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Old 13th May 2004, 19:47   #1
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One query i have is...is there any system on sports cars which can be used to drive them in economy mode when u r not in the mood to be a boy racer? and is it cheap?
I mean like in a v10 engine can we use only one bank of cylinders if required and get more efficiency?
Or are there any presets for power and torque curves to get more mileage or more power?
If such techonology is made available in our road cars like the Vtec we can possiblely enjoy the best of both world's.
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Old 14th May 2004, 08:47   #2
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Quote:
Originally Posted by [b
Quote[/b] (Wraith @ May 13 2004,18:17)]If such techonology is made available in our road cars like the Vtec we can possiblely enjoy the best of both world's.
Hi Wraith,

One of those technologies IS the VTEC !!!
Look at the Acura NSX, almost everyone will agree that this was a supercar that was as tame as a daily driver when you wanted it to be. This was almost totally due to the VTEC engine.
Other such features that exist are auto/SMG etc transmissions that let you choose the driving style and hence shift points.
Electronially lockable suspension components and adjustable suspension also help in this aspect.
Some of the large engined luxury cars have the option to shut off cylinders when in cruise mode, but i havent heard of a "sports car" that has this feature...

thats all for now..gotta run
cya
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Old 14th May 2004, 09:17   #3
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Hi I think the new cadilac sixteen prototype and few other road going cars will be having this soon. I dont know of any sport cars which have then yet, but I am sure if chrysler comes out with ME-4-12 thats what it would have...

OOps I didnt say what it is..eg sixteen is actually a 16 cylinder engine, but when in city driving you dont floor gas only 4/8 of the cylinders run, but when you do floor the gas all the cylinders kick in, I dont know if that adds lag, but I am pretty sure it would be configurable(2 allow or not to, something like what intel does with speed step)

so this would make the car extreemly economical and powerful depending on what you want..

Cheers
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Old 14th May 2004, 13:04   #4
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Yup Vtec is meant for best of both worlds...but we dont really have control over what the system is doing.
Can we have mode's like city driving or boy racer which at the press of a button will change the engine power and torque characteristics to suit the occassion? and instead of the ecu selecting the number of cylinder's working we can choose how many cylinder's to work it would just make driving more
interesting.
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Old 14th May 2004, 22:49   #5
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Well the Accord V6 (US) also comes with this function. It's called VCM or Variable Cylinder Management. It's works in the same way the Cad engine works.

When flooring the throttle all 6 cylinders do duty but 3 get sacked as the ECM senses the driver's need to cruise.

So you can drive a M800 "3 cylinders" in the city and turn it into an S Class "6 cylinders" when you hit the highways.

I'm not sure if the Accord V6 sold gere has that option, but it did manage 13.1 kmpl during the OD road test where as the Sonata V6 with a 2.7 ltr engine producing almost 55 bhp less could manage just 9.8 kmpl under the same driving conditions.

I think another way would be to set your overdrive gear, such that when you cruise it can be kapt at a low rpm where min power can be used to propel the car at that constant speed.

Another way is to used hybrid engines "combination of a petrol engine and an electric motor". The Acura DNX is a prototye which produces 400 bhp but can still average around 14.5 kmpl. How about that!!!

Regards...
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Old 20th May 2004, 23:09   #6
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Aha this reminds me of a discussion i had with Dom sometime back.

Though this technology is nearly coming to light, one where u can shut down half the cylinders, there seems to be a problem with the thought. Now if 4-cylinders work, while the other 4 are shut down in a V-8, the problem would be that those cylinders and part of the engine block would be subject to high amount of stress and strain leading to early wearing out of that part of the engine. Which means, your engine life is probably halved in the process. How will companies manage to work around this problem is something we have to wait and watch. One possibility is there could be sensors on the engine block directly connected to the main micrprocessor chip onboard which would constantly feed information about wear of the other parts so that the wearing out is evened-out in the process. Its all a possibilty, but we have to wait n watch.

Keep Revvin
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Old 21st May 2004, 00:36   #7
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Now why would there be a strain? When the Accord V6 shuts off 3 cylinders the capacity of the cylinders doesn't change.

You'll still have a 1.5 ltr 3 cylinder engine propelling the Accord. It won't put much load on the engine as the car is not accelerating but it's just maintaining that speed.

Regards...
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Old 21st May 2004, 00:42   #8
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Shan2nu

with regards to what u said, yea true it will work like a 1.5 litre. But when u run it as a 3 litre engine, the cylinders which run it as a 1.5 will have more strain and would wear out faster. Its not very practical unless engineers have come out with a way to beat it.

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Old 21st May 2004, 01:06   #9
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Quote:
Originally Posted by [b
Quote[/b] ]he cylinders which run it as a 1.5 will have more strain and would wear out faster
I would disagree with this. Take my Vtec for example...It needs nowhere close to the 106 bhp it makes when I am cruising at 100kph odd on the highway. Similarly, the S Class and the V6 Accord only shut off the cylinders when the driver is not demanding outright acceleration out of it, just cruising along. When the power is required, the rest of the cylinder bed it switched on.

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Old 21st May 2004, 06:40   #10
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Quote:
Originally Posted by [b
Quote[/b] (Revvmaster @ May 20 2004,23:12)]But when u run it as a 3 litre engine, the cylinders which run it as a 1.5 will have more strain and would wear out faster.
Hey Revv,

There wont really be more "strain" because the half of the engine working will not be required to be doing more than say maximum 45% of the work.
However, i see what you mean, in the sense that if your car has done 50,000km total, 25,000 of which has been run on half cylinders, half the engine has opened up to 50k-km and half it "tighter" at 25k-km. But, once again, i still dont see this as a major problem.

Maybe a more specific explaination of what you mean would help us get what your thinking.

cya
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Old 26th May 2004, 17:01   #11
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Hey guys check out the latest AutoCar India issue...it has got some of the answers to our very queries in here!!! The article is awesome!



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Old 26th May 2004, 18:09   #12
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they must have been reading this thread....LOL
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Old 26th May 2004, 18:35   #13
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shutting of cylinders is a very efficient way and harmless one at that.. the ecu are programmed to guage the load and adjust the cylinder firing.. and while cruising at speed the amount of power req is quite less compared to acc and while negotiating slopes..
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Old 26th May 2004, 18:39   #14
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reg wear, shutting down means, cutting of the fuel or regulating.. not that the pistons n the parts r stopped from running.. so even wear is possible i guess :P
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Old 26th May 2004, 21:02   #15
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Thanx Jaggu. You've finally answered my doubts.

Revv
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