Hi All,
I have an early Morgan +8 (1969) that is presently fitted with a well-running SD1 Rover V8 engine block from around 1979-80 I think with an 8.13 compression ratio. I do have the original engine block for the car which is a 10.5 compression ratio. Can anyone tell me generally how compatible (or not) the components of these two blocks would be? Asking from the perspective I want to work towards getting the original engine block back in the car, but I literally only have the old engine block as spare... would the cylinder heads, intake manifold, crank etc. on the SD1 presently in the car otherwise be interchangeable?
TIA!
Rover V8 10.5cr & 8.13cr Overlap
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Re: Rover V8 10.5cr & 8.13cr Overlap
As a general statement compression ratio with the RV8 is determined by the pistons used, not the block.
Clearly mods such as shaving heads and block will make small differences and there was a small change in head design with later engines that made a small change but to change compression ratio you will need to change pistons.
Clearly mods such as shaving heads and block will make small differences and there was a small change in head design with later engines that made a small change but to change compression ratio you will need to change pistons.
Re: Rover V8 10.5cr & 8.13cr Overlap
I guess the obvious question is "What are you looking to achieve?"
If it is to maintain originality/matching numbers then you should be able to build a hybrid but if it is to get the higher compression (as the thread title seems to indicate) then as Garrycol says this is down to the pistons which it seems you don't have.
You can increase compression by skimming the heads or decking the block but this changes the head location due to the angle of the V and if you remove a significant amount of material this can give problems aligning the inlet manifold.
Later blocks are stiffer but I'm not sure when this was done.
Later front covers are 'better' as they have a modern type of crank seal (early ones were rope I believe) and a larger capacity oil pump, they also use the later, electronic distributor.
Rear crank seal may be similar too.
Later heads have larger ports (possibly valves also) and/or smaller valve guide in the port (can't remember which) although reducing the valve guide size is recommended anyhow.
So, in short, unless you want the originality you would be best to keep the SD1 engine and change the pistons to get the higher CR, possibly clean up the original block and make a coffee table!
If it is to maintain originality/matching numbers then you should be able to build a hybrid but if it is to get the higher compression (as the thread title seems to indicate) then as Garrycol says this is down to the pistons which it seems you don't have.
You can increase compression by skimming the heads or decking the block but this changes the head location due to the angle of the V and if you remove a significant amount of material this can give problems aligning the inlet manifold.
Later blocks are stiffer but I'm not sure when this was done.
Later front covers are 'better' as they have a modern type of crank seal (early ones were rope I believe) and a larger capacity oil pump, they also use the later, electronic distributor.
Rear crank seal may be similar too.
Later heads have larger ports (possibly valves also) and/or smaller valve guide in the port (can't remember which) although reducing the valve guide size is recommended anyhow.
So, in short, unless you want the originality you would be best to keep the SD1 engine and change the pistons to get the higher CR, possibly clean up the original block and make a coffee table!
Re: Rover V8 10.5cr & 8.13cr Overlap
Are you sure you have an SD1 engine? I thought these were 9 or 10:1.
I thought the 8:1 were reserved for the Landrovers?
I thought the 8:1 were reserved for the Landrovers?
Dax Rush 4.6 supercharged V8 MSII
