So if I were to rebuild my r53 motor , would it be possible to go with higher compression pistons in order to increase power without increasing boost because let's face it the m45 is limited ?

 

You planning on running on race fuel?
Compression is limited by fuel octane and intake temps....

 

Nothing past 94 no . I guess it's not a viable option then . I gotta say though , aren't the scion frs and Subaru brz running something like a 12:1 CR on pump gas ?

 

i wondered if it were possible to use the regular mini engine (10:1 compression or so, vs 8:1?) and then just supercharge that thing... bolt all the MCS engine parts on... but, again, there is prolly a reason mini dropped the compression when supercharging...

but hondas run high compression engines with turbos.... why couldnt we do the same? we have a cast iron block!

again, just thoughts... i have not researched enough on the subject to know "officially"

 

You will want to take into account that those numbers are static compression numbers. If you raise the static compression to 10:1 your dynamic compression under boost will be higher.

The FRS/BRZ engines are direct injected they can run higher ratios on pump gas.

 

What would I be ale to raise it to on pump gas like 94. Approximate , or is there no room for play at all ?

 

Beyond that....
Part of the answer is engine management....
If you want to run a standalone ecu, add a few sensors, run some custom software ( with non oem compression pistions you will need custom tuning/maps anyway).....with some of the diy tuning kits, it is possible....
I would shoot over to revolution motor works....rmw...they have done many rebuilds and race motors, strokers...if the parts make sense...they will stock them as custom parts they made, use, and then sell.
My thoughts....
To the south in the us, 94 was once prevalent.... But Sunococ shut down their refinerys....so 93 is the best "common" octane in most area....even then some locals sell only 91 or 92....

Just to be the devils advocate...youbbuild you motor... Tune it, have it running 94...on the ragged edge...maximized...
Take a trip...no 94...boom...or a load of slightly out of spec fuel...boom...or they stop selling 94...drop it to 92....boom...
Sure there is some margin....
But the designers have found setting compression at one point...then using timing advance to get more power back from the slightly lower compression (which is adjustable on the fly) works...
Not saying you can't do better....just saying if it was a simple road.......

 

Canada here, 94 everywhere plus my cooper way to uncomfortable for long trips .

Thanks for the input

 

Zippy hit upon what would be your biggest issue, ECU, most anyone whose tried anything more than a "slight" bump in compression has had issues with tuning, many have actually gone through the trouble of pulling them out and going back to stock compression because of this.
So as Zippy said, you'd prob. have to go to a stand alone ECU to avoid many issues, not to mention, more compression = more heat, so of you were to do it, W/M would almost be a necessity, but it would also fix any octane issues.

 

Stand alone ECU

 

don't suggest it. the R53 had upgraded internals vs. the R50, also I don't think the R50 engine has oil squirters to cool the pistons.


Cars are generally built with parts that are adequate but not overkill for the intended application; just because the block uses the same basic layout doesn't mean that all MINI 1.6l motors from the same generation are the same other than exterior boltons...

 

here's a better list of the differences, and reasons this would be a "BAD IDEA":
https://www.northamericanmotoring.co...862-post8.html