Engine Compression Ratio

[MajorL]

I have an EX MOD Army Traveller. The engine number is 10V/189E/L45838. As I understand it this is a low
compression engine. What difference does this make and what should the readings be on a compression test?
The mileage is coming up to 97000. Andy

[minor65]

The low compression engine which is in my 65 4 door reads 140 psi on all 4 cylinders. I expect yours to be similar or maybe higher.

[bmcecosse]

I wasn't aware they continued the low compression farce on the 1098 engines. So yes - 140 is about all you can expect. Not important is you are just pottering around in the car - but the reduced power will be felt on Mways.

[philthehill]

The MOD army traveller was never intended for motorway use more like going from the Officers Mess to the respective office/workshop and use as a general run about.
We had a 1098cc traveller when I worked for REME and it was allocated to a REME Major for doing the above tasks.
The furthest it went was to local suppliers (on averaging about 15 miles) when local purchasing parts.
It was more polished to death rather than being used to an inch of it life.
MOD POL (petrol/Oils/Lubricants) points if I remember correctly only had low octane petro & diesel available so it would be no good having a high compression engine. At that time there was no facilities to purchase fuel from local garages and if on a longish journey you would have to plan your journey so as to be able to call in at a MOD POL point to obtain petrol on your work ticket.
Phil

[bmcecosse]

Not too difficult on that 15 mile trip to the pub (sorry -'local supplier') then !

[philthehill]

Unfortunately in those days I was only a lowly vehicle/plant fitter and not eligible for to use a staff car
Only years later did the luxury of a staff car become available and by then the Minor had been replaced with a Ford Escort and later a Vauxhall Astra.
The REME workshop had two dedicated MT Drivers who ferried the Major around (in those days (1970s) Officers in the main did not drive themselves) and fetched the spares and washed and polished the car. They also drove the Unit Recovery vehicle which was a Scammell 6 x 6 fitted with a Meadows 6 cylinder petrol engine which did no more than 3 miles per gallon - its petrol tank held just over 100 gallons.
My days working for REME were very enjoyable as you never knew what you were going to deal with from day to day. Repairing Heavy Plant - bulldozers & cranes were my favourites.
Phil

[MajorL]

Many thanks for your interesting information. What made the engine low compression? When I have an engine rebuild I would like to make it high compression. Is this just a change of pistons plus any other worn parts renewed.

[philthehill]

The lower compression was indeed induced by using deeper dished pistons.
The compression can easily be raised by using flat topped pistons or smaller dished pistons.
As you no doubt aware the compression ratio is determined by dividing the swept volume of the piston by the total volume above the piston/rings when the piston is at TDC - that total volume is comprised of the cylinder head combustion chamber volume (with valves fitted), the volume created by the cylinder head gasket, the volume of the piston dish, the depth of the piston below the top of the block at TDC and the volume of the space around the piston from the top ring to the top of the piston.
Anything else will not improve the compression ratio but will help maintain the compression ratio.
I hope the above is of help.
Phil

[MajorL]

Phil,
Many thanks for the information. As the engine is on 97000 will need something doing soon. Will go for flat headed pistons. My Traveller was with the Railway Group RCT then the ARMY Freight Org RCT before being disposal at Ruddington in1974. In my Army days during the 1970s travellers were used to run the Padre and Paymaster around. Driven by a WRAC driver. Lots of new clutches! Andy.

[philthehill]

Andy
The above info is very interesting as I worked for the RCT Railway Group/Army Freight Org from 1984 as a Depot Railway Superintendent until the groups disbandment - in 1994 I took up employment as a Railway Staff Officer with the Railway Staff Office located in Andover, Hants and then Abby-wood, Bristol dealing with all aspects of military railways in their various forms both S/G & N/G until I retired four years ago.
Was your traveller stationed at the Andover HQ or at an other RCT Railway out station/depot? The info should be on the record sheet.
If it was at the Andover HQ - I have a picture of a HQ staff gathering - the majority who would have driven your Minor as they had been there a long time. I will try and find it and let you have a copy.
Being involved with military railways was the best job I ever had
Phil

[MajorL]

Phil,
It may very well have been serving at Andover. The record sheet only gives area Div/Dist codes. 23.6.70
code F. 28.8.70 code C. Its an interesting little car. I have all its History to date.
Andy

[liammonty]

Just to say that, having run several 1098s with standard high compression engines, and one with a low compression original engine, there really isn't much difference in performance at all if the engine is in good order. I wouldn't rush to change your lc engine in the quest for power gains unless it is obviously worn. Book figures for power are 48 bhp vs 43 bhp, but in my experience, torque was much the same.

[MajorL]

Many thanks. That clears the mind. I will wait until the engine needs a recon. Then change to H/C pistons.
Andy