SouthernBoy

Oops, I believe I have my RPMs and effects backwards. I meant the secondaries opened up at 4000 RPM.

F23A4

Maybe I misunderstood but, Nissan's VQ35DE cams only have one profile where the timing advances/retards on the fly via CVTC. If Nissan's CVTC were complemented with Nissan's VVL system then, there'd be secondary lobes.

EZZ

Thats because Nissan de-tuned the Altima v6 for marketing purposes. The same engine in the G35 has smooth power delivery throughout the rev range. I've run my car plenty to redline and never notice a change in pull anything like vtec.

SouthernBoy

To EZZ;

Before I installed my after-market intake (Frankencar WAI with Apexi filter.. better than Injen or AEM), power delivery from my engine was linear with no noticable surge at any particular RPM. In fact, it was rather boring and I was not impressed. The intake made a BIG difference with this and both horsepower and torque output.

EZZ

Interesting. Perhaps Nissan designed it that way because they feel that a surge in power is not the effect they want. The Z/G35 has always been marketed as a car with linear acceleration. I'm sure Honda could mimic the TL to have linear acceleration by using different CAM profiles and intake/exhaust tuning but people have come to expect the VTEC feeling (and many LOVE that extra surge). I don't really compare the VQ to the J series just because they feel so different. The 3.2 really feels like an inline 6 because of its smoothness (although the inlines exhibit better torque across the powerband) and the VQ feels like a small displacement V8 (and its pretty rough compared to the 3.2). Be it SOHC or DOHC, Honda engines have always "felt" better at high rpm than the VQ.

F23A4

IMHO, that high RPM Honda feel is probably be attributable to the Jekyll/Hyde VTEC powerband. My friend's S2k felt like a Civic under 6k but like rocket above it; the sub 6k slug like performance just further exaggerates the feel above 6k. His previous car was an RSX-S that felt MUCH more linear than his S2K thanks to iVTEC. Hondas VTC (the 'i' in iVTEC) makes the crossover from low cam to high cam not nearly as noticeable in the K20A as it is in the VTEC F20C.

With the Odyssey's new iVTEC SOHC, I hope to see how well that enhances the TL's J32A (assuming it trickles down).

But , it's hard to compare the J32 with the VQ35DE as they're very different animals (like comparing a Tiger to a Grizzly Bear, so to speak). The SOHC J32A on the one hand has variable duration/lift, using two cam profiles which results in a more two stage power delivery (though not as pronounced as other Honda VTEC motors). The VQ35DE uses continuously variable cam timing but with a single cam profile and creates a more linear power delivery.

Jirzlee

iTrader: (1)

I think the ivtec in the odyssey refers to the variable displacement, not cam timing.

F23A4

Wrong.

i = Variable Timing Control (aka continuous cam phasing)
VTEC = Variable Valve Timing and Electronic Lift Control
VCM = Variable Cylinder Management

Jirzlee

iTrader: (1)

Tough guy huh, the picture shows a normal cam sprocket, not a hydraulically controlled one that would need to be used to offer cam phasing like that of a K20a 4 cyl.

Jirzlee

iTrader: (1)

I did a quick search to back up my statement so read on;

http://info.detnews.com/autosconsume...x.cfm?id=16130

Honda uses the "i" in i-vtec to refer to multiple different advanced "intelligent" systems on their motors, whether its vtc or vcm (variable cylinder management).

F23A4

I stand corrected, the iVTEC setup in the Ody is a reference to VCM (unlike in the K-series, which is cam phasing). You are correct.