[Aroy]

Originally Posted by REagle&Firefly

..............................
P.S. he has been inflating his conti's to 35 PSI and getting 11 KMPL in city traffic.

Also is there a significant increase in road noise after upgrading to the conti's?

There is a tradeoff between braking performance and fuel efficiency. The higher the tyre pressure the lower the rolling resistance, hence higher FE. But with higher pressure the contact patch reduces, so braking suffers. If you surf the net for very high FE rallies, you will notice that the first thing they do is to increase the tyre pressure to a very high value.

Similarly for better traction in soft soil, you decrease the tyre pressure to around 10 PSI to get a larger contact patch, hence more traction.

Another way to get higher FE is to keep the engine in the "optimum" RPM band. What we seldom realise is that many modern petrol engines are high revving engines and the optimum RPM range is quite high. So if you use a lower gear in the city, say second instead of third below 40 km/h, you may get better FE. I have experienced this with both my Esteem MPFI and the Alto K10. Both love high revs and give better FE at high revs.

[REagle&Firefly]

Originally Posted by Aroy

There is a tradeoff between braking performance and fuel efficiency. The higher the tyre pressure the lower the rolling resistance, hence higher FE. But with higher pressure the contact patch reduces, so braking suffers. If you surf the net for very high FE rallies, you will notice that the first thing they do is to increase the tyre pressure to a very high value.

Similarly for better traction in soft soil, you decrease the tyre pressure to around 10 PSI to get a larger contact patch, hence more traction.

Another way to get higher FE is to keep the engine in the "optimum" RPM band. What we seldom realise is that many modern petrol engines are high revving engines and the optimum RPM range is quite high. So if you use a lower gear in the city, say second instead of third below 40 km/h, you may get better FE. I have experienced this with both my Esteem MPFI and the Alto K10. Both love high revs and give better FE at high revs.

You're absolutely right, I do have a question regarding the "optimum" RPM band. How does one find that out?

[Aroy]

Originally Posted by REagle&Firefly

You're absolutely right, I do have a question regarding the "optimum" RPM band. How does one find that out?

If you can get the Torque curve, then it is easy. The optimum band is where the torque is 90% or more.

Otherwise it is a hit and trial. On an open road try accelerating in 2nd and third gears starting from 20 km/h to 80+. The vehicle will pull like mad when it is in the high torque region.

[REagle&Firefly]

Hi @ChauhanSaurabh I appreciate your patience. I have finally got the snow chain pictures from the person I rented those from. I'll be replying to your query by the end of this week positively.

Regards

[swiftLife]

Awesome post!!!

Originally Posted by REagle&Firefly

I've seen a lot of people spreading hate towards the 4 speed AT. In reality, I believe its the RWD configuration of the Jimny which has caused the 4 speed AT to be sluggish.

I also own an Scross paired to a 4 speed AT and I can affirm that the 4 speed AT with the 1.5 Litre K15B engine is a hoot to drive in the Scross. The same engine and transmission combo are extremely responsive in the Scross.

But this part just completely bowled me over. How does RWD affect the responsiveness of the transmission. Can you please explain to noobs like me

[REagle&Firefly]

Originally Posted by swiftLife

Awesome post!!!



But this part just completely bowled me over. How does RWD affect the responsiveness of the transmission. Can you please explain to noobs like me

Thanks!!

So the RWD has a propeller shaft and the propeller shaft transfers its power to the differential. There is a universal joint between the propeller shaft and the differential.
Hence the RWD has more no. of rotating components compared to a FWD in the same spec and tune of the engine. There are ways to tune to engine to offset this. But when Maruti can't get the pricing right, expecting Maruti to tune the engine is similar to expecting unicorns on Earth.

[swiftLife]

Originally Posted by REagle&Firefly

Thanks!!

So the RWD has a propeller shaft and the propeller shaft transfers its power to the differential. There is a universal joint between the propeller shaft and the differential.
Hence the RWD has more no. of rotating components compared to a FWD in the same spec and tune of the engine. There are ways to tune to engine to offset this. But when Maruti can't get the pricing right, expecting Maruti to tune the engine is similar to expecting unicorns on Earth.

Thanks for explaining!

I just would have thought, okay, instead of a transaxle, the components are just decoupled with few more rotating and connecting bits. How much difference would it have made.
But clearly I was wrong. Learning new things each day

[REagle&Firefly]

Originally Posted by ChauhanSaurabh

Very well articulated. Clearly one needs to choose the priorities and pick one. None of them is perfect. But think by method of elimination and one will definitely strike the chord.

Even if its slow this is one car after Punto that I have been able to make a connect to in the same way. Somehow the slowness in acceleration does no really result into any delays in trip timings at least for local runs(highways need patience). It cuts through traffic almost like a bike.

I am on the lookout for snow chains for my Jim. Can you share which one are you using and any +/- for same?

Hi, sorry for the delayed response.

On the snow chains front, the prime consideration was ease of use in the cold weather. We opted for the snow chain which wasn't cumbersome to mount.

The first image is the snow chains I rented for my jimmy.



It can be clearly seen that this particular snow chain can be closed in a loop. This makes mounting a lot easier. It proved to be extremely beneficial in sub zero temperature.



It is said that the above snow chains are as strong as the army issue snow chains. It is true but I didn't face any issues.

If you're looking to go at a moderate pace, this is the snow chain to go for.

The second option was the following snow chain, which was LEFT Out.



The only reason to leave it out was that mounting this snow chain is difficult. It requires one to go under the vehicle if required. Yes it handles more speed, the army uses this particular snow chain. But I'm not a fast driver especially on snow. I saw cars going down the valley.




If I again have to pick one, I will go with the first one thanks to the convenience I experienced. When your hands are freezing and the metal is just too cold to touch, you just want to get the job done! That's where the first one outshines the other. Its hassle free.

[ChauhanSaurabh]

Originally Posted by starter

I agree with everything except for the mileage on the Jimny.
My Jimny is shod with Continental 215 tyres on stock rims. Other than that, it is completely stock and has clocked 7K kms.
In Bangalore city, i get 9 kmpl and on highways at around 80-90 kmph, i get around 11 kmpl.
I have no idea how you are managing 15 kmpl.

I had Conti 215 for 5k kms until I switched to Apterra AT2 225. A mileage of 12-13 kmpl(mine is 4AT) in Noida Delhi moderate traffic was quite easy for me. Even the roundtrip mileage for a Noida-Adi Kailash-Darma valley trip (approx 1400 kms) was 13kmpl with some spirited run on the return leg since I was is no mood to take a night halt. I had a manual Jimny as company, which was evidently returning almost 20% more mileage in mountains. Overall trip mileage was 13.7 for him.

Originally Posted by REagle&Firefly

You're absolutely right, I do have a question regarding the "optimum" RPM band. How does one find that out?

Without any technical data on torque vs power curve for Jimny, all I can say is try forcing the gear change in AT at around 2k rpms, which is quite easy in 2 to 3 and 3 to 4 in AT Jimny by gently lifting the feet off accelerator. 1 to 2 cannot be less that 2200-2300 rpm, so stay close to it with same technique. The round trip mileage for Noida-Zanskar-Nubra-Umlingla-Noida, approx 3000km was 14kmpl for both the automatic Jimny with Apterra AT2. All this when we took the remotest route or shortcuts possible. Basically we started hating paved road after experiencing how beautifully it behaved over no road.

I did Sissu to Noida in a single tank with low fuel warning popping up only on the last 500meter patch before my apartment

I have gone through this idea of a Petrol AT Thar multiple times before Jimny, but now I am pretty sure the net fuel expenses would have been vastly different on that even with a light foot as mine. By light I don't mean I don't indulge in fun. I have a GAN tuning chip on my Jimny, so I do floor it whenever I find open stretches just to enjoy the free revving lag free nature of this NA engine. the feeling is surreal as it completely masks the inherent lag in AT.

Originally Posted by REagle&Firefly

Hi, sorry for the delayed response.

On the snow chains front, the prime consideration was ease of use in the cold weather. We opted for the snow chain which wasn't cumbersome to mount.

The first image is the snow chains I rented for my jimmy.

Attachment 2694706

It can be clearly seen that this particular snow chain can be closed in a loop. This makes mounting a lot easier. It proved to be extremely beneficial in sub zero temperature.

Thanks for sharing this. Can you get more details on this first one. What make and where to get these from?

[REagle&Firefly]

Originally Posted by ChauhanSaurabh

Thanks for sharing this. Can you get more details on this first one. What make and where to get these from?

Hey, sorry for the delayed response.

Get the snow chains from any accessory shop, if you can, or even bimbra from that matter. All these are generic.
Also, I am at Narkanda right now, it is advisable that if you're travelling in peak winter, get 2 pairs of snow chains. I have one pair with me right now. Even with the chains on in criss cross manner in my Thar, I went into the boundary wall, yesterday night when going down the property slope.

You will rarely use both pairs at once, but it's better.

[ChauhanSaurabh]

Originally Posted by REagle&Firefly

Hey, sorry for the delayed response.

Get the snow chains from any accessory shop, if you can, or even bimbra from that matter. All these are generic.
Also, I am at Narkanda right now, it is advisable that if you're travelling in peak winter, get 2 pairs of snow chains. I have one pair with me right now. Even with the chains on in criss cross manner in my Thar, I went into the boundary wall, yesterday night when going down the property slope.

You will rarely use both pairs at once, but it's better.

Thanks for sharing this. Between my last post and today a friend from Gurgaon found these at Bimbra. But somehow they are suggesting me to buy R16 model for my Apterra 225 70R15. I will visit them and try it over the weekend.

[REagle&Firefly]

Originally Posted by ChauhanSaurabh

Thanks for sharing this. Between my last post and today a friend from Gurgaon found these at Bimbra. But somehow they are suggesting me to buy R16 model for my Apterra 225 70R15. I will visit them and try it over the weekend.

I only see two sizes in snow chains in Bimbra’s catalogue. When I had enquired the one prized lower was for Jimny and the one prized higher was for the Thar.

Also I am a newbie so I can’t reply to any PM’s

[REagle&Firefly]

Originally Posted by ChauhanSaurabh

I had Conti 215 for 5k kms until I switched to Apterra AT2 225.

Any particular reason for switching to Apterra AT 225?
I’m assuming you previously had Continental CrossContact AT.
Also did you consider Ceat Crossdrive AT before waiting to Apterra AT2 225?

[ChauhanSaurabh]

Originally Posted by REagle&Firefly

Any particular reason for switching to Apterra AT 225?
I’m assuming you previously had Continental CrossContact AT.
Also did you consider Ceat Crossdrive AT before waiting to Apterra AT2 225?

Yes, it was Cross Contact AT. Which is a very good tyre but not for my usage. 60% of my usage is on well paved roads in Noida and Delhi. Since Jim is my daily driver as well. Conti CC AT has a very harsh ride quality over such roads and minute undulations. I found it to be worse than Yoko Geolander LT for the urban users. There was a constant bounciness even on smoothest of the road. For somebody with majority usage over rough to no roads, its a terrific tyre with equally good looking treads(not the ideal way to choose a tyre) in 215 section.

I drove a friends Jim with Apterra AT2 on a trip to Adi Kailash and I was completely blown away how well it performed over highways, mild undulations in cities and acceptable off road performance. Conti has a contact patch width of 170mm and AT2 has 175mm. This might be negligible but the difference observed in stability for Jim was noticeable.

In last 6k kms with AT2, including one trip to Zanskar, Ladakh, few off-roading and jungle trail sessions, I am fully satisfied with AT2 for my needs.

I know one would argue why would one need an AT tyre for 60% tarmac usage. I totally agree with the fact that ideal way is to retain the stock HT for city usage and another set for such excursions. But that is a luxury for most city dwellers now to have the space and energy to maintain and swap. But for people like me with such limitations/laziness AT2 provides the best balance of comfort, stability and offloading capabilities.

No, I never considered Ceat Crossdrive as I didn't have any opportunity to drive it. I didn't want to repeat the same mistake. My first lesson in off-roading, not to jump onto any mod until I have a feel of it.