ignition retard and high compression

[olliewtf]

Is it possible to use a retardable ignition to run higher compression than most currently recommend due to todays fuel?
I suppose the answer is yes, but its a question of fine tuning the compression ratio vs ignition timing vs reliable running....
so... has anyone tried this? compression is still a bit of a dark art to me, but as ever im endeavoring to learn!

whilst we are on the topic, has anyone had any real world experience of overheating/seizures due to changes in cruising speed? Its been brought up before, the fear of running advanced ignition and slowing say, on the motorway, and cruising at say, 4000 revs with timing of erm, say, 21*? and if so, what spec were you running in terms of ignition retard, compression etc?

Cheers all.

[Muppet]

Is it possible to use a retardable ignition to run higher compression than most currently recommend due to todays fuel?
I suppose the answer is yes, but its a question of fine tuning the compression ratio vs ignition timing vs reliable running....
so... has anyone tried this? compression is still a bit of a dark art to me, but as ever im endeavoring to learn!

whilst we are on the topic, has anyone had any real world experience of overheating/seizures due to changes in cruising speed? Its been brought up before, the fear of running advanced ignition and slowing say, on the motorway, and cruising at say, 4000 revs with timing of erm, say, 21*? and if so, what spec were you running in terms of ignition retard, compression etc?

Cheers all.

what would you say is a hi compression?

[olliewtf]

I don't know. But i have only a very basic understanding of it. And apparently everyone revisited their ignition timing or their CR when the fuel got worse, so my thinking was, the more compression, the more power, and with a retardable ignition, you could dial in reliability whilst running higher compression ....
I that awful sinking feeling ive not fully understood this and im gonna make meself look stupid... can anyone see where im going here or have i missed something important?

[Adam_Winstone]

I'd say that this was a fact that went completely hand in hand with the purpose of auto advance/retard ignitions. As you rightly pick up on, an engine is a range of elements that need to work in harmony with each other to result in a single unit that functions to the best of its ability. If we all chose to drop compression drastically and run retarded static ignitions, that would result in perfectly reliable motors capable of running on today's hot burning fuel... for low performance return. However, want to get some grunt back and you will want to bump up compression a bit, advance static ignition, etc, etc. but this will start to increase engine temps and slim the safety margin down. How far you can go is the big question.

The suggestion of using advance/retard ignition is a good one and one of its main purposes is to keep a motor cool when improving other factors that would otherwise push up motor temps, whilst providing a much better torque curve from low throttle positions. So, to answer your question, yes, fitting an advance retard ignition will allow you to raise compression somewhat. How far is the big question again you should not consider just compression and/or ignition, rather you need to consider all aspects of the motor, from revs/gearing to plug choice and jetting, looking at all elements and trying to achieve harmony.

Watch out for thinking that fitting such an ignition will cure all the problems with today's fuels and/or hot-running issues.... but it is a step in the right direction and will allow you to increase compression a little.

Adam