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Old 17th January 2022, 16:13   #1
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Taller 5th gear ratio for better fuel efficiency & top end speed

Hello everyone,
I own a maruti esteem 2002 petrol model. It has done almost 2.72 lakh. Km on the odometer.
We had replaced the engine at around 2.5 lakh km from MASS on 2017 and duly endorsed the changes on the RC.
Now the engine is very peppy and almost in new condition but the rising fuel prices is now worrying me and I am seriously thinking of modifying the gearbox to lower the fifth gear ratio from .79 to around .65 - .7.
OR to modify the FWD ratios.
My query is
1. Is the maruti esteem gearbox a direct swap into the petrol avatar or I need to modify the engine mounts?
2. If any other gearbox fits my requirements eg Like Tata vista TDI ratios looks attractive..
Kindly suggest..
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Old 17th January 2022, 19:34   #2
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re: Taller 5th gear ratio for better fuel efficiency & top end speed

Have you considered the engines power and torque figures and how it will work with changes in gear ratio. The petrol 1.3 litre engine is not really a torque monster Vs the diesel so do double check the calculations before going ahead.

A better option would be to do a full overhaul of the gearbox and fill her up with new oil to reduce any transmission loss. With regards to the query if it will fit? Different engine most likely will mean different gearbox covers and mountings, and at the least you would need adapter plates. Input shaft and clutch assemblies also need to be checked if they are a match. Best is to goto an authorised dealer and go through parts manual and check the details of both.
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Old 17th January 2022, 20:16   #3
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re: Taller 5th gear ratio for better fuel efficiency & top end speed

The new gearbox will have it's cost. And it may make a difference of just 1 - 1.5 kmpl. So it will still take another 50,000 to 1,00,000 km (or maybe more) for the cost of new gearbox to pay back. Are you going to retain the car that long?

If your existing gearbox has more than enough torque output in the first four gears, you can upsize the tyres to make the engine run at lower rpm for a given car speed. That will be easier to try, less costly and easily reversible option.

Another option is to check if the fifth gear pair and a few related parts from diesel gearbox can be fitted to the petrol gearbox.

Last edited by Rahul Bhalgat : 17th January 2022 at 20:23.
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Old 17th January 2022, 21:32   #4
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re: Taller 5th gear ratio for better fuel efficiency & top end speed

Quote:
Originally Posted by Sourav@1977 View Post
I am seriously thinking of modifying the gearbox to lower the fifth gear ratio from .79 to around .65 - .7.
I dont know about the Esteem but kits with longer final gears for many makes are available in Europe. The Swifts are used in winter rallies and there should be kits available. There are kits for the Volvo at specialized shops. Longer 5th gears are available for some VW cars for sure.

I know that some suzuki gearboxes can be bolted on to the Nissan engines so that might be a possibility for you but it will cost you some serious cash.

This is a shop that converts the VW 5-gear box to 6 gears. This kit reduces the RPM by 500 in 6th gear.They sell you the kit or do the job for you the same day.

http://www.eurotuning.cz/images/imag...rsion_kit.html
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Old 17th January 2022, 22:03   #5
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Quote:
Originally Posted by Rahul Bhalgat View Post
The new gearbox will have it's cost. And it may make a difference of just 1 - 1.5 kmpl. So it will still take another 50,000 to 1,00,000 km (or maybe more) for the cost of new gearbox to pay back. Are you going to retain the car that long?

If your existing gearbox has more than enough torque output in the first four gears, you can upsize the tyres to make the engine run at lower rpm for a given car speed. That will be easier to try, less costly and easily reversible option.

Another option is to check if the fifth gear pair and a few related parts from diesel gearbox can be fitted to the petrol gearbox.
Thanks bro..
I am going to retain the car till it's RC expiry on December 2032.

Presently my car runs on 155/80/R13 tyres.
If I upsize the rims to 14 inch., Will it not overheat the engine?

Thanks everyone...
Please suggest whether the maruti esteem diesel gearbox will fit directly in the petrol avatar or it will need certain modifications??

Last edited by bblost : 17th January 2022 at 22:16. Reason: back to back.
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Old 18th January 2022, 00:31   #6
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re: Taller 5th gear ratio for better fuel efficiency & top end speed

Quote:
Originally Posted by Sourav@1977 View Post
Thanks bro..
I am going to retain the car till it's RC expiry on December 2032.

Presently my car runs on 155/80/R13 tyres.
If I upsize the rims to 14 inch., Will it not overheat the engine?

Thanks everyone...
Please suggest whether the maruti esteem diesel gearbox will fit directly in the petrol avatar or it will need certain modifications??
A quick search on Boodmo website shows that the 5th gear pair is same on Esteem 1.3L petrol and 1.5L diesel. The part numbers are:
24351-64B51: Gear, countershaft, 5th.
24114-64B51: Gear input shaft, 5th.

So the change of gears / gearbox isn't going to help you. Try to locate 15" rim of suitable PCD and no. of bolts. If available, you can use 195/65R15 tyre. Esteem has kerb weight of around 875 kg. Your 1.3L engine giving 110 Nm torque shows reasonably good torque per ton. But take your own call to confirm if more than enough torque is available in the first two gears, at present. Also check if the wheel well can accomodate 195/65R15. If all checks are positive, you can give a try. Possibly with the used rims bought from scrapyard first. Similarly, source two used tyres from some Anna, just for trials.

If you find in the trials that you have enough pickup and better FE, you can go ahead and buy new rims and tyres.

Compared to your stock tyres, 195/65R15 is bigger by around 10%. That shall not burn your engine. But you will need to give the car the gear she needs with the new tyres. First and second ratios are high, so the first two gears shall be comfortable for the car. Third and fourth gears shall be selected at correct rpm (upshifting at maybe a bit higher rpm) but only trials can confirm this.

Your speedometer will still show the old speeds as it gets the speed signal from the gearbox. But your actual speeds will be higher for the same engine rpm.

So, take a trial of you are really keen. By the way, how much do you use the car in the city and on the highway? How much FE are you getting at present?

Last edited by Rahul Bhalgat : 18th January 2022 at 00:32.
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Old 18th January 2022, 00:54   #7
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In the past I had cleared the error codes of idle control sensor with help of tech II obd scanner.
Set the idling rpm at 650 only and disconnected the idling control sensor connector.
So rpm never shoots above 650 rpm even when cold.
Normally the rpm shoots up to 1500 rpm on startup and takes 2/3 minutes before attaining optimum engine temperature in 2001-2005 manufactured Zen and esteems consuming a lot of fuel.
FE is around 22kmpl without AC and 18 kmpl with AC on highways. While i don't cross 2000rpm on any gears and always keep tyres at 32psi.
I am missing a sixth gear on this car badly.

I have seen my friends Honda city 1.5 zx 2007 model returning 27-28kmpl without Ac on highways.
A car with such an aggressive power to weight ratio as esteem should have achieved that figure with ease practically with a more aggressive gear ratios.

Last edited by vb-saan : 18th January 2022 at 06:40. Reason: Back-to-back posts merged. Please use the EDIT or QUOTE+ (multi-quote) button instead of typing one post after another.
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Old 18th January 2022, 08:38   #8
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

Back when I used to take my Jeep on the highway, I'd changed the final drive ratio to 4.2. It did make a difference and led to easier cruisability as in stock form, the Jeep used to scream even at 90 kmph. But it did lead to an offroading deficit, so I changed back to stock ratios when I got the Bolero 2.5L engine swap.

Not a good idea in your situation though. Don't mess around with an old car for marginal improvements (if at all).
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Old 18th January 2022, 09:13   #9
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

Quote:
Originally Posted by Sourav@1977 View Post
I have seen my friends Honda city 1.5 zx 2007 model returning 27-28kmpl without Ac on highways.
A car with such an aggressive power to weight ratio as esteem should have achieved that figure with ease practically with a more aggressive gear ratios.
Esteem is geared tall as is , in city roads it needs frequent downshifts unlike the zen with a smaller engine. Esteem's 5th gear is also tall, you need frequent down shifts for overtaking in comparison to a zen, again. I also think that the vacuum assist of the brakes will suffer if the rpm drops any further as well as the alternator output, and the lubrication system and the cooling system besides the engine produces its power higher up the RPM band, so no point running it at low engine speeds.

I think It is impractical to run a vehicle on highways to return 28kmpl , I'd rather reach the destination than worry about extracting the maximum out of the fuel.
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Old 18th January 2022, 09:33   #10
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

Surprised there are not aftermarket solutions for the vehicle that needs it the most. The 1st gen Innova!!! Considering how popular it is, that too as a long distance highway king, it just screams (literally) for a taller 5th gear.

And guessing (as a technical noob), it being a BoF vehicle, with a longitudinal mounted engine setup would be much easier to play with the transmission ratios. Looking at how it is almost given in pickup crazy USA to swap, tinker with and modify transmissions in old pickup trucks for better highway economy. Have seen old Ambassador mechanics tinker with transmission, some even giving the old ones an Isuzu 5 speed with column mounted shifters. How hard can it be?

If there were ready kits like mentioned above, lots of vehicles would become so much desirable, only if they had a taller top gear for the highway.

Last edited by DicKy : 18th January 2022 at 09:34.
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Old 18th January 2022, 09:55   #11
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

Quote:
Originally Posted by Sourav@1977 View Post
Set the idling rpm at 650 only and disconnected the idling control sensor connector.
So rpm never shoots above 650 rpm even when cold.
Normally the rpm shoots up to 1500 rpm on startup and takes 2/3 minutes before attaining optimum engine temperature in 2001-2005 manufactured Zen and esteems consuming a lot of fuel.
FE is around 22kmpl without AC and 18 kmpl with AC on highways. While i don't cross 2000rpm on any gears and always keep tyres at 32psi.
I am missing a sixth gear on this car badly.
High idling for a minute or two after a cold start is not fuel wastage, it has been provided deliberately to bring the engine to the operating temperature quickly. This is good not only for the FE but also for the engine life. It isn't advisable to bypass this warming up.

While I understand and appreciate your desire to increase the FE, it does have an upper limit (which I think you have reached if your FE figures are correct).

Also I would suggest you not to benchmark Honda City (or any other car) for the FE. Your engine has a different displacement, different valve train, different clearances and different moving masses. It has been differently designed by a different company (possibly with a different philosophy). Just understand how much FE your engine is designed for, extract that and be satisfied. Any modifications like idling rpm are likely to make you spend money (and cause troubles) instead of saving.
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Old 18th January 2022, 10:44   #12
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

If fuel efficiency is such an issue then don't go for wider tyres at all. Make sure your tyres aren't worn out, you'll end up wasting torque.

And like someone said you'll end up spending more, even chances are of damaging the engine or ending up buying a gearbox that probably wouldn't suit your car.

Had it been Europe, then the Cultus sedan did come with different engine options like a 1.0, 1.6 or 1.8 with different gearboxes. But here, I assume the Esteem's gears are taller than Gypsy's or Versa's or even 1st Gen Swift's.

Focus more on improving the fuel economy:

I use S-oil Synthetic personally and i feel my engine revs much better now.
Buy wind deflectors if highway efficiency is hurting you so bad.
Try decatting your car and a conical air filter with a Cold Air Intake. With all these your engine will end up being more efficient and not just pumping more power.

Since your car is very old :
If your wheel bearings are gone they'll make low pitched noise > 80 kmph and would definitely be increasing friction.
Make sure that the injectors and throttle body are clean.

You might wanna try lowering the suspension but then you'll end up hitting bad speed breakers or even deteriorating the ride quality as Esteem is a very low car already.

Last edited by dr.aviansh : 18th January 2022 at 11:00.
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Old 18th January 2022, 14:29   #13
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

Quote:
Originally Posted by DicKy View Post
Surprised there are not aftermarket solutions for the vehicle that needs it the most. The 1st gen Innova!!! Considering how popular it is, that too as a long distance highway king, it just screams (literally) for a taller 5th gear.

And guessing (as a technical noob), it being a BoF vehicle, with a longitudinal mounted engine setup would be much easier to play with the transmission ratios. Looking at how it is almost given in pickup crazy USA to swap, tinker with and modify transmissions in old pickup trucks for better highway economy. Have seen old Ambassador mechanics tinker with transmission, some even giving the old ones an Isuzu 5 speed with column mounted shifters. How hard can it be?

If there were ready kits like mentioned above, lots of vehicles would become so much desirable, only if they had a taller top gear for the highway.
Very rightly said bro..
Back in 1996 we had purchased the premier 138d. It was a well composed car but matched to 4 speed Nissan gearbox. It literally screamed to touch 80kmph, not to mention engine temperature and FE drop.
We didn't find a good mechanic for modifying the gear ratios then and we scrapped the car in 2012.
So I don't want the esteem to meet the same fate. I want it to be retained as a highway cruiser rather than a city car.
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Old 19th January 2022, 11:21   #14
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

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Originally Posted by Sourav@1977 View Post
the rising fuel prices is now worrying me .
If fuel cost is the main concern why not put a cng kit instead. It could be like your eco mode for times when you need efficiency and switch to petrol when you need to have some fun
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Old 19th January 2022, 11:27   #15
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Re: Taller 5th gear ratio for better fuel efficiency & top end speed

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Originally Posted by puneetakhouri View Post
If fuel cost is the main concern why not put a cng kit instead. It could be like your eco mode for times when you need efficiency and switch to petrol when you need to have some fun
You are right bro.. that's the only option I am thinking to explore now.
I don't know whether the RTO regulations will permit me to install a CNG kit in 2002 kharagpur RTO, WB registered model.
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