Laser ignition?

http://www.bbc.co.uk/news/science-environment-13160950

Someone is looking at the possibility of replacing spark plugs with
lasers. I thought the population here may be interested.

 

I was interested in other applications said units might be put towards

 

Yah, saw that elsewhere; El Reg I think. I was interested that
a powerful lase could apparently be built fron two ceramic materials.
The BBC article suggests that it's a secondary laser, stimulated from
outside.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

"pulses just 800 trillionths of a second long."

Wiki says the Cosworth F1 engine is capable of 20K RPM. That's 333
sparks/second. Just wondering what the theoretical RPM limit of a
piston engine might be. I'm thinking at some point it comes down to
the rate of atomization of the fuel and its expansion after firing.

 

Piston speed is generally the limiting factor. A short stroke and wde
bore reduces the speed, but you do then run into problems, at ultra-high
rpm, of valve float.

A desmo system would eliminate this, of course. The alternative would be
a rotary valve, rather than poppet valve, intake system. I believe BSA
experimented with this, way back when.

I've heard of around 20k rpm for the old Honda race bikes in the 1960s.
I don't know what the highest recorded revs for a (four stroke) piston
engine are, and would love to know.

 

The best alternative would probably be hydraulic valves, given that's
what F1 cars use.

 

Yes, indeed. Or maybe pneumatic?

 

Um, *only* 166 a second (per cylinder) I think unless they've gone
two-stroke. ;-).

I could have buggered up my sums though.

Tim

 

That's what we call a checker trap, to see if you're doing your job.

At least, that's my excuse.

 

Isn't it quite common these days for all the plugs to fire every time
one needs to?

 

Not all plugs, just the ones on a pair of cylinders where one pot is on the
compression stroke and one is on the exhaust.

 

Presumably every cylinder in a V8 (as used in F1) is part of a pair, in
which case Thomas may be right with his 333 sparks/second.

 

Yeah, I did think about that but I assumed that most folk would know I was
talking about real manly power stroke sparks rather than effeminate girly
exhaust stroke sparks. ;-)

Tim

 

A friends late 80s CBR250RR redlined at 21 grand. Insane for a four stroke.

Fraser

 

Holy hell. Impressed.

 

You'll note that the second hand supply of such beasts is, shall we say,
limited.

 

Ah. Yes. Good point.

 

You don't see many GSXR400s of the era around either.

Rare grey imports become even rarer twenty years on. Hardly unusual.

 

GSXR400 was available as a proper UK bike.

 

Really? Crikey.

OK, replace with Bros 400 or any other grey.