Compression ratio numbers

Hi guys, Im not a very active member but I always keep an eye here and as I can't figure out how to make a post I just messaging random members...

I am at the mo trying to locate my compression ratio of my V8 1985 County
It was registered here in New Zealand 1987 and is a twin Stromberg original set up
I have been told the truck was actually assembled here but not to sure about it

Have searched the whole engine and cant find anything but these numbers on the photos below and non seems to me a compression figure

Anybody got an idea?

Img not working but you can just test compression ratio and you are looking for them to be pretty even. Anything lower than the rest means head off and investigate.

I can see the images, They ain't gonna help.

Rik666 said:

Hi guys, Im not a very active member but I always keep an eye here and as I can't figure out how to make a post I just messaging random members...

I am at the mo trying to locate my compression ratio of my V8 1985 County
It was registered here in New Zealand 1987 and is a twin Stromberg original set up
I have been told the truck was actually assembled here but not to sure about it

Have searched the whole engine and cant find anything but these numbers on the photos below and non seems to me a compression figure

Anybody got an idea?

Click to expand...

i cant see the pics but number is stamped on the flat bit where dipstick tube enters the block on lhs,defender v8s are low compression as bstandard 8.13

Oops it was ratio you wanted.

Cant you see the images?
Weird...
Well I have looked at every possible place to locate the compression ratio numbers and they should be next to the motor oil stick but there is only a 09795 number there with possibly a G in front
And they should read something like 09.35:1
I want to know this as I am trying to get a few more ponies out of a very tired motor
So by knowing that I can choose to go for rev or torque depending on the compression ratio
Any suggestion where to look?
Cheers

If the motor is tired it probably needs a reborn and new Pistons. What are you planning, a head skim? Engines tend to tire unilaterally, tweaking part of it for more performance usually leads to premature death elsewhere in its mechanicals.

Col

I just want to know where I can find the compression ratio numbers mate
I want to know what it is so I can tune it back to how it was originally running after my own knowledge
I dont want more power, I just need it to run as well as it can, petrol savings etc etc
But nobody seems to know where to find it...

Well, the v8 engine used in the rover sd1 in the mid 1980's was a 9.35:1 compression ratio and I don't think landrover retuned it any more, originally it was something like 10.8:1

Col

Well, this motor sits in a Landrover County from 1985 and I am told it was assembled here in New Zealand

I believe the landrover v8 engine is exactly the same as all the other rover v8's from the period. They didn't build special ones just for landys. If your engine is a none standard engine made in NZ it's any bodies guess as to what the compression ratio is, or do you mean the landy was assembled in NZ using all landrover parts in which case see my previous post.

Col

I believe the Rangies had a lower 8.15:1 ratio for a heavier vehicle and more rev compared to the Rover and yes it would be a guess as I don't even know if it is the original motor in the first place and therefore only want to know WHERE the number could be imprinted on the motor
And you have 9.75:1 or 9.85: 1 are common too, even 10.25 or 10.5 : 1 are around and the 10.5 : 1 is what I hope I got... higher comp = better torque
So I do not want anybody to guess, I want to know WHERE the number is printed on the motor so I can read it myself...

All i can recall about early V8s was they generally had the lower compression ratios for manual gearboxes and lower octane fuels and the higher ratios for automatics and higher octane fuels.

Whilst I don't know the answer to what the compression ratio is on the Member's engine - you cannot test for what the value is, it's just a mathematical calculation based on volumes. You can of course test for the compression value in psi etc. using a gauge.
The static compression ratio is calculated by the following formula for 4-cycle OVERHEAD VALVE DESIGNS:

COMPRESSION RATIO (CR) = SUM OF THE SWEPT VOLUME BY THE PISTON IN THE CYLINDER/HEAD COMBUSTION CHAMBER PLUS THE CLEARANCE VOLUME DIVIDED BY THE CLEARANCE VOLUME

Thank you, but thats way over my skill set and tool box...
However, I have figured out that the motor have been changed, so whatever it was original is kinda irrelevant now
So it has a 3.5 V8 NZ Army model... Year or model number so far unkonwn... most likely out of a 109 S3 I say as they where quite common here (I use to have one, my first Landy)
Whatever this means compression ratio wise I have not a clue of...
What I do know is that after upgrading the ignition wires to 9mm AT and put 8 TorqueMaster plugs in it goes quite well compare to earlier
And when I get the Coby extractors on and get my Stromberg calibration tool and get the timing 100% right I think I can cram a few more ponies back out of it
Even if I can get maybe 80% of the original power I would be really happy
Sooooooo, anybody knows much about the NZ Army V8 engines????

Cheers boys