History Lesson

The very first Honda VTEC engine was in a 1989 JDM DA6 Honda Integra with a 1.6L DOHC 16-valve B16A engine and 160 hp. Sound familiar? The NSX came a year later in 1990.

Link1: http://asia.vtec.net/spfeature/vtecimpl/vtec1.html
Link2: http://www.leecao.com/honda/vtec/dohcvtec.html

However, it's a little known fact that Nissan actually beat Honda to the market with a variable valve timing system. Their NVCS (Nissan Valve-Timing Control System) dates back to 1986 and was used first in the VG30DE 3.0L 24-valve V-6 and I believe the RB20DE (Skyline) engines. By 1990 it was in many of their vehicles including the VH45DE (Q45) and also a 1.6L 4-cyl but I'm not sure of the engine code or car. It was also used in the 92-94SE Maxima with the VE30DE engine. Honda was just starting to deploy VTEC while Nissan's NVCS was already in widespread use throughout the company.

Link3: http://www.autoweb.com.au/start_90/s...wsarticle.html




Example of NVCS Operation, 1990 Nissan 300ZX TT

Paraphrasing from SAE documentation I have on the VG30DETT engine from the 300ZX TT, here is how the NVCS system worked.

NVCS ON
Intake Valve Open: 19 BTDC
Intake Valve Close: 49 ABDC
Exhaust Valve Open: 59 BBDC
Exhaust Valve Close: 9 ATDC

NVCS OFF
Intake Valve Open: -1 BTDC (1 ATDC)
Intake Valve Close: 69 ABDC
Exhaust Valve Open: 59 BBDC
Exhaust Valve Close: 9 ATDC



Note, example follows VG30DETT engine, but NVCS is a little more clearly illustrated with the VE30DE from the 92-94 Maxima SE below:



Light Load
At light loads and below 6100 rpm, NVCS is OFF with the intake valves retarded. This helps to promote a smooth idle and engine stability.

Medium to Heavy Load, < 6100 rpm
At higher loads but lower RPM's, it is possible for air that has flowed into the cylinder to bounce back out again. This decreases volumetric efficiency and therefore an earlier valve closure is desired. So under these conditions NVCS is ON and the intake valves are advanced by 20 degrees. Doing this can increase engine torque in this range by close to 20 lb-ft.

Medium to Heavy Loads, > 6100 rpm
Now at higher RPM's, whereas before the problem was that air was bouncing back out through the intake port, now the problem is that not enough air has had a chance to flow in yet. In order to take advantage of inertia effects, a later valve opening is preferred, even if it is the same duration. So at high revs, NVCS is now switched OFF and the intake valves are retarded back 20 degrees to their original position. This can help with top-end torque by as much as 10 lb-ft.


Nissan NVCS and "Cam-Phasing" vs Honda VTEC

Nissan chose to focus their NVCS system mainly at low and medium speed torque production because the vast majority of the time, engine RPMs will not be at extremely high speeds. The NVCS system can produce both a smooth idle, and high amounts of low and medium speed torque. Although it can help a little at the top-end also, the main focus of the system is low and medium range torque production.

We all know how Honda's VTEC system works, but here is where it runs into trouble. Since it only has one profile with fixed phasing for low-RPM's (cannot advance or retard valve opening/closure), the low-RPM profile must be able to produce a smooth idle and stable running at light loads. This means retarded intake valve opening. At low and medium revs but high load, the intake valves cannot advance on the low-RPM profile like they could on Nissan's NVCS, so volumetric efficency is possibly lost, and torque production cannot be optimized in this range. Finally at the top-end, a higher lift and duration cam profile is used and the system drastically improves top-end torque production (peak horsepower), but it is never able to optimize torque in the low-end or mid-range.

So the NVCS system and in general cam phasing technology helps significantly in the low-end and mid-range with torque production, but really not that much at the top-end. Honda's VTEC helps significantly at the top-end (peak horsepower), but not at all in the low-end and mid-range.

Summary

Nissan's 1986 NVCS system took advantage of the fact that the optimal intake valve opening and closure position for a given duration is different for every RPM and load combination. Varying the phase helps significantly with low and medium range torque production which is most important for most people. The engine is only going to spend a very small amount of time at or near redline, so perhaps optimizing an engine for operation in this range does not make as much sense? Indeed, the vast majority of variable valve timing systems in use today (Audi/VW, BMW VANOS, Porsche Variocam, Subaru AVCS, Toyota VVT-i, Nissan's 2nd Gen CVTC, etc) are all "cam phasing" systems just like Nissan's original NVCS system that favor low and medium speed torque production over all-out top-end. Additionally, these systems are also cheaper to adopt and less complex than cam-changing systems as well which lower manufacturing costs and costs to the consumer.

As a final punchline, even Honda has now finally adopted a cam phasing system with their i-VTEC engines which also uses their traditional cam changing technology as well. Maybe Honda has finally seen the light and realized that some of us do actually expect some power below 5000 rpm? Now if only they would put i-VTEC systems in their V-6 lines (4-cylinder only so far). They still need some help in the torque production department, especially when pulling 3300-3500+ lb automobiles with only 3.0-3.2L engines! ;-)

Another misconception.


Cam-Changing Systems

- Honda VTEC
- Mitsubishi MIVEC
- Nissan Neo VVL (not used in US market)

Cam-Phasing Systems

- Audi 2.0-litre - continous inlet
- Audi 3.0 V6 - continous inlet, 2-stage exhaust
- Audi V8 - inlet, 2-stage discrete
- BMW Double Vanos - inlet and exhaust, continuous
- Ferrari 360 Modena - exhaust, 2-stage discrete
- Fiat (Alfa) SUPER FIRE - inlet, 2-stage discrete
- Ford Puma 1.7 Zetec SE - inlet, 2-stage discrete
- Ford Falcon XR6's VCT - inlet, 2-stage discrete
- Jaguar AJ-V6 and updated AJ-V8 - inlet, continuous
- Lamborghini Diablo V12 since SV - inlet, 2-stage discrete
- Mazda MX-5's S-VT - continous inlet
- Mercedes V6 and V8 - inlet, 2-stage ?
- Nissan QR four-pot and V8 - continuous inlet
- Nissan NVCS - late-80's, early-90's cars (added by SteVTEC)
- Nissan VQ V6 CVTC- inlet, continuous ?
- Nissan VQ V6 CVTC since Skyline V35 - inlet, electromagnetic
- Porsche Variocam - inlet, 3-stage discrete
- PSA / Renault 3.0 V6 - inlet, 2-stage
- Renault 2.0-litre - inlet, 2-stage discrete
- Subaru AVCS - inlet, 2-stage ?
- Toyota VVT-i - continuous, mostly inlet but some also exhaust
- Volvo 4 / 5 / 6-cylinder modular engines - inlet, continuous
- Volkswagen VR6 - inlet, continuous ?
- Volkswagen (Audi) W8 and W12 - continuous inlet, 2-stage exhaust

Cam-Changing *and* Phasing Systems

- Toyota VVTL-i
- Honda i-VTEC
- Porsche VarioCam Plus


The number of cam-phasing systems in use is far more than cam-changing systems.


Source: http://autozine.kyul.net/technical_s...tech_index.htm


The thing that Honda can take credit for is for popularizing the technology, though. Nissan didn't plaster NVCS all over their engiens and didn't even really advertise it because they honestly didn't think anybody would really care and the difference it made didn't really show up that much in the peak advertised numbers anyhow. VTEC makes a big difference in top-end and peak horsepower figures though which is very visible to consumers, so that's what really made it stand out and popular.

i wish i knew what u was talking about. You lost me after the talk about variable intake on older nissans...

A pic is worth a thousand words.

Good job of collecting and summerizing the info Steve. I appreciate what you give back to the org. I'll be sending this to my brother who recently switched from Honda to Nissan.

Very excellent post no doubt FAQ material!

you are genious

Very nice history lesson Steve Thanks for posting it.

Thanks for that bud, you are always coming up with interesting and helpful posts
keep 'em coming

Awesome history thingamajig Funny thing is, it's actually a nissan engine that holds the N/A record (that I know of) for HP/liter. The SR16VE N1 get's 197 out of 1.6 liters. 123 HP/liter. Too bad there were only 5 of of them made...

the NA racing VQ30 makes 415 hp and there is one that is being tested that makes 450 hp. it is used in hte nissan telefonica series
415 - 138.333 hp/liter
450 - 150 hp/liter

I was talking about stock production engines...

so now hand over the link on the v6 board that sparked this research

Damn Steve, you know your ****

i've told the honda kids in my area about nissan doing variable valve timing years before honda when they talk about their v-tec controllers as if they were boost controllers. They shrug it off

How many times did you have to write it before the server actually let you post it

http://forums.maxima.org/showpost.php?p=2467290&postcount=8

NEO VVL ownz all...Cam changing on the intake and exhaust side...Did I mention better mid-range torque too...

Edit: Pre I-vtec anyway...

I copied to clipboard before hitting submit. Would have been REALLY po'ed if the server ate that.

yes the neo vvl is a bad *****

Shut yo mouth...

Wow........

uzza bad motha shut yo mouf good work steve! damn thats a mouthful but so so so informative

Its a even smaller known fact that Alfa Romeo introduced the world's first variable valve timing system.

Nissan's introduction of their NVCS in Japan back in 1986 did not cause as much fanfare as Honda's VTEC introduction in 1989 because:

1. Alfa Romeo's system was the cam-phasing type and was introduced in 1980, therefore the technology is considered "old news" when Nissan brought out NVCS.

2. Based on the links provided everyone can see the difference between Honda's VTEC and Nissan's NVCS. The changing of the valve lift/duration in Honda's VTEC is the big news- this is why Honda's variable valve timing system was highly publized as a "first" because it was the first to come out with the variable valve timing and lift/duration system.

I felt like I was watching a matrix movie.

ooOoOooo...very nice info

The articles I found were saying Nissan had "Japan's" first, so I figured somebody out there must have had Nissan beat because Japan /= "world" Just didn't have the slightest clue on who it might have been.

Thanks for the info.

1991-1999 GA16DE Chain driven version. There was also a belt driven earlier GA16DE I found in a Pulsar but I don't think it have the variable intake gear.
The first chain driven GA16DEs were rated at 110hp but was later bumped to 115hp due to microfinishing.

1991 -1994 B13 Sentra and B12 NX1600
1995-1999 B14 Sentra

The powerplant was replaced in the North American market by the QG18DE in the 2000 model year.

Wow, didn't know the GA16DE had NVCS in it...

I know the Pulsar NX used the GA16i, maybe it used the GA16DE in its last model year... the GA16i was the weak bastard child engine for the XE model... to the Pulsar NX SE's CA18DE though

I don't think variable lift is worth having anymore. As you stated many times, the low end power is where people want it, especially in this country. Also with the advances in cam phasing, variable intakes, and other developments in software and sensors, I don't think variable lift is necessary. Especially when you consider the cost and complexity of the vtec system.

I've learned to never argue with vtec nuts, it's pointless. Just leave them in their own world.

I wouldn't say that variable lift is pointless. It's just another way of doing things. It favors top-end over low-end, but some people prefer that. I don't, though.

Have you looked at a VTEC/i-VTEC torque curve lately?? It is practically the same from 3k to 8K except for the slight jump when VTEC engages. They're not as top-end biased as many ppl think (except the B16) They may not be torque monsters, but power delivery is constant to redline, and since they rev so high, they can get away with super short gearing (read torque multiplication)...like SteVTEC just said, it's simply a different philosophy that has it's own advantages...

But the problem is that even with said flat VTEC torque curves, there still just isn't enough of it where people want it. Even with shorter gearing and higher revs and more torque multiplication. The number 1 complaint on the S2000 was always a lack of responsiveness in the low-end and mid-range. So what did they do? Up the displacement for more torque.

I never said vtec was pointless, only arguing with those that don't understand it is pointless.

My point was that with all the new technologies vtec has reached a point of diminishing returns. Since Honda has been doing it for years they can probably do it for significantly cheaper than a company could who wanted to get their feet wet in variable lift. That's probably why Honda has it on almost everything they make including motorcycles and marine motors. It's a great technology, but now-a-days a camshaftless engine would be much cooler.

Excellent Info my friend.
i have this friend on msn messenger who happens to own a honda. he always brags about honda inventing vtec and blah blah. i guess this info could make him settle down


btw, check out the new TL showing off VTEC!

my friend was shocked ! check it all out here:

http://www.angelfire.com/ultra/doggy/1.JPG
http://www.angelfire.com/ultra/doggy/2.JPG
http://www.angelfire.com/ultra/doggy/3.JPG

As result, many VTEC engine owners are mostly younger. They love to hear their engine + exhaust reving all the way up to redline and "engage" their vee-tek thingy and feel cool like that, in fact they didn't know they are shorten the life of their engine and wasting gas.

at least IMO that's how it is...

Nice article Stev. If Nissan utilized a varible cam profile head also(ala VTEC for the VG3.5), this engine could EASILY be in the 310-325 hp na range. I mean with a full factory warranty, reliable as hell and good gas mileage.

Good job Steve.

LMK if you want info on AVCS. I am now running AVCS on the swapped motor.

FAQ material? more like Thesis material Very nice and informative read as usual, SteVTEC. How ironic that the guy who posts this goes by the name of SteVTEC

DW