Originally Posted by lonewolf1015
Hey guys first time here since you guys seem really knowledgeable on Mr motor soon I'm going to be doing a bigger turbine on the turbo in my juke along with crank pulley and bigger intercooler and stuff but wanted to ask if any parts from the mr20 would transfer over to the mr16ddt to help beef up the internals like cams or pistons I'm new to the whole turboed cars and this is my first nissan ever always had Toyotas so some insight would be greatly appriciated
Pistons, head, and cams are different, bottom end structure is probably all the same from crank down barring additional mounts or flanges added to the original MR casting. I believe the MR was designed as a 2.0 in the drawing board stages and destroked
Direct injection gas is extremely high pressure, generated usually off one of the cams or timing belt/chain, though i believe every gas direct injection system is too new to use that method, they are all cam driven because that is the simplest and most refined method. The head is a different casting redesigned to accomodate the additional length added by the fuel pump lobe.
The MR20 is not too strong in the bottom end, girdle is not too thick, but ok for up to 300HP i would say. I have talked to TURBOSENTRA08 (Jim, highest HP MR20 so far) and he said 300 is a "daily driver" reliable amount, although 500 is not out of the question on stock crank. He has a fully built motor i think. Direct injection should be boost friendly, much more accurate and micro-adjustable, plus higher dynamic compression ratios are attainable for a given octane number. Really better all around. The only problem i conclude with gas direct injection is cylinder wall wetting from poorly placed injectors or re-used combustion chamber design that has large surface area. Realistically it should go full circle to diesel design where there is no combustion chamber in the head, and it's all in the piston. The only reason for that is the manufacturers don't like to disturb the production line too much at once, they are still using very much the same components as the conventional multi-port MR20's/18's. Money basically.
Edit: I just finished posting then saw buddys post above.
To expound on higher boost pressure, he's right, you can screw around with the stock wastegate and a boost gauge to get a little bit more, but realistically that turbo is perfectly sized, for the intended design powerband and desired characteristics. So, it's probably already stretched far enough to provide stock boost, spinning it faster will wind it up too fast and it may not last long.
One day VGT will come to gasoline engines and all of the problems of low RPM boost vs high RPM boost tradeoffs will be a thing of the past.
Also the guy above is thinking a little bit too old school, things have moved on since his frame of reference for getting more power. You can do alot to new cars without having to tune anything, most things will be adapted to with a couple hundred KM of driving. They have wideband/wide range O2 sensors stock, knock sensors and all the usual A/F inputs, safest most idiot proof engines yet. GDI works the same as a conventional multi port system, just higher rail pressure, and more micro-pulsed injection due to faster opening time. They use piezo-electric injectors which are now affordable. Your inputs and feedbacks tell the PCM it is failing to meet the target AF and it subtracts or adds fuel compensating for calculated load, RPM, whatever, then from there we go to fuel trim and blah blah blah.