Head swap LQ4 timing suggestion?
06-02-2012, 02:06 PM
#1
Head swap LQ4 timing suggestion? Stuck an LQ4 with "car" heads in my blue chevelle. The smaller chamber nets around 10:1 with the dished LQ4 piston. Been out beating around with 25 degrees of timing at WOT, runs pretty good, but I want to start creeping up with it. Any suggestions? It's fuel injected with a fast intake, 90mm DBW throttle body, texas speed 231/237 cam, run 91 octane fuel.
I run a solid motor mount and must have something banging around in the chassis because my knocks sensors are going nuts even at idle, so I turned them off. Thus using KR to monitor excessive timing isn't an option..
Thanks,
TJ
I run a solid motor mount and must have something banging around in the chassis because my knocks sensors are going nuts even at idle, so I turned them off. Thus using KR to monitor excessive timing isn't an option..
Thanks,
TJ
06-02-2012, 06:23 PM
#2
If the KR are disabled, then you may be able to hear the detonation if your exhaust isn't crazy.
If your exhaust is too loud then the next best thing that I know of is having a listen while it spins up on a dyno. This is the best place to set the timing because you can find the point of diminishing returns....where you want to set the timing anyways.
Its likley your peaking timing is going to end up somewhere around 28-32 deg (I'm guessing your not FI?), but I'd be careful about walking the timing up if you can't listen for the ping.
If your exhaust is too loud then the next best thing that I know of is having a listen while it spins up on a dyno. This is the best place to set the timing because you can find the point of diminishing returns....where you want to set the timing anyways.
Its likley your peaking timing is going to end up somewhere around 28-32 deg (I'm guessing your not FI?), but I'd be careful about walking the timing up if you can't listen for the ping.
06-02-2012, 06:52 PM
#3
Thanks Kevin, my exhaust quieted down quite a bit with the LS swap, I think I would be able to hear audible detonation. It is FI, but something about it makes the knock sensors go nuts. Going to turn down the sensitivity and maybe some other tricks like silicone on knock sensors. Anyway, curious if anyone has a typical WOT timing value like vintage SBC usually end up around 36deg...if these are 28 or something.
06-02-2012, 07:50 PM
#4
Its not uncommon for a solid mount to set off the KR sensors.
If you are FI, then 28 is going to be too high. 24 deg is pretty high already depending on your static compression and FI type.
Turbo or blower?
As a point of reference, I run 17 psi on an LQ9 head at 8:1 compression and my timing is set at 19 deg for 93 octane.
I can go as high as 24 if I want to set it on kill, but that is the absolute max.
If you are FI, then 28 is going to be too high. 24 deg is pretty high already depending on your static compression and FI type.
Turbo or blower?
As a point of reference, I run 17 psi on an LQ9 head at 8:1 compression and my timing is set at 19 deg for 93 octane.
I can go as high as 24 if I want to set it on kill, but that is the absolute max.
06-03-2012, 11:05 AM
#5
did you ready my initial post? Said it's FI and 10:1 
Ran around on 25 last night N/A, pulled 7 for a .073 jet in the plate and went 10.66 @ 128. Timing mark on plug showed I could probably put one more degree back in on the bottle. Converter still too tight, hope to find some ET with higher stall speed.
On the timing deal, going to fiddle around a bit, but judging by the strap mark on the bottle, I'm pretty close there.
Ran around on 25 last night N/A, pulled 7 for a .073 jet in the plate and went 10.66 @ 128. Timing mark on plug showed I could probably put one more degree back in on the bottle. Converter still too tight, hope to find some ET with higher stall speed.
On the timing deal, going to fiddle around a bit, but judging by the strap mark on the bottle, I'm pretty close there.
