The pistons sit a low in the block so I wondered if anyone has skimmed the top of the block to raise the compression ratio?
:cornut: I honestly don't know. Most people investing that kind of time, effort, and money usually do it with an 'S' engine. Jason
On the r50.... NO! However your idea is right on the money. We do it on the r53's.. Measure the distance between the top of the piston to the top of the block ( with piston at TDC) then it is easy to figure the compression results using that 'deck Height'. Then remove .010 at a time to find the end result ( thru math NOT actual). Raising the compression is a fast way to power. ( to a point with unleaded fuel) IF you are rebuilding the engine... do it a few ways. 1) Pistons!! IF you need pistons anyway, then buy with a different compression height and bump compression. ( cost $580.00 to $650.00) 2) keep all stock, and change the cam phase ( degree the cam and then advance it) Cost?? just the time to do it. 3) deck the block!! 'skim' as it were, and remove .020 or .030 off the deck and bump the compression. cost: 45.00-65.00 ish The r50 is pretty high as it is already. The r53 is at a 8.3:1 and will love a bit of a boost in compression. Good thought here......... Thumper
IF you mill the head... from a 33 CC chamber, to a 30 CC the results will bump compression from the 8.3 to a 8.7:1. how about .040" that will be a 8.9:1 , and to mill a head is $25.00-45.00 !! Decking the block.... .020 off the deck is..8.68:1 , or at .040 OFF the deck and you are at a 9:1 compression. MOST correct engine builds will have the block surfaced to smooth it anyway.. There are an infinite thickness Copper Gaskets, to allow the compression back if there is a need to get back to the OEM compression... just a win - win !! Just a thought..................... Thumper
Be sure to treat that math as just an example since it's for an R53 (W11) engine. The R50 (W10) stock engine compression is 10.5 ... if I remember correctly. I don't personally have any idea what effect increased CR might have on W10 performance. Don't think I've ever seen any discussion of it...but I'd love to know. :yesnod:
It may be a good idea to use S internals if one is sticking with OEM sourced parts. The S rods are stronger then the Justa rods.
There is an additional benefit to decking the block besides increasing the compression ratio. You change the squish area. Because the piston is closer to the head, the flame travel is faster because more of the air fuel mixture is swirling around in the combustion chamber. The faster burn makes the engine less sensitive to higher compression, so an engine with good swirl can run a higher compression ratio on the same fuel.
Milling the head or the block will make the cam chain seem to get longer and may exceed the reach of the chain tensioner. But there is a remedy.... It's called "Nate's Gnat Spacer"...
I'm for a head skim as I need to have the block back in the car next month due to a customs inspection. I've got the engine out and after a check all looks well so I prefer to leave the engine as is as I have other cost priorites. I did think about using a S block but I've more chance of finding hen's teeth than a S block in Costa Rica! The block weight reminds me of the Maestro 2.0L block= boat anchor! I cannot use non stock piston to bump up the CR due the rules but the block and head deck height are free so I want to get around 11.0:1 CR so based on Thumpers calculations I should shave off around 30 thou ??? for the tensioner what size is that spacer?
I would look at .030 off the head... I have a stock tensioner, but that Idea from Nate is rocking.. I am going to do that nest week. Size of spacer?? DoNo, maybe Nate has experimented.. I dont think more than a .050 washer or less than .035 thick. I have the bit on engine noise on first start, and have it down to that tensioner, I was going to just let it go as there is no engine issue, just the bit of noise on first start. But... Damn, never thought of that spacer!! Rocking Nate!! Just saying.............................. Thumper
A coupla of notes here... Some posts that said in short " You are wrong" have been removed. Mostly because all thet said is you are wrong. The posts did not address who is wrong, what wrong information is provided nor was there any attempt to provide what they felt was correct information. Secondly, there was nothing at all scientific about how the spacer washer was chosen for the tensioner. We dug around in a used washer bin and pulled out some likely candidates. Cleaned the rust off, grround them to the right diameter and test fitted by slipping the tensionor back in with the spacer in place until we felt that the tensioner was hitting something.
Not sure if the S rods will fit a justa crank. They are forged as is an S crankshaft. You might look into the possibility of switching both out. Since you are going to use your MINI in competition beefing up the engine internals may pay big dividends in its longevity. DNF's are no fun.
Rods will bolt to the r50s crankshaft. the crankshafts are interchangeable... the rods, and PISTONS are of different spec. S rod and piston, or R50 rod and piston. On the Not blown engine the r53 ( S ) rod and piston yields around a 8.3:1 compression. ( .145" deck) and that is all wrong on where you are trying to go... cool?? Thumper
The crank journals on the R53 are significantly larger than the R50. R53 connecting rods will not fit the R50 crankshaft. Nathan's issues probably have more to do with a perfect storm of component wear, combined with material removal; in his case it's a temporary adjustment I would not recommend for competitive use.
sorry my bad on that!! Thumper ( too much holiday cheer last nite!!) K-huevo.. what are the dia of the r50 and the r53 rod journals?? I have specs on all the rod info 'cept the big end of the rod size and the difference in the crank journals. I also read the rod bearings are interchangeable also. Thanks for you info...
Have you actually found anyone yet who's done this on an R50 engine with a positive result? I don't know that you'll be unhappy but personally I tend to want to know there's likely success before I jump in. Unless you're just happy trying new things with your fingers crossed? Just wondering.....plus if you have any good intel I'd like to know about it too. :biggrin5:
Actually i didn't ask anyone who had fitted Subaru STI struts to a Mini or a WRX radiator for that matter. So based on past experience I can only ask, chew on the info and make my move. I'll go with the MC bottom end and maybe skim the head to see what happens. DNF's are going to come from suspension issues rather than the engine/midland box. Saying that I really appreciate any comments good or bad to help me. Thanks everyone.
I would not do anything to an R50 motor besides an air intake since it is really not made for performance. The R50 "Justa" is more of an entry level high fuel milage Mini. If you mod an R50 just buy a used R53 motor and build it up while it is on a stand and then do a motor swap. It will be a nice little "sleeper".
i concur with Dave. There use to be a very nice JCW Performance Tune/Sound Kit that will add some performance, add powerflex bushings and 22mm sway bar with some lightweight 16inch sticky shoes and you'll be driving a different car. Just remember, the R50 weighs around 200+ pounds less than the R53 (even less without sunroof), your fuel economy will be better and you'll be able to break later and go through turns faster. Want to go faster, shave more weight...Justa thought