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Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 9:30 am
by gridgway
911hillclimber wrote:
Wont be doing another modified engine!
Surely that's all part of the challenge and fun Graham?

Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 10:30 am
by hot66
you're also probally over thinking things a little ...

Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 10:35 am
by 911hillclimber
Challenge is right.
Fun?
Well, started that way, but delays and delays and finally the expense.
Thought I had costed the bulk items, but so much else has crept in.
Hard to justify on this very limited running time car, BUT, we are where we are!
If it all goes well in 2022 then the memories will quickly fade.
Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 11:10 am
by gridgway
I know how you feel Graham. It's a hobby and all supposed to be fun, but sometimes it's hard to keep it that way. I've certainly felt (self-imposed) pressure to perform when I had a shot at 2nd or 3rd in the championship. Had to keep telling myself to enjoy it, but even so I screwed it up and had a half spin at Luffield. Came equal third on points, but 4th on count back. Was very grumpy. All self-inflicted
Hope it goes well Graham with the new motor.
Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 11:18 am
by jwhillracer
911hillclimber wrote:Wont be doing another modified engine!
I recognise this point in a 911hillclimber winter project!
JW
Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 1:49 pm
by 911hillclimber
I think you know me too well J!
Waiting today for Fed Ex, but tracker says today, and no other notification...
Doing some cosmetics on the engine and some errands for Loton Park hillclimb working parties coming up.
Grumpy today, but 44th wedding anniversary tomorrow!
Re: Plug (tip) length difference: Problem?
Posted: Thu Jan 27, 2022 10:37 pm
by 911hillclimber
Having waited in all day, the FedEx promise of delivery today has vaporised, though the tracker now says two things
It will be delivered by 6.00pm today (I type this at 10.30pm)
It will be delivered by 00.00 today, 27th Jan 2022.
Not waiting up to midnight, hope it may arrive tomorrow, will believe it when I have it.
Everything from the USA or involving America with this engine has broken promises, I only paid $180 for this Service, 8 days later nothing.
FedEx should get the Post Office to handle the UK delivery.
Re: Plug (tip) length difference: Problem?
Posted: Fri Jan 28, 2022 11:02 pm
by Jonny Hart
gridgway wrote:"With the XDI’s charging circuit, the
more load you put on an engine, the more voltage will be applied to the plug. "
That's curious, how does it do that?
That sort of marketing grinds my gears. Answer: all ignitions do that. Read my previous post.
Here’s an analogy:
Imagine destruction testing a piece of wood by hanging weights on it. If you keep adding heavier weights (force), the wood will eventually break (spark will fire).
As long as there is enough weight available (e.g. energy in the coil), the wood will eventually break. Let’s say that it takes 1kg to break the wood. Even if you added 10kg or 100kg the breaking force was still 1kg. Eg the force is dictated by the strength/resistance of the wood, not by the weight available.
The same is true for the sparking voltage. It is dictated by the gap resistance which depends on the size of the gap and the cylinder pressure (engine load). As long as there is enough energy in the coil. The voltage will rise to a point where the spark ‘jumps’ the gap.
Nothing required in the ignition design for that to happen.