Ignition Timing

[Chronos]

After some searching, i have learnt the effects of advancing ignition timing on Honda engines. Previous discussions have concluded that running high grade fuels without advancing ignition timing could have an adverse effect on performance. I wish to discuss these effects, specifically on the B18C7, running high grade fuel.

Goal:
To fully utilise the benefits high octane fuels offer to those who run it in a B18C7 (AUDM DC2R). From the factory, this setup requires 95RON fuel. Would running 98+ result in lower performance?

Question:
By how much should ignition timing be advanced, running no less than 98RON fuel?

Thanks guys.

[Slow96GSR]

Could, but it'll clean your motor out nicely! I have run high octane and didn't notice any difference on a stock motor, maybe gained 5 hp. With a modified motor you will see higher gains. Also having it tuned for using higher octane will help out. I can’t really help you with timing as at an altitude 7500 feet ours is much different than yours.

[iamhappy46]

I wrote a REALLY long and indepth post about this a few months ago. Basically, the effect of ignition timing on fuel economy and peak power, etc. I will find it and link it

[iamhappy46]

Here (http://www.ozhonda.com/forum/showthread.php?t=24948&page=6)

Read pages 6 thru to page 9

[Limbo]

Timing is when the spark is gonna ignite when the piston hits down on it. If you advance too much you spark too early and thus not enough spark when the piston forces the pressure down.

The whole idea is that you want to maximise the pressure of the piston and the time of sparking so both are at their max. Since the fast the engine move the harder to get this sparking right.

Higher Octane fuel allows you to ignite better as it is more combustable. So even if you ignite late it is still easier to ignite the petrol. The whole idea of advancing is that when the pistons move fast then you need your spark to be there when it hits. And not be too late.

[TODA AU]

http://www.immediart.com/catalog/images/bigger_images/SPL_R_T165126-Atomic_bomb_explosion-SPL.jpg
Result of too much timing... :p

[Chronos]

Thanks for the replies everyone.

iamhappy46, i have read that thread and found it interesting, despite the fact a couple of users decided to turn it into a flame war.

Unfortionatly, i have not clearly expressed my question.

I understand the effects of ignition timing. My question targets the B18C7 specifically. I would like to discuss results people have recorded with this engine though their experiences.

There must be a few people who have worked on this engine or at least own a DC2R, who could shed some light on this topic.

Thanks again all.

[iamhappy46]

It would be wiser to have the ECU 'chipped' for optimum ignition timing across the ENTIRE rev range.

As I have stated, a 2 or 3 degree advance would be beneficial when using 98RON fuel. But at hi-rpm, where the ECU might already have very aggressive ignition timing the knock sensor would engage, retarding timing/torque/power. Therefore, a ECU chip with correct adjusted ignition table(and fuel remap) would yield VERY good gains.

[Chronos]

Yeah a nice Hondata ECU would allow me to customise fuel/ignition maps, but i really dont want to go down that road with this car. Maybe next car.

Ill push forward by 2 degrees this weekend. I'm hoping with this small amount and with good fuel, the ecu wont compensate unnecessarily.

Ill report back with results next week.

Thanks again all.

[EfiOz]

www.efi101.com

They have all the answers.

[saxman]

Timing is when the spark is gonna ignite when the piston hits down on it. If you advance too much you spark too early and thus not enough spark when the piston forces the pressure down.

The whole idea is that you want to maximise the pressure of the piston and the time of sparking so both are at their max. Since the fast the engine move the harder to get this sparking right.

Higher Octane fuel allows you to ignite better as it is more combustable. So even if you ignite late it is still easier to ignite the petrol. The whole idea of advancing is that when the pistons move fast then you need your spark to be there when it hits. And not be too late.
this really isn't entirely accurate.


Spark timing needs to be timed so that you're achieving maximum combustion(about 20% burn) at peak cylinder pressure to maximize power. Ideally, you want the fastest burning gas possible without knock occuring when maximum combustion at peak cylinder pressure occurs. The higher the octane, the more resistant to knock it is, however, it burns longer, which results in LESS power(with the exception of gas with higher caloric values, but for pump fuel, you want the lowest octane gas you can run safely) due to less combustion during the stroke.

Because higher octane gas burns slower than lower octane gas, you must advance the timing to compensate, to get back to peak cylinder combustion.

Running higher and higher octane gases, and advancing timing accordingly really isn't the key to making more power. The octane rating of the gas you're running is there so that you can make power safely. Going further than what's required isn't going to help anything.

[e240]

The higher the octane, the more resistant to knock it is, however, it burns longer, which results in LESS power(with the exception of gas with higher caloric values, but for pump fuel, you want the lowest octane gas you can run safely) due to less combustion during the stroke.

Running higher and higher octane gases, and advancing timing accordingly really isn't the key to making more power. The octane rating of the gas you're running is there so that you can make power safely. Going further than what's required isn't going to help anything.

True, MotoGP specs show that they are actually regulated to 95RON, yet they rev stratosphically and make around 250hp from 1 litre.

and for the ignorant, a four stroke engine is a four stroke is a four stroke (Sorry, this is for one idiot who cared to tell me bike engines are different from cars.)