To rev or not to rev. That is the question.

[Sharky]

Mhhh, hadn't noticed this part of the forum. Anyway, here's my question. I've heard a lot of different opinions regarding how much should one rev up the car in normal driving. Some say that you will screw up the engine if you don't rev it up as there is poor lubrication, an uncoplete combustion and the engine is "forced". Others say that if you rev it up you'll damage the engine because there's too much friction, heat, forces, etc etc etc. I heard somewhere that one should always run the engine over the max torque mark. So, for instance, if the max torque of the car should come at 2500Rpm then one should rev it up so that when you shift down the revs fall to 2500 rpms. But, that would mean that if the max torque of the car comes at 5000 rpms then one should always keep it above that rpm level despite being very high.

So, how much should one rev up the car in normal driving.

My particular case. I have a Pug 205 and it's max torque comes at 3200Rpm and the rev limiter starts at 6200 rpms. I always run it between 3000 and 4000 rpms. Am I doing it right or wrong?

[Ray Bell]

Welcome to this brand new forum, Sharky, nice to have a fellow Peugeot owner around here... even if it is FWD!

I think you're doing it pretty well, I wouldn't be afraid to give it a bit more of a rev, but running in the range you are is probably a very good conservative approach.

The lower limit for general running, I was taught, is somewhere comfortably above the point where the engine starts to 'lug' or 'labour', though not far above it. Low revs probably put more side load on pistons under acceleration, though I've never heard the suggestion about oil distribution before.

Let's face it, there's litres of oil constantly being pumped around, and the pump is a positive displacement unit, it pumps the oil as long as there's some there to pick up. The oil to lubricate cylinder walls is that thrown out of the big end bearings as they are fed by indirect pressure through the main bearings, and by centrifugal force.

Ever tried to let go on a fast-turning merry-go-round? I don't think you need all that many revs to keep the oil supply up to the bores... oil is constantly flowing to the bearings, thus constantly tossed at the cylinder walls.

Top revs used constantly will certainly reduce engine life, but most engines are pretty good these days. Also, with wet sleeves, the Peugeot is blessed with just about the best material for bores that you can get. Iron-block engines with one-piece cast blocks (most engines, in other words) have compromises in the iron to facilitate casting, the liners are spun-cast and have excellent density etc.

The one area where you might have problems at revs is in the valvegear. I'm not familiar with your model, but if it's the single-cam version, I understand they tend to wear the cam-following pads on the rockers. Good oil is the answer. The 604 V6 had this problem.

[Sharky]

Well, mine has a 1.1L engine. 8 valves and one camshaft. The engine is the same model as the Citroën AX line (at least for petrol cars), the peugeot 306 and 106 in their 1.4L and for the 1.4L 206 (at least the one made in Chile).

Anyway, Even if I wanted to run the car at lower revs I can't because of 2 reasons. First, living 2600 meters above sea level takes off about 40% on the car's power (unless ytou're running some kind of overcharging) and second, the route I take each day is located "in the mountains" (just to give it a name) so you have to climb a lot and there are some parts that are very steep and the road is very fast as well so sometimes I have to keep it in secong gear at 60+kmph or 3rd gear at 80+kmph.

Oh, and thanks for the welcome. BTW, how long has this part of the board been running?

[Ray Bell]

How long?

Oh, all day....

With an engine that size, I'd certainly go for a few more revs. Have you had any special tuning done to counter the altitude?

I think this might not be a bad idea.

As for my assumption of engine size, we don't get all these models here, the only 205 in Australia has rather larger engines (up to 2-litre?) and they're the up-market twin-cam versions.

I assume it doesn't have fuel injection, which would be designed to compensate for the altitude. Carburettors are generally more of a compromise, and lots of the earth is closer to sea level...

[elephino]

Ray, the 205 was sold in GTi and lesser forms. 1.4 I think.

The 206 is being sold in 2.0 and 1.6L forms.

With 99% of modern cars, where in the rev range you run them doesn't really matter as long as it above where the engine labours, as Ray said. A lot of consistent high revving (ie near the red line) is not very good for the engine and a few WRX STi's in Australia have blown because of this.

[Sharky]

The car has a monopoint Magneti Marelli injection. It does have a compensation system for altitude but it doesn't do much for the loss of power. Mainly it keeps the car from stalling at low revs but can do nothing about the loss of atmospheric pressure (up here it's about 0,6-0,7 atms compared to 1 atm at sea level)

I haven't done any tuning to the car....mainly because the altitude has it's advantages. Because of the lower atmospheric pressure I can run the car with regular fuel (86 octanes) without any problems and that saves me a lot of money.

Some of the 205 GTi (1.9L) arrived here. Also some CTi's and another version of the 205 GTi but with a 1.6L engine.....no relation with my engine though.

[Ray Bell]

Does yours have the engine lying on its side with the gearbox housing partially cast into the lower part of the block?

Talk about French! This was the 104 arrangement...

Why you lose so much power, these facts being given, is that the power you have to have is all still there, the power that's moving the car. But the surplus power has been severely eroded.

That's what you use for acceleration. If it takes 40hp to drive a car on a given grade at a given speed and with given headwind and other conditions, then the horsepower that's there in excess of 40 is the surplus power, and as you accelerate to higher speeds, or strike a grade or get into headwinds, it's reduced.

Sounds like there's nothing you can do about it but have a transplant... any wrecked 1.6 models lying around?

[Sharky]

Ah, the lack of power is a constant in every car over here. In fact, mine does pretty well as in that road I'm usually overtaking a lot of people. We also had a 1.5L mazda and it was the same situation....no choice but high revs. The only car that I've driven that doesn't need a whole deal of revs to make it trough that road is my dad's Renault 19 RSi but that car has 1.8L engine with a great deal more power and torque than mine.