Controlling KR with high SCR & DCR
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From: Bergen County, NJ
Controlling KR with high SCR & DCR A little background is probably in order;
Last fall, my futral f13 cam self destructed and took the lifters with it. In speaking with AFR, I had explained that I was not happy with the F13 to begin with, it pulled hard in the high RPM range but was weak in the lower RPM range where I do most of my driving. We agreed that the approach should be to mill the heads .018 to bring the chambers to 63cc, use an .040 cometic gasket to keep the quench tight and put in AFR's 220 224 114 +4 cam. The result is that my SCR is 11 to 1 and my DCR is 8.8 to 1. We felt that with the proper tuning and 93 octane that would be fine.
As the weather was getting colder it ran fine on the tune for the f13 cam and I have been making minor modifications to the VE table to correct the LTFTs. Now that the weather is warmer, it's knocking from 1800 to 6000rpm anything above 60 MAP.
I have been adding fuel in the areas where the KR is occuring and I redid the timing table this morning to reduce the advance but it is still knocking and I am really getting concerned about burning a piston.
Should I just pull a bunch of timing?
Note in the log BTW almost everytime it shows KR it is right after 02 #1 drops down to about .05 to 1.5v and fuel trim cell number jumps to #12?
Last fall, my futral f13 cam self destructed and took the lifters with it. In speaking with AFR, I had explained that I was not happy with the F13 to begin with, it pulled hard in the high RPM range but was weak in the lower RPM range where I do most of my driving. We agreed that the approach should be to mill the heads .018 to bring the chambers to 63cc, use an .040 cometic gasket to keep the quench tight and put in AFR's 220 224 114 +4 cam. The result is that my SCR is 11 to 1 and my DCR is 8.8 to 1. We felt that with the proper tuning and 93 octane that would be fine.
As the weather was getting colder it ran fine on the tune for the f13 cam and I have been making minor modifications to the VE table to correct the LTFTs. Now that the weather is warmer, it's knocking from 1800 to 6000rpm anything above 60 MAP.
I have been adding fuel in the areas where the KR is occuring and I redid the timing table this morning to reduce the advance but it is still knocking and I am really getting concerned about burning a piston.
Should I just pull a bunch of timing?
Note in the log BTW almost everytime it shows KR it is right after 02 #1 drops down to about .05 to 1.5v and fuel trim cell number jumps to #12?
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From: Bergen County, NJ
That's true assuming that you have the right timing and mixture to begin with. With increased compression and less overlap, the vacuum at Idle is greater, and the MAP is greater. I am told this combo works for many, but I need to tune for it and it is turning out to be little trickier than I first thought.
Here's the tune I'm running now.
Here's the tune I'm running now.
If KR is always following a lean dip from tip-in then you want
to either pull back timing or perhaps fatten up the VE table at
the areas you "slide through". If you see the O2s dip every
time throttle opens, either VE is short or it's slow. There are
some filter settings you could play with but not much guidance
there. I'd concentrate on the plain VE tables first.
You might choose to cover it up by enabling burst knock and
yet limiting it to a sane maximum. Look at what your delta
dynamic cylinder air is, see whether KR always attends a
greater-than-XXX air-step. I do not know how EFILive does
the units / display there, you may have to work in Excel and
correct the logger vs PCM time-tick (for HPTuners I take the
dynamic cylinder air PID, and make delta as =(X2-X1)/8 for
the 1/10 sec scanner frane, 1/80 sec PCM tick.
People tend to run a lot of timing, as much as possible, but
with CR up you need less than before; don't be afraid to pull
out timing in the midband even if it makes the car feel less
"responsive". You don't need it to be edgy on a daily driver
and you still have kicked-down, big end for power. And there
is a flat-top where more spark makes no more torque, just
more sensitivity to environment.
Be sure you have the fans keeping a consistent coolant temp.
This has been my biggest difficulty in hot weather, the cooling
system is short on capacity and gets out of the tuned-for
range on occasion. I am going to upsize radiator one of these
days. Determine meanwhile whether it's ECT or IAT that is more
the indicator of KR a-coming and work the spark adder tables
as you see fit.
to either pull back timing or perhaps fatten up the VE table at
the areas you "slide through". If you see the O2s dip every
time throttle opens, either VE is short or it's slow. There are
some filter settings you could play with but not much guidance
there. I'd concentrate on the plain VE tables first.
You might choose to cover it up by enabling burst knock and
yet limiting it to a sane maximum. Look at what your delta
dynamic cylinder air is, see whether KR always attends a
greater-than-XXX air-step. I do not know how EFILive does
the units / display there, you may have to work in Excel and
correct the logger vs PCM time-tick (for HPTuners I take the
dynamic cylinder air PID, and make delta as =(X2-X1)/8 for
the 1/10 sec scanner frane, 1/80 sec PCM tick.
People tend to run a lot of timing, as much as possible, but
with CR up you need less than before; don't be afraid to pull
out timing in the midband even if it makes the car feel less
"responsive". You don't need it to be edgy on a daily driver
and you still have kicked-down, big end for power. And there
is a flat-top where more spark makes no more torque, just
more sensitivity to environment.
Be sure you have the fans keeping a consistent coolant temp.
This has been my biggest difficulty in hot weather, the cooling
system is short on capacity and gets out of the tuned-for
range on occasion. I am going to upsize radiator one of these
days. Determine meanwhile whether it's ECT or IAT that is more
the indicator of KR a-coming and work the spark adder tables
as you see fit.
Given than you have a 2000 camaro which has a fairly aggressive timing table from the factory it would be safe to say that with that your high compression combo you will probably need to pull timing in a lot of areas to stop detonation.
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From: Bergen County, NJ
Thanks so much gang, I really appreciate the input.
I hooked up the LM-1 today but haven't tied it into the PC so it was just monitoring standalone. This of course very un-scientific but interestingly it appears that it's running lean which makes sense as far as KR is concerned but why? My theory is this - higher compression and DCR equals more flow? I pulled up some logs from right after the f13 cam install and the MAP rarely goes above 80 in the lower RPM ranges and rarely above 90 at any rpm, now it goes into those ranges often and that's where all the KR is ocurring. Thoughts?
I hooked up the LM-1 today but haven't tied it into the PC so it was just monitoring standalone. This of course very un-scientific but interestingly it appears that it's running lean which makes sense as far as KR is concerned but why? My theory is this - higher compression and DCR equals more flow? I pulled up some logs from right after the f13 cam install and the MAP rarely goes above 80 in the lower RPM ranges and rarely above 90 at any rpm, now it goes into those ranges often and that's where all the KR is ocurring. Thoughts?
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I can't read the above log but I'm suspecting you are ussing the same timing MAP as the F-13. That would be too much timing for the new setup.More timing NEVER means more hp.I would expect full timing to be at 24-26 degree's with that setup.
Thread Starter
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From: Bergen County, NJ
Originally Posted by Slowhawk
I can't read the above log but I'm suspecting you are ussing the same timing MAP as the F-13. That would be too much timing for the new setup.More timing NEVER means more hp.I would expect full timing to be at 24-26 degree's with that setup.
Thread Starter
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From: Bergen County, NJ
Looking at the 2002 stock timing table it has much less timing in the low to mid range area - should I start with the stock table and add or go with my table and subtract - any thoughts?
Originally Posted by DaddySS
Looking at the 2002 stock timing table it has much less timing in the low to mid range area - should I start with the stock table and add or go with my table and subtract - any thoughts?
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From: Bergen County, NJ
Ok, I think I'll take this approach:
Use the table for VE, Spark and PE/RPM from the current tune to make sure it runs and I haven't missed anything in 2000 to 2002 conversion.
Log VE and clean up fueling
Replace timing with stock and adjust for optimum (especially lower it in the upper ranges where it is currently in the 30 to 44 range).
Thanks, I appreciate the input.
Use the table for VE, Spark and PE/RPM from the current tune to make sure it runs and I haven't missed anything in 2000 to 2002 conversion.
Log VE and clean up fueling
Replace timing with stock and adjust for optimum (especially lower it in the upper ranges where it is currently in the 30 to 44 range).
Thanks, I appreciate the input.
Thread Starter
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Joined: Dec 2001
Posts: 2,907
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From: Bergen County, NJ
Update:
Got the OS upgarde completed last night and loaded it this afternoon.
I only missed CAGS (so far) everyhting else seems to work great.
The initial drive and log looks real good with only two cells of 1.2 KR in the middle of the map.
I'll drive and log further, get the WB installed and logging, work on the fuel trims and the start attacking the timing and PE tables.
Thanks for all the help so far!.
Got the OS upgarde completed last night and loaded it this afternoon.
I only missed CAGS (so far) everyhting else seems to work great.
The initial drive and log looks real good with only two cells of 1.2 KR in the middle of the map.
I'll drive and log further, get the WB installed and logging, work on the fuel trims and the start attacking the timing and PE tables.
Thanks for all the help so far!.