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Old 21st January 2014, 17:16   #76
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Originally Posted by GTO View Post
Why was NOTHING impressive about this engine highlighted in the press release? All we see as of date is lower power figures than their naturally-aspirated competition, SOHC & 8 valves.
Didn't you know that Tata feel SOHC + 8 valves are more important?

Can we send some Marketing guru from our side to Tata to help them communicate better to sell their products and create the awareness?!

Tata guys need a break and a holiday before they do any advancement.

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Very good point. Tata's diesels are highly economical. But they couldn't sell when the market was diesel obsessed!
Their diesels are good and economical but not refined silent which is the need of the hour if they intend to sell.

Anurag.
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Old 21st January 2014, 18:57   #77
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by a4anurag View Post
Tata guys need a break and a holiday before they do any advancement.



Their diesels are good and economical but not refined silent which is the need of the hour if they intend to sell.

Anurag.
The famed 25kmpl CR4 engine returned a puny 16kmpl when we had travelled it for a trip. The driver rarely exceeded 90kmph and was a middle aged sedate driver. He was not impressed with that and told he brought the vehicle only for the promised FE.

As GTO has mentioned, they go wrong when it comes to portraying features. When they launched this engine, they should have highly stressed about how they have optimised it for efficiency and driveablity. That would have reduced half the brickbats it got in this thread itself. When they start with the introduction of an all new first time technology, we certainly have the right to expect something new in terms of specs. The final production specs may change. To be honest when I saw the word 'Revotron' I had a different picture in my mind. That entire picture was shattered when I saw the specs. Instead if they had a name based on efficiency, economy, optimisation etc I wouldnt have been disappointed to see 85ps.

The Xeta had an ARAI efficiency of 14kmpl, less than a C segment sedan with a 1.6l engine, read Fiesta classic, SX4, old Verna and the like as each had >15kmpl figures. At the same time the 1.2l gave out mere power compared to competition. Now there is a bump in power due to the TC. How much boost in mileage can be expected given this criteria? If the jump in FE was really high, I dont find a reason why they cant exhibit that in the spec sheet. At least an estimate could be given assuming its used in the vista. That will say a lot IMO rather than just using adjectives before each point in the brochure.

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The name "Revotron" looks like the result of some guy high up in Tata watching too many Transformers movies.

Last edited by audioholic : 21st January 2014 at 19:16.
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Old 21st January 2014, 19:04   #78
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

The name "Revotron" looks like the result of some guy high up in Tata watching too many Transformers movies.
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Old 21st January 2014, 21:15   #79
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by audioholic View Post

The Xeta had an ARAI efficiency of 14kmpl, less than a C segment sedan with a 1.6l engine, read Fiesta classic, SX4, old Verna and the like as each had >15kmpl figures. At the same time the 1.2l gave out mere power compared to competition. Now there is a bump in power due to the TC. How much boost in mileage can be expected given this criteria? If the jump in FE was really high, I dont find a reason why they cant exhibit that in the spec sheet.
The reason for an outstanding FE being "Its an Italian Petrol Engine".
Now they are tweaking "so called Saffire engine" (As per what we know). If i am not wrong, the new engine would prove Xeta engine's younger brother.

I would love to see TML proving me wrong.
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Old 21st January 2014, 21:33   #80
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I am sceptical about Tata's petrol foray. Do Tata have something up their sleeve for petrol cars which we do not know about? Are they making a statement by first displaying a petrol engine?

By the way, what happened to the Nano's CRDI? Will it be used elsewhere?

The CR4, from what I have heard from users, gives around 22-23 kmpl.

The USP of Revotron could be driveability and good FE what with the peak torque available from as low as 1750 which is quite an achievement.

After all, they only showcased the engine, not the car itself. That might be the reason they didn't highlight its strengths. But why display the engine in first place?

Last edited by simplyself : 21st January 2014 at 21:43.
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Old 21st January 2014, 21:38   #81
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by RSR View Post
There is a reason why they have tuned the engine to 85PS (which sounds modest for a 1.2 turbo-petrol) especially when naturally-aspirated 1.2 petrols with variable valve timing from Hyundai, Maruti Suzuki and Honda produce 84PS, 87PS and 88PS respectively. Even Chevrolet's 1.2 NA motor without variable valve timing produces 86PS. So why is Tata's turbo-petrol producing an output that is comparable to similar size NA petrols?

It's NOT about the power, it's about the torque! In fact, it's about the torque that can be handled by their TA65 gearbox.

It's a known fact that the TA65 can safely handle only around 140Nm of torque or thereabouts. This gearbox with some tweaks will continue to do duty with this 1.2 Revotron, apart from the 1.4 CR4 and TDI engines.

Tata's 1.4 lit. CR4 (an improved DiCOR engine) is a pretty advanced unit, with 16 valves, twin cams and a variable geometry turbocharger. Yet it churns out a modest 70PS only, which is similar to the old 8v SOHC indirect injection turbo-diesel. This is because the torque had to be limited to 140Nm due to the limitations of the TA65 gearbox. Therefore, Tata concentrated on improving fuel efficiency and drivability of the engine, instead of going for maximum output.
If torque is the limiting factor, It still doesnt explain the lack of power.

PS: to the people who are asking why tata can't coax enough horses out of this engine, they used to have a 1.4L dohc mill which churned out 100+ horses with just 124 Nm at 1800 rpm , without a turbo!

and this engine was used with the TA65 GB methinks (any guesses which vehicle?)

Last edited by greenhorn : 21st January 2014 at 21:43.
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Old 21st January 2014, 22:07   #82
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

Good effort by engineering but like GTO said, a very poorly written press-release by marketing

ACI have done a huge favor to TATA by digging deeper, analyzing it more detail and showcasing its virtues.

Its all about torque at low rpm and this is where Revotron beats the competition hollow. Only thing remaining is to see how well lag has been addressed

Quote:
The less noticed but arguably more significant performance figure in the real world is the torque output, and here’s where Tata’s new engine has the others beaten. It produces a meaty 14.3kgm from as low as 1,750rpm to 3,500rpm.

The average max torque the naturally aspirated engines on this list produce is about 11kgm, and you have to rev most of them all the way to about 4,000rpm to reach it.
worst of the lot being the Chevy Beat where torque peaks at 5000 rpm


Source:
http://www.autocarindia.com/auto-new...on-370051.aspx

Last edited by Mpower : 22nd January 2014 at 18:41.
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Old 21st January 2014, 22:29   #83
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by greenhorn View Post
If torque is the limiting factor, It still doesnt explain the lack of power.

PS: to the people who are asking why tata can't coax enough horses out of this engine, they used to have a 1.4L dohc mill which churned out 100+ horses with just 124 Nm at 1800 rpm , without a turbo!

and this engine was used with the TA65 GB methinks (any guesses which vehicle?)
The Indigo XL's petrol engine does produce 101PS. The motor is also used in the Indigo XL cabs (if they are still being sold, that is) with a CNG kit. In CNG mode, it produces 86PS and 105Nm. In petrol mode, the output is 101PS@6100rpm & 124Nm@3500rpm. It does use the staple TA65 gearbox, as the peak torque generated is only 124Nm, which is well below the CR4's and Revotron's 140Nm.

http://cars.tatamotors.com/IndigoXL/...L_Brochure.pdf

There is a key difference here. This 1.4 lit. 16v twin cam mill is a high-revving naturally aspirated Mpfi engine, and not a turbo-charged one as opposed to the 1.2 lit. Revotron.

So while it can produce 101PS at a dizzyingly high rpm (for a Tata engine ), it's torque stays well within the limits of the gearbox.

The 1.2 Revotron T, on the other hand, is basically a Xeta's 475PL motor with a turbo bolted on. So it's torque would go up disproportionately to its power (when compared to the high revving 16v twin cam on the Indigo XL). The 85PS is still produced at a low-ish 5000rpm, which is similar to the Xeta.

If Tata were to use a more powerful version of this engine (say 100PS) with a big turbocharger, then the torque would probably go up more, which the old TA65 gearbox cannot handle. I don't think they have a compatible gearbox that can handle the torque for now (the utility vehicles ones' that handle more torque must be different in size and layout). So till the time the gearbox is ready, this will have to do. They did hint that a new gearbox is on the way, according to this report:

http://indianautosblog.com/2014/01/t...-petrol-113680

Last edited by RSR : 21st January 2014 at 22:47.
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Old 21st January 2014, 22:36   #84
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by Mpower View Post
Only thing remaining is to see how well lag has been adressed
Idling rpm of a petrol engine is near about 1000 rpm. And max torque starts from as low as 1750 rpm.

So do you call 750 rpm difference in a petrol engine as turbo lag? I dont think so this can be called as a big turbo lag for a petrol engine specifically.

The major advantage what I see with this engine is fantastic driveability and if I am not expecting too much a good fuel economy.

Gear shifts will be minimum and less amount of use of clutch and gear.
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Old 21st January 2014, 23:46   #85
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

If you look at this introduction of new engines with a macro outlook , you`ll notice that Tata`s sales numbers over the past couple of years have seen a downhill path losing their position to Mahindra earlier and recently to Toyota so they needed to create a differentiator value add in their offerings ,generate volumes and regain the lost ground on their home turf.

They will be the First Indian OEM to offer a Turbocharged petrol (Read:in mass segment unlike Volkswagen who kicked off the proceedings with a rather premium offering) . The kind of specs(85 ps, 140Nm 1750-3500rpm) are on offer surely implies that they want to satisfy the bigger chunk of masses who want an all rounded performance from their machines rather than few insatiable enthusiasts.
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Old 22nd January 2014, 00:54   #86
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

Tatas always create a flutter when they do things first. When turbocharged petrol cars are being offered at a higher price than naturally aspirated ones, if Tata offers a turbocharged car at a comparatively lower price then they can use this opportunity coupled with good after service and reliability as an advantage. Fingers crossed.
Talking about the engine specs, I am too confused to comment. I drive a Honda Brio (4 months old) and my dad drives a Beat diesel (2.5 years old). I feel Honda lacks initial punch, it just doesn't pick up that fast when overtaking or starting from zero when loaded with 5 persons. Plus, the average fuel consumption reduces when driven in the range of 3000 to 4000 rpm (where all the torque lies). It can easily go above 120kmph though. Compare that to the Beat diesel, I do wheel spins even with my whole family on-board and a full boot, overtaking is faster than Brio, but it struggles above 90-95 kmph. All this action takes place around 2000 rpm so fuel consumption is comparatively low.
I think Tata is trying to hit the sweet spot where torque and bhp are favorable for both fuel efficiency and power (the specs are closer to the strong points of Beat diesel (150 Nm at ~1750 rpm) and Honda Brio (~88 bhp) ). Lets see how it goes when they launch a car with this engine, the power to weight ratio will be a crucial factor. Eagerly waiting for a team-bhp review !
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Old 22nd January 2014, 01:36   #87
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by amit_purohit20 View Post
Idling rpm of a petrol engine is near about 1000 rpm. And max torque starts from as low as 1750 rpm.
No It isn't. For a 4 cylinder it is generally 700+/- 50.
Manf. are going down on idle RPM to improve FE at the expense of Durability & NVH.
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Old 22nd January 2014, 01:43   #88
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

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Originally Posted by amit_purohit20 View Post
Idling rpm of a petrol engine is near about 1000 rpm. And max torque starts from as low as 1750 rpm.

So do you call 750 rpm difference in a petrol engine as turbo lag? I dont think so this can be called as a big turbo lag for a petrol engine specifically.
I didn't say there was!

If I had to take an educated guess, lag should be zero to nil for 2 reasons

1. its a 8v engine (2 valves per cyl). That itself will ensure good low end torque
2. Its power is 20 bhp down on the same disp 105bhp Polo Tsi, which tells me its a teeny tiny turbo (which is good for lag)

But lets wait and see!

Lastly, there is no such thing as "Idling rpm of a petrol engine is near about 1000 rpm"
BMW's E90 NA petrol engine has a 600 rpm idle

Last edited by Mpower : 22nd January 2014 at 18:40.
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Old 22nd January 2014, 07:35   #89
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

Quite a brave move considering the market is now all about diesel dazzle mileage. Keeping aside a few folks on this forum, I don't see anyone buying petrols. Every time I see a Swift or an Amaze, the badge that I see 99% of the time is a I-dtec or Ddis. For a company like Tata which has always had strong focus on diesels, a turbo petrol is a surprise. This is good but I'd wait to experience the engine. Apart from the exhaust note of a Indica Xeta, there was nothing else to highlight about the engine or the car.
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Old 22nd January 2014, 09:30   #90
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Default Re: Tata Motors introduces 1.2L turbo-petrol Revotron engine

What is this big hullabaloo about this engine is low on power, it is not even 100bhp etc etc? Is 100bhp the holy grail? Or is a car going to be fast with 100bhp? Lets first see where is this engine going to be used. Only power is meaningless without the associated gearbox and the drive train and the car. 85bhp in a light weight 800kg car is stonking performance compared to 120bhp in a 1.5 ton car.
Even discussing about the torque or the turbo is meaningless, not to mention silly talk about 'expected' turbo lag, using only the engine specs. First let this engine be coupled to a gearbox, drive-train and a body, and then we can discuss its merits or lack of it.
Example: The most meaningless waste of an good engine is the old and new Hyundai Verna. A great engine in an atrociously designed borderline unsafe car, which cant corner or hold decent speeds on a wavy road. Now putting the same engine in a good Fiat Punto or a Ford Fiesta, would see the makings of a great car.
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