Race Engine Forum UK

I have just changed out the original 1592cc motor in my 124CS and inserted my tried and true 1756.

I know that, when I built the 1756 it was bored out to max oversize 0.6mm, and the OEM big oversize pistons are all but impossible to get now. Thinking to the future, I know that, eventually, my 1756 will wear out. It's as inevitable as death and taxes. It would be nice to slowly prepare for the event and, when it comes, have a ready-prepared engine with newly manufactured items, like new, custom-made forged pistons etc.

So my question is: "Is the 1592 block and crank able to be transformed to 1756cc?"

To quote your book: "...the fact that models have a common bore size means that if an owner wants to move up in cubic capacity he simply adopts a longer stroke model."

What I am looking at is the opposite. I want to use a 132 "family" engine with 79.2mm stroke and 80mm bore and increase it to 84mm bore.

Is this possible? Presumably it requires bore sleeving or I'll be in the water jackets. But is there enough space between the bores? Is the bore spacing the same?

By using increased bore size, can I miraculously transform a 1592 engine into a 1756?

Your thoughts and advice, as always, greatly appreciated.

Kind regards
Greg Ashe
Australia

Hi Greg,

easy, just bore the 1592 straight out to 84 or 84.6mm and it becomes the 1756.

Having done it 4 times and knowing a thing or tow about production costs and methods I formed the view that it was actually just a 1756 bored out with smaller bores than same, and though I have never sectioned one to prove it I am as certain as I can be that it won't break thru. If it does it will not be all cyls for sure and you can sleeve the errant one.

GC

Hi Guy!

So let me be absolutely clear on this...you are advocating bore the standard 1592 block out by 4mm each cylinder...and no problem...bingo...you have a 1756cc motor?

Thanks for your input!!!

Greg

That is indeed what I would do, and bearing in mind that the 1756 were bored out by 2mm on dia to 86mm on works engines 4mm on dia on the 1592 is not as much as it seems.

Don't shoot me if one breaks thru, but boring out from 80 to 84mm on the 1592 is what I'd do, and as I said, I've done it before with complete success.

G

I totally agree with Guy.
The two blocks are identical.
I recently transformed my sedans 1592 to a 1756 .
Do not need to think about it. Just do it