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smurfbus smurfbus is offline
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Join Date: Aug 2009
Location: Europe
Posts: 1,422
Turbo spool vs. timing with CIS

What are your findings over this with different sized turbos?

It seems spark timing (heat) has a huge effect on turbo spool so turning the distributor a bit can make your car spool early and make wild boost (over your WG spring) or spool late and boost low (under your WG spring on lower gears) but still run pretty good in both cases. Advanced timing feels more like NA cars so I like the feel of it when not on boost. I'm not sure yet which setup is faster though. I could not pull any runs in my usual test spot so I could compare runs but this new setup feels faster but the atmo has been cooler now.

I dialed more advance in small increments and made some runs and the turbo spools now at about 4000rpms on lower gears and the car goes strong with about 0.8bar (3rd gear) and with much less boost on 1st and 2nd gears. Earlier it would spool already after 2000rpms and WG could not limit the boost so I had 1.1 to 1.2bar on 4th gear. It still starts to spool (slowly) after 2000rpms on 4th gear.

Earlier it would also spin the tires on 1st gear when the boost romped on wildly. Not anymore and I bet the engine temps are much lower now too.

I made some high speed wot runs too and the engine did not ping or give any signs of trouble and the max boost on 4th was 1bar so I might stick to this timing setting (you don't want to copy my timing values so I won't publish these!). Interesting to see if WMI will lower the boost too.

I just wanted to let you know that the 'norm' timing really does not work on my engine. It would suck donkeys balls to run with less than 10BTDC on idle on my engine, don't know why! I have 1mm~0.4 spark gap with superconductor wires, MSD6A , vacuum pot plugged on dist and single plugs so your setup/results can be different.
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79 930: HX40S#16, MS3pro+ID1000+044+E85, Ignition: 123/TUNE/MSD6A, True split BB, 2*turbosmart38

Last edited by smurfbus; 08-25-2011 at 03:39 AM..
Old 08-25-2011, 02:23 AM
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