If you are running a small rear housing on your turbo, the exhaust manifold pressure will exceed inlet boost pressure,

in that case a large overlap cam will allow a small amount of exhaust gas to be pushed back into the inlet.

The result is detonation.

 

 

Well that's what the mechanic said down here in SA, i am getting the detonation problem!

 

The motor has no timing or a dead spot between 2500rpm to 4500rpm

 

The timing in the rpm range up to 2500rpm the timing is around the 10-15 degrees advance

 

The timing in the rpm range from 2500 to 4500rpm sits around 0deg

 

Then after the 4500 to about 6000rpm the timing goes to 15-20deg advance and has top power!

 

So he said i am getting no timing due to the cam being "Too Hot" for the engine and thats causing detonation,

then he said replace the cam with a standard one or a turbo grind cam and then get it re tuned!

I've got a stock cam you can buy. I'll just pull it out of a spare 4k.

 

Your timing sounds a bit whack!!! But the tuner must have pulled this back.

 

I run about 32o off boost, which comes down to about 28o on boost.

So a cam shaft from a 4k will fit the 5k?

 

I was told that you can only use the 5k cam only in the 5k engine.

 

Because of the hydraulic lifters?

Convert to solids!! :D