10 Questions about Engines...
Discussion
1. what is a VCT engine?
2. what is a polymotor engine?
3. what are the pro's an cons of a boxter engine?
4. what are the pro's an cons of a rotary engine?
5. is direct-injection the same as electronic fuel injection?
6. is there a benefit to having a transaxel in a car?
7. what are the pro's an cons of a flat-4/6 engine?
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time?
9. could an engines casing be built from kevlar like F1 gearboxes are?
10. do hybrid engines work ok in cars or only benefit big buses?
- an hopefully there answers will interest more than me here
>>> Edited by vlc on Wednesday 28th April 18:57
1. what is a VCT engine?
Variable cam timing?
4. what are the pro's an cons of a rotary engine?
Low compression ratio (possibly)?
Very smooth - Less friction (which means they should be more efficeint, theoretically).
5. is direct-injection the same as electronic fuel injection?
Think so - Not 100% on throttle bodies though.
7. what are the pro's an cons of a flat-4/6 engine?
Reduced friction?
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time?
Errrrrrrrrrrm, I think that would probably depend on alot of variables.
>> Edited by DanBoy on Wednesday 28th April 19:21
Variable cam timing?
4. what are the pro's an cons of a rotary engine?
Low compression ratio (possibly)?
Very smooth - Less friction (which means they should be more efficeint, theoretically).
5. is direct-injection the same as electronic fuel injection?
Think so - Not 100% on throttle bodies though.
7. what are the pro's an cons of a flat-4/6 engine?
Reduced friction?
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time?
Errrrrrrrrrrm, I think that would probably depend on alot of variables.
>> Edited by DanBoy on Wednesday 28th April 19:21
vlc said:
3. what are the pro's an cons of a boxter engine?lower centre of gravity but awkward for exhaust plumbing
4. what are the pro's an cons of a rotary engine? very low vibration but tend to use a lot of oil
5. is direct-injection the same as electronic fuel injection? No, Direct injecttion is a form of electronic fuel injection whereby the fuel is injected directly into the combustion chamber, rather than into the airflow before it enters the cylindeer
6. is there a benefit to having a transaxel in a car? Better weight distribution cause there's less weight in the nose
7. what are the pro's an cons of a flat-4/6 engine? Same for boxer
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time? not a lot...
9. could an engines casing be built from kevlar like F1 gearboxes are? I should think heat dissipation plays an important part here so not really
10. do hybrid engines work ok in cars or only benefit big buses? Toyota Prius anyone?
- an hopefully there answers will interest more than me here
>>> Edited by vlc on Wednesday 28th April 18:57
2. what is a polymotor engine? It is, as its name suggests, a plastic engine - pioneered in the 1980s
4. what are the pro's an cons of a rotary engine? rotary engines have no reciprocating parts giving them much lower parasitic losses than can be acheived with a conventional internal combustion engine. They rev high and subsenquently give very good specific power outputs. The downside is potentially high maintentance
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time? Do you mean nitrous or nitro-fuel? How heavy is the mini, is it one of the new BMW ones or an old rover one?
9. could an engines casing be built from kevlar like F1 gearboxes are? kevlar might not be the best choice but potentially yes, plastic engines are possible (see the answer to 2)
10. do hybrid engines work ok in cars or only benefit big buses? depends what you want out of a car, if it is just big performance at top end then hybrid is just extra weight to carry but for a daily run around then the answer is yes but don't expect things to work quite the same way as a single engine install
4. what are the pro's an cons of a rotary engine? rotary engines have no reciprocating parts giving them much lower parasitic losses than can be acheived with a conventional internal combustion engine. They rev high and subsenquently give very good specific power outputs. The downside is potentially high maintentance
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time? Do you mean nitrous or nitro-fuel? How heavy is the mini, is it one of the new BMW ones or an old rover one?
9. could an engines casing be built from kevlar like F1 gearboxes are? kevlar might not be the best choice but potentially yes, plastic engines are possible (see the answer to 2)
10. do hybrid engines work ok in cars or only benefit big buses? depends what you want out of a car, if it is just big performance at top end then hybrid is just extra weight to carry but for a daily run around then the answer is yes but don't expect things to work quite the same way as a single engine install
vlc said:
1. what is a VCT engine?
Variable cam timing, I think.
vlc said:
2. what is a polymotor engine?
Dunno. Quick googling suggests (a) an engine [partly] made of plastic, (b) a hybrid internal combustion / electric power plant and (c) a particular shape of combustion chamber.
vlc said:
3. what are the pro's an cons of a boxter engine?
Pro: better balance, lower C of G, sometimes the shape makes it easier to fit in. Con: more parts to machine, crankcase joint can be awkward, sometimes the shape makes it harder to fit in.
vlc said:
4. what are the pro's an cons of a rotary engine?
(Assuming you mean a Wankel or similar, not an early aero engine) Pro: excellent balance and smoothness. Con: long narrow awkwardly-shaped combustion chamber leads to low compression ratio, low efficiency and high emissions of unburnt hydrocarbons, lubrication is difficult, sealing the rotor is a PITA.
vlc said:
5. is direct-injection the same as electronic fuel injection?
No. Direct injection means the engine draws in pure air and the fuel is injected directly into the cylinder, similar to a diesel. In a four-stroke this means you can do neat tricks like stratified charge combustion - essentially allowing you to run a leaner mixture as part of the cylinder is filled with just air and part with a fuel-air mixture of normal richness. In a two-stroke it also means you don't lose fresh charge during scavenging.
vlc said:
6. is there a benefit to having a transaxel in a car?
It puts the weight of the gearbox at the rear instead of at the front, which usually means you get better weight distribution.
vlc said:
7. what are the pro's an cons of a flat-4/6 engine?
See 3.
vlc said:
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time?
The same as for a non-nitro engine with the same power and torque curves.
vlc said:
9. could an engines casing be built from kevlar like F1 gearboxes are?
It's more difficult, but work is being done on this.
vlc said:
10. do hybrid engines work ok in cars or only benefit big buses?
They do work well in cars, it's just harder to fit all the bits in and keep the weight down.
slinksport said:
What sort of Nitro engine are we talking about? but why????
I'm talking about a nitro kit i heard a guy bought for his NEW mini's engine so he could boost its stats - an so wondered what they'd be....?
[quote] a polymotor engine? It is, as its name suggests, a plastic engine - pioneered in the 1980s/quote]
An i thought it was an all-new invention!
besides - what bits are plastic an why dont they melt/fracture etc?
ps- an this 'variable cam timing engine' - whats its big benefit then?
>> Edited by vlc on Saturday 1st May 00:24
>> Edited by vlc on Saturday 1st May 00:24
vlc said:
1. what is a VCT engine?
2. what is a polymotor engine?
3. what are the pro's an cons of a boxter engine?
4. what are the pro's an cons of a rotary engine?
5. is direct-injection the same as electronic fuel injection?
6. is there a benefit to having a transaxel in a car?
7. what are the pro's an cons of a flat-4/6 engine?
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time?
9. could an engines casing be built from kevlar like F1 gearboxes are?
10. do hybrid engines work ok in cars or only benefit big buses?
- an hopefully there answers will interest more than me here
>>> Edited by vlc on Wednesday 28th April 18:57
1 VCT alters the cam profile by sliding the cam in relation to the follower to change the valve timing and opening characteristics effectively giving you better breathing at different RPM.
3&7 The flat configuration and "boxter" or Boxer" are all the same. The horrizontallu opposed engine has better balance characteristics than any other configuration, except an X or radial type aero engine. The better the dynamic balance the less weight is needed to be added to the crank webs therfore the more responsive the engine.
The downsides to this are maintenance is more difficult and oil consumption may be increased as a result of the tendancy for oil to be retained when the engine is stopped.
4 Rotary engines are again better balanced and have fewer components. The downside is the seal between the rotor and the combustion chamber is difficult to engineer and the engine will rev until it destroys itself.
5 No, Direct injection is high pressure injection into the already pressurised combustion chamber. Like a diesel engine. Almost all petrol engines have fuel sprayed into the induction chamber prior to fuel air mixture being sucked into the cylinder. The electronic bits are only the control system. Michanical fuel injection has been around for a long time. This is why I got annoyed the other week when some tosser tried to tell me diesel car was produced with a carburettor.
6 Yes it is the transmission system. Basically a diff uses hypoid gears which lose about 12% of the power the engine produces because they turn the drive through 90 degrees. A transaxel does the same thing, but is about 3% more efficient because the gears mesh on centre.
8 Daft question, how long is a piece of string?
9 Kevlar is not as good a material for engines as ceramics are going to be.
10 Depends what you mean by hybrid. Some hybrid vehicles are small.
2 I have no idea what a polymotor is.
Is there a prize for the best answer?
vlc said:
1. what is a VCT engine?
2. what is a polymotor engine?
3. what are the pro's an cons of a boxter engine?
4. what are the pro's an cons of a rotary engine?
5. is direct-injection the same as electronic fuel injection?
6. is there a benefit to having a transaxel in a car?
7. what are the pro's an cons of a flat-4/6 engine?
8. if a Mini had a ‘nitro’ engine, what would be its top speed an 0-60 time?
9. could an engines casing be built from kevlar like F1 gearboxes are?
10. do hybrid engines work ok in cars or only benefit big buses?
- an hopefully there answers will interest more than me here
>>> Edited by vlc on Wednesday 28th April 18:57
3 the smartarse answer is that without it a Boxter wouldn't move under it's own steam
7 this is what you meant in 3 , good natural balance and they sound great too apart from Beetles perhaps but that is more down to the air cooling fan etc
Apache said:
What defines a rotary then?
Ah, it has two different meanings: this...
Apache said:
The early ones were bolted to 1stWW biplanes by the crank and the whole plot span round it with a propeller bolted to the engine
and the Wankel type, in which you have a thing that goes round and round instead of reciprocating like pistons.
Pigeon said:
What defines a rotary then?
Ah, it has two different meanings: this...Apache said:
The early ones were bolted to 1stWW biplanes by the crank and the whole plot span round it with a propeller bolted to the engine
and the Wankel type, in which you have a thing that goes round and round instead of reciprocating like pistons.
The Wankel rotary is a special case - the Mazda rotary is NOT the same. According to a few egg-heads it is a real bodge of one too
tvrgit said:
The Wankel rotary is a special case - the Mazda rotary is NOT the same. According to a few egg-heads it is a real bodge of one too
How is it different? (not challenging, just curious)
Think someone is getting confused here with a aircraft style radial engine and a wankel engine.
A Mazda RX is most definately a wankel engine, they won the patents & the licence a rotory the piston rotates in the cylinder as opposed to going up & down.
A radial engine the pistons are aligned radially but still slide up and down.
Wankel is famous for 2 rotary engine designs both very similar, the most famous of course is the one we find in the mazda rx-8/rx7. Starting out life in the NSU-80?
mazda bought the rights to the design in the late 60's or early 70's i believe and they developed it.
the engine the purists talk about is the original design, which the engine case rotated about the crankshaft. Although a much better design (could rev to over 35000rpm) had a habbit of destroying itself, not to mention difficult to produce and mount in a car!
mazda bought the rights to the design in the late 60's or early 70's i believe and they developed it.
the engine the purists talk about is the original design, which the engine case rotated about the crankshaft. Although a much better design (could rev to over 35000rpm) had a habbit of destroying itself, not to mention difficult to produce and mount in a car!
Direct injection in the diesel sense means fuel is injected directly into the cylinder, rather than into a 'pre-chamber' as was traditionally the case. DI requires heftier injectors IIRC.
DI on a petrol car is more difficult, since petrol is more volatile and will tend to ignite at the wrong time (dieseling, in fact!). Hence it's more usually added to the airstream, ideally just behind the inlet valve.
Ian
DI on a petrol car is more difficult, since petrol is more volatile and will tend to ignite at the wrong time (dieseling, in fact!). Hence it's more usually added to the airstream, ideally just behind the inlet valve.
Ian
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff