SHVS Auto Start / Stop in Turbocharged Engines Confusion

[jonahmano]

We know that Maruti taste of success with their mild hybrid system SHVS for their diesel vehilces Ciaz and Ertiga but my doubt is the turbo charger is a very important thing to take care of and will not the SHVS system be a hinderance in the reliability of the turbo engine?

For example: I have read in the forums that a turbocharged engine should not be stalled immediately after a long run but with the SHVS system a sudden stop would shut off the engine immediately. Though Maruti hasn't said anything about this, will there be any ill effects on the turbo charger if the SHVS system stalls the engine when the break is applied during a long highway journey (for example you are stopping a car to have tea/lunch, the SHVS will not wait for 1 or two minutes it will shut off the engine immediately)

Should the SHVS system be de-activated during long highway runs or is it ok to keep the SHVS on if you are driving the car under 2 rpm and without revving it?

Thank you

 

[bhvm]

You have raised a very valid point mate.
Even the user manuals suggest idling for 30 sec before shutting down.
Apart for the turbo, there can be ill effect on Battery/Alternator and wiring kit, as cranking is known to draw over 100 amps of current! (Could be 300~600A for large SUV diesels).

 

[Alpha]

I guess a delay of 1 or 2 minutes is enough to cool down the turbocharger before stopping the engine. AFA my understanding goes, SHVS won't stop the engine the very moment brakes are applied but will sense that the car has been stationary for a minute (or some preset time) before stopping the engine. So the effect on the turbo would be minimal. In regular cars also, we hardly wait for more than a minute before switching off the diesel engine.

Nowhere is it mentioned that one needs to wait for the turbo to cool down according to the distance driven. The delay does not depend on the kms done and is a generalised 30-60 seconds, no matter if you do 50 kms or 500 kms.

Agreed that there would be an effect on electricals (mainly battery) due to frequent starts and stops, but I guess the energy regenerated during braking would make up for this problem. This would lead to fuel savings without affecting the electricals during start-stop. Maruti researches would have thoroughly thought that out before bringing the technology to the market. Nothing to worry.

Regards,
Alpha

 

[bhvm]

Alpha,
the time delay in Start-stop system is only 10~15 sec in most cars. I do not think its good enough to cool the turbo.

And Indian Hybrids (They're hybirids for namesake) do not have that kind of Brake Energy recovery as you've seen on Nat geo/Discovery etc in Japanese/American Market. What in Indian context about brake energy recovery means alternator is mostly engaged when vehicle is De-accelerating or braking. Indians often get very half baked products.

There are no Electric motor/Generators in wheels do that "Real" Energy generation.

 

[Alpha]

Alpha,
the time delay in Start-stop system is only 10~15 sec in most cars. I do not think its good enough to cool the turbo.

Agreed. At least 30 second delay should be there.

And Indian Hybrids (They're hybirids for namesake) do not have that kind of Brake Energy recovery as you've seen on Nat geo/Discovery etc in Japanese/American Market.

Not Discovery Channel but on our very own TV ads. The latest official ad mentioned about "brake energy regeneration" and that made me think so. Thanks for clarifying.

What in Indian context about brake energy recovery means alternator is mostly engaged when vehicle is De-accelerating or braking.

One question - Is Mahindra's micro-hybrid tech similar to SHVS in functioning?

Regards,
Alpha

 

[bhvm]

2> Haha. You know how misleading these ads are. They blow things out of proportion and add the usual Mirch-Masala.

3> Mahindra Mirco Hybrid= Fancy Name for start-stop tech.
Maruti SHVS= Start stop, Plus Starter and alternator is made in one piece, so Alternator can be used at will of the ECU. (Works sorta for brake energy regeneration)

Inviting more Tech experts to chime in and explain things in depth.

In my definition, Proper hybrid is (1) can be driven in pure electric mode for some time (2) can use both motors (Electric+engine) to accelerate for sports/offroad or extreme terrain. (3) Recharge their Large batteries mostly by using Brake energy or spare power from Fossil fuel engine, I mean there shall be no need to plug your car in Mains socket for Battery charging.

Indian "hybrids" offer none of above.

 

[jonahmano]

I guess a delay of 1 or 2 minutes is enough to cool down the turbocharger before stopping the engine. AFA my understanding goes, SHVS won't stop the engine the very moment brakes are applied but will sense that the car has been stationary for a minute (or some preset time) before stopping the engine. So the effect on the turbo would be minimal. In regular cars also, we hardly wait for more than a minute before switching off the diesel engine.

Nowhere is it mentioned that one needs to wait for the turbo to cool down according to the distance driven. The delay does not depend on the kms done and is a generalised 30-60 seconds, no matter if you do 50 kms or 500 kms.

Agreed that there would be an effect on electricals (mainly battery) due to frequent starts and stops, but I guess the energy regenerated during braking would make up for this problem. This would lead to fuel savings without affecting the electricals during start-stop. Maruti researches would have thoroughly thought that out before bringing the technology to the market. Nothing to worry.

Regards,
Alpha

I'm using a vehicle with SHVS system and when the brakes are applied the engine shuts down in less than 3 seconds.

It's mentioned in the maintaining your turbo charger guide and manuals of certain cars that after a heavy pedalling or long drive we need to keep the engine idle from 1-2 mins but with the maruti SHVS feature, it will shutdown the engine immediately after the brakes are applied

I don't have any worries but more things should have been mentioned in the manual that if you are halting the vehicle then we must idle the vehicle for a couple of minutes by either pulling off the seat belt or putting the SHVS feature off.

 

[bhvm]

"brakes are applied the engine shuts down in less than 3 seconds."
Does this happen when vehicle is Running, Idling, Coasting etc? or only when FULLY stopped?

 

[Alpha]

I'm using a vehicle with SHVS system and when the brakes are applied the engine shuts down in less than 3 seconds.

It's mentioned in the maintaining your turbo charger guide and manuals of certain cars that after a heavy pedalling or long drive we need to keep the engine idle from 1-2 mins but with the maruti SHVS feature, it will shutdown the engine immediately after the brakes are applied

I don't have any worries but more things should have been mentioned in the manual that if you are halting the vehicle then we must idle the vehicle for a couple of minutes by either pulling off the seat belt or putting the SHVS feature off.

Hello jonahmano

I didn't knew that the SHVS feature can be manually turned off. If it is so, owners should turn this off to protect their turbo charger units. Tax savings, and the resulting lower price, should be considered a big enough and only benefit of this feature. Who wants a prematurely failed turbo for a few saved drops of fuel?

Does this happen when vehicle is Running, Idling, Coasting etc? or only when FULLY stopped?

Hello bhvm

3 seconds of being fully stopped I think. Turning the engine off while the vehicle is im motion would damage the gearbox, since the vehicle would be in gear. Also the power steering and brakes won't function normally without the engine fired up.

Regards,
Alpha

 

[stingray91]

Don't worry, let's say svhs system saves u 2% of fuel. And you don't care about turbos, this idling rule is followed by 5% or even less ppl on roads, the probability if turbo failure is 30% if u don't follow this rule, I have seen many cars ridden more than a lack and still going without following this rule, turbo can handle temps safely from 200 °C, on morden day cars , especially BS IV , oil cooler us there, where it brings oil cooled to near coolent temperature, 100° to 120° Max, also the temperature of turbos depends on many factors, external temperature, radiator efficiency , egr (which cools down combustion and in turn turbos) placement of turbo, etc.

Coming to the point, let's consider failure point of turbo is 50k kms, if we don't follow,
If fuel cost is 3rs per km. Then 1.5l , 3percent savings is nothing compared to the new turbo cost.

So let's break this stupid marketing technology and keep our car safe.

 

[jonahmano]

"brakes are applied the engine shuts down in less than 3 seconds."
Does this happen when vehicle is Running, Idling, Coasting etc? or only when FULLY stopped?

When the vehicle is fully stopped.

My another question is if there is any theory of turbo getting harmed when the engine is started within one or two minutes after it's halted. Engine getting shut off is a nice feature especially in city traffic when you can lessen the pollution in cities or stop and go traffic.

Is it ok that the turbo engine shuts down after a long run for a couple of minutes and then start again as it happens in the SHVS engine Start/Stop feature.

I'm very much in plan to switch the feature off when I'm going to halt the vehicle say for 30 mins or higher so that I can idle for a couple of mins but I'm in doubt to understand that if it affects the turbo for shutting it off for a couple of mins and then again start as done automatically by the SHVS feature?

 

[bhvm]

hello jonahmano,
Theories remain theories. Practical world is not perfect.

1> Most of engine wear & tear during start-stop cycles. Because the cylinders /Turbo are not well lubricated (before start), or You are shutting down oil supply & Cooling system on Just hot parts (during stop).

2> Fuel saving is only a theory. Because Start-stop will consume more fuel/Money/Maintenance in average. Alternator will work harder to replenish battery. The other car electrical like sensors, music system etc will keep sapping battery which needs to be recharged after crank.AC compressor will revv up to cool the cabin because cooling was interrupted. Also, Cranking sends spikes throuout the Car electrical systems which could damage High end Audio system, HID kits, Relays and accessories.

3> Never touched the start-stop feature on my XUV 500, Don't even know how it works.

Rest explanation is Given by Sting91