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THEORY





think i have got a little theory. I could be absoloutely wrong or on the other hand this could be common knowledge and i am really not that clever for pointing it out. Anyway, the main difference between the willy and the 16V is where the power band kicks in. I was always under the impression that this was simply down to the bigger capacity of the willy. After speakin to jon and a couple of others at the clio meet on sat i now reckon that the reason for the willy kicking in at lower revs is down to the diesel crank. The shorter throw in the crank causes it to be able to create power in the lower revs??
 


it uses the crankshaft from a diesel engine so the throw is shorter, hence it only being able to reach 6500rpm compared to the 16Valvers 7200. In standard trim
 


That also sounds strange, wouldnt a shorter throw mean a reduced piston speed therefore the possibility of higher revs?
 


i thought it was the other way round? A shorter throw therefore pistons move quicker?? Could be very wrong but thats why i put this post up
 


I think the whole willy/16v/diesel crank scenario has been discussed in depth previously, try searching for old threads in the power/exterior mods forum...
 


The diesel crank (same stroke as williams) has a longer throw than the 16v, the extra capacity of the 2.0l is achieved by increasing the bore from 82 to 82.7 and the stroke (throw) from 83.5 to 93 . A shorter stroke crank shaft will rev higher than a long stroke which is why formula 1 engines rev to 18,500 and good old diesels only to 4500. Hope this helps.
 


dont worry about it, im trying to read a book about 4 stroke tuning at the moment, and i have to read about a page a day to take it in.:confused:
 
  BMW 320d Sport


Yeah the Willy is longer throw than the 16v; it takes a bit of figuring out if youre not an engine expert (which Im not) but think about it like this.

You know when youre a kid and you pick up bits of tree branch off the ground and swish them about pretending youre having a sword fight or whatever...as you quickly learn, the longer the branch the more likely it is to just fold up or snap in two as you swish it around. A shorter branch is tougher (assuming the thickness of the branch is the same), theres not as much flex in it and it takes more to break it. If you were to put both a long and a short tree branch in a swishing machine that swished them back and forth, as you turned up the swishing speed you might find that the longer branch broke at 500 spm (swishes per minute!) but the shorter one went on until 700 spm before it bent.

I think that examples right, but then again it might just all be my fevered imagination. Anyway, AFAIK, if you have two virtually identical engines but one has a larger capacity, the bigger one naturally will create more power, because you can get a greater amount of air/fuel into it. The longer throw of the Willy over the 16v also creates the greater torque, because every time each cylinder is fired the Willy piston travels further than a 16v one, for a given RPM.

Again, this might just be my imagination, i could have it all wrong, but AFAIK, capacity creates power, stroke creates torque, surely for the ultimate engine , youd give it a big capacity made up of a very long stroke compared to its bore, that way youd get the power *and* loads of torque? Well, no, the problem with that would be that the long throw crank would be weak and you couldnt really rev it very much at all, and although torque usually peaks lower down the revs, power is a function of rpm and eventually the engine reaches a point much higher in the revs were the physical design of the head/inlet/exhaust means even if you increase rpm further, the engine physically cant get any more air/fuel in to a cylinder each time, because the cylinders need to be filled, compressed, fired and exhausted so quickly at higher engine speeds. And from that point of course, engine power starts to drop - the faster you run the engine, the less air/fuel mix you can get into the cylinders, therefore less power.

Hopefully this explains the power/torque characteristics of the two engines? Please correct if Im wrong on any of this though.

1.8 16v: less capacity, short throw crank = less peak power and torque, and both peaks are found at higher rpm than on the Williams, can be revved hard, in fact, *has* to be revved hard to get it going properly!

2.0 16v: more capacity, longer throw crank = more power and torque, both peaks found at lower rpm than on the 1.8 16v, cant be revved very high, but makes up for this because you can be lazy - the power/torque of the engine are there much earlier in the revs so you dont need to be constantly stirring it up.

In other words unless you like the sound of a screaming 1.8 16v at 7000 rpm (which isnt a bad sound!), get a Willy and drive lazy!
 
  BMW 320d Sport


One thing I would like explained to me though - is there any actual advantage to having to wait until 10,000 rpm on a race engine until you get any power? Why not just have a nice big torquey engine that gives peak power earlier on? Or is it because the further you tune any engine for peak power, the further up the revs the power goes? SO for a given engine, to get the most power out of it, you *have* to get it to rev high at the expense of the rest of the rev range? That seemed to be what I was hearing when I was doing research on cam profiles etc.
 


Thats basically it i think.

Power is torque times revs, so if you can shift the sam amount of torque further up the rev range, you can get more power
 


Quote: Originally posted by Nick Read on 03 December 2002

One thing I would like explained to me though - is there any actual advantage to having to wait until 10,000 rpm on a race engine until you get any power? Why not just have a nice big torquey engine that gives peak power earlier on? Or is it because the further you tune any engine for peak power, the further up the revs the power goes? SO for a given engine, to get the most power out of it, you *have* to get it to rev high at the expense of the rest of the rev range? That seemed to be what I was hearing when I was doing research on cam profiles etc.
Nick, the basic reason is rules. in any and every form of racing there is usually a capacity limit.

as we all know, power is made by burning fuel, to burn fuel, we need air...well o2.......

Fuel is the easy part, we can add as much as we need, but passing and processing air is the hard part. you need as much air passed to process with fuel, the more you process the mroe power you get.

now porting a head will end up witha finite size reached when its perfect shape/size/texture/volume. This finite amount is only finite at whatever RPM you are at. so, for what ever size engine, teh easierst way to process more air is higher rpm...thus more power.

the plroblem then becomes cam profiles which work well enough to allow a high enough VE at those rpms to be of economic use. i.e there is no point revving to 17,000rpm if VE is 12%......but if its 86.....hell, you could go even higher. But these cam profiles are generally so wild that the tradeoff is low rpm VE. which is poor bcause the overlap and duration let fresh cahrge excape out the exhaust befoer its compressed and ignitied. this is why F1 cars idle near 3000-4000rpm.

if capacity was not a problem, then F1 would probbalby run larger capacity, more reliable and cheaper engines to get the same power......and they will be more drivable too...but that wouldnt be F1 now.....
 
  BMW 320d Sport


So if there were no rules and no spending limit, you would run basically the biggest engine you could physically fit in the car?
 


Nick,

Sure if there where no rules youd run the biggest cc engine you could without going overboard on the wieght. Also youd want to stick on a turbo running 60psi of boost like in the good old days, lol.
 


In the old days of GT racing, eight litre plus engines were not uncommon (old mark donahue days, like the porsches and that stuff), even now, the mclaren is nearly 7 litres isnt it? or six and a bit or something. I think the weight becomes the limiting factor, i remember reading somewhere that the mclarens drive train weighs 650kgs, which makes the overall weight of 1050kgs really impressive.
 


yeah, just under, and teh viper is a good 7ltrs........

but youll end up with what they ahve in classic touring cars now....big cameros and mustangs with 5ltr small blocks and piddly 1.3 clubmans......all doing similar lap times....
 
  BMW 320d Sport


OK so instead of messing about with cams why dont they just have all the valves controlled electronically with solenoids or magnets or something, so you can just time the valves to give optimum power at every point in the revs and have it all controlled by the ECU? Or has someone already thought of that?
 

Tom

  EV


Yes they have but one very very big problem is that it weighs so much more than cams. but the up side being its infinately variable (spelling not my strong point) and it wont break because theres no stress on the components

the magnets need to be resistant to vibration and very powerful also the system requires the new 48/42v system being used in some cars. So power consuption is poor.

oh and with no mechanical link to the cams friction is reduced and the engine could (in theory) rev up to 50% higer than before

so 20,000 rpm - 30,000 rpm

renault are supposed to roll it out into f1 in 2005

Electromagnetic Valve Control + Timing

EVC+T

http://www.grandprix.com/gif/camless.gif
 
  Clio Williams 1, 182,197


Hey you lost me there !! But what do I care !! Ive got a willy and had its trip to Hill Power to improve things further !!

Yes it is worth taking it to Hill Power for a stage 2 conversion !! I love it even more now !! Thank you Nick !!



Leigh
 


haha, you b*****d!

i was gonna answer with that! didnt we talk about electromagnetic valve train a wile ago and its downfalls.

Renault have been working with it for a while now and it was meant to come out 2003.......but indeed, it is way too heavy.

as Nick pointed out, F1 cars use hydraulic systems as bounce and float become real probs at 18,000rpm. anyhow, the new motoGP bikes use the same technology, but msot remove teh hydraulic system to reduce complexity, although the new petronas is meant to run with it. well, see.

one last problem is time, moving any mass, the strength needed to move that same mass faster increases. so, with 30,000rpm, the time to open and close a valve will be so minute that....well, time will become a problem......then so will actually getting the air in.....you try fill 200cc cylinder in 0.05 sec.......madness.
 
  Corsa 1.3 CDTI


Quote: Originally posted by BenR on 05 December 2002


i was gonna answer with that! didnt we talk about electromagnetic valve train a wile ago and its downfalls.
Ben that was me and you told me about the new F1 engine being produced with this.

If you did use this type of system and you could rev to say 20,000+ rpm wouldnt you need to turbo charge the engine so you could fill the cylinders up with enough air because as you said the valves would be open for a minimal amount of time ? Then you might get a problem with betting the burn gases out quick enough as well ?
 


Has anyone seen the rotating sleve valves Cosworth are supposed to be working on, no recipracating parts so 50,000rpm is possible :confused:

Also Ive read about an engine with variable length stroke and another that uses a Ducati V-twin ad the botom end and 2*2 stroke singles as cylinder heads.
 

Tom

  EV


there is currently alot of idead circulating on how to get the msot flow with least trouble......and i have come up with 2 ideas which i am actualyl trying to check patents on at the mo. Lets just say that neither involves a throttle as a butterfly or a roller barrel, and the valve train is reciprocationg but involves NO camshaft and NO valves...........and when @ WOT and profile is at max, there is be NO disruption to flow....i.e. stright shot port tract......with nothing in the way.

anyhow, tom, that sleved valve design is very very old and was used by rolls to quiet down their engines int eh early early 20th century....like 1910....anyhow, it was also the first hemi head design, i production, but they only used it for a short while as it was a wholey inefficient design.

im still learning, but @ 20,000rpm, the engine should still be able to breath through inertia of inlet and exhaust charges, whith super lairy profiles which will mean that valves basically dont close (well, you know what i mean). but around the 35,000rpm mark thing should get very difficult. but hell who knows.........
 


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