What is it ?
Low speed pre ignition
Premature self-ignition of the fuel-air-mixture before ignition by the spark plug by low engine speed
Not to confuse with high speed engine knocking.
What happens with engine ?
Engine can easyly get damaged, cause the highest cylinder-pressure thats usually about 60 bar increases up to 200 bar and more.
Which motors are affected ?
Direct injected, turbocharged, downsized high output engines.
When does it happen ?
Only by low motorspeed (about 1250 - 2500 rpm)...
...and high load (full acceleration) at the same time.
What are the reasons ?
Hotspots from sediments
uncorrect fuel-air mixture
Detachment of oil drops from the piston ring gap
Oil-fuel-interactions
Particles
Residual gas
So, what helps preventing ?
we can not influence:
1) the number of injections per working stroke - but the danger of LSPI by only one injection is 4 times higher than by two injections (becauce of much better fuel distribution and circulation)
but we can influence many things:
2) do not demand the engine at low rpm (1250-2500) with heavy acceleration - and everything is good !
(why? by full acceleration at low rpm, there is much fuel injected, by low circulation at the same time)
3) the danger of LSPI sinks with warm engine (oiltemp over or at least 100°C, watertemp over or at least 90°C) - so always take care of good tempered engine, before having fun.
4) use premium fuel (high octane is good) becsauce premium fuel has good volality and good detergents
5) fuel with up to 30% Ethanol is very good against LSPI (over 30% LSPI increases again)
6) use oil that prevents LSPI (API-SP - good, Dexos1Gen2 - stronger)...they have no Calcium as detergent - cauce calcium changes the size of oiltrops, that may be detached...
7) oil with low volality and high flashpoint decreases oil-fuel interactions (my faforite: Ravenol-DFE)
8) dont use foam-filters with bad filtration-rate - so you dont get any Silicium in your intake-air
So, is the GR Yaris engine endangered of LSPI ?
I do not know, but becauce of the additional port-injection by low rpm (but this just till middle load) it may be better prepared against LSPI than other engines...but who knows?
Still if he had no LSPI-Problem...if you take the above standing to heart, your engine will live longer...
Sorry for bad English...
Regards Grinder
Low speed pre ignition
Premature self-ignition of the fuel-air-mixture before ignition by the spark plug by low engine speed
Not to confuse with high speed engine knocking.
What happens with engine ?
Engine can easyly get damaged, cause the highest cylinder-pressure thats usually about 60 bar increases up to 200 bar and more.
Which motors are affected ?
Direct injected, turbocharged, downsized high output engines.
When does it happen ?
Only by low motorspeed (about 1250 - 2500 rpm)...
...and high load (full acceleration) at the same time.
What are the reasons ?
Hotspots from sediments
uncorrect fuel-air mixture
Detachment of oil drops from the piston ring gap
Oil-fuel-interactions
Particles
Residual gas
So, what helps preventing ?
we can not influence:
1) the number of injections per working stroke - but the danger of LSPI by only one injection is 4 times higher than by two injections (becauce of much better fuel distribution and circulation)
but we can influence many things:
2) do not demand the engine at low rpm (1250-2500) with heavy acceleration - and everything is good !
(why? by full acceleration at low rpm, there is much fuel injected, by low circulation at the same time)
3) the danger of LSPI sinks with warm engine (oiltemp over or at least 100°C, watertemp over or at least 90°C) - so always take care of good tempered engine, before having fun.
4) use premium fuel (high octane is good) becsauce premium fuel has good volality and good detergents
5) fuel with up to 30% Ethanol is very good against LSPI (over 30% LSPI increases again)
6) use oil that prevents LSPI (API-SP - good, Dexos1Gen2 - stronger)...they have no Calcium as detergent - cauce calcium changes the size of oiltrops, that may be detached...
7) oil with low volality and high flashpoint decreases oil-fuel interactions (my faforite: Ravenol-DFE)
8) dont use foam-filters with bad filtration-rate - so you dont get any Silicium in your intake-air
So, is the GR Yaris engine endangered of LSPI ?
I do not know, but becauce of the additional port-injection by low rpm (but this just till middle load) it may be better prepared against LSPI than other engines...but who knows?
Still if he had no LSPI-Problem...if you take the above standing to heart, your engine will live longer...
Sorry for bad English...
Regards Grinder
