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It all depends Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 2 May 2003 13:48:25
In Reply to: fuel usage for turbo engine?, 89 9kturbo, Fri, 2 May 2003 07:03:04 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The APC (automatic performance control) will dial back boost if it detects knock. Higher octane fuel is more resistant to knock. However, you can use the lowest octane fuel that doesn't cause your engine to knock.
Every engine is different, and the older they get, the more they differ. Some engines build up carbon and hot spots, and are very prone to knock - they'll require 93 to get any boost at all. Other engine loosen up and are very tolerant of low octane fuel.
Of course, make sure you're using the right spark plugs gapped properly, and the timing is correct. Then try different grades of fuel and see. You'll know when boost is being reduced because the boost gauge won't go past half-yellow.
There are times when engines are more prone to knock - hot days, heavy loads, low RPM.
My 2 '88 9000T's both get full boost on good old 87 octane, even on hot days. There is absolutely no reason to use higher octane fuel. However, my '86 900T needed 91 octane to get decent boost, and really preferred 92. Really, the same engine, just that the '86 engine was a little more prone to knock.
Every car is different, so you'll have to try for yourself. Asking what octane other folks need for their cars is like trying to decide what shoe size you are by asking other folks what shoe size they need.
posted by 192.249....
, Fri, 2 May 2003 13:48:25 <-- Viewing This Message
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