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Just what I thought! The two are similar in so many ways. I am a big fan of the 2.1 due to its simplicity, torque delivery and rugged build; good to hear that the 2.5 has its roots in the 2.1.

AFAIK, the 2.5 Bolero XD3 is an overbored 2.1 XDP engine. :)

The XDP4.90 (2.1) is a wet liner engine. The XD3 (2.5) is not.

Best regards,

Behram Dhabhar

saw your jeep last night at about 830 or so opposite siddhivinayak. it looks really good.

Dear Behram Dhabhar,

If you could please give your technical insights on these point: (Arka please feel free to comment also).

This would mean that the XD3 is not just a bored out version of the XDP4.90. Correct?

Can you comment on why M&M went with a dry liner in the newer XD3, as a dry liner does not cool as effectively as a wet liner?

Is the cylinder head of the XDP4.90 the same as the XD3? If not what are the differences?

What about the Scorpio 2.6 engine? Is this a wet or dry liner? I know for a fact that its cylinder head is cast iron and very heavy. Can a XD3 lightweight aluminum head be used in its place?

Lastly can you comment on the new 2.2 mHawk engine in terms of wet vs. dry liners. Can its 16 valve head be adapted to the 2.6 / XD3 / XDP4.90 ?

Thanks,

okie so finally your jeep is back on the roads. so now i can expect you for the next trip with your classic. what say?

300 kms up! :) Only a couple more hundreds, complete the running-in and then we are on, Pdev.

GTO, what is your fuel average?

Dunno, since I rarely check the FE of my cars. Its done about 330 kms and the needle is still shaky around the 1/4 mark (40 liter tank). Maybe its a good idea to check the FE. Will do and update.

By wet liner we mean removable bores right?

What are the advantages/disadvantages of both?

WOW! is the only 3 letter word that i can say to you and your love for the Jeep. The baby looks the best!!

Dear Red MM340 (actually it is CL340) / Mr.Gaurav Prabhakar,

My comments are given in bold after each of your query.

This would mean that the XD3 is not just a bored out version of the XDP4.90. Correct? - you are correct, they belong to the same family but the XD3 cylinder block has strengthening ribs for handling the extra power.

Can you comment on why M&M went with a dry liner in the newer XD3, as a dry liner does not cool as effectively as a wet liner? - it is not correct to presume that one is good over the other. In XD3, the piston is in the block in OE and liners may be used for reconditioning. Both cooling systems are capable for their own power / torque outputs. In case of wet liner, a complete overhaul kit is available which includes the liners with new pistons. As replaced, the engine becomes as good as new. It is for the user to decide what he wants

Is the cylinder head of the XDP4.90 the same as the XD3? If not what are the differences? - the cylinder heads are different. The XD3 head is stronger to handle the power / torque. You can see the ribbings in the casting next to the injectors. The combustion chamber layout details are different.

What about the Scorpio 2.6 engine? Is this a wet or dry liner? I know for a fact that its cylinder head is cast iron and very heavy. Can a XD3 lightweight aluminum head be used in its place? - this is the NEF engine and is a dry liner in OE. There is no harm in having a cast iron cylinder head.

Lastly can you comment on the new 2.2 mHawk engine in terms of wet vs. dry liners. Can its 16 valve head be adapted to the 2.6 / XD3 / XDP4.90 ? - The mHawk is a DOHC 16 valve engine and parts are obviously not interchangeable as the engineering dynamics are entirely different.

It is futile to try and fit something of some engine on to another engine. It does not work that way. I recommend that nobody should resort to such practices. You will only waste money. Normally, the person's ego makes him want to do something to his vehicle just for the heck of it. If you want more power, buy a more powerful vehicle. Then it will work properly (reliably). It is as simple as that.

Thanks,

Best regards,

Behram Dhabhar

Interesting comments, Behram. What do you think of the mdi3200tc, any comments upon its strength, reliability and torque?

And, can you give a simple definition of dry versus wet liner for us unwashed infidels?

Dry - Liners absent - There is no liner between the bore and the piston.
Wet - Liners present - There is a liner between the bore and the piston.

Any simpler and i will need to meditate. :D

Dear Spitfire - please start meditating (just kidding).

Dear Dirty Dan - the answer to your second question first - in wet liner, the coolant touches the liner, in dry liner the coolant does not touch the liner. Therefore in the bare cylinder block of a wet liner engine, THERE IS NO BORE ALONG THE FULL LENGTH OF THE BLOCK. The cylinder block has a bored out ID at it's top and bottom ends and a liner is PRESSED in it. How do you prevent coolant from spilling over into the sump and other undesireable areas? Simple - you use O rings to seal the bores. Liner projection above the deck height of the cylinder block is a critical design parameter. In dry liner engine, the block has the primary bore or there may be a liner pressed in the bore on the block in which the piston moves. In any case, this liner does not come in direct contact with the coolant and is therefore called "dry". I hope everything is clear now. If you bugger up a wet liner engine, you can make it as good as new by replacing the "piston and liner" set available. As this is pre-machined, you are not left to the vagaries of an incompetent machine shop. Now to answer your second question - the MDI/TC is essentially a very robust and simple engine. Peak crankshaft speed is 3200 rpm. Torque @ low speeed is very good. Contrary to all expectations of power etc, the turbocharging is done to meet the ever increasing emission norms. There are 2 versions, the MDI/TC with gear driven csamshaft and the MDI/TC with chain driven camshaft. The former is used in utility vehicles. The latter is used in the Scorpio M2DI.

Best regards,

Behram Dhabhar