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Old 07-20-2012, 05:38 PM   #10 (permalink)
renault_megane_dci
Master EcoModder
 
Join Date: Feb 2009
Location: France - Paris
Posts: 762

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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Quote:
Originally Posted by Electictracer View Post
I think the main hang-up with our motorcycles is the cam. Manufactures want high HP-weight ratios to sell bikes, but this also means inefficient engines with high top-ends. I shudder to think what a modestly geared up Ninja 250 with a more reasonable cam could do for mpg. Since this is the most commonly used bike for modding, is it possible we as a group could go in together to have a batch made? Personally I don’t have the knowledge or skill to design a better cam, I only know enough to know it could be done. That being said, with fuel injected bikes like the Honda 250 this option is less attractive because of tuning issues.
Does anyone else think this is viable?

That's the spirit !

How about checking if the exhaust cam is hotter or "colder" than the intake ?
If it is colder (as in less duration) maybe a swap is possible with the inlet?

Overlap goes with high power per litre engines and it is what kills FE.
If we could reduce overlap, we might see a very good improvement (as well as a big drop in powwer or max RPM).
Together with less duration (higher dynamic CR) and it would be FE heaven
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