So with the VQ35HR approaching the market pretty soon, I wanted to get your opinions on this engine? Supposedly 306hp (new SAE, but with the old system, probably 10hp more) and a 7500 rev limiter...it's also got equal length exhaust manifolds and other goodies....however, it never mentioned anything about direct injection....

what are your opinions on this? I know very little about direct injection...I just know it shoots gas straight into the chamber, rather than the IM....but is it really necessary for the VQ? Do you guys think Nissan is cutting corners by not inputting this new HR engine with the direct injection?

I wanna know how many people are highly anticipating for the release of this new engine...I'm part of the crowd...but I wanna make a highly educated decision when buying this engine...I mean, this will be my first expensive car that I'll be pulling a loan...what do you experts think at this point in time...about this engine?

 

the main benefit of direct injection is its ability to run a leaner air-fuel mixture. Also injecting fuel straight into the combustion chamber cools intake air and is a cleaner burn/spark. So you get better fuel consumption as well as a slight gain in power/torque

Alfa Romeo were the first to market with a direct injection petrol engine. I drove both the regular 2.0L Twin Spark 4 cylinder and the direct injection 2.0L JTS 4 cylinder back to back when i had my Alfa 156 and there was a noticeable improvement in smoothness at high rpm and more torque at low revs

But i thought the current VQ35 in the Z had direct injection?

 

naw, the current vq35 has direct IGNITION...but not direct INJECTION...I actually got into an arguement with a friend of mine...becuz he argued that the Vq35 comes with direct IGNITION...but I disagreed (although I was referring to INJECTION, but they sound alike)...

how much is "slight" gain in hp/tq? it couldn't be that significant....can it? I mean, Nissan's been running the VQ without direct ignition (in america that is) for such a long time...could it be "that" much more beneficial in terms of...hp/tq and fuel economy? I just want to make sure that when I buy this new VQ35HR in January, I want to make a good investment

 

Direct injection has been know to give 1 or 2 more laps per stint on endurance racing. So it does make a difference.

Plus, you have so much more control on the actuall combustion. VW/Audi even managed to create stratified fuel mixture (basically making layer of fuel sandwiched in air, in the cylinder while compressing the mix!).

Another benefit, since fuel pressure is so much higher, you get better atomization of the fuel (smaller droplets), increasing fuel to air contact and better, fuller combustion.

It's all good stuff!

 

direct injection has very real benefits. eventually all gasoline engines will probably go in that direction.

however, is it necessary for the VQ right now? no.
the current revup VQ designs is scalable up to about 300whp without touching the head or block. the new VQ design will likely do a little better.

btw the s2000 revs very high yet that engine does not feature direct injection.

 

what about the engine itself? are you guys criticizing it? or are you guys praising nissans engineers for building the vq35hr as is?

another question worth mentioning, do you guys think nissan is not saying the vq35hr will feature direct injection...but when the engine is released, it will have it?

 

Gasoline spray takes up room in the air flow............if 12:1 AF you are displacing 8% of the air that could flow into cylinder by gasoline. Injection after the intake closes adds up to 8% more power.

The problem is the lack of quality in US gasoline*, ours contains too much SULFUR [and now water in Ethanol] which is detrimental to high pressure injectors. EPA was suppossed to limit Sulfur years ago but they have suspended rules to ease production woes...........Direct injection may be a mainteance time bomb until we reduce Sulfur. Let Toyota and others be the testers seems to be Nissan's plan.

* US gasoline is really really bad compared to Japanese and EU standards and requirements.........besides these contaminents US industry/EPA has reduced the BTU content compared to years ago [104-114,000 BTU vs 123,000 BTU in 1990] so engines run on US fuel produce less power output and less MPG.

People buy by price not quality seems to be the norm.
More than half the world's produced oil is heavy and sour in quality and this proportion is expected to increase.

http://www.platts.com/Oil/Resources/...anroadshow.ppt

The above shows in middle of slides the current and proposed US Sulfur reduction progression from 2004 thru 2007 by 2008 the US will only be 3 times worse than EU 30 ppm vs 10 ppm...............

Mexico and Venezuela oils are very very very very high in SULFUR and they are number 2 and 4 respectively in our imports with Canada suppyling the most #1.

 

Havent they said that the compression ratio for the new engine is 10.6:1? If it was going to have direct injection wouldnt the compression ratio be something crazy like 12:1 like it is in the Audi's with direct injection?

 

Had nissan made it direct injection.....the nomenclature would follow Nissan's lineup with Direct injection motors and be a VQ35DD, not HR. R, on Nissan's nomenclature, means supercharged.....unless they're totally revamping their motor designation system

 

your right...but at the same time, I have never seen the "HR" letters in Nissan engine codes...maybe Nissan might be sneaking something up there sleeves? While this HR stands for "high revolution"....it doesn't even indicate DOHC or what kind of injection...?

 

yeah i did read the compression ratio was raised to 10.6....DI engines are suppose to have real high compression ratio?

 

Heres something from audi.com:


DOHC aluminum 90-degree 3.2 V6 with FSI® Direct Injection, variable intake valve timing and intake manifold
Displacement: 3.2 liters (190.57 cu. in.)
Bore: 3.33 in.
stroke: 3.65 in.
Compression ratio: 12.5:1 <--------------
Horsepower: 255 hp @ 6,500 rpm
Torque: 243 lb-ft @ 3250 rpm

 

what about other DI engines? like the toyota and mazda ones?

 

OEM's do things for a practical reason, always. Direct injection allows very pressure AF metering/measurment, allows the OEM to run higher CR's, less chance of detonation, improves fuel economy, reduces emissions, and improves throttle response and power (slightly), and its generally a very good thing.

My fear, is that direct injection oftentimes requires a seperate fuel computer/controller, and I only hope the new system will be as tuner friendly as the old.

 

I've never seen H, but R means supercharged. VG33ER (supercharged frontier), and there was a twincharged small 4 nissan made years ago as well.

 

oh yeah, you are right about that....but then again, i doubt this one is going to be FI...it already says in the spec sheets it stands for "high revolution"

 

The biggest benefit of direct injection on high performance engines is that it reduces the possibility of detonation. Basically, instead of the gasoline being drawn into the engine and then heated/compressed, it is injected directly into the CC at the exact moment that the PCM wants the combustion to occur. One of the limiting factors with high compression engines is that the high compression creates alot of heat and pressure which pushes the gasoline past its flash point and causes it to detonate before the desired point, causing a ping or knock. With direct injection, the air gets compressed without fuel, so detonation is very unlikely. This is also a big plus for boosted engines, since they have the same issues with detonation as high compression engines.

Diesels have been using direct injection for some time, out of necessity. Most turbo diesels use 18-20:1 compression along with 20-25psi boost.

 

Consider a 370 cc injector might take 10-12 milliseconds to inject enough fuel at 43.4 psi to create 38-40 lb/ft in a cylinder. If you double the psi you only increase flow [or decrease time by the square root of the ratio]

Newer DI engines use 1600-2250 psi injection pressure that allows the injection time to be reduced by 1/6-1/7 or down to 2 milliseconds or less.

GM projects that by 2010 one out of every six GM vehicles in North America will be equipped with a direct injection engine

 

http://headlines.yahoo.co.jp/hl?a=20...4-maip-bus_all

85 Million on a new engine factory!!!!