the compression makes the gas hot - without this it won't fireTommy Cookers wrote: ↑Sun Mar 26, 2023 11:58 amnot so ?
the spark typically has by design .......
enough energy (50-100 mJ) to ignite the mix when it has been heated by compression (engine cold) and ....
not enough energy to ignite the mix when unheated ie without compression (or residual engine/exhaust heat)
yes more energetic sparks are possible by design - but this in various ways has more costs
eg an 85 kV dragster distributor has a diameter of 14" (and spark energy measured in J not mJ)
of course if there's enough compression heating no spark is needed for ignition
said a breakdown mechanic when my 750 Triumph had the usual undetectable compression leak between the cylinders
but thinking now the leak left the cylinder with about 15% of the usual combustible gas ... so ...
if this fired energy might be too low to sustain running - but Lenoir gas engines ran ok though efficiency was low
https://crohmiq.com/minimum-ignition-en ... y-product/
Pavel Malonik made a replica 1910 J.A.P. V8 aero engine (run in an appropriate replica speed record motorcycle)
with 3:1 compression ratio it won't combust normal petrol (early engines used petrol more like cigarette lighter fuel)
isn't this a similar thing ?
one hundred years ago most cars (being mostly model T Fords) had untimed sparks (from trembler coils aka buzz coils)
ie a continuous stream of sparks was passed to in each cylinder in turn
sparks were (vs today's) very low power so combustion wouldn't start without compression ie towards/near TDC
timed sparks weren't necessary - or desirable (without self-starters)
(I had a Sherman tank buzz coil with my RR Meteor (Centurion tank NA Merlin) - starting at near zero cranking speed)
buzz coils were preferred by Ford as requiring only a household eg radio battery (no car dynamo, starter, or battery)
(later they added a small flywheel 'magneto' to energise the BCs - no the magneto didn't produce sparks)
it's said model As Bs even early B V8 1932 had BCs (1 coil streaming sparks to 8 cyls not 4 BCs as in 4 cyl T, A, & B)
BCs were particularly favoured as enabling catalogued use of low-grade or alcohol fuels (and use of worn engines)
(Ford made all these engines for industry, boats, and tractors etc for decades after their car application had stopped)
yes except for the T you'd have difficulty finding parts now as most would have been modernised in-period
yes there's a lot of mis-description and mistaken terminology
this is the right stuff ...
https://www.larescorp.com/toolbox/skinn ... buzz-coil/
Honda 'invented' the 4 stroke 180 deg crank parallel twin cylinder (1 piston up, 1 down) motorcycle c.1959
it had 2 ignition contact breakers at 90 deg camshaft-driven - so exactly the sparks needed (none redundant)
(btw the later and larger CB450 was somewhat related to their 1960s F1 engines)
other makers emulated this 180 deg crank(when switching to 4 strokes in the oil and pollution panic c.1975) but ....
using simple crankshaft driven ign 'pickups' at 180 deg ie redundant spark ignition systems ie seemingly ....
relying on sparking c.bdc each cylinder full of explosive gas without effect ...
then 180 deg later c.tdc sparking it to the normal effect (there were 3 redundant sparks per 1 useful spark)
(not the conventional redundancy ie 1 redundant on the exhaust stroke and so without effect)
my 250 Kawasaki (like GPZ 305) would idle on both cylinders but only run at power on one cylinder
(partial carb drying-out had blocked one main jet but neither pilot jet - I later discovered)
I swapped each plug lead over to the other plug - and the behaviour was the same - the same cylinder ran at power
doesn't this prove the above ? - these engines spark c.bdc into a cylinder of explosive mixture without exploding it
unless I'm wrong
the Suzuki GS 400 etc seems to have used the same ignition layout
yes these days spark energies are by design made to be much greater
modern or old, the conventional (4 inline cylinder) car engine has no redundant sparks
but (by suitably moving each plug lead to another plug) could be changed to have every cylinder's spark 180 deg early
(rather as the Kawasaki mentioned already)
every cylinder full of explosive gas sparking around bdc - what would happen ?