivery will or should be trimmed down.
Remember - mass air flow engines calculate everything on mass, not volume. This was a major turning point in engine development and followed aircraft which have used mass measurement for a long time.
This theory is the justification of why Shell market Optimax as giving more distance from every tank.
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The impression I got from the letters in Drive was that the owners were saying their stock cars could be specifically tuned for PULP, rather than after market programmable chips or automatic adjustments in the system. Does this sound right? I'm interested because I'm wondering whether the writers were deluding themselves or whether their mechanics might be having them on.
I have bumped the timing on the Big Block Camira by 3 degrees and run premium most of the time. Same can be done on your EA. Reason for this timing advance for PULP is PULP is less volatile and burns slower. So you have to light it up sooner.
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BA'1.5' Pursuit 290
Lightning Strike / Reflective Orange Stripes 'General' Dog - AP's German Shepherd and Best Mate - 02Dec1998-15Dec2003.
'Pepper' Dog - General's and My Little German Shepherd Sweetie - 1996?-02Apr2006. 'Sako' Dog - My Beautiful and Pretty German Shepherd - 2001?-23Aug2006.
Originally posted by Aussie Pete I have bumped the timing on the Big Block Camira by 3 degrees and run premium most of the time. Same can be done on your EA. Reason for this timing advance for PULP is PULP is less volatile and burns slower. So you have to light it up sooner.
Zigactly!! I have done the same to the beast, it was pinging its tits off at 29deg, even on Sloptimax. So I rammed it up to 33/34deg and she's sailing smooth now. As Pete says, it's not so much "tuning" as in extra power etc, but more getting ignition right and proper.
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Originally posted by Aussie Pete I have bumped the timing on the Big Block Camira by 3 degrees and run premium most of the time. Same can be done on your EA. Reason for this timing advance for PULP is PULP is less volatile and burns slower. So you have to light it up sooner.
I experimented with that, because there's no crank angle sensor and advancing the base setting remains constant throughout the range. Tried it with PULP and advanced 2 and 4 deg and no difference. Actually a bit worse on 0-100 times. Not sure if that's the definitive result as there's still an ECU / KAM problem coming up on my diagnostic codes and I'm not sure my engine management is 100%. Might try it again when I sort that out, which will be after I sort out a few other things.
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