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[2woody]

Actually, I can't think of a variable cam-timing turbo engine off hand - I suspect the use of the variation reduces considerably with a turbo car.

Nissan VG30DETT  N-VCT so it's a single-step intake cam advance/retard by way of a solenoid actuated oil passageway used to force a helical gear forwards & backwards in the cam sprocket to rotate it with regard to the cam itself.

Used, IIRC (having just sold mine  ) to reduce valve overlap once on boost - so there's more overlap for scavenge at low & mid range RPM and less overlap so you're not wasting mixture back out of the exhaust at high RPM. It's not used for EGR as the VG30DETT has a ye-olde EGR vacuum solenoid EGR valve ported into the plenum.

N-VCT was dropped in 1994 in US markets and peak power dropped ~20hp.

probably used to reduce overlap at low and mid revs to avoid exhaust manifold pressure pushing exhaust back into the inlet - allowing higher boost. As a guess i'd say the boost would have been reduced on the later car ?

[2woody]

Volvo 2.4 T5 and 2.5 R engines have intake and exhaust vvt
all the S60's had exhaust vvt but the later 2.4 and 2.5 engines with the KKK turbo had it on both cams

thats what i had before,sold the engine from it yesterday but could easily get 350bhp with just a map.... used oil operating solenoids to control them, when logging though- stationary 3 degrees advance then 27-30 at wot then over 5500ish it'd pull it back slightly because i had a standard intercooler

that's a shame - i've got two T5's and neither have got variable cams.

[aaronjb]

probably used to reduce overlap at low and mid revs to avoid exhaust manifold pressure pushing exhaust back into the inlet - allowing higher boost. As a guess i'd say the boost would have been reduced on the later car ?

Boost pressure (at least on paper ) is the same on all years at 8psi (6psi until warm and/or if the knock threshold is reached), and from memory the part number for the cams themselves is the same - sprockets are different on the intake, of course. I've never put a set of cams side by side to check, though .. having one VG30DETT in bits was quite enough

(This is not helping me get over the loss of having sold it last week, at all )

Whether it sheds any light on things, but the official reason for dropping the N-VCT was US (Cali) emissions regulations - so the 20hp drop could easily be down to a difference in the tune rather than the engine, I suppose

Great powerplant, just a shame mine urinated oil at a fairly constant rate.

[2woody]

I promise not to mention the car again 

[aaronjb]

I promise not to mention the car again 

 

[ngrainqey]

Volvo 2.4 T5 and 2.5 R engines have intake and exhaust vvt
all the S60's had exhaust vvt but the later 2.4 and 2.5 engines with the KKK turbo had it on both cams

thats what i had before,sold the engine from it yesterday but could easily get 350bhp with just a map.... used oil operating solenoids to control them, when logging though- stationary 3 degrees advance then 27-30 at wot then over 5500ish it'd pull it back slightly because i had a standard intercooler

that's a shame - i've got two T5's and neither have got variable cams.

what are they? v70's? 850's? the me7's all have atleast exhaust vvt so 2000ish onwards

[ngrainqey]

found some stuff which i might be trying:

Tighter lobe centers: 
more peak power,
higher fuel consumption
rougher idle
more torque at low RPMS,
peak power occurs at LOWER RPM,
higher emissions,
power RPM band gets narrower and moves DOWN

Wider lobe centers  opposite of above

and

Advancing the cam
slightly improved low rpm torque,
slightly reduced peak power
imperceptible change in emissions, idle & fuel consumption

Retarding the cam 
opposite of the above


so im fancying less overlap and retard the timing or more overlap and advance the timing
im not sure which way round yet as i like the rougher idle sound lol but dont want to mash the valves lol

will keep people updated anyway, might dyno it after and compare it to standard timing at a later date when i can be arsed to alter it bak basically lol

alex

[cem_devecioglu]

I dont think v6 engine will permit custom valve timings.. even if so ,you may loose high end or low end..