Comments by "crazypj" (@1crazypj) on "Engineering Explained" channel.

  1. I'm a motorcycle mechanic so not trainedin engineering or engine design but I've done a lot of reading over the years. Doesn't connecting rod length have an effect on piston acceleration, side loading and when maximum torque is developed?( rpm) Burn time is relatively fixed which is why ignition has an advance curve to start burn BTDC with maximum pressure somewhere around 14 degrees ATDC. Unless a manufacturer is designing a totally new engine, 'ordinary people' are looking for ways to maximise what they already have , bigger bore generally being the cheapest and easiest but with limitations on maximum bore size due to cylinder spacing. The largest overbore I've ever done was 14mm which actually utilised the oversize ports way better than the manufacturer (1970's designs, big ports, high cfm, low gas speed)
    3
  2. Any follow up on this? It is incredibly clever and probably fantastic for countries that don't try and break things (pretty much anywhere other than USA or my brother in Britain)
    3
  3. If you read anything about oil since around 1985 you would know it's due to lowering of ZDDP from 'optimal' 1800PPM to less than 100PPM (or zeroin many synthetics). ZDDP kills catalytic converters which have to be covered by manufacturer warranty for 5_7 yrs/100,000 miles. (last time I checked, around 2012)
    1
  4. I used to be a motorcycle mechanic, Honda CX 500Turbo of mid 1980's could boost to a max of 52psi with waste-gate disconnected and still feed enough fuel (until rev limiter shut down fuel pump :( ) Honda had similar style combustion chamber 'lean burn' engines in scooters on test in Belgium in the late 80's, early 90's. (Honda had it's main distributions center for Europe there) The scooter engines could run main combustion chamber around 32:1 fuel air ratio with the 'mini' chamber around 12:1. Honda were using motorcycle engines as 'test beds' for future car technology (the 3 valves per cylinder came out in motorcycles in 1978) What it actually means though, the technology isn't new or ground breaking just computer control has become much faster and more effective. Oh, BTW, Didn't Renault have almost 1400 hp from 1200cc in early 1980's? (on the qualifying engines when rules were different)
    1
  5. Looks a lot like some 1950's experimental engines. Dual diameter compressor piston and high pressure piston can use single bore. Limiting factors were always exhaust valve temperature and sealing any type of rotary valve. Sleeve valve engines are a very mature technology but have the same sealing issues. maybe new materials can help and may have been the basis of the FORD ceramic engine experiments in 1980's? You still need to somehow limit combustion temperature to lower the amount of nitrogen compounds produced though
    1
  6. Using what manufacturer recommends is great on newer engines but what about 'Classics' ? I have no idea where (or why) I would want 1950's, 60's or 70's oil. Have you done a video on oil clearances in internal combustion engines and how that affects required oil viscosity? Do old style engines have tighter tolerances when being re-built today ?
    1
  7. Basically, electronic throttle operation allows people who should take the bus drive cars. Explains why insurance is so high due to bad drivers
    1
  8. Static compression ratio is just as irrelevant now as it was 50+ years ago. Dynamic compression is the only thing that matters and that is variable depending on rpm due to the 'pulse tuning' you kinda touched on. Another reason for using multiple injectors is the duty cycle. Using port and direct means both can be smaller and be combined to get correct F/A ratio almost all the time. It's been done on motorcycles revving much much higher for at least the last 10 years (as has chain driven DOHC to 18~20,000rpm) a V configuration engine has other issues with chain drives though not just the chain whip at high rpm,
    1
  9. Can you do a video on motorcycle engines? WSB are rumored to be making over 220BHP from 1 litre NA and have been for several years
    1
  10. I'm not an engineer (think I've mentioned it before on your channel?) Two points. 1. Oil jets are not to lubricate cylinder walls but to cool piston tops. It's a very old 'technology used in 1930's piston engine aircraft. A byproduct is much better lubrication of small end bearings 2. Thinner oils do a much better job getting into area's designed for 'splash lubrication' as the oil can fling around at lower rpm so provide better lubrication and cooling. (valve springs, etc) Biggest issue with oils is the type of drive system for camshafts, belt drives give oil easiest time, chain drives break down VI and gear drives break viscosity improver's very fast. VVT engines, I'm not sure about as I haven't done any testing Motorcycles where engine oil is shared with transmission can and will destroy V.I. within a few hundred miles particularly if there are any helical gears in system, oil change interval drops to 300 miles or less (about 1/10 normal interval)
    1