what i need to do to reduce compression ratio
- Thread starter stefany
- Start date
Hello and Welcome to Torquecars.:bigsmile:
Hope you enjoy your time with us.
Hope you enjoy your time with us.
Why not just do an engine swap with the Starlet turbo engine?
To drop the compression you'll need low compression pistons, a stroker kit and potentially a thicker gasket (although I consider this a bit of a bodge).
Alternatively get a rebore done and fit larger diameter pistons to suit (I think the block is aluminium with steel linings though so a rebore will not apply but check this, not sure on the ages of Starlets and engine types.
You could add a low boost supercharger fairly easily? You'd just have to worry about fuelling and timing then.
To drop the compression you'll need low compression pistons, a stroker kit and potentially a thicker gasket (although I consider this a bit of a bodge).
Alternatively get a rebore done and fit larger diameter pistons to suit (I think the block is aluminium with steel linings though so a rebore will not apply but check this, not sure on the ages of Starlets and engine types.
You could add a low boost supercharger fairly easily? You'd just have to worry about fuelling and timing then.
T9 man
TC ModFather
Greetings and Welcome! 
Err, won't this increase the compresion ratio?
Well spotted that man. Bigger cylinder = more air to squish not less squish! :embarrest:
HDi fun
TC ModFather
Shorter con rods alone will lower the geometric compression ratio very effectively without changing the actual swept volume.
7 to 1 is a bit low I think. This is likely to make engine startup quite difficult.
7 to 1 is a bit low I think. This is likely to make engine startup quite difficult.
MasterAuron
Very Senior Member
7:1 is too low unless you're building a drag car or something. It will be a pig to drive off boost. Just to put it in perspective Escort Rs Turbos are 8.2:1 from the factory and early Punto GT run 7.8:1, later ones 9:1 and the difference between the way the two drive is night and day.
HDi fun
TC ModFather
Largely because we now have very sophisticated CAD techniques which allow combustion chamber design to be optimised to withstand high BMEPs under compression without detonation being a problem.
It's one of the things that's helped diesel smoothness no end and is probably accountable as much for derv development as much as ultra high pressure direct injection has.
In general high compression ratios contribute to cleaner emissions, apart from Nitrogen Oxide (NO), the emission of which increases as combustion temperature increases. Thankfully this is not tested in the UK MOT. Yet!
So, in general, high compression ratios are good.
