[pganapathy]

What I try to do is do one night drive every week or two and give the car its legs for a bit. Rev it up, drive it hard. Of course, my first priority is doing it safely, but still.

The reason is as simple as using the entire range of revs. I try not to rev the engine in neutral and at standstill unless I am forced to. High revving is one or two drag type drives on empty roads at night.

[TaurusAl]

Originally Posted by pganapathy

I try not to rev the engine in neutral and at standstill unless I am forced to. High revving is one or two drag type drives on empty roads at night.

Can you explain why don't you rev in neutral please ? I find it too difficult to red line my DDiS in city because of its turbo kick over 2k RPM. So I always raise the engine's RPM once in a while in my parking lot. (Diesel Exhaust Smells Awful while reving ).

But, Now after reading your post I am wondering if am I doing the right thing..

[mempheS.D]

My redline's at 6000rpm, but my manual says max power at 5250rpm ie 105bhp. So if I'm only looking at getting out max power, then the only thing I'm doing over the remaining 750rpm to redline is burning petrol with no significant gain, correct ?

[devrajman]

This redlining is called Italian TuneUp. This is done only when all parts of car is in good condition. There are few threads here in which this is discussed. Also here is wiki page:

Italian tuneup - Wikipedia, the free encyclopedia

I do it once in every ~100kms. Mine is '99 Carb Zen with no rev limiter clocked 94K kms. Its recommended to do it when engine is warm, put it in 2nd/1st and try to rev the engine till max (you can take). Take it to 3K then 4K then 5K and lastly 6~6.5K. Keep in each step for few time. Do not go 0->6.5K, this can damage the engine/gearbox/etc.

Some people do it in neutral, but i think this isnt recommended. I do it rarely in my basement to hear the engine roar! Its so awesome feeling...

My tacho shows 7.3K rpm max!

[pganapathy]

Originally Posted by TaurusAl

Can you explain why don't you rev in neutral please ? I find it too difficult to red line my DDiS in city because of its turbo kick over 2k RPM. So I always raise the engine's RPM once in a while in my parking lot. (Diesel Exhaust Smells Awful while reving ).

But, Now after reading your post I am wondering if am I doing the right thing..

If you have a turbo charged engine, NEVER, rev an engine in neutral. The reason for this is that your turbo is spooled up with the revving, but engine oil is not circulating. Understand a good turbo can rev as high as 100,000 RPM and you can understand what damage can be done if there is no lubrication for long periods of time.

What I will suggest is take the car out maybe one night a week and find some long and empty roads and do a drag or two. Should be satisfactory

[IQBAL VEERJI]

This is not pertaining to cars but to my R.E.Bullet. Till about a fortnight my son was revving the engine immediately when kick started in the morning,without realizing that in bullets the engine oil settles down in the sump during the night, thus when started in the morning it takes a while for the engine oil to reach the tapppets and cylinders,So now he has started to let the bike in idling it for a while before riding off.Gurus pls say if it is RIGHT OR WRONG???

[d_himan]

In the i10 AT, pretty often to 5.5K - the autobox doesn't upshift if one drivesaggressively/put overdrive off

Accord AT - rarely over 4K. Pretty tough to redline - accelerates way too quickly for peak hour city traffic.

[carbookie]

Originally Posted by IQBAL VEERJI

This is not pertaining to cars but to my R.E.Bullet. Till about a fortnight my son was revving the engine immediately when kick started in the morning,without realizing that in bullets the engine oil settles down in the sump during the night, thus when started in the morning it takes a while for the engine oil to reach the tapppets and cylinders,So now he has started to let the bike in idling it for a while before riding off.Gurus pls say if it is RIGHT OR WRONG???

The cold engine should not be revved hard. This its true for cars and bikes both.

[Ford5]

This is what happens if you rev or continuosly redline a cars engine. Link to the youtube video

honda civic 2005 engine blow up - YouTube

Found this on pakwheels. You can hear the morons surrounding the car and understand that this was done intentionally. Black smoke from the beginning seems to indicate an existing engine problem. But too bad such a good looking car fell into bad hands.

[JohnKT777]

I drive a Fiat Linea Petrol (FIRE) 1.4, which is naturally aspirated . My odo has clocked close to 40,400 kms. The Fiat Petrol unit is not one of the smoothest around, and is no match for the rev-happy nature of the Honda or even Toyotas. The engine becomes harsh after 4000 rpm, and the rev limiter is at 6.5 K rpm I think. The harshness becomes particularly aggressive post 3K rpm. The engine is not very quiet at operating speeds either. Anything about 2.5 K rpm is progressive louder.

I too have the same queries as above, although I haven't seen any scientifically valid explanations in the thread so far. I don't red-line my car during driving, but do occasionally rev it to close to 6K rpm (I mean like once or twice a month, when car is in neutral, and after the engine has warmed up to operating or near-operating temperature). This is never for more than 5-6 seconds at a time, and never repeatedly. I did this especially this week, after my car was kept idle due to the Coronavirus lockdown for close to 30 days now. I start the car every alternate day, and let it run for 15 mins. I also operate the A/c for 15 mins twice a week.

Still, I am fearful about revving the car to high rpm's especially at neutral. I am worried about engine damage, damage to piston, vales, head gasket among other moving components. But I hear digressive views on this, with some enthusiast drivers recommending this too...I got the following questions to the community:

1. Is revving the car to peak RPM in neutral dangerous? The counter-idea is that there is little compressed gas in the combustion chamber to "cushion" the piston at the top of its compression stroke. Can anyone clarify this please? I read this in a VW drivers forum.

Other arguments I have read are the following:

a. High manifold vacuum at high rpm reduces the pressure over the piston as it passes over TDC is reduced so the stretch on the rods is higher at least on the power strokes and probably also on the exhaust strokes as there is little exhaust gas to displace.

b. Redline with a 4-stroke at exhaust TDC subjects the rod to max tensile loads, but running no load would likely make the former firing TDC load similar, with a slight discount of at least compression pressure * piston area. The end result would double the rate at which those max loads are accumulated. Valve train loads are not much different under power, except maybe the force required to crack open the exhaust valve.

c. When the transmission is in neutral and the engine is “revved” without any load, the spinning engine internals will accelerate, gathering rotational and lateral forces at a faster rate than designed by the manufacturer.


2. Temperature: What about problems in the cooling system? The argument is that when you rev the car in standstill, the radiator will receive less air, thus it will cool the coolant less efficiently. This means that the engine will operate in the higher threshold of temperature. Can any Senior-BHPian clarify this please?

3. Unnecessary wear issue: The engine wears is a factor of the number of revolutions it will do over its lifetime. Will this be considered in the case of my revving the engine at neutral?

4. Piston Compression Ring Expansion: Rapidly revving an engine will heat up the piston rings much faster. Because they have a much smaller thermal mass than the cylinder liners they expand at different rates. If the compression rings expand too much, they will generate increased friction on the cylinder liners, causing the cylinder liners to wear out (reducing compression). In the worst case scenario, the compression ring ends touch, pinch the cylinder liner and will most likely cause the piston to crack. On a very cold engine or while lean (not enough fuel), it is easier to get a larger thermal differentiation between the cylinder liner and piston rings. The cooling system is not able to help, as piston failure happens within 4-10 milliseconds after a hotspot develops on a piston or compression ring.

5. Oil System Starvation: The issue is that the cylinder head & block doesn’t drain the oil at the same rate that oil is pumped out of the sump, leaving the sump empty. Apparently, this is common in engines that don't have the minimum oil required. Engines that are not serviced have dirty oil systems and are prone to blockages at high rpm. This can also be caused if the block uses the same pipes to drain the oil that is also used to ventilate the sump causing oil vaporisation. (Is this applicable in contemporary Indian cars of BS-IV? ) Some poorly designed oil pumps (and water pumps too) can aerate and are unable to pump oil when increased in rpm too rapidly.

6. Connecting Rod Warping: Some con-rods will stretch/bend during excessive rpm acceleration. Worst case scenario is it will put greater unbalanced forces on the crankshaft and bearing. It will also bend valves. Can any BHPian clarrify this?

7. Crankshaft warping: The crankshaft isn’t designed to withstand a sudden increase in internal force (similar to harmonic imbalances). It only takes a thou or two (0.0254 - 0.0508 millimetres) for the crankshaft to gouge a main bearing. Taking an engine to high RPM under load (where the piston is cushioned at the top of the stroke by a large charge of fuel/air) is far better than to reach the same RPM unloaded. An unloaded engine, with a relatively small fuel/air charge, relies entirely on conrod bearings to stop the piston at the top of its stroke. in a "loaded" engine, the large charge and therefore high compression pressure, cushions the piston action.

BHPians, it will be great if someone could clarify these above concerns with suitable explanations and examples so that we don't have to rely on hear-say and personal testimonials. A good explanation would trump hunches and innuendo any day....would help me a lot as well...please!

[Kosfactor]

Originally Posted by JohnKT777

BHPians, it will be great if someone could clarify these above concerns with suitable explanations and examples so that we don't have to rely on hear-say and personal testimonials. A good explanation would trump hunches and innuendo any day....would help me a lot as well...please!

Some bits from the Fiat Linea user manual I found on the internet.

"HOW TO WARM UP THE
ENGINE AFTER IT HAS JUST
STARTED
(petrol and diesel engines)
Proceed as follows:
❒ drive off slowly, letting the engine turn
at medium revs. Do not accelerate
abruptly;
❒ do not demand to performance for the
first few kilometres. Wait until the engine coolant gauge starts moving."

DRIVING STYLE
Starting
Do not warm the engine up with the car
standing: the engine warms up very slowly in these conditions, increasing consumption and emissions. It is advisable to
start off immediately and slowly keeping
the engine speed down: the engine will
warm up much faster this way.

I`m sure there is a lot more than what I could read, go ahead and give it a shot.

[bharatbits]

I drive a 2016 Linea Diesel. I revv the engine while in motion probably once a year when i find the car to be a bit sluggish. It emits quite some amounts of black smoke and the engine feels nimble again. This happens when i am approaching the service schedule of 15000 kms.

[Sreesh1009]

I have a 2005 Santro and a 2014 Amaze AT.
The Santro has a very raw and nice revv. The Amaze on the other hand doesn't sound that great and very free revving for some reason.

[speedracer05]

There is some theory around regularly revving engine to high RPM to unclog the engine and clear carbon deposits. This guy goes into some details -

https://www.youtube.com/watch?v=5C9Ie4BcYew

[kiku007]

You can trust Jason Fenske to get into the details and try to separate milk from water.

I really feel for people who think revving the hell out of the engine in their parked car is going to help. There's a reason why my car has a low rev-limit when the transmission is not in D.

I own a car with a Direct-injection engine and one of the perennial issues I have is engine-misfiring due to carbon deposits. The engine will make a metal pinging sound once in a while during heard acceleration/heavy load. Example: Driving pedal to metal on a incline.

The car sees some spirited back-road runs and goes to the track once in a while. You can be certain that the engine is revved and loaded very well.

The engine goes through what's called as an engine-upper cleaning every six-months and the dealer has even done a engine soak cleaning.

None of the above has resolved the car carbon deposits issue.

For me,
The Italian Job - Yup.
Italian Tuneup - No, thanks.