[sijuko]

Hi Experts,
I have a MM540 4WD with MDI engine and also changed the crown and pinion ratio to 4.27. I still wanted to have some more top speed, Please let me know what is the best way to achieve it?

When I had original xdp 4.90 with crown pinion 4.27 I felt much better but when I moved to MDI engine its not doing that good in terms of speed.

@Mods - Please approve or point me to the right thread if it is repetitive.Thanks

[Arjun.hb]

You can try 3.73 crown pinion as was available on Thar DI. But your low end torque is compromised. Bigger tyres is the other option. Don’t go over 31” though. Are you running 5 or 4 speed gearbox?

[Kosfactor]

Originally Posted by sijuko

@Mods - Please approve or point me to the right thread if it is repetitive.Thanks

I think you need to read this thread.

Originally Posted by dhanushs

Hi,

The XDP 4.9 rebuild will cost you only about ~15k. Original Mahindra rebuild kit will cost you only ~6k, and it can be done perfectly even out side A.S.S with medium skilled labour. It is a pretty good engine in an off roader. Also, an engine swap if not done properly is a head ache, and has its legal issues too (assuming engine is not new). So, my first take is to keep the XDP 4.9.

However, if you are keen on changing the engine for more performance, and assuming the engine picked up will be second hand, I will list out few pros and cons of both.

XD3P pros:

• Great engine, smooth, refined, and enough power for a SWB.
• Weighs less, so, less stress to the chassis while off roading.
• I think its got better engine braking than the MDi.
• Higher rpm, so, its easier to drive on road.
• No need to change the crown/pinion ratio.
• If swapped properly, will last a long time.
• I think its an easier swap than the Di. (not sure)
• Will cost you only ~1/3rd the price of an MDi in the used market.

XD3P cons:

• Assuming the engine is second hand, the XD3P is very difficult to rebuild, requires precision and skilled mechanics.
• XD3P rebuild is very expensive. Can cost till ~50k.
• Even after a perfect rebuild, I know many engines that overheat. I somehow tend to think that overheating is an inherent character of this engine while revved hard for a long time. ie, I've not seen a single XD3P + KMT 90, that doesn't overheat @100kmph consistent.
• Low end torque is less than the Di.
• Less fuel efficiency then the Di.
• IMO, its not as reliable as the Di.

MDi pros:

• Very Robust and Reliable engine.
• Less tendency to overheat. I have seen an end-of-the-life engine driven in 1st and 2nd low at high rpms, for a full hour continuously without overheating.
• More Fuel efficiency than the XD3P.
• Assuming the engine is second hand, the MDi is easy to rebuild.
• Cheaper to rebuild.
• High purchase cost. ~3 times the price of XD3P.
• Low end torque.
• No glow plugs

MDi cons:

• Heavy engine. So, mounting needs to be perfect. Also, heavier engine causes heavier stresses in chassis while off roading. Especially whist jumps.
• Very Noisy.
• I think: Lesser engine braking.
• You will need to change the crown/pinion to match the low end torque, which is again an expense.

If you are getting a new engine, and you are not bothered about fuel efficiency, my pick would be XD3P. If its a second hand engine, then my pick would be the MDi, assuming you have a good place to mark the mountings and swap the engine.

A Jeep that can go fast is only possible by purchasing a Thar, in this case a Thar CRDe , looks like the old MM series and goes better than many modern cars!

[sijuko]

Originally Posted by Arjun.hb

You can try 3.73 crown pinion as was available on Thar DI. But your low end torque is compromised. Bigger tyres is the other option. Don’t go over 31” though. Are you running 5 or 4 speed gearbox?

3.73 needs any change in diff case or is it a direct fit. I have a 4 speed gearbox.

Originally Posted by Kosfactor

I think you need to read this thread.



A Jeep that can go fast is only possible by purchasing a Thar, in this case a Thar CRDe , looks like the old MM series and goes better than many modern cars!

Sure

[Arjun.hb]

Originally Posted by sijuko

3.73 needs any change in diff case or is it a direct fit. I have a 4 speed gearbox.

I personal have not tried 3.73 diff ratio. Around here we like low end torque. But my mechanic says it’s a direct fit. Mod Dhanush will be the last word on this discussion.

[GTO]

I own a '97 Classic that at one time had a 4.2 final drive. The top speed increased, but I soon realised that the engine was capable of delivering a speed that the rest of the vehicle couldn't keep up with. The handling is downright scary, the steering slow as a snail, the brakes poor (by current standards) and the vehicle has no real safety to speak of. These are cars that were designed without even 1% crash safety in mind. Not to mention, the engine would be screaming so loud at 100 kmph that I'd go deaf in 10 minutes.

Make your peace with it. Just as you wouldn't take a Ferrari offroading, similarly, don't drive your old Jeep at high speeds. My recommendation = drive it at a max speed of 60 - 80, enjoy the scenery on your calm drive and be happy. Your MM540 will be very old today and many parts of it would have worn out. My '97 Classic is still on its original steering column, who knows when it will give up.

If you want a faster Jeep, buy a Thar. Although, even in the stock Thar, I don't recommend cruising above 100 - 120 kmph.

[anjan_c2007]

The first option will be to go back in time, try for a good 4.90XDP engine and feel at home with your 540DP. You may still get these in the Mayapuri scrap market in Delhi. And the other option is the MSTC listed contractors who buy written off jeeps at govt auctions, en masse.

Coming to the International Harvester MD 2350 engine, I am yet to come across a tougher workhorse. Having used the MD 2350, 4.90 XDP and the XD3P, if ruggedness, endurance and withstanding abuse are all considered, nothing comes closer to the MD. Not even the older petrol Hurricane engines.

But the MD2350 is crude, very rudimentary, archaic etc with any other synonym you may have to describe it. The engine is fully mechanical and runs without a battery which is no mean feat.

It has its limitations and that is why in the present day scenario it is disliked. Its NVH is the highest among all Indian made light motor vehicles (LMV) ever manufactured. The body rattle with the rock'n roll it does, doesn't allow passengers to be seated in peace, while travelling. Talks with a co-passenger are not normally audible amid the noisy diesel engine clatter. A 500 plus kms journey may require the driver to have rest for 12 hours.

Since this is an ancient engine, it's best to leave it that way, rather than expecting miracles which would be like administering steroids and boosters to a senior citizen to become more nimble, run around and play football with 15-20 year olds.

Yes a case in point here is that Hindustan Motors fitted an intercooler turbocharger in 2013 to its similarly archaic and crude BMC OHV1489 cc/Stride/39 bhp diesel engine to make it BS IV compatible. They named it Stride Plus and boosted the output to 45 bhp as they claimed. But the TC overheated this age old engine in the long term. As a result, taxis with thd TC in Kolkata have in a majority of cases removed the TC and are again happy with the 39 bhp.

[dhanushs]

Originally Posted by sijuko

..
When I had original xdp 4.90 with crown pinion 4.27 I felt much better but when I moved to MDI engine its not doing that good in terms of speed.

..

The reason being the the MDi revvs ~30% lesser than the Peguot. Also, the max performance of the MDi would be at lower rpm's, unlike the Peguot.

If you really want more speed go for 3.73 which will make the vehicle drive similar to a Thar Di. However, I personally think for a 540 4.27 is the best. It will give you good driveability and decent speed for which the vehicle with front drum brakes and decades old steering and chassis can handle. (Note: Thar Di has an entirely different Chassis, Suspension, Steering and Brakes)

Yes, 3,73 will require you to change the diff casing along with the spider gears

Originally Posted by GTO

... My recommendation = drive it at a max speed of 60 - 80, enjoy the scenery on your calm drive and be happy. Your MM540 will be very old today and many parts of it would have worn out..
...

This is probably the best advise you can get.

[supermax]

Originally Posted by GTO

Make your peace with it. Just as you wouldn't take a Ferrari offroading, similarly, don't drive your old Jeep at high speeds. My recommendation = drive it at a max speed of 60 - 80, enjoy the scenery on your calm drive and be happy.

Couldn't say it better. I've never owned a jeep, but have always admired it for it's coolness factor. My favorite level in the old Indiana Jones PC game (The Infernal Machine) was Meroe, where we could drive an old, original army jeep! Much like in the world of bicycling, there isn't really a one bike or car that does everything. A jeep is for the awesome experience of being able to go where nothing else can go, offroad, or taking it easy and taking in the sights and admiring glances of fellow road users, while chilling on the streets, so as such, the need for more speed fom a jeep almost feels like a misplaced wish. Harsh noise, vibrations that feel like the entire jeep would fall apart etc can hardly be worth the effort and expense of modifying it.

[DirtyDan]

Most people give up on this, and yeah, this question has popped up many times on this site. GTO and Danushs know whereof they speak. For the money it would take to make this thing appreciably faster SAFELY,
you could buy yourself some pretty good oil stock in Bahrain or maybe set yourself up as a military dictator in South America.

The MDI3200tc is a pretty darn good engine IMHO. It is robust and has a very strong crankshaft. I'd be happy as a clam if I had a jeep with a healthy one of these.

To drive 80-90 in a MM540 is to know the meaning of terror....been there, done that, bought the Tee shirt.