Lots of KR downshifting

I don't really get much KR when I'm at WOT usually 3-4* but when I'm downshifting I almost always see knock with even like 20% throttle. Going at like 70% throttle on the highway in 4th I get up to 6* knock.

Would there be any reason that I would have so much at the downshift but not upshifting?

I normally see more KR when upshifting and downshifting, and it seems others here see the same. Upshifts apply extra load to the engine, downshifts create high revs = peak boost. Both are times when knock occurs most easily. This is why it's best to have 0º KR at WOT, so your KR peak will be minimal (1-3º) when your engine is asked for more torque or when it's pushing max boost.

Need to do one of the following: tune PCM, drop pulley size, increase octane, add IC, or wait for cooler air.

AA wrote:

I normally see more KR when upshifting and downshifting, and it seems others here see the same. Upshifts apply extra load to the engine, downshifts create high revs = peak boost. Both are times when knock occurs most easily. This is why it's best to have 0º KR at WOT, so your KR peak will be minimal (1-3º) when your engine is asked for more torque or when it's pushing max boost.

Need to do one of the following: tune PCM, drop pulley size, increase octane, add IC, or wait for cooler air.

So your saying it is normal to see more KR when downshifting? I was just wondering why I don't get so much when upshifting.

I'm hoping to get it tuned soon. I haven't changed the fuel filter in about a year either so I'm going to do that but the line was a bit rusted so I'm bringing it somewhere to get it done.

If the tune doesn't work I'll probably just go with a SSIC.

Do you think 4* of KR is unrealistic to tune out? Or is it too hard to say without scans?

I think it's normal. Have always seen more KR in the upper RPMs, especially after setting the shift points higher. Think about it, when do you see the most KR at WOT? For me it's at the top of 2nd gear, near 6kRPM, when I'm making the most boost and the most power. When you downshift, you're making the engine work up in the top of the band.

4º KR might not be that hard to tune out. I'd try drowning it with some fuel at the MAFF where the knock is occurring. Tuning takes time... Good luck.

Of course, I'm sure you mean go up a pulley size

D'oh... Don't listen to me!

AA wrote:

4º KR might not be that hard to tune out. I'd try drowning it with some fuel at the MAFF where the knock is occurring. Tuning takes time... Good luck.

agreed, a tune might not erase it all, but will surely help lower that KR.

and a 3.3 pulley aint helping (as I say running a 3.25 myself)