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Old 10-20-2012, 04:25 PM   #22 (permalink)
renault_megane_dci
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Join Date: Feb 2009
Location: France - Paris
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la_voiture_de_courses - '03 Renault Megane Estate
OldContinents
90 day: 44.34 mpg (US)

xiao lan - '01 Audi A2
90 day: 38.88 mpg (US)

Brit iron - '92 Mini Mini
90 day: 45.5 mpg (US)

Prius - '09 Toyota PRIUS Lounge
90 day: 47.37 mpg (US)

Beemer - '06 BMW F800 ST
90 day: 53.06 mpg (US)
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I have been doing some thinking about cam timing and assuming we don't use came phasers (which I believe we realistically can't) I believe we need at least 295° cams :
20° advance + 180° + 95° retard

I am not very sharp on bike cams but it doesn't seem too wild (the hot factory cam for beemer airheads are 336 IIRC) at least for 2 valvers.

As for FE, on top of Atkinson timing on the inlet, we don't want a lot of overlap to promote low RPM efficiency as well as not too much duration on the exhaust (that's where we might need a regrind).

The timing of my particular bike is 260 on the inlet.
I think I will investigate 2 valver timing of the same base engine.
GN 400's and 125 are on the top of the list.


By the way, I could build a nice 12,2 to 1 CR engine with a DRZ 250 head and barrel on top of a DR 350 bottom.

Anybody can find the DRZ 250 (complete) head and piston + barrel in the US ?

Last edited by renault_megane_dci; 10-20-2012 at 04:26 PM.. Reason: duration ON THE EXHAUST
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