EFI vs carbed timing
10-26-2010, 10:32 AM
#4
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I agree but when you put more efficient heads on one, such as afr 225's like mine, you would think you could run less timing. I have found my setup needs more timing and have thought the same way as you.
10-29-2010, 11:08 AM
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Timing between the 2 might be more related to intake & engine design and therefore charge mass per cylinder. Though obviously AFR will have a large affect on timing too.
(ie) Assuming the same AFR look at the mechanical side of things rather than how its fuelled for the difference in timing. My 2p.
(ie) Assuming the same AFR look at the mechanical side of things rather than how its fuelled for the difference in timing. My 2p.
10-29-2010, 12:54 PM
#10
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weird i was wondering the same thing ! my tune is around 26- 28 deg on my old ls1 car but most performance small blocks I have built that were carbed are right around 30 -35 deg
I allways wondered why that was
I allways wondered why that was
10-29-2010, 04:07 PM
#13
I have noticed that my L92 head'd 6.0L performs almost the same with timing from 32-37*, so I have it at 36 on the top end right now. Kepp in mind its a 9.6:1 motor, so it will want more timing than an 11:1 motor.
The low end, below 3500, likes even MORE timing, I have it at 38* from 1K through to 3500, then tapering down to 35 at 5K, then back to 36 through till top revs.
I know that the 3500 and below range is below where the cam is really happy, so it makes sense that it wants more timing there, and I programmed in the drop back to 35* at 5K because thats where the torque peak should be with my single plane intake, and theoretically thats where it would be most detonation sensitive. I ramp another degree back into it, because it seems to mph better at the track with more timing.
My season is over here in MB, so further testing will have to wait.
Barrett
The low end, below 3500, likes even MORE timing, I have it at 38* from 1K through to 3500, then tapering down to 35 at 5K, then back to 36 through till top revs.
I know that the 3500 and below range is below where the cam is really happy, so it makes sense that it wants more timing there, and I programmed in the drop back to 35* at 5K because thats where the torque peak should be with my single plane intake, and theoretically thats where it would be most detonation sensitive. I ramp another degree back into it, because it seems to mph better at the track with more timing.
My season is over here in MB, so further testing will have to wait.
Barrett
Last edited by 3pedals; 10-29-2010 at 07:56 PM.
03-25-2011, 05:23 PM
#17
On The Tree
hope to be on chassis dyno next week. I hope to have our car running next week and on the dyno. I'll be trying diferent timing ramps to see what the engine wants. Also I'll be using the wideband on the dyno. I've got both a downleg and annular booster 750 body. I'm going to keep tabs on A/F changes and power #'s just from a main body change. Last time I had to remove 4-6#'s in jetting. I'll also see what the changes are in A/F @ 3,000 rpm cruise. It will be interesting to see what changes happen at part throttle.
Lucky for me dyno is just a turn of my shop key away.
Aleck
Lucky for me dyno is just a turn of my shop key away.
Aleck
