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Timing on you SC or Turbo

Joined
10 November 2003
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1,066
what are your base settings and do you pull out 1 degree per PSI? I think at idle i have it set at 12 and will pull out when boost comes in. Does this sound correct?
 
Are you saying you pull timing to go below 12 as boost comes in? For example at 1psi you'll have timing set at 11?

If so, that sounds very low to me. In addition, your non-boosted driving performance will probably be quite sluggish.
 
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previous thread by Andy:

The spec for the NSX engine at idle is +/- 15° BTDC.

At steady-state cruising on the street, much like the emissions test roller dyno, the timing for the NSX engine is approximately 39° BTDC.

A naturally aspirated NSX under wide-open-throttle will have timing in the mid to mid-upper 20's° BTDC.

If they are failing you at 39° BTDC on the roller dyno, they DO NOT know what they are doing.

By the way, to the point of pre-detonation, advancing the timing will usually result in cleaner emissions. For them to not recognize this telsl me that they REALLY DO NOT know what they are doing. Run. Fast.

__________________
Happy VTEC-ing ..... with boost, of course
 
Ken,

I've forgotten what you are using for engine management, but as suggested by Andy's old post the ignition timing is a map much like the fuel map, with axis of RPM and load. So your timing at idle isn't directly relevant but if you have the stock ECU then changes at idle are global, whereas with something like the AEM/Motec etc. you can redefine the entire timing map rather than just sliding it up and down a scale. Piggyback systems may have varying degrees (pun intended) of adjustability.

The thing to remember is that a good timing curve is fairly complex, especially in a boosted car. Advance may be reduced at points where problems most often begin such as the transition into boost, or mid RPM but high load (like up a hill). Turbos are considerably more difficult than an SC because boost can cover a broad range at a given RPM, but the SC still needs careful tuning and all the more so as you push the limits and have less margin for error. You are obviously a guy trying to do things “right”, and the key to that for the timing map is EGTs. They’ll go up if you re significantly outside the correct range. Too little advance can be just a fatal as too much, so don’t assume you are playing it safe by pulling out a little extra.
 
This is the current timing on my paxton setup.

load-timing-o2_2.JPG


I don't have any audible detonation, and haven't been able to find any similar datalogs from other SC nsx's, so I'm not sure how mine compares to other setups. Hope it helps..

-mike
 
mikeh said:
This is the current timing on my paxton setup.

I don't have any audible detonation, and haven't been able to find any similar datalogs from other SC nsx's, so I'm not sure how mine compares to other setups. Hope it helps..

-mike

Timing looks reasonable for the boost levels and possibly even conservative, but why rely on "audible" detonation when you have an AEM? Their latest software seems to do an excellent job of "listening" to the stock knock sensors.

Do you plan to leave it that rich? Not outrageous, but it seems like a bit too much fuel.
 
sjs said:
Timing looks reasonable for the boost levels and possibly even conservative, but why rely on "audible" detonation when you have an AEM? Their latest software seems to do an excellent job of "listening" to the stock knock sensors.

Do you plan to leave it that rich? Not outrageous, but it seems like a bit too much fuel.

I haven't had time to sit down and setup/play with the knock sensors in the EMS properly, that's the only thing holding me back.

It won't stay that rich. I'm running without an intercooler rite now (waiting to finish the piping, and then fine-tune the car after I finish moving into my new shop space). Given it's current semi-tuned status, and the fact that it's running ok, I deceided to leave it a bit rich since I'm using it to commute back/forth for work.

If only I didn't have a day job... :)

-mike
 
Not sure why I never noticed your reply until now, but regardless--

I've beaten on it a bit without an IC on the street (although not as much as I will be once I
do some more tuning) and have done 9 or so dyno pulls without any problems.

The IAT's are actually pretty low on the street, below is a graph of the IAT's during the
same freeway pull as the above timing graph:

edit: the ambient air temps for the below graph was around 65 deg F.

load-iat-o2_2.JPG


Don't mistake that for meaning I don't need a intercooler, but it isn't so horrible. :)

ps: My IAT's (measured in the TB by the OEM sensor) on the street dropped around 15-20
degrees at cruising speed, and around 50 degrees at 9+ psi by putting the intake cone in
the fender instead of having it in the engine compartment. On the dyno the air temp
reduction was about half of what it was on the street (to be expected).

-mike
 
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