High Compression Ratio ----> Detonation

[apardal]

Hi!

I'm experiencing some detonation on my 4AGE MAP Blue top after I've done some modifications on it.

- Wiseco Pistons 81.5mm
- Head decked 0.6mm
- Block decked 0.1mm
- TRD Metal head gasket 0.8mm
- (Calculated Compression Ratio 12:1)
- HKS Camshafts 264/264 8.1mm lift
- Fidanza cam gears
- Complete 2.25" SS exhaust with Tsudo Headers
- Stock intake without TVIS
- Mild head work (smoothed combustion chamber edges, cutted bronze valve guides, polished exhaust...)
- Beru Silverstone Spark Plugs and TRD spark plug wires
- OEM ECU with new HC Crystal, changing rev limit to 8500 rpm
- Apex'i SAFC1 Piggy back
- NGK Powerdex AFR
- Running Unleaded 98.

The problem I'm dealing with is Detonation under normal Ignition Timing (10º, measured as the manual recommends). I've installed a home made stetoscope (copper pipe, bolt and canister) to hear detonation while driving.

Using this gadget, I started lowering the Ignition Timing until I reached 0º, and I still had detonation. If I get it around -5º I'm able to stop engine knock. This knocking sound is heard around 6000rpm under load and the more I advance the ignition timing, the sooner (lower rpm) I'll hear knocking.

My camshafts are dialed in the exact same way stock ones are, and I think I have the exhaust cam 2º retarded. HKS states 110º BTDC and ATDC for both cams, I might have to re-check that.

What do you guys think my problem is? Incorrect mapping? Incorrect cam timing? Unapropriate spark plugs? What?

Thanks in advance