Woody (Forum Supportum)
Woody (Forum Supportum) MegaDork
3/18/24 7:59 a.m.

Everything seems to be DOHC lately, even the cheap stuff. Does anybody still sell a new SOHC 16 valve engine?

CyberEric
CyberEric SuperDork
3/18/24 9:17 a.m.

I haven't heard of one lately that I can remember. 

Snrub
Snrub Dork
3/18/24 10:12 a.m.

Was the Fiat 1.4l engine the last SOHC 4-cyl engine sold here?

Edit: I'm not positive, but I think the 1.3l engine in the fiat 500x is SOHC. In general, Fiat seems to have some SOHC, some DOHC engines.

gearheadE30
gearheadE30 Dork
3/18/24 11:00 a.m.

I thought the Fiat was SOHC but with that freevalve setup or whatever they were calling it on the intake side. Solenoid controlled valves. 

In general, I think SOHC with 4 valves per cylinder has gone away because VVT can be used as a fairly strong lever for emissions while retaining great power delivery characteristics. It is much harder to vary LSA with SOHC than it is with DOHC. Without varying lobe separation, SOHC makes more sense if you can get the rocker lever arrangement set up well.

maschinenbau
maschinenbau PowerDork
3/18/24 11:38 a.m.

Technically yes, the Fiat 1.4 MultiAir had a single camshaft. 2 lobes for exhaust, 1 for intake. The intake lobe pushed a hydraulic cylinder that moved oil through a complicated hydraulic circuitry to activate the intakes. This gave the MultiAir variable valve lift and timing.

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