knock issues???

[rickisrad]

hi all,

I am doing some scanning and am having some issues with knock. Mostly between the 4000-5200 rpm range and .92g cylinder airmass. the knock average is 9 for the 4k/.92 and 4 for the others. The high Octane/spark timing is already down to 10 in those cells. The o2 Readings at the 9000 hz up range from 910-945. I am not sure what to adjust from here. The trims are all within 5%. It drives fine and has good power. Any suggestions on where to adjust or look for the issue?



I have a rollmaster timing chain, 90# springs, 1.85 roller rockers so I dont think valve float is an issue.

[Scottydoggs]

so your seeing 9 degrees kr?

how many miles are on your blower? ive seen them cause kr when you get bad bearings.

have a wb? and whats your timing set to wot?

[rickisrad]

Yep 9 degrees KR. The blower has about 160k on it. I will probably have to look into getting the blower rebuilt. I don’t have the presses to do it myself. Unfortunately I do not have a WB. I really need to get one sooner than later!!

[Scottydoggs]

take the blower belt off, then go beat on it, see if the kr went away with no blower.

[rickisrad]

Ok I will try to get it off before the drive home from work.

[rickisrad]

Well I pulled the belt and scanned for knock on the way home. Besides the POS HPT app freezing I did not see a blip of knock. I was not able to get to the cells that was showing before but was able to get a couple of wot runs and no knock what so ever. Looks like I am going to have to buy a rebuild kit and a press from Harbor freight.

[Scottydoggs]

lets not get crazy yet on a new blower.

whats your timing set to wot? it might be to high. simple fix.

[rickisrad]

I’m not really sure where to find that. I’m seeing the high/low octane advance and the Max Torque Timing. The High Octane is where I adjusted the timing at in HPT. In that the timing at .92g airmass 4K-5200 rpm is 10 degrees. 5600-6400 rpm it is 15 degrees.

[Scottydoggs]

if you have the stock file still from your saved first read, copy that back over. im willing to bet you have the timing adders still on and your getting more timing then what you see in the timing table.

in the scanner scan for timing advance. if you figure out how to put it in a graph you'll see the timing over all much better.

[SgtMarshal]

maybe it's as simple as a pulley too small

[Scottydoggs]

3.4 on a gen 5 is a bit much, will likely need to run less then stock timing wot.

[rickisrad]

I do have the advance timing charted. It is reading about 16 degrees in those few cells. That is about what they were set at. The base correction added for fuel is adding but the IAT and ECT are zeroed out.

[SgtMarshal]

that just means it's not adding timing advance at full throttle. you need to pulley up, I would try a 3.6. 9* of kr will chip a piston sooner than later.

[rickisrad]

Yeah you are probably right on that. May be a combination of that and the sc age. I need to get a 3.5 pulley to try out. I want one of Ed’s intercoolers but that is probably 5 months away.

[Scottydoggs]

or drop the timing by 4 degrees.

[rickisrad]

I will drop the timing some more and scan some more in the morning.

Have either of you rebuilt a supercharger?

[Scottydoggs]

little story, my cars a kr monster too, well used to be. a aem meth injection kit is cheaper then a ic. and likely do more.

i have a l36 bottom end, gen 3 blower, diy ported heads, 1.95 rockers, and a fsic. i was running a 3.2 with all that, and like 14 degrees wot timing.

added a meth kit, got it to take 21º wot and running a 2.8 kr free.

im willing to bet you could run a 3.0 with meth and more timing.

[Scottydoggs]

[SgtMarshal]

I doubt it's the blower itself, just the fact that there is too much boost. you would be seeing kr at idle too if the blower was bad.

[rickisrad]

I think that may be the route to go with the meth kit. I have access to methanol at work.

Marshal, very true. I would probably see/hear more