jon haney Posted March 30, 2011 Author Share Posted March 30, 2011 ECM and electronic retard/anti-knock might be able to help out some Using 91 octane at 12.3:1 compression should not be pinging. That is about where I am at. No pinging even on 87 octane, but I do have an FI Bird. I think you have some other issue causing your pinging, but I lack the experience to give any advice on what to look for. I guess that the difference lies there...I've done it with an engine that isn't electronically controlled by a computer. Maybe I'm missing something but it just seems to defeat the purpose when the ECM has to dial the spark back so far that it basically nullifies the potential gains on the mechanical side for lack of a stable fuel. And the loss could really be transparent except in direct comparison...bet you could dump a load of VP or high dollar Sunoco in there and pick up significant gains.... This is a long shot, but I've heard that if you have any sharp edges on a piston crown, such as the ends of a valve pocket, they can get hot enough to pre-ignite the air/fuel mixture. I'm assuming this would require some other issues like a lean air/fuel ratio or poor cooling system. Does it only ping when it gets hot? Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted March 30, 2011 Share Posted March 30, 2011 Does it only ping when it gets hot? No. Running anything commonly available at under 100 octane is the culprit. Good fuel = good horsepower and great torque under any loads in all conditions without any pre-det even with high advance timing numbers and split overlap(100/105C) cam timing. 93 pump gas with a shitload of canned octane boost will get me home in a pinch if I can't find a racetrack(or friendly airport) nearby to fill her up. Still sounds like a coffee can with about a handful of steelies being shaken violently if it's hot and humid out and I get rev/torque happy with the throttle. It's more a result of intake air temp and density than it is the actual engine temps. My compromise so that I could enjoy riding it on the street was to decrease the squish by increasing chamber volume and dialing the static ignition timing to the OE stop(-15 to -18) on the retard side. I learned the hard, expensive, and time consuming way that pumping a 25+ year old air cooled mill up into the performance output range of a Blackbird was possible, just not very practical. But again, I'm sure that the computer will cure nearly all ills but may never reveal what the potential output could be if we had something besides watered down Zippo fuel available at the local gas stations... Quote Link to comment Share on other sites More sharing options...
tomek Posted April 1, 2011 Share Posted April 1, 2011 What ? Air cooled ? That is whole different issue . Sir , the ECU , computer retard ,etc. will not get your performance numbers and reliability to the level of modern 4 valve water cooled mill with nice and tight cylinder head . The design of cylinder head / combustion chambers is compromised ( wide valve angle ) and water cooling does wonders in carrying away heat from hot spots preventing detonation . All things being relatively equal water cooled engine will tolerate CR higher by 2-3 points vs comparable air cooled mill . Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted April 1, 2011 Share Posted April 1, 2011 Apparently.... but I still wonder what it would be capable of doing on good fuel... Quote Link to comment Share on other sites More sharing options...
jon haney Posted April 1, 2011 Author Share Posted April 1, 2011 Apparently.... but I still wonder what it would be capable of doing on good fuel... I'd guess emptying your wallet. Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted April 1, 2011 Share Posted April 1, 2011 That too... Quote Link to comment Share on other sites More sharing options...
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