Quote from XCNuse :

then spell it right lol, its pi
its a greek letter not... a word
(or food for that matter heh)

This should clear it up.

Quote from Jamexing :

Power = Torque x Angular Velocity

Whereby power is in watts, torque is in Nm and angular velocity is in rads/s aka RPM/60x2xpie.

im pretty sure its not angular velocity but just rps

Quote from Vain :

It's an inhabitant of a country called Radis in the west pacific.
It's a very small and unknown country because it only has 6.28 inhabitants.

Vain

n1

Quote from herki :

race-prepped cars can rev that high... the engine just won't last very long...
or do you want to tell me, that 2.4l V8 can't rev up to 20k-rpm?

Well, I believed that XF GTI isn't a race car, but a common road car, besides, with a very short cc.

I also think they rev too high, and therefore achieving speeds in lower gears, which are just plain ridiculous... See attached replay, I've tested redline speeds with the LX4 with gearings taken from a Caterham-dealing homepage... Apart from the bike engine-like redline, the speeds are just unrealistic...

Quote from Haduken :

The XF GTI rev too high for the type of car it is. In real life a 1.3 four-cylinder can't rev to 10.000 and have 120ps illepall My old R-11 it's a 1.4 carburetor and cannot pass over 5000rpm

Mazda rx-8 it's a 1.3, but it's wankel engine, totally different
The Clio Williams had 150ps, but it was a 2.0

Peugeot 106 rallye series 1.
1.3 litre 4cyl, in standard tune 100bhp at 7200rpm, and would (apparently) rev round to 9krpm if you abused it. 115bhp is not unreasonable for a car engine of this capacity.

I have always thought that most of the cars are a bit too willing to rev way above their peak power, but it doesn't really bother me, I always shift at the light.

Quote from wheel4hummer :

Hey, at least I didn't say "Power = torque x rpm"

I tried to keep it simple just to support the above what I was saying about xfg..

Bit I forgot the unites used in lfs and from country to country…

With kgr and watts it just works and it just a Simple “version” of the original Power = Torque x Angular Velocity.

But it was my mistake after all.

Quote from sinbad :

I have always thought that most of the cars are a bit too willing to rev way above their peak power, but it doesn't really bother me, I always shift at the light.

Exactly that!

Quote from Haduken :

Well, I believed that XF GTI isn't a race car, but a common road car, besides, with a very short cc.

well, you can always get a sophisticated honda engine, like in the civic type-r or the s2000, they rev pretty high for road car (up to 9k, with some aftermarket tuning the s2000 can get to 11k)

Quote from herki :

well, you can always get a sophisticated honda engine, like in the civic type-r or the s2000, they rev pretty high for road car (up to 9k, with some aftermarket tuning the s2000 can get to 11k)

s2000 it's a 2.2 DOHC 16v VTEC 237ps

honda civic it's a 2.0 DOHC 16v VTEC 200ps

This cars are road cars, also are sport cars. A small car with 1.3 4-cylinder, taking away the special RX-8, are most cars for daily use, with low use of fuel, I think.

Top fuel dragsters can actually rev to almost 9000rpm iirc.

No, the truth is MOST LFS cars do NOT rev too high. For instance, the turbo GTRs make maximum power at about 6000rpm. Last time I checked, the 600hp twin turbo 3.6L engine of the Porsche GT1 reved to about 7500rpm, though unrestricted ones would go to about 700hp at similiar peak rpms. Though the LFS 2.0L GTR engines are based on the principle of making massive torque with the use of massive turbos and around 3bars of absolute inlet pressure, so it isn't too bad.

Most cars actually rev perfectly, but have absurdly bad powerbands. The classic case is the RB4. It revs easily to 7500rpm, which is reasonable for its kind of engine, but maximum power comes at only 6000rpm. Again, there are serious turbo modelling issues here. Yes, the RB4 will rev to the 9000rpm peak of its rev counter, though this is as far as it will actually go with no rev limiter and doesn't do any good. For a RL comparison, the 4G763 2.0L turbo would rev to 9000rpm if the rev limiter was removed, though then again such excessive revving does it no good anyway. In fact, the engine can safely withstand short transients to that rpm, though it is not advisable.

Next is a RL DIESEL case study. I happen to be familiar with the 4D56 diesel engine. It's pretty revvy for a diesel engine, redlining at 4500-4700rpm, depending on tune, with peak power usually between 4000 to 4200rpm. Some fellow Pajero drivers that use the same engine have actually reved it to its 6000rpm peak for a couple of seconds without too much incident, though the timing belts, etc and other drive belts tend to go before the engine suffers really significant damage. So yes, it CAN overrev to such rpms, though it makes no power there, so it's pointless.

The only car I've REALLY noticed to have a silly redline is the FZ50. Last time I checked, such flat sixes from RL Porches redline a around 8200rpm, and it's the latest 997 model GT3 with about 415hp! Maximum power is at around 7600rpm anyway. That 9000rpm redline for such an "underpowered" (360hp) car is just absurd. Hmm, must be a revvy and torqueless unit, but it certainly doesn't drive like one. I can reasonably accept that a 9000rpm redline is a necessity for a 3.6L NA to achieve 490hp, but a 9000rpm redline from such a relatively large engine that somehow makes only 360hp is a bit silly. Maybe the LFS tuning division used MASSIVE bores and tiny strokes...

Well, at least the TBO cars have realistic redlines. So do all the single seaters. The GTRs aren't far off considering what they are. The LX cars are also good, given that they make great power from such small engines. Last time I checked, my friend's Corolla Sportivo has a 8200rpm redline with a peak power of 191hp@7800rpm at the output shaft, though RL tests confirm the value to be around 180hp at similiar revs with all the accessory belt drives on. So the 9000rpm redline for a 190hp 1.8L engine is perfectly realistic. As for the RA, it's powerband values and rpms are copies of the real thing and thus, just fine. Just need to fix that absurd turbo model that requires even a less than 1bar boost turbo an eternity to spool up and the RA would be as great a drive as it should be.

Quote from Haduken :

s2000 it's a 2.2 DOHC 16v VTEC 237ps

honda civic it's a 2.0 DOHC 16v VTEC 200ps

This cars are road cars, also are sport cars. A small car with 1.3 4-cylinder, taking away the special RX-8, are most cars for daily use, with low use of fuel, I think.

normally with bigger displacements you get lower revs, so a small 1.3l should be able to rev higher ... I'll search for an example in the GTi range
oh btw: IMO the cars do really rev to high for common cars, but I just want to explain, that it's possible to have such engines

Last time I checked, 4G62 (1.8L turbo) equiped Mitsubishi Cordias could easily rev to 6500rpm without poblems. In fact, that's the optimal shift point, since it makes maximum power at 6000rpm.

Well, the original 4G63 equiped Mitsubishi Starions had 7000rpm redlines anyway, though they can easily be revved to 7500rpm with no problems.

Well, it seems that all this LFS cars rev too high business is absolutely obesessed with the XF Gti. For a RL comparison, a 1.3L NA econobox engine form a Mitsubishi lancer revs to 6000rpm and makes 88hp at around 5000, though that's in its OEM state. Though 7000+rpm 1.3L engines are possible to build and operate IRL, there aren't any cases that I know of yet. Well, to keep the XF GTi in the same class as the XR, its needs its 120 or so hp, but to do so while remaining NA requires increased revs, since torque production won't skyrocket without forced induction.

If we take an oversimplistic view and simply shift the peak power point to higher revs while maintaning the torque generated at maximum power, then the XF would need to rev to 6800rpm to generate 120hp, if the engine I talked about just now is used as a template. So given the power required for the XF and its remarkably small engine, its current redline isn't TOO bad. Granted, it is technically possible to tune 1.3L NA I4 engines to rev and generate such power reliably, though it won't be a cheap exercise to get 90+hp per liter out of it. Expensive, but doable, especially for a track used road car such as the XF GTi.

Quote from herki :

normally with bigger replacemnts you get lower revs

I assume you mean displacement, and that is NOT true.

Quote from wheel4hummer :

I assume you mean displacement, and that is NOT true.

As a general rule of thumb it certainly is.
RC motors = tiny displacement = silly high rpm
Car motors = normal displacement = normal rpm
Boat motors = fecking huge = very low rpm

Obviously there are lot of variables involved, but increasing size generally increases the mass involve, which just has to slow things down.

Mass increases by the cube of linear dimesional increase. In essence, if you compare a 1mx1mx1m block of solid steel compare it with a 2mx2mx2m block of identical density, the latter will weigh EIGHT times more.

Unfortunately, area increases by the square of dimensional increase, so the bigger it is, the samller the strength to weight ratio. Since stresses increase linearly with increase of mass, if an engine was simply scaled up in every to increase capacity, its revving ability MUST fall due to the reasons stated above.

For a RL example, if elephants were to possess the agility of cats, they would need to be over 90% bone. So bigger is absolutely sronger, but weaker relative to one's own mass.

Quote from herki :

normally with bigger replacemnts you get lower revs, so a small 1.3l should be able to rev higher ... I'll search for an example in the GTi range

Quote from Jamexing :

hough 7000+rpm 1.3L engines are possible to build and operate IRL, there aren't any cases that I know of yet.

Keep looking, but the closest you are likely to find is the example I posted above.
I've always felt the figures are so close, and the engine size so unusual, that the XFGTi is based loosely on the 106rallye Series 1 http://www.rallyeregister.co.uk/specs.htm, although, as you have said Jamexing, it has been made faster to compete with the XRGT. It doesn't cost a fortune to get 115bhp from a series 1 1.38v engine though.

Honda s2000 99 - 03 engines where 2L producing 240ps @ 8300 rpm
And they appeared in 90s civic , crx with an 1.6L engine producing 160ps ,185ps (type r) revving at 9000+ rpm

None of the lfs cars are usual road every day driven cars…

In no usual road going car you can tune all that suspension, steering, braking, and camber characteristics… not even with an aftermarket suspension system… there must be a lot of custom work to adjust all these… and if we are able to do this why not having a race tuned engine?

Quote from kaynd :

Honda s2000 99 - 03 engines where 2L producing 240ps @ 8300 rpm
And they appeared in 90s civic , crx with an 1.6L engine producing 160ps ,185ps (type r) revving at 9000+ rpm

None of the lfs cars are usual road every day driven cars…

In no usual road going car you can tune all that suspension, steering, braking, and camber characteristics… not even with an aftermarket suspension system… there must be a lot of custom work to adjust all these… and if we are able to do this why not having a race tuned engine?

Not completely true. Yes, it's expensive, but 2 way adjustable suspensions are very common for road cars used on the race track. Last time I checked, Toperformance could make custom 2 way KONI sport coilover dampers for my Mitsubishi Tredia for 300+AUD per side if I wanted to. Of course, the spring stiffnesses would be bespoke to the customer's specifications.

And last time I checked, i could easily increase the camber adjustments of my Mitsubishi Tredia by +-1.5 degrees with a simple set of camber bolts from whiteline suspensions. And they cost less than 80AUD!

The one adjsutment that defies realism in LFS is the brake torque. No car IRL could adjust braking torque exactly as such. As for the brake balance, just get a brake balance bar form AP Racing or some other reputable manufacturer. They aren't horrifically expensive anyway and provide an excellent degree of adjustability as you upgrade your brakes.

Conclusively, LFS road cars aren't OEM, but are simply examples of what road cars with serious track use in mind would be.

You can’t adjust all that parameters in a usual road going car as it comes from the factory…
Off course you can have some restricted adjustments, it in some cases, with several aftermarket parts
It is also easy to reprogram or put an aftermarket ecu ... and tune it to rev in higher rpm.

But if you put aftermarket parts… that is no more a normal car…

LFS cars are not normal… they are all race prepared.
So it is not strange that lfs cars rev to high

@Jamexing We don’t disagree I am just explaining what I am saying…

As it was explained to me, its all a matter of mass, material strength, and ballance. The better all of things are then higher an engine can rev.

Quote from Jamexing :

Last time I checked, 4G62 (1.8L turbo) equiped Mitsubishi Cordias could easily rev to 6500rpm without poblems. In fact, that's the optimal shift point, since it makes maximum power at 6000rpm.

i think optimal upshift is when you upshift so that the higher gear is at max torque. For example, the Cordia 1.6 turbo you mentioned, has max torque at ~4K rpm which means you need to shift to a higher gear so that when you get into that higher gear, the engine will be at about 4K rpm. Am i wrong?

Yes, you are wrong.

You want to shift when the torque at the wheels in the next gear is equal or more than the torque at the wheels in the current gear. Thus, in your example, you might need to shift so that you end up at 3500rpm in the new gear, but it depends on gearing and torque curve shape.

ah, so i was correct. your wording is better than mine, is all. the whole deal was that it was the torque needed to be more in the higher gear not the power.
(note that if at 3rd gear you are at 5K and the engine has max torque at 4K, the condition "next gear at peak torque" is more 'tight' than the condition "4th gear torque more than 3rd gear torque". like if x>y, if i tell you that z>x then you certainly know that z>y)

anyway i am very tired... going to catch some Z:sleep1:

Quote from tristancliffe :

Yes, you are wrong.

You want to shift when the torque at the wheels in the next gear is equal or more than the torque at the wheels in the current gear. Thus, in your example, you might need to shift so that you end up at 3500rpm in the new gear, but it depends on gearing and torque curve shape.

Almost perfect - only if you have a very effed-up torque curve would you want the revs to drop below the rpm of peak torque (assuming you're not limited by gear ratios). Usually the revs would drop to somewhere between peak torque and peak power (in this example ~5000rpm).

Indeed Sir Bob, just making a point that it's dependant on gearing and torque rather than the revs at which peak power is generated. Next we'll have Jeff coming in and getting all excited by yet another gear ratio/power/torque discussion, and I've got too many welding burns on my fingers to type a satisfactory argument