View Single Post
Old 02-24-2008, 04:59 AM   #29 (permalink)
trebuchet03
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
Thanks: 0
Thanked 22 Times in 18 Posts
Quote:
Originally Posted by LostCause View Post
I think the best technological implementation of a turbo to improve fuel economy would create one hell of a complicated engine.

First, take a small atkinson cycle engine - 13:1 CR with an effective 8:1 CR. Use a small, efficient turbo ducted through an intercooler to raise the effective CR to ~10:1 (i.e. miller cycle). Use variable valve timing to increase the CR to 13:1 w/ turbo (which should already be operating in its most efficient range) and switch the injectors over to feed from a smaller tank holding 91 - 100 (avgas?) octane fuel during acceleration. Route the spent gasses through the primary turbo and feed the residual gas into a turbocompound that sends power back into the flywheel.
I really like this idea... But I'd say remove the separate fuel tank and such....

Just go for a miller cycle engine with variable valve timing. It's probably not very difficult to have a valve profile that switches the engine from Atkinson to Otto while off boost... And considering Atkinson cycle isn't new and VVT isn't new and both concepts are implemented into mass produced vehicles - I wouldn't call it complicated at all

Alas, this isn't something that's easily DIYable It sorta has to start from the mfr...
__________________
Cars have not created a new problem. They merely made more urgent the necessity to solve existing ones.
  Reply With Quote