Quote:
Originally Posted by Charles Freeborn
Yes, you can get high octane (racing) fuel, but it is very expensive. Here in the Portland Area it's nearly $8 per gallon.
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And doesn't actually make as much difference as you might think.
At least, that what I found; based on my not-exactly-extensive test of filling up with 100 octane in at PIR and watching the knock sensor on the next few laps
My J&S Safeguard paid for itself last week... - I only noted a tiny amount less timing getting pulled with 100 octane, as compared to premium pump gas. I tried a partial fill of 110 octane another time (heck, that's not cheap - and I didn't want the lead to hurt the narrowband sensor), and got much the same results as 100 octane.
I really believe that the CIS ignition curve throws power away almost everywhere by being far more conservative than it needs to be in most places - while actually still being risky in a couple of places given exactly the right (wrong) conditions. I found this with both US and RoW ignition curves, although the RoW was more aggressive - exactly as you'd expect.
Although the 80's Motronic is better, it also has no way to detect (or more importantly, compensate for) conditions/events that will damage the motor, like almost all modern cars do.
I'm biased. I'm a fan of active knock detection/control in general - and a huge fan of the J&S Safeguard in particular. Much simpler/cheaper to add it than than to fix any detonation damage afterwards. Plus, on CIS motors, it allows you to add back some ignition timing for those parts of the map (almost all of it, it seems) where it's too conservative.