Cam timing effects, 32V
04-23-2012, 09:17 PM
#166
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What Dan said... if you continue using Super (92 AKI/98 RON).
87/89/92 octane all have the same energy potential, just different burn rates. Retarding keeps the intake valve open longer, letting the engine breath better, but lowers the effective compression ratio, so a lower octane/faster burn rate must be used to keep the ignition advance constant for best power.
Conceptually, it has been difficult for me to accept 'Regular' but I'm getting used to it.
My '86.5 auto has much more useable power running on 87 octane at -12° cam retard. After further logging, the LH and EZ chips are now very little changed from my normal 92 octane chipset. The main change is using the gears more, requiring just a little tightening of the Bowden cable, and hitting the kickdown switch more often.
I imagined that the (small) loss of low end torque would be a bad thing on the auto, but the auto changes gears so quickly that it has proven to be nicer to drive than my manual trans car.
S4-up stock WOT fueling is over rich, the LH manages it's own idle speed, and the EZK knock sensor loop should manage what I've had to do by hand. If I had a S4/GT, I would reset the ECUs and try ~8° retard, with 89 octane (95 RON).
It would be nice to have a SharkTuner to see the knock count, if you want to use 87 with even higher retard.
87/89/92 octane all have the same energy potential, just different burn rates. Retarding keeps the intake valve open longer, letting the engine breath better, but lowers the effective compression ratio, so a lower octane/faster burn rate must be used to keep the ignition advance constant for best power.
Conceptually, it has been difficult for me to accept 'Regular' but I'm getting used to it.
My '86.5 auto has much more useable power running on 87 octane at -12° cam retard. After further logging, the LH and EZ chips are now very little changed from my normal 92 octane chipset. The main change is using the gears more, requiring just a little tightening of the Bowden cable, and hitting the kickdown switch more often.
I imagined that the (small) loss of low end torque would be a bad thing on the auto, but the auto changes gears so quickly that it has proven to be nicer to drive than my manual trans car.
S4-up stock WOT fueling is over rich, the LH manages it's own idle speed, and the EZK knock sensor loop should manage what I've had to do by hand. If I had a S4/GT, I would reset the ECUs and try ~8° retard, with 89 octane (95 RON).
It would be nice to have a SharkTuner to see the knock count, if you want to use 87 with even higher retard.
04-23-2012, 09:43 PM
#169
Race Car
I was under the impression that Ken shunned S4+ cars like that 1 month old left-over container of shrimp cocktail in the fridge...
Dan
'91 928GT S/C
475hp/460lb.ft
Dan
'91 928GT S/C
475hp/460lb.ft
04-23-2012, 09:52 PM
#170
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Just put a little hot sauce on it... it'll be fine. 
Jeff - it's not that difficult to adjust the cams (especially with a Bumpstick). It's much easier done cold, and you might save on gas on the way up...
I haven't used a ST on a S4-up car, so I know about as much as you on how to use it.
Jeff - it's not that difficult to adjust the cams (especially with a Bumpstick). It's much easier done cold, and you might save on gas on the way up...
I haven't used a ST on a S4-up car, so I know about as much as you on how to use it.
04-23-2012, 09:55 PM
#172
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true, true
04-26-2012, 10:19 PM
#173
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I 'fixed' the idle problem on my auto by returning the O2 loop behavior to the stock program, which, on average, is a little rich of 14.7.
Combined city MPG has improved from 14.5-ish to ~16. (Mostly stoplight, lots of WOT bursts, some highway.) Highway only should be even better. (21 MPG @ ~70 was the best I've gotten in the auto, before.)
Coolant temps on the freeway are just above the first white line, on both the manual and auto.
Oddly, oddly, quiet. I put an RMB on the auto with X-pipe, big mids, and it is still quiet. You can feel the pressure wave, but the frequency is out of hearing range?
Cheaper gas, better mileage, cooler running, quieter, yet significantly more power...no more zero for me!
Combined city MPG has improved from 14.5-ish to ~16. (Mostly stoplight, lots of WOT bursts, some highway.) Highway only should be even better. (21 MPG @ ~70 was the best I've gotten in the auto, before.)
Coolant temps on the freeway are just above the first white line, on both the manual and auto.
Oddly, oddly, quiet. I put an RMB on the auto with X-pipe, big mids, and it is still quiet. You can feel the pressure wave, but the frequency is out of hearing range?
Cheaper gas, better mileage, cooler running, quieter, yet significantly more power...no more zero for me!
04-27-2012, 12:07 AM
#174
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I just retimed the cams on Zelda and went with +4° of advance, will be plugging in your 91 octane chips. Once it is on the road I'll get it dynoed to see what the overall effect will be, and give you another data point to consider. I should be able to do a 5th gear pull with the lower 2.7272 final drive.
04-28-2012, 02:36 PM
#175
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Ken,
Sean did the TBWP on the GTS yesterday. He checked the cams on her cold w the 32V tool and they were set at:
(1-4) -1
(5-8) -6
He adjusted out to:
(1-4) -2
(5-8) 0
The car is dramitically smoother, Exhaust is quieter. Before, the car seemed rougher (at idle and also on acceleration) almost like it had higher lift and duration cams in it. I imagine is was the initial difference in cam timing on each bank???
I haven't driven it enough to tell about throttle response, torque, etc. Thought Id drive it a while before we made any initial changes in cam timing. The car has X-pipe, Hight flow cats and RMB.
Any suggestions??
Thx!
Sean did the TBWP on the GTS yesterday. He checked the cams on her cold w the 32V tool and they were set at:
(1-4) -1
(5-8) -6
He adjusted out to:
(1-4) -2
(5-8) 0
The car is dramitically smoother, Exhaust is quieter. Before, the car seemed rougher (at idle and also on acceleration) almost like it had higher lift and duration cams in it. I imagine is was the initial difference in cam timing on each bank???
I haven't driven it enough to tell about throttle response, torque, etc. Thought Id drive it a while before we made any initial changes in cam timing. The car has X-pipe, Hight flow cats and RMB.
Any suggestions??
Thx!
04-28-2012, 05:05 PM
#176
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I've found it's good to set the timing to 0 | 0 cold with a new belt as the belt retards ~2° on the 1-4 after it settles in.
Best to revisit the timing after 1K miles, though, anyway.
The GTS has a 61° ABDC intake closing, the most of all 928s (followed by the S2 at 54°, S3 50°, GT 46°, S4 36°), but kind of a lame exhaust cam, AFAIK.
Since you have installed a PKT, and so can rev it out with confidence, (
) you might try -10 | -8 cold, and switch to 89 octane...
Reset the ECUs so they will relearn. May run poorly, initially. If Keith hadn't sold his '93 5-speed, I could have experimented on it.
Best to revisit the timing after 1K miles, though, anyway.
The GTS has a 61° ABDC intake closing, the most of all 928s (followed by the S2 at 54°, S3 50°, GT 46°, S4 36°), but kind of a lame exhaust cam, AFAIK.
Since you have installed a PKT, and so can rev it out with confidence, (
) you might try -10 | -8 cold, and switch to 89 octane...Reset the ECUs so they will relearn. May run poorly, initially. If Keith hadn't sold his '93 5-speed, I could have experimented on it.
04-28-2012, 05:46 PM
#177
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If you don't want to be on the bleeding edge of cam timing : octane, then setting the 5-8 to -2 after 1K miles (bringing the timing to -4 | -2 cold), may work well with your upgraded exhaust system and manual trans, still using Super. (A little less compression might help with GTS ping syndrome, too.)
04-28-2012, 06:26 PM
#178
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I just went out and spent about 45 minutes driving the car at temp.
several 1st, 2nd, 3rd gear romps.
The exhaust has a lower tone, its definately quieter at idle and smoother driving as I mentioned in my prior post.
Not sure if it's my imagination, but I don't think it pulls as hard. Normally I can smoke first gear with about 1/2 to 3/4 throttle, today I really needed to romp on it to get the same effect.
Now it is 90 degrees out according to my temp gauge, so that may have something to do with my "perception" that It may be down a little bit. When its cool out, I can spin second as well at less than full throttle with 295s out back.
Would the original setting we measured (1-4) -1 (5-8) -6 make sense on how the car was performing vs the current adjustment to (1-4) -2 (5-8) 0 ??
Thx!
several 1st, 2nd, 3rd gear romps.
The exhaust has a lower tone, its definately quieter at idle and smoother driving as I mentioned in my prior post.
Not sure if it's my imagination, but I don't think it pulls as hard. Normally I can smoke first gear with about 1/2 to 3/4 throttle, today I really needed to romp on it to get the same effect.
Now it is 90 degrees out according to my temp gauge, so that may have something to do with my "perception" that It may be down a little bit. When its cool out, I can spin second as well at less than full throttle with 295s out back.
Would the original setting we measured (1-4) -1 (5-8) -6 make sense on how the car was performing vs the current adjustment to (1-4) -2 (5-8) 0 ??
Thx!
Last edited by Chuck Schreiber; 04-28-2012 at 06:58 PM.
04-28-2012, 06:56 PM
#179
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Could be. 7° (hot) is a big change.
It takes a few days of driving to relearn the pedal to torque relationship after a major change, for me. First time out, I usually floor the throttle, and expect it to fly, but it 'feels' slow. In actuality, you have to limit the throttle for the load/rpm for the best torque. (That's why most all throttles nowadays are fly-by-wire.)
You might try the -10 | -8 cold and see. (Reduce the octane for best effect.)
It takes a few days of driving to relearn the pedal to torque relationship after a major change, for me. First time out, I usually floor the throttle, and expect it to fly, but it 'feels' slow. In actuality, you have to limit the throttle for the load/rpm for the best torque. (That's why most all throttles nowadays are fly-by-wire.)
You might try the -10 | -8 cold and see. (Reduce the octane for best effect.)
04-28-2012, 07:09 PM
#180
Rennlist Member
Come on Down..
I just went out and spent about 45 minutes driving the car at temp.
several 1st, 2nd, 3rd gear romps.
The exhaust has a lower tone, its definately quieter at idle and smoother driving as I mentioned in my prior post.
Not sure if it's my imagination, but I don't think it pulls as hard. Normally I can smoke first gear with about 1/2 to 3/4 throttle, today I really needed to romp on it to get the same effect.
Now it is 90 degrees out according to my temp gauge, so that may have something to do with my "perception" that It may be down a little bit. When its cool out, I can spin second as well at less than full throttle with 295s out back.
Would the original setting we measured (1-4) -1 (5-8) -6 make sense on how the car was performing vs the current adjustment to (1-4) -2 (5-8) 0 ??
Thx!
several 1st, 2nd, 3rd gear romps.
The exhaust has a lower tone, its definately quieter at idle and smoother driving as I mentioned in my prior post.
Not sure if it's my imagination, but I don't think it pulls as hard. Normally I can smoke first gear with about 1/2 to 3/4 throttle, today I really needed to romp on it to get the same effect.
Now it is 90 degrees out according to my temp gauge, so that may have something to do with my "perception" that It may be down a little bit. When its cool out, I can spin second as well at less than full throttle with 295s out back.
Would the original setting we measured (1-4) -1 (5-8) -6 make sense on how the car was performing vs the current adjustment to (1-4) -2 (5-8) 0 ??
Thx!
