ignition timing on an historic methanol fuelled v-twin

[Incorrigible]

As the title says really, anyone got any links to some old fashioned engine specs. I'm thinking drag or speedway people may know where to start

The engine is JAP based (I say based; the geometry is the same but it's not the same) but it's a 1,000cc twin

Hopefully should be running 120hp ish but I've heard horror stories about rods exiting stage left if you fk it up and them being desperately sensitive to ignition timing...

Hence the question really

[Steve_D]

I don't know the engine but will throw in a few thoughts.

If as you say it is sensitive to timing then I would suspect that the existing method of varying the timing will be both worn and perhaps not very well controlled even when new.
Do you have the option of adding a trigger wheel and running Megajolt? This can be set up either by experimentation or on a rolling road. Once set it will produce very accurate control.

Steve

[Mr2Mike]

Steve_D said:

Do you have the option of adding a trigger wheel and running Megajolt?

Only if the firing angles for his V twin happen to be exactly the same as an in-line 4, an in-line 6 or a 90 degree V8.

[Incorrigible]

I've got a sort of megajolt, can't remember the details as it's at the workshop, but basically 2 triggers, 2 boxes, 2 cylinders.

Also apparently you time each cylinder individually, and the advance is bloody ridiculous; 86deg for the front cylinder and 85.5 for the rear

I have to confirm this as I've now found out who built it etc etc

One's foray into historic motorsport begins.....

[Pumaracing]

No engine runs with advance numbers like those. Clearly there's some sort of trigger offset built in to those numbers but it's a concern you don't immediately realise that and think that such advance numbers could be real.

[Incorrigible]

I was told that methanol engines run "massive advance" but yes even the numbers quoted seemed ridiculous

I have checked and as expected the advance is a much more reasonable, but still huge, 35 deg fixed

It would be nice if, rather than picking up on my already admitted ignorance, you could have given a slightly more informative answer

I suppose "You don't know what you're on about" has it's place....

[stevieturbo]

What answer do you need ??

Build the engine. Install a proper ignition system, and take it to a dyno to build your ignition map.

The process seems relatively straightforward.

[Incorrigible]

Stevieturbo said:

What answer do you need ??

The question was "ignition timing on a historic engine" so the answer I need would be "try 20 deg" or "FFS don't eek the advance up too fast they cannna take it captain" or "Ring XYZ" or "look at the piston tops/valves/other as methanol behaves differently to petrol in these circumstances"

Stevieturbo said:

Build the engine. Install a proper ignition system, and take it to a dyno to build your ignition map.

The engine's already built, I already have the original ignition system that I would like to keep (it's a historic racing car, they seem to like originality)

I just want to get it running in the first instance without too much fuss

Stevieturbo said:

The process seems relatively straightforward.

The process you describe is fairly straightforward, even an idiot like me can do it, and get cars to win races

Any advice on plugs ?

Too late now, but the engine had stamped on it A85 which was suggested could be the specified advance. I didn't think it could possibly be right. But having never worked with this fuel I didn't know. Wish I hadn't asked now

[stevieturbo]

So you would rather take information for ignition timing from the internet, rather than actual testing on a dyno ?

You say the ignition system is standard...and will likely stay that way for originality.

So can you actually change it in the first place to be worrying about it ?

[Incorrigible]

stevieturbo said:

So you would rather take information for ignition timing from the internet, rather than actual testing on a dyno ?

I would love to spend all day on a dyno but funds don't allow, I just want to get it running. It is apparently a good engine (I know we've ll heard this before) I don't even know if knock sensors pinking etc work like they do in petrol engine

I just want anyone who has fired up a meth engine to tell me any potential pitfalls. If you have and want to keep your cards close to your chest then fair play I guess

stevieturbo said:

You say the ignition system is standard...and will likely stay that way for originality.

Well I don't know if it's completely original but it's certainly staying as it is until I find out otherwise

stevieturbo said:

So can you actually change it in the first place to be worrying about it ?

Yes, basically there's a spinning disc attached to the crank which you can adjust and then each pick up (one for each cylinder) can be moved around ~ 10deg. So the disc can be adjusted through 360deg, like turning a dizzy really

Edited by Incorrigible on Thursday 20th May 00:10

[camelotr]

I would start with much less advance - as if You have a late spark, it would not hurt the engine, just as an early would deffiniatly. Especialy in a race engine. Start with a "mundane" setup - lets say 30-40 degrees, and fire it up. Run it a bit. Take care of the temperature, read plugs etc. And try giving more advance. Best would be to do it on a dyno, as at the point the engine starts to detonate, the power drops.

By the way metanol engines are also quite sensitive on mixture conditions. Soo if I were You, I would stop the building here and collect a bit of funds to be able to buy a long dyno day at a good specialist, and set everything up with professional equipment.

120bhp/L is quite remarkable...

[stevieturbo]

This gets more confusing.

You say its an old fashioned engine, then go on to mention knock sensors etc.

Does your engine even have a knock sensor fitted ?

Im sure with standard petrol timing, the engine will start and run just fine. Assuming you take control of the fuelling side of things.

And the ONLY way to determine optimal ignition timing will be on the dyno

[Mr2Mike]

stevieturbo said:

And the ONLY way to determine optimal ignition timing will be on the dyno

With an engine producing this kind of specific output and apparently being ultra-sensitive to ignition timing it would seem silly to avoid using a dyno. At best you will have to set the engine up conservatively to give less power, worst case is your engine is scrap metal.

[cerealsurfer]

Try contacting the Morgan 3 Wheeler club:

http://www.mtwc.co.uk/index.shtml

Several of the Morgan Supersports run Methanol JAP V-twin 1000ccc engines in the circuit and hill climb series. They have a wealth of knowledge and a library of technical articles. They might be able to put you in touch with someone who can give practical advice on how to run & set up one of these engines.

Hope this helps.

[Incorrigible]

stevieturbo said:

This gets more confusing.

You say its an old fashioned engine, then go on to mention knock sensors etc.

Does your engine even have a knock sensor fitted ?

I'm obviously not typing what I'm thinking, no nothing of that sort fitted. My point was more do these things behave in the same way as for a petrol engine

Anyway, suitable expert found, through as suggested, JAP people. I can now set it up and get it running conservatively