411 swap

[0xDEADBEEF]

I guess you have not looked at many imports in the last 20 years. Almost all Nissans use a header style manifold or manifolds.

It absolutely can help fuel economy. I recently put a Volant air intake, plenum spacer, and JBA shorties on my Nissan Pathfinder with the 4.0L. While it had tubular manifolds they were log style without a decent functional collector. It gave a very noticeable torque increase. I use less throttle in normal driving and my fuel economy is up to about 16.5 average in town from 14.6.

I haven't. I would assume that's for power out of the small displacement engines.

 

[0xDEADBEEF]

They may not have gone to K&N filters, but many OE manifolds are basically headers now. They also use VVT to reduce pumping losses.

I hadn't thought about VVT having an effect on pumping losses. Can you expound on that?

The pentastar in my Jeep has no exhaust manifolds at all.

 

[L31MaxExpress]

I hadn't thought about VVT having an effect on pumping losses. Can you expound on that?

The pentastar in my Jeep has no exhaust manifolds at all.

They do it by altering intake closing and LSA which changes dynamic compression ratio and overlap. More overlap resultes in a more exhaust diluted mixture which equals less torque output via less air/fuel charge to burn. EGR is an inert gas that does not change air/fuel ratio. Less charge density with the inert EGR means a torque reduction which means the throttle plate is more open and the engine is not having to fight as much vacuum to pull the pistons down, leaving more power to drive the load. Here are a couple intake cam phasing tables for a Nissan VQ40DE. They changed the phasing for given applications. The intake phasers advance the intake cams. On my 2007 G35 with the VQ35HR it adds exhaust cam phasing. The exhaust cams are retarded as needed. There is whole map there as well. The factory envineers main concern is emissions, power and mpg are secondary and take a back seat to emissions output.

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VQ35HR

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I setup a cam phasing change on my G35 through testing. Let another tuner use it on a near stock car because he doubted the gains would be signifigant. Near stock automatic 350Z test subject with my cam phasing I was running on my 2007 G35 proved him wrong. My car came alive alot quicker with the change and delivered increased fuel economy, also easily held overdrive and even accelerated in OD on one section of uphill road it always downshifted to 4th on just to maintain speed. My car saw bigger gains from the phasing adjustments and alot more power overall because it has headers with merge collectors, high flow cats, dual 2.5" exhaust with a X-pipe and straight through magnaflows as well as a less restrictive intake setup.

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[L31MaxExpress]

If you look at the exhaust cam phasing on my G35, you notice alot of exhaust retard in the 1,500-3,000 rpm range. That is to help reduce pumping losses. I am at nearly 3,000 rpm at 70 mph and can still touch nearly 30 mpg highway. Normal cruising is up to about 14 on the base fuel. As load climbs above 14, it is starting to need power to climb hills or accelerate, which is why it quickly tapers to no exhaust cam retard. The factory tuning had retard under under alot more throttle, hit a hill and the exhaust would just resonate as the increasing cylinder pressure was dumped out of the exhaust wastefully. Advancing the exhaust cams at about 18 on the base fuel at about 3,000 rpm livened up the part throttle torque and made the exhaust much quieter.

 

[618 Syndicate]

They do it by altering intake closing and LSA which changes dynamic compression ratio and overlap. More overlap resultes in a more exhaust diluted mixture which equals less torque output via less air/fuel charge to burn. EGR is an inert gas that does not change air/fuel ratio. Less charge density with the inert EGR means a torque reduction which means the throttle plate is more open and the engine is not having to fight as much vacuum to pull the pistons down, leaving more power to drive the load. Here are a couple intake cam phasing tables for a Nissan VQ40DE. They changed the phasing for given applications. The intake phasers advance the intake cams. On my 2007 G35 with the VQ35HR it adds exhaust cam phasing. The exhaust cams are retarded as needed. There is whole map there as well. The factory envineers main concern is emissions, power and mpg are secondary and take a back seat to emissions output.

You must be registered for see images attach

You must be registered for see images attach

VQ35HR

You must be registered for see images attach

You must be registered for see images attach

I setup a cam phasing change on my G35 through testing. Let another tuner use it on a near stock car because he doubted the gains would be signifigant. Near stock automatic 350Z test subject with my cam phasing I was running on my 2007 G35 proved him wrong. My car came alive alot quicker with the change and delivered increased fuel economy, also easily held overdrive and even accelerated in OD on one section of uphill road it always downshifted to 4th on just to maintain speed. My car saw bigger gains from the phasing adjustments and alot more power overall because it has headers with merge collectors, high flow cats, dual 2.5" exhaust with a X-pipe and straight through magnaflows as well as a less restrictive intake setup.

You must be registered for see images attach

If you look at the exhaust cam phasing on my G35, you notice alot of exhaust retard in the 1,500-3,000 rpm range. That is to help reduce pumping losses. I am at nearly 3,000 rpm at 70 mph and can still touch nearly 30 mpg highway. Normal cruising is up to about 14 on the base fuel. As load climbs above 14, it is starting to need power to climb hills or accelerate, which is why it quickly tapers to no exhaust cam retard. The factory tuning had retard under under alot more throttle, hit a hill and the exhaust would just resonate as the increasing cylinder pressure was dumped out of the exhaust wastefully. Advancing the exhaust cams at about 18 on the base fuel at about 3,000 rpm livened up the part throttle torque and made the exhaust much quieter.

So if what you're saying is accurate, why haven't manufacturers done this themselves? What's the trade off?

 

[L31MaxExpress]

So if what you're saying is accurate, why haven't manufacturers done this themselves? What's the trade off?

As I mentioned emissions wins. The trade off is purely higher emissions in a parts per million standard. However ppm is not looking at overall total output and has always been a piss poor testing method for analysis of total emissions output. Lets say it has 30% more PPM, but the total exhaust output in millions is slashed in half. Doesn't make much sens does it.

 

[618 Syndicate]

As I mentioned emissions wins. The trade off is purely higher emissions in a parts per million standard. However ppm is not looking at overall total output and has always been a piss poor testing method for analysis of total emissions output. Lets say it has 30% more PPM, but the total exhaust output in millions is slashed in half. Doesn't make much sens does it.

Which emissions are higher? Not sure how using less fuel creates more emissions?
Ppm is a fairly standard method of determining chemical contamination, what do you think would be more suitable?

 

[L31MaxExpress]

Another trade off of say a freer flowing intake and or exhaust would be more noise. Take the Volant air intake on my Pathfinder. Under normal driving it is virtually no different than stock. In the mid throttle and mid rpm you start to hear the air sucking into the throttle body. Stick it to the floor and that long, smooth intake tube has a very noticeable howl to it and the headers make even the factory exhaust have a louder tone. WOT it screams, but its not annoying to me and I am rarely WFO anyway.

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[L31MaxExpress]

Which emissions are higher? Not sure how using less fuel creates more emissions?
Ppm is a fairly standard method of determining chemical contamination, what do you think would be more suitable?

Total output, grams per mile.

 

[618 Syndicate]

Total output, grams per mile.

But exhaust gas isn't consistent across a mile (or any other distance), so how does knowing the total output help? What matters is the concentration of what's put out right?