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Old 07-02-2012, 06:51 AM
WDRAcing WDRAcing is offline
Officially Welcomed to the 'Fest
Location: Dover DE
Join Date: Apr 2012
Posts: 151
Mein Auto: 99 540iA
Just a couple things to add. Preignition is what takes place before the spark event, detonation takes place after the spark event. Preignition almost always ends with a part of the rotating assembly failing, usually a hole in the top of the piston. Preignition is mostly caused by the wrong heat range spark plug and or hot spots that form in the combustion chamber. Using the correct heat range plug and making sure the engine doesn't run hot will keep preignition at bay.

Detonation is what happens when you reach the octane limits of your fuel. The higher the octane of the fuel, the more boost you can run for any given compression.

The "knock" sound you hear is actually the rotating assembly absorbing the shock load of the detonation occurring. A motor can run for years with light knock. However, you don't want ANY knock if you're going the FI route.

The best way to avoid detonation is with alcohol/water injection.

Turbo's own superchargers in almost every category. You'll make more useable power with a turbocharger since they'll produce full boost far earlier in the rpm band then a centrifugal supercharger will. The centrifugal type supercharger, imho, represents the ultimate form of lag. Full boost comes as you max out your desired rpm.

Lets use 8 psi as a max boost #. The turbo will be at full song by 3000 rpm give or take, the supercharger will likely only be at 3-4 psi and slowly increasing until it peaks at 8 psi as you're about to shift.

Another benefit of the turbo is your ability to control the amount of boost with a simple controller. No swapping pulleys around and messing with belt tension. Just turn a knob. Very handy because you can run 2 different levels of boost real easily. Use a low boost setting for daily driving and use a high boost setting while you're at the track, or feel the need for a little irresponsible hwy driving.

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