What do you think is faster? 24 timing w/ 13-14 psi, or 27 timing w/ 14-15psi

[Thumper]

Like the title says. I can run either 27 degrees timing with 13-14psi or 24 degrees timing with 14-15psi. My question is what settings will make me faster in the qt mile or on the top end. I will be going to the dyno one of these days but intill then my butt dyno is not sensitive enough to feel a difference. TIA

 

Ted

[Forrest]

You sound like just the guy to tell us. Buy a Gtech for 40$, make 5 runs at each setting and let us know!

[Guest Magnum Rockwilder]

My educated guess is that boost will rule timing.

[Clifton]

27* is alot of timing. I think you have it backwords though. Your 24* is with 13-14 and 27* is with 14-15. I would and do run less timing and more boost.

[Thumper]

Well I think I will run the 24* timing with 14-15 psi. The stock timing on a 83' 280zx turbo is 24*. And the car pings when I run 27* and 14-15psi so i can't run that, but I can run 27* and 13-14 psi with out pinging. That is why I say 27* w/ 13-14psi, or 24* w/ 14-15psi.

[Guest Magnum Rockwilder]

You mean 27º?

 

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[Thumper]

27º 24º i couldn't remember for the life of me what the command was thanks

[yo2001]

more airflow is more power. IMO

[Guest bastaad525]

Yet there are also guys on here who've posted gaining decent gains, like one or two tenths in the quarter (or maybe it was 1 or 2 mph), from bumping the timing a couple degrees. With the stock turbo... you're really starting to push it at 15 psi, getting the air real hot, and really at the point of dimishing returns in hp per pound of boost... so at that point you may be better off bumping timing.

 

I prefer the more advanced timing because it makes big, noticeable differences if off boost driveability as well... you gotta keep that in mind, you dont drive around with your foot planted all the time... also remember you need more fuel to handle more boost, whereas you don't really need more fuel for more timing, if you have cold enough intake air.

[Tony D]

timing is relative. If you are going by initial timing as set on the stock system, that is your total timing. ACTUAL timing can only be determined by putting a timing light on it and running it on a dyno. While you may have 24* at idle, the timing is determined by the computer.

I don't have my maps in front of me, but the big advantage to standalone like the MS is that you can actually get 40 degrees because the initial is set beyond that, and then you delay it.

 

Anybody actually taken numbers while on a dyno to see where the factory timing bins are really at under boost? Sounds like another "dyno project"!

[Cody 82 ZXT]

You mean 27º?

 

(hit alt + 167 for a º sign)

 

Off topic but. where do I find a key for all the emblems and stuff like this?

 

 

Back on topic. I think the lower timing and more boost would win out on the track. On the street I think that more timing and less total power would make for a better driving car. Like Tony, said it would be nice to make a custom map so you could have the best of both worlds.

[cygnusx1]

I am running 27 deg initial at 14psi and I love the torque and the engine growl as boost comes on. I am probably pinging at WOT but on the street I am hardly ever at WOT. I had it on the race track and I think I just about brought the engine to it's knees. I think it was pinging or on the verge of ping during full throttle uphill and down the main straight. I ran it for about 40 miles on the track like that and my plugs look like they went through a nuclear war. Personally, I like the torque of the 27 degrees. It is a 1983 motor with a higher initial advance spec. than any other year. It's a stock EFI with FMU set for about 55-60psi fuel at 14psi boost. TO4B Intercooled.

[TimZ]

Off topic[/b'] but. where do I find a key for all the emblems and stuff like this?

 

Start -->

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System Tools -->

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[Scottie-GNZ]

I am with Tony on this. From some of the comments I see, it looks like folks are confusing initial timing with what is really meaningful as it relates to timing at max boost. There are 4 things to consider with timing on a forced induction engine: 1. initial timing which is set at idle and what everyone is familiar with. 2. Total advance which is how much the timing is advanced and to what RPM as RPM and load increases. 3. Retard, which is how how timing is retarded as boost increases. 4. The one that is of primary importance, Total timing, which is total advance minus retard.

 

More boost/less timing will always make more power than more timing/less boost and decreasing total timing (more retard) will allow you to run more boost. While you need more fuel to support more boost, it is somewhat of a fallacy to think that is not the case with more timing. Increasing boost or timing will require more fuel and/or more octane. I am sure no one running 14+ psi of boost with the stock ECM has any idea what their total timing is and I wonder if anyone even knows what the ECM actually does with timing beyond the factory set 7psi. As Tony said, the beauty of a programmable system is that you build your own timing curve to ramp the advance as quickly and as high as you want for crisper throttle response but feed in the appropriate retard for increasing boost.

[Thumper]

Scottie thanks for the detailed answer. It looks like I was actually at 22º inital timing on an 83 ecu. So I advanced to 1º over stock so its at 25º. I had to lower the boost to 13 psi to get it not to ping. I think my limitation right now is my stock fuel pump, although I did rewire it with a relay and 10 gauge wire. So intill I get an aftermarket fuel pump I will be at 13 psi. I also have some intercooler piping on the way to redo my ghetto galvaniced(sp) plumbing pipe I am running right now. Soon my car will no longer be ghetto beast. Just UGLY BEAST!!!!

[cygnusx1]

Yup absolutely correct! I have NO idea what my timing advances to after I come off idle. I put good faith in the factory timing curve...and that may be a mistake but I have no say in the matter. Also, timing curves don't effect max power only, they effect the shape of the power/torque curve. I can tell you that more initial advance on a stock EFI will give you a "fatter" power/torque curve...seat of th'ol pants. More area under the curves= faster 1/4 mile times.

[Cody 82 ZXT]

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Thanks Tim!

[Guest bastaad525]

well... most of us don't live on a racetrack so I still say go with more timing and less boost on the street. The L28ET has such low compression... it's a DOG off boost, and the advanced timing helps with that immensely. You could always flip flop back and forth... advanced timing and less boost for daily driving, then when heading to the track, drop back timing and bump the boost, no doubt this should get you faster times.

 

 

From what I understand of how the factory L28ET EFI works, it's a pretty set-in-stone advance curve. The ECU has no way to compensate for the added boost. And when you adjust the initial at-idle timing, you are adjusting the whole curve... as when you adjust the timing you're really only adjusting the position of the crank angle sensor relative to the actual position of the crank... the ECU has no real way of knowing you've messed with the timing at all. In other words, advance initial timing 2*, and you have advanced timing 2* at EVERY point of the timing curve.

 

By the way, with 14 psi on a stock T3, and timing advanced 2-3* from stock, I have yet to get any ping, not a peep, and no signs on the sparkplugs of any detonation either. That's on 91 octane fuel, and running high 11:1 air/fuel ratio for the most part. And I do beat on it