Quote from tristancliffe :

With the throttle closed you want the throttle closed, not a couple of % open. Carbs have idle bypasses for that. If you can see light around the butterflies with the throttle closed then your carbs are knackered

Hmm...not, but probably we're both over generalizing. My bike has a screw that blocks the throttle low limit, used for adjusting idle rpm, so the throttle is always open at least a little. But be it bypass or non-closed throttle, idle means allowing very restricted air intake, which in the case of engine braking should be exactly the same thing.

Quote :

My bike had the same ignition cut. I never tried using it whilst riding though

I was ignoring heat because on a closed throttle the heat processes aren't important. Besides which we are dicussing whether the air pump nature of an engine provides the braking or the engine friction. My sources are: Caroll Smith, Guy Croft, Keith Duckworth (though I couldn't tell you where I read Keith's prose on the matter, because I've long forgotten which book), and my research lecturer at Uni. None of this has been tested by me.

Your logic is circular. Heat processes aren't important so heat is ignored. Heat is ignored so compression loss is negligible. Compression loss is negligible so heat processes aren't important... It just doesn't say anything. Otherwise there's no good reason to ignore heat processes.

Can you quote anything that says pumping air through a tight opening offers negligible engine braking?

Last edited by yoyoML, Thu 18 Oct 2007, 02:52.

Quote from tristancliffe :

Your bike will have idle control, otherwise it would stall and not idle. At zero throttle, there are idle bypasses and jets (and drillings) that ensure the right amount of fuel/air is metered to hold a steadyish idle. That is idle control. All engines will have it, from lawnmovers to F1 cars. That means that at lower revs the rate of decelleration (in terms of revs) will fall as the fuel on a closed throttle starts to balance what the engine needs to idle.

Perhaps do the test without the engine running, so that there is no fuelling, and no ignition?

Engine braking reduces to zero because you have some throttle (i.e. the fuelling is correct for that load condition to maintain engine speed). Just like at full throttle, max speed there is no engine braking because the fuelling matches the load requirements.

Yes there will be a difference in energy used to compress air versus energy gained by expanding air. If you ignore heat, which just makes everything harder to examine, you will see that friction in bearings, rings etc will have more of an effect than compressing some air (and it won't be much air, because the throttle will be closed and intake pressures will be negative gauge).

Ok I thought your "idle control" meant some computer controlled fuel injection as engine speed drops, that is probably present on all modern sedans. But old-style idle doesn't need control, really. Idle is just a set % of throttle that remains open no matter what.

My bike has this switch that cuts ignition. Once cut, the engine braking is generally stronger, and only drops to 0 right at standstill. But, like said, the engine braking is still higher at higher rpm even without burning fuel.

Here's a test: go to 1st gear and slide down a long slope, throttle off. Does the car settle down to a steady speed? If the car settles to a speed, then you have higher engine braking at higher rpm which brakes you more when you're fast, and brakes you less when you're slow. Autos don't work as their engine braking doesn't go through the torque converter, but my bike does that.

If you'd like to argue heat is not important by ignoring heat, then we may as well ignore friction and argue friction isn't important. Besides, trying to pump all the air from intake to exhaust through a tightly closed throttle is probably a very big drag source. That I can experiment by switching off ignition and compare open/closed throttle.

Quote from tristancliffe :

But that's the thing - compressing the air doesn't cause engine braking - most of the energy goes back into the engine on the expansion stroke.

Do you REALLY get more engine braking at higher engine speeds? Or is it just that at 6000rpm there is more noise and speed so you think you are slowing quickly, but at 2000 the idle control is starting to become noticable and effectively opens the throttle.

People think that compressing the air in an engine must slow it down a lot, but don't for get that another cylinder is expanding, taking energy from the air at the same rate. Net energy 'used' is very little. Even on a single cylinder, the compression will be balanced by the expansion, just not at quite the same time.

Yes it does use energy, but at road speeds the engine friction is way more!

Do you really NOT get more engine braking at higher engine speeds? I do. My motorbike redlines at some 20km/h in 1st gear, where the air drag is still negligible. The braking I get out of a closed throttle is much greater at 20 km/h than at 10km/h. And the engine braking reduces to 0 when speed corresponds to idle rpm, as it should. Oh, and it uses a simple carburetor so no such thing as idle control.

The force used to compress can't be balanced by expansion from another cylinder. Not because the time is out of phase, but the force used to compress will be different from the force from expansion. Without some proper data concerning the heat conduction, I don't think you can conclude if the energy loss through heat is way less or more than through other friction. You only know it is present.

Quote from sgb27 :

But, that doesn't explain why you get more engine braking at 6000rpm compared to 2000rpm (forget changing gear, just lift off at different rpms).

I think you pump air 3x as fast through the whole engine at 6000rpm than 2000rpm, and that air flowing through the whole thing creates some drag that takes energy away from pistons. I guess 3x as fast translates to 9x as much drag...

Also, the simple act of compressing air then expanding it back costs energy. Compressing heats up the air, raising its temperature above the outside. Since the air is hotter, some heat (energy) is lost to the outside and can't be reclaimed while expanding. You do that more cycles per minute, you lose more energy per minute= higher engine braking.

Quote from Shotglass :

im sure he was really helpful when it came to improving that mod
"hte engine on a porsche is in the back guys !"

To elaborate if anyone doesn't know yet: Those guys shouted everywhere "we have real life drivers this and this drive thousands of laps to test this mod, and they say it's very accurate" when in fact, in the Porsche Carrera mod they put engines in the front of 911's.

What a joke. It proves that real life driver inputs are utterly useless, if said driver had insufficient simming experience.

Quote from Manijack :

Ok, ive got photoshop now, but how do i use the Wireframe and mask? im sooo noob here.... i Thought i would get a 3D model of the car which i could paint on?

I'm afraid there's no 3D model to paint on. You can only paint on the flat skin then open the game or model viewer to see your work.

Quote from 510N3D :

Ok, first game was Test Drive with my good old 286 machine ...

That one was my first. I played it on a monochrome CRT so it looked a lot worse. Reminds me of all those cracked widshields!

CMR2 and Porsche Unleashed got me racing seriously. I've held LAN parties with them and still play them from time to time.

Thanks for the reply guys!

So is there an "editor" (other than notepad)? I know how to edit the text and buttons' colors, but if their shapes and positions can be edited then it'll be much better.

I'm afraid only black can be used to hide some of the hard-coded stuff.

I'd like to put some real life emblems on the road cars, which use the DEFAULT skins and can freely change color. The problem is, the emblems/markings can look good when a light body color is chosen, but when a dark color is chosen all becomes way too dark.

Is there a way to force emblems/markings on a different, higher layer so that changing the body color in-game does not modify them?

Quote from Crashgate3 :

That's just the word she was given. People get assigned a single word in sequence. I can only assume the story had something to do with a door at that point.

Imagine all those "the" guys carrying their part of "the" story.

I was expecting something more positive LOL! Yeah I tried to make the buttons/options red as in RBR, but the LFS menu is not keyboard driven so it doesn't highlight things in red. The text colors need to be simplified somewhat, but not done with these files. Thanks for trying anyway!

I find the XBox 360 pad with its dual analogue triggers quite nice for driving games. You of course need some damping and non-linear steering to go with that, but even RBR is managable after a while.

Just remember to get XBCD360 drivers instead of the official drivers, which curiously support neither rumble nor separate trigger axes.

Sorry for my lack of knowledge, but is it necessary to have both left-to-right and right-to left in order to write Arabic? Does anyone write it in one direction only?

I ask this because Chinese can be understood left-to-right, right-to-left or up-to-down. But we use more left-to-right than any direction these days, probably to make it work better with numbers and English.

Since the original menu backgrounds feel very disconnected from menu contents, I made this simple pack of backgrounds to give the menus a coherent, RBR look.

Please let me know what you think!

See the attached .jpg's for low-res previews.

Come on! This one's top notch
http://30sixpics.com/1/show.php/2860_1178669263661.jpg.html

Try this with CRT's: Turn off all other lights then put the screen in your peripherial view, as far from the center as possible. You should see severe flickering at 60Hz, but sometimes at higher refreshrates, too. Now do that with an LCD you're guaranteed not to notice any of that.

Anyway, our eyes have faster response at the edges of view, so if you use a large CRT and sit too close (high FOV), your eyes can get tired really quickly.

Here in Taiwan, more than 60% of students in 9th grade already require glasses. So I think some of you people are very lucky, only worrying about eyesights after reproductive prime times...

Quote from Mr-Apex :

Yep it is 1:1 but there's no stop there, oh well i guess i'll just have to live with it. Thanks all that have listened, it was my first thread and im glad that there were so many that responded very quickly. The LFS community really is GREAT!

A variable stop will be very welcome addition. I hope it's included one day.

Quote from JTbo :

+1

My IRL car has over 1700 degrees of lock, it is RWD, can't remember what my other car has, but it had bit less as that has even power steering among other luxuries

Oh yes, I would like to have ffb wheel with 1800 degrees of lock or so, but I guess that is something not even money can buy.

The way the wheel is constructed, I think it would be done by removing the hard lock and tweaking the driver a bit. Because there's no potentiometer inside, but an optical sensor that only senses how many "clicks" you turn. There's no hard limit to how many clicks the sensor can read, if only the software allows for that. Then just use FFB soft lock at the ends.

I had wanted to mod the MOMO to some 900 degrees, but the driver wouldn't count anything above the original 240 degrees, even with hard lock removed.

Oh, dear, it's completely new as I said. Not even taken out of its plastic bags.

Check my location, though. I wouldn't want to sell it overseas, or the shipping costs would be quite prohibitive. Or am I wrong?

Quote from wheel4hummer :

I am pretty sure shifting at 6000rpm would not nessasarily change the fuel economy. If you are WOT, then shifting at 6000rpm will give you better fuel economy then if you shift at 4000. You should constantly be in a gear which is within the power band. If you are driving down the highway, you shouldn't nessasarily be in the highest gear. The whole purpose of a transmission is to keep the engine in it's powerband, anyway.

The problem is, "the powerband" often quoted is the WOT powerband. It changes with throttle, with the torque peak lowering below idle rpm when you lift off completely.

So, an ordinary road car cruising on the highway generally prefers the highest gear/lowest rpm due to the small amount of throttle.

Quote from rubberbrush :

And turning in two directions...shocking I know.

I wonder what NASCAR would be like if speedways were figure 8's?

To stay on topic, how about some reverse ovals so people do RHD for the sake of weight balance? Perhaps there's internal balast that took care of this already?

...has only 3 months warranty left.

Ok the original's pedal spiked as per usual DFP, so I sent it in for repairs under warranty. I've since bought a G25, but Logitech sent back a completely new DFP.

I'd like to sell it, but I'm curious how much you'd ask for (or how much you'd pay), perhaps in % of original buying price?

Quote from Robiik :

So if I understand it right, if I set the rotation to 900 degrees in profiler, the wheel will turn 900 no matter how I setup the game.

The in-game wheel rotation setting is not a setting at all. It's simply where you "tell" LFS how much rotation your real wheel has, or how much rotation you have set in the control panel. Suppose you had a MOMO you'd have to "tell" LFS you had only 240 degrees here.

Quote from dcToro :

My steering setup is:
240° because i have the GRT Pro FF(which has an angle of 240°).
then i set the steering compensation to 0.

But now the problem, if i have my wheel steered 90° in the FO8, the wheel in the game is more than 90°. So its not 1:1, although i have no steering compensation.

How can i handle this? I mean if it would be realistic, than the wheel in the game could only turn to 240° even if the F08 itself could theoretically do more.

Is there a way to make it 1:1 realistic?

The wheels turn compensation setting is supposed to be a semi-realistic and simple solution. If you set it to 1 and input 240 as wheel rotation in game, the steering will be 1:1 around the center but grow up as you go to the locks.

If you don't mind a little non-linearity, that's the easiest way out.