Air Filter/Intake rubber

[philip]

SNIP While getting aquainted with this cool little engine found the same cracking rubber boot to the stock air box and thought I had a brilliant idea by just replacing that setup with an universal k&n filter right on the end of that powder blue sheet metal contraption coming out of the throttle body(and it went on so nicely). So when it didn't work out like I thought (more air=more power) I was dissapointed.

For the SD22, there are two intake air systems. Non Air Conditioning and factory A/C. Hanging an air filter on the end of the non A/C intake (air inlet adaptor / plenum) would put the air inlet in the stream of warmed air coming off the radiator. This in itself would reduce power a bit due to hotter, less dense intake air. BUT, if the Fuel Control Lever position were optimized for this warmer air all the time, your fuel mileage could improve slightly. Plenty of variables however.

After the clueless 2 hour fuel filter replacement fiasco in parts store parking lot the day before -so the lesson is research then do -even when it looks super simple.

Do read the "Fuel Filters" thread.

when the Fuel Control Lever position is optimized

where would i find this and how is it's position optimized?

Read "Smoke Setscrew" thread.

Except for times of heavy throttle application, the air throttle itself flows less air than either air filter.

i didn't realize this engine breathed like that. i did notice the puny exhaust pipe and was looking into changing the exhaust system for somthing that breathed better. what are the pros and cons of changing the muffler to a high flow system?

Refer to "SD22 Exhaust" thread.

To this I would say that having a slightly larger header pipe fitted to the stock exhaust manifold should help. I think 2" or 2-1/8" pipe is likely sufficient. In my truck's case, the original muffler appeared to be a bit restricted from soot so I replaced only the muffler with a used straight-thru resonator from a late model Toyota sedan. It was cheap ... $40 installed. There was no engine power improvement at lower rpm. But the engine would now rev quicker to maximum governor speed (4,300 rpm). No change in fuel consumption.

[philip]

The OEM exhaust is plenty large enough, unless you plan on running it above the governed RPM. It looks small, but the engine never turns the RPM that a comparable gasser would -- the 2.2l gasser has to move up to 30% more air! SNIP

The typical gearing in 720 pickups has the engine turning 2,500 rpm at 60 mph. Are you suggesting wide open throttle at 2,500 rpm that the 2.2 liter gasoline engine will pump 30% more air through than the 2.2 liter diesel? For than matter, at light throttle cruise are you suggesting a substantial air pumping difference? I believe there is little air flow difference between gas and SD diesels having the air throttle fuel system during cruise.

Now with the VE injection pump (no air throttling), the SD so fitted will pump much more air at our 60 mph cruise speed than the 2.2 NapZ gasoline engine because the gasoline engine's air is being choked off.

I think Nissan sized the exhaust system as a "seat of the pants" governor of sorts. It is sized for maximum torque rpm ... not maximum horsepower rpm as is the case for the NAP-Z gasoline.

[philip]

The OEM exhaust is plenty large enough, unless you plan on running it above the governed RPM. It looks small, but the engine never turns the RPM that a comparable gasser would -- the 2.2l gasser has to move up to 30% more air!

This is misleading, Al. The SD won't rev beyond "governed RPM" ... except down a steep grade. The SD's maximum torque occurs over a 500 rpm range (1900-2400 rpm). The exhaust is sized for the torque range, not peak horsepower rpm. Maxium governed engine rpm is 4100 rpm. Now the gasoline 2.2 NAPZ engine's maximum horsepower rpm is supposedly 5000 rpm (found conflicting specs) while maximum torque occurs over a range of 700 rpm (1900-2600 rpm) and produces about 15 ft/lbs more torque. The SD's 61 hp vs the Z22's 98 hp does not reward the SD driver for flirting with the rpm limiter.

There is no advantage to replacing the muffer, other than to make it louder.

That would assume (a) the OEM muffler is not choked with carbon and (b) one did not operate at full throttle beyond 2400 rpm. In the mountains and/or with higher payloads, it's hard not to run these motors in the low 3,000 rpm range given the WIDE gear spacings of 2-3, 3-4 gear shifts.

Properly operating diesels -- any diesel -- operate with an excess of air. One of the reasons you see visible smoke from a diesel is a miscalibrated IP -- often this is done intentionally by the owner, in an attempt to gain more power. You can squirt in more fuel, but without sufficient oxygen to completely combust it, what you mostly get is soot (visible smoke) and cracked exhaust manifolds from the overheat condition.

"We want TURBOS!"

With some situational exceptions, adding more air to a diesel will not gain power. It will, however, cool the pistons, valves, and exhaust, and that can lead to longevity gains. The cone filter you describe may counter those benefits. The OEM intake tract does not pull underhood air into the intake, it gets air from in front of the hot bits (more or less). A cone filter right above the alternator is going to draw warmer, less dense air than the OEM system. That's not an improvement.

That is all well and proper theory. But we have a strong mitigating influences.

(1) My intake point is way out of the heated air blast leaving the radiator.

(2) Regardless of air filter (OEM or washable cone type) the fact is the intake air picks up substantial heat by flowing through the sheet metal air plenum because the pleum is surrounded by hot air having just passed through the radiator. This factor is probably made worse by the broad surface of my "factory a/c" accomodating air plenum.
Factory A/C plenum . Washable cone

I've taken temperature measurements at the top of the plenum just before the air throttle with cone and then OEM filters in place and found no significant temperature difference (significant meaning more than 5 degrees)(yes, I freely admit I have WAY too much time on my hands ).

Perhaps some benefit would be achieved by insulating the entire air plenum from radiator air heat? Dunno.

[asavage]

Philip, I can't find my thread in the other place, where I stated the ID needed for replacement of the OEM hose (for non-A/C 720s, anyway). Lacking a working Search feature, I was resorting to just poking and prodding over there.

Do you have a link to that thread over there? Or are you certain about the exact (non-rounded) diameter -- measuring the male portions of the system?

[philip]

Philip, I can't find my thread in the other place, where I stated the ID needed for replacement of the OEM hose (for non-A/C 720s, anyway). Lacking a working Search feature, I was resorting to just poking and prodding over there.

Do you have a link to that thread over there? Or are you certain about the exact (non-rounded) diameter -- measuring the male portions of the system?

2-1/2" for the BLUE parts.

[asavage]