Changing Gears at a High Rev Count?

GusherING

Hey guys, just a query for you. I'm driving a 1.8 litre VW Passat Estate and just wondering if its a good idea if, when I'm in second gear and moving into third (or moving from third into fourth) to let the rev counter go as high as 3000 or so, I usually change about 2300/2500 cos anything above that and the engine really revs up if you know what I mean. I'd just like to find out if I'm doing much damage to the engine, cos it doesn't sound too good. Thanks.

JB123

I like changing @ 8500rpms .Is this a petrol car?

Esel

The redline (on the rev counter) should be about 6500/7000 rpm FFS! Is the car new? If so, read the owner's manual re running in the engine, building revs etc. You won't do it any favours by keeping the revs so low all the time. Ask your mechanic TBH.

Maybe it's diesel? If it is, the redline may be lower, and lower rev gearchanges are more normal.

causal

You should take your foot off the accelerator when changing gear.
After selecting a new gear, as you release the clutch you should gradually start accelerating again so that the, er, gear speed matches the engine speed. There should be no clunk or drag as you release the clutch.

If the engine is over-revving when changing gears then you'll wear your clutch out quicker than normal.

Normally for a given speed the revs will drop by about 1000rpm when changing up one gear.
So if you change up one gear at 2500rpm, you should be expecting to be at about 1500 rpm in the higher gear.

But you don't want to be looking at the rev counter the whole time - better to be familiar with the sound of the engine. Always try and be smooth.


hth,
causal

AMurphy

Do whatever feels comfortable for you and the car/engine /gearbox.

2K or 7K, whatever works. However the average VW is not your "No Flywheel" Italian sports car, so anywhere you choose is good.
Frankly, I'd suggest somewhere about 3500... and be quick about it.

SouperComputer

redline on my 1.6 passat is at 6100, even if pushing hard i wouldnt rev above 5500 as it makes too much noise and produces no power!

Dagon

I got a Honda Civic recently and I'm having lots of fun with the revs. My last car had no revometer - it's a whole new world

I was actually going to ask a similar question, because recently I've gotten into the habit of getting revs up really high when I want a bit of power. The car is a petrol 1.4i, but is *very* lively when I get those revs up, it just takes off big time.

Often I will be tipping away nicely in 5th at 3000rpm, then if I need to overtake or just want some serious acceleration on a safe stretch of read I will drop her down a gear or two and get her up to 5500+rpm, then she takes off like a sports car! The engine gets a lot louder of course, so perhaps I shouldn't be pushing the car like this? The redline is around 8000 I think, although I don't think I've even hit 7000 yet.

Just wondering is this ok for my car, or am I in danger of burning anything out? I take it that as long as I don't redline, the head gasket is not going to blow. Also, I should say that I don't drive like this very much, I only do it when I want more power (I'm not driving around the carpark at 6000 rpm in first gear, lol)...

causal

Below the redline you should be fine.
Think: Red Line = Engine Damage

If you always rev it highly then things will need replacing sooner than if poot-along-Pete was driving it, but nothing should blow or break. Of course you need to keep it serviced properly etc.

causal

Tobias Greeshman

Its not just a matter of, under the red line and your fine. This is not always the case, if you rev the engine to close to 4000rpm frequently enough, you WILL damage your engine â la cam/valve/crank damage. My fathers a mechanic and I used to work with him, so I aint trying to sound intelligent by saying this.

Dagon

silas wrote:

if you rev the engine to close to 4000rpm frequently enough, you WILL damage your engine

That's basically what I wanted to know. Some people say, under the redline, and you're fine. But I guess keeping the revs up a lot can't be too good. That said, 4000 is quite low, is it not?

mike65

Trust an old fella - change gear at the point where you'll gain momentum, anything higher is a waste of fuel and adds wear (as stated above).

Mike.

Dagon

I agree Mike, and this is what I usually do when I'm driving. I'm a safe driver and I take care of my car, and drive it sensibly... but....

I'm just curious if the odd blast of high RPM to get more horsepower is ok for my car or not? Everything in moderation and all that!

mike65

4000 rpm in most cars is quite high enough in truth. The ocassional blast is not going to kill your car but just make sure its done on a warm engine and in a progressive fashion. Cant stand to hear ppl jumping on the gas in low gear you know the valve gear is going "stop please stop!"

Mike.

Squirrel

Then again, look at all the classic Ferraris, the ones that are used on tracks are generally in better shape due to the fact they are taken to high revs, this is most likely due to the fact that they are Ferraris. My advice is don't do anything stupid, ie: anything you'd do in a rental car

Armen Tanzarian

Its ok to drive to the red line once in a while. I did it constantly in my golf gti, I figured I'd bought a gti, its built to be driven fast. Not the case, 1 new clutch, gearbox, oil pump, engine rebuild, Its a 01 with 30,000 miles cost me a fortune.
The same goes for any car, you redline a ferrari all the time it will break, the name just makes it more expensive to fix.

Squirrel:
"look at all the classic Ferrari s, the ones that are used on tracks are generally in better shape due to the fact they are taken to high revs, this is most likely due to the fact that they are Ferraris"

What a ridiculous statement.

causal

When to change depends on what you want your priority is:

Fuel Economy - never go above 3000rpm (petrol anyway, lower in diesel perhaps)
Speed - change at the rpm where your power drops off*
*you can either get ur car dyno'd or look at the users manual

Generally the more highly tuned an engine is the less reliable it is and the shorter it's lifetime.
Car engines are typically tuned for torque, reliability and longevity; not racing.

causal

Squirrel

I'm talking about the ones that are owned by the track, my uncle was a Ferrari mechanic in England and he regularly had to deal with blown engines from cars not used often, and they blew when taken to high revs, whereas the rack cars made do with regular servicing, because they were used.

Ernie Ball

causal wrote:

When to change depends on what you want your priority is:

Fuel Economy - never go above 3000rpm (petrol anyway, lower in diesel perhaps)
Speed - change at the rpm where your power drops off*

HP or torque?

causal

Sorry Squirrel my reply wasn't directly in response to your post - it was just a follow up to earlier posts.

But what you're saying makes sense - an unused car suddenly having it's nuts revved off is going to cause problems. Oil doesn't do much for an engine when it's just sitting in the sump, rust forming, rubber perishing etc.

causal

causal

Ernie Ball wrote:

HP or torque?

Power (kW or HP). The torque curve tends to drop off at lower rpm than the power curve.

causal

Alun

Surely it depends a lot on the engine, what the red-line is and the shape of the power and torque curves?

I had an MX-5 once, and if you'd changed up at 2,500 rpm every time in that you'd never get anywhere very fast. The red line on the 1.8 is at 7,200 rpm and taking it to 4 or 5,000 rpm before changing up for the 5 years that I had it, driving it on a regular basis, never did it any harm at all. In fact if my wife drove it for any length of time (and she is of the change up at 2,000 rpm persuasion, because it's "too noisy" otherwise) I could tell afterwards. It needed a good blast afterwards to get it back to "normal".

It also clearly has to do with what you're trying to achieve at the time, and putting an arbitrary limit on revs that is valid in every traffic situation is not very hepful IMO. If you need to accelerate briskly, such as when joining a 100km/h dual carriageway, you just have to do what's necessary and not rely on arbitrary self imposed "limits".

causal

That's in agreement with with my earlier post

causal

AMurphy

Ernie Ball wrote:

HP or torque?

Peak Torque is what gets you peak acceleration. The power is just a function of the torque x RPM.

GusherING

silas wrote:

Its not just a matter of, under the red line and your fine. This is not always the case, if you rev the engine to close to 4000rpm frequently enough, you WILL damage your engine â la cam/valve/crank damage. My fathers a mechanic and I used to work with him, so I aint trying to sound intelligent by saying this.

Thats what I thought, my cars a petrol eng., by the way. My red line is about 6000 or so, I'd never go past 4500 anyway, I'm just wondering if its alright to even get up to that sort of number. Thanks for all your opinions guys, I appreciate it.

unkel

AMurphy wrote:

Peak Torque is what gets you peak acceleration. The power is just a function of the torque x RPM.

Exactly! And there are big differences between engines. The torque curve will show you the best gear changing moments for maximum acceleration

The 0-100 times a manufacturer quotes for a car can only be done as quick if you know these points. If you don't, your car will be slower than advertised :eek:

What I do about revving high: I never go over red line minus roughly 2k rpm until engine is fully warmed up

The engine is not gonna blow if you'd try going over the red line - the rev cutter will prevent that

RicardoSmith

My old CRX was gutless under 4500rpm. You really needed to be between 6-7k to get any oomph. Was driving a turbo diesel astra recently. That also was gutless under 3k. But between 3 and about 5000rpm there was a real surge. No point going past that however. Then another (none turbo) diesel golf we have is best at around 3K. No point reving it those much further.

It all depends on the engine. Every engine has a different power delivery and a different torque curve. You need to drive accordingly.

AMurphy

Just checked and changing at 3K is fine for relaxed driving, but for a brisk entrance onto the highway, 3500 to 5000 is fine. If needed, a quick burst to 5000+ in 2nd gets things moving quickly, but that's reserved for critical situations.

davkav

in the car manual it should have a graph of torque and bhp against revs. this should roughly tell you where your bhp peaks before it starts dropping back down. driving at high revs all the time though is bad for the engine it puts it under alot of pressure and strain which can cause oil leakage

Ernie Ball

AMurphy wrote:

Peak Torque is what gets you peak acceleration. The power is just a function of the torque x RPM.

This site seems to suggest that you're wrong about that and it makes some sense. Just looking at the torque peak doesn't take the gearing of the transmission into account.

davkav

im driving a opel astra 1.4dohc basically the peak bhp in my car is 6000rpm and then you can physically feel the power dropping off so when im feelin a bit mad i rev it all the way up to 6000. I have an inductoin kit in the car though so the rated max bhp at rpm is probably lower. When i got this kit from ripspeed in halfords of all places the difference in acceleration and power is much better. I put the old filter back in at one stage to see what it was like and the sluggishness of the car was unreal. If I drive the car normally i.e. never over 4000 Im getting more miles to the gallon also. I think manufacturers dont put cotton filters in instead of paper because in the long run the paper ones are cheaper, unless of course you buy a mercedes or bmw

davkav

AMurphy wrote:

Peak Torque is what gets you peak acceleration. The power is just a function of the torque x RPM.

Eh isnt it the case that shifting at peak BHP gives you the best acceleration. Torque doesnt really matter in european cars when it comes to acceleration unless its a 4.0L mustang or something