Thread: Project 100mpg
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Old 10-23-2009, 11:40 PM   #45 (permalink)
Master EcoModder
Join Date: Jan 2009
Location: USA
Posts: 257

Winsight - '06 Honda Insight
Gen-1 Insights
90 day: 72.19 mpg (US)
Thanks: 236
Thanked 82 Times in 58 Posts
It definitely takes a lot more to swap on a sohc head. Head bolts, head gasket, intake manifold, exhaust manifold, coolant temp pigtail, egr tube, throttle position sensor, timing belt/covers, passenger side engine bracket and filing down the edges of the piston domes? A whole list of stuff, unless you were just thinking that would be obvious, or maybe you were just kidding.
I'm not even sure that's CA legal.

I looked into why the sohc just feels to have more low low end torque under 1500rpm, especially in my sohc/3.55 final drive trans vs my dohc/3.94 final drive trans (apart from the intake manifold). Maybe it's partially due to the sohc having 9.8:1 compression instead of the dohc's 9.6:1. Otherwise the older dohc head also has larger valves. The new style dohc head has sohc sized valves. More low end? Maybe. They did use the new style dohc head for boats like the pt cruiser and minivan after all.

My scangaugeII says my sohc neon uses .27-.31 gallons per hour at idle (calibrated) vs .35-.4 gallons per hour from my dohc (loosely calibrated). Really cuts into my ICE on pulse and glide.
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