Base timing values

[Kai]

Right - i'm posting this in hopes of a definitive answer. About 3 years ago, the subject was broached in the GE section, again, by me, but i don't think anyone ever got an answer.

Basically, i know that stock timing is supposed to be 10' BTDC, however, with people reporting that higher base timing values can 'give you more power', i'm interested of course.

Now, i know that this has some bearing on the quality of the fuel. Bearing in mind that the lowest octane we have over here in europe is 95 RON, which is 91 PON for you, and even higher 98 RON, which is 94 PON for you. Obviously, i stand less chance of detonation than the majority of you lot in the US - but, at the same time i'm still wanting to play it safe, to keep my cylinders from turning into a plasma cutter...

12' BTDC is 'safe' value for me, so i'll go with that for the moment. Is this effectively likely to lean out the mixture, save a little fuel, and also give me slightly better performance, or, is there something i'm missing?

Are higher values going to have an exponential effect?

 

[whitemike]

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Hi Kai.

 

[Kai]

16 views - no replies....we're waiting

 

[IJ.]

Why do you think changing the base timing is going to lean out anything?

Detonation damage from doing the above if the octane can't support the new timing ISN'T going to turn the engine into a plasma cutter it may BHG or break ring lands.

 

[Kai]

This is why i'm asking Ian, simply because i don't know for sure what benefits (if any) there are from advancing the timing...

 

[IJ.]

Personally I think any gains are so small they're outweighed by the risk of damage/decreased performance if you get a dud load of fuel.

Think of the Knock Sensors as "Explosion Detectors" they take action after the fact and often with a 7M that can be too late and ends in :cry:

 

[Kai]

You reckon a 2' advance on 95 RON would be risky, even as a trial?

 

[grimreaper]

your 95 RON would be similar to our 91 PON. Your 98 RON would be 94 or so PON US. Your not running more octane then us, yours is labeled differently.

Our labels show the average of RON and MON. Not just RON.

Wiki page

Now, i know that this has some bearing on the quality of the fuel. Bearing in mind that the lowest octane we have over here in europe is 95 RON, which is 91 PON for you, and even higher 98 RON, which is 94 PON for you. Obviously, i stand less chance of detonation than the majority of you lot in the US -

how?

 

[IJ.]

Try it and see.....

Without some way to monitor knock it's all just guesswork.

I tend to go for a conservative tune and don't like to run on the ragged edge so as I said any gains you get from doing this are fqr outweighed by the potential for disaster. (you would struggle to see an increase on a dyno as it's would probably fall into the dyno's + - error range)

 

[Kai]

Well, don't forget, i have the TCCS Tester - which has a knock sensor output/display built into it (kinda handy!) - I'll set it at 12' BTDC as a test, but if it proves to be too unreliable or doesn't feel right, i'll reset it to 10' BTDC.

 

[Kai]

your 95 RON would be similar to our 91 PON. Your 98 RON would be 94 or so PON US. Your not running more octane then us, yours is labeled differently.

Our labels show the average of RON and MON. Not just RON.

Wiki page

The point is - we can't GET shitty low octane stuff here. The lowest we have is 95 RON. Or 91.

how?

 

[Kai]

Well, it's been set to 12' BTDC and i can so far report no ill effects, even at WOT, 3rd & 4th gear pulls like a train, and i know it's unscientific, it 'feels' faster. Ass-dyno FTW!

Would be nice to put this on the rollers and see if theres any difference in power/torque just from 2 degrees of advance.

 

[tekdeus]

Makes sense. Guys running E85 fuel get more power because they run more timing. I run 94 octane and water/meth injection so I have lots of headroom to avoid roasting my stock pistons When dyno'ing my car at 22-24psi we experimented, and ended up dropping down to 8* base timing for the best power and no knock. We tried going down even lower, around 6 degrees, and lost 30+hp. Keep in mind, this was with 22%+ fuel pulled on the SAFC which can put the timing up pretty high. At 10* base timing we only noticed 4-5hp more than 8* and pushed into the threshold of knock at 24psi.

How much boost are you running? How big is your turbo? A/F ratio? It is always best to do these changes on a dyno with proper knock detection systems. (guy wearing headphones and listening for knock). That's what I did. I pushed my setup as far as it could go before slight knock, then I backed it down a few notches and just leave it there.

 

[Kai]

Stock CT26 - adjustable actuator set to 8 to 9psi. I'm not after silly power really, just a bit more zip than standard.