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Discussion Starter #1
I realize that there are a million variables that can affect when an engine begins to detonate such as the intake charge temps, the amount of C buildup on pistons, timing advance and so on. I just wanted to see how much boost people safely run on 93 octane. I am in no way gonna say "oh, so-and-so runs 25psi....so can I". I am just trying to see what others can do.

Please list the max boost you run on pump and what your a/f's are.

JZ's welcome also.....

Thanks :)
 

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I've run 15-16 on premium, at the track and every now and then on the street. No problem. Dyno'd at 15 and had AF around 11:1. I do have an AFPR and a SAFC and had to pull out signal over 5700 to keep out of the 10:1 range.

HTH Dennis
 
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An interesting question.

How exactly are people monitoring how close they are to detonation limits on a certain fuel grade, and how much boost you can run at various conditions (setups)?

A/f ratio doesn't tell you, and apart from hearing audible knock there isn't much to tell you how much more you can push it.

This is exactly why I'm working on the ignition monitor and comprehensive data logging. It should allow me to determine very closely how much further one can or cannot go. I speculate the maximum boost you can run will vary considerably depending on the RPM the engine is running at. Obviously there are other variables to take into account, but you should be able to run much more boost at higher RPM than you can closer to the torque peak RPM, due to the different volumetric efficiency of the engine.

That probably didn't help you at all though. :)
 
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Discussion Starter #6
Are you saying that we can know how close we are to detonation by monitoring the ECU's timing behaivours due to the knock sensors?

If so, why not just use a S-AFC or a little homemade device to monitor the knock level?
 

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with my upgraded ct-26 i ran 1.2 bar (17.4 psi) which resulted in 372 rwhp and 367 rwtrq. A/F ratio was right around 11.5-12.0. Ran a best of 12.71 @ 111.96 mph on pump gas. this was my everyday conservative setting, never ever gave me any problems at all.
 

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Hello

I have been running 27 Psi on European 98 octane without any pinging(at leas I could not hear it :)) ) I think the Euro octane is similar to your 93(rated differently in Europe).
I know that just because one can’t hear pinging, it does not mean the there is no pinging. Therefore I'm looking forward to my AEM EMS that will display knock and is able to control boost/timing with input from the knock sensors.


Happy New Year from Denmark

Later
Karsten
www.supra4ever.dk/index.htm
 
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Silver88Turbo said:
Are you saying that we can know how close we are to detonation by monitoring the ECU's timing behaivours due to the knock sensors?
I'm really hoping it will be that simple, but until I see how well the ECU copes with knock, I won't know. It may just massively retard timing and not recover quickly enough to be very useful for judging this. I have a backup plan if this proves to be the case. :)

Silver88Turbo said:
If so, why not just use a S-AFC or a little homemade device to monitor the knock level?
If the computer retards timing at the verge of knock like it should, then we won't see any knock, even though the timing is being retarded, showing us we're at the limit at that boost/rpm/fuel. We need to see how much the timing is being retarded to give us an idea where we stand.
 

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ok, dont stock knock sensors go offline after 3k because theres too much noise? someone clear this up for me once and for all...
 
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SuprAng said:
ok, dont stock knock sensors go offline after 3k because theres too much noise? someone clear this up for me once and for all...
Never heard of it, or read about it. If such was the case, it would be a rather useless system.

There isn't any "more" noise at high RPM, the noise only occurs more often in a given time period. If you slowed it down after recording it, it should be the same "amount" of noise.

Dang, that sounds retarded but it makes sense. :)
 
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isnt this all dependant on what turbo you use?

or is it the same amount of boost b/c larger turbos are more efficient at higher boost levels?
 
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Discussion Starter #15
Yes it does matter what turbo is being run due to the efficiency of different turbos. There are also a million other variables....I just want to see what others run. I myself have never intentionally gone over 16psi (with the exception of spikes) on pump with my upgraded ct.
 
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