[renault_megane_dci]

Hi folks,

With a broken GN 250 engine (shopping list not done so far), I am starting to think about my options.

I had the DR 350 bottom end project under the blanket wich would add a 6th speed and boost capacity throught stroke to 280 and added 10% torque increase but now I am starting to fancy this setup with an atkinson ground cam à la PRIUS.

Unlucky for me, I only have a single cam so it means the cam needs to be reground rather than simply retarded on twin cam engines (but those might require shorter exhausts cam anyway)

Anyway, I would like to discuss the topic with fellow motorbike ecomodders because lets face it, our engines have either barely enough power (125) or too much (250 and up).

From what I have red, the Prius cam timing is extended inlet timing for at least a third of the stroke up.
I couldn't find the actual numbers, does anybody has it ?

I am worried about the inlet charge point of view with carbs, what is gonna go out and how will it affect accuracy of the mixture (I am fearing it will richen it) ?
Maybe it is a case of switching to injection.

I am worried about the compression ratio boost required : not usually easy on bikes (the longer stroke of my particular setup should help beautifully here)

I am worried about the violent sidetrack from the original setup : motorbike top speed is made through high rpm but how will atkinson engines perform in this domain and will the new lower output of a smaller engine (say a 250) end up in a much slower top speed wich streamlining can not bring back from the dead ?
My top speed is already a very modest 83 mph @ 8K ish rpm.
A prius peak power is 4.5 rpm.
I can't deal with a 60 mph top speed in my trafic conditions.