Intake evaluation on 2K2 Maxima, pics

[LarryS]

A good method of determining if your intake flows enough to support your engine flow needs is to hook up a vacuum gauge in the plenum or intake manifold. If the gauge reads zero vacuum at maximum rpm, full throttle then there would be zero or very little gains from an aftermarket high flow intake.

I spliced a gauge line into the vacuum line on the manifold of my 2K2 Maxima and ran it to a vacuum gauge. See pics for gauge and installation.

http://www.fbody.com/members/LarryS/vacuumline.JPG
http://www.fbody.com/members/LarryS/vacuumgage.JPG

At full throttle, maximum rpm (about 6300) I read about 1/2" of Mercury of vacuum. This indicates a restriction. I removed the cold air intake box assembly from the box that holds the filter and ran again. This time zero vacuum. This indicates to me that the factory filter is sufficient to flow enough that adding a cone type filter would do nothing for hp with the cold air plastic assembly removed.

If you have an aftermarket exhaust then the factory filter may become restrictive. All my testing was with factory exhaust.

In summation, an aftermarket freer flowing intake with stock engine and exhaust will help but you can do the same thing by removing the cool air box. My next project is to modify the factory piece so I keep cool air coming in and get a zero reading on my vacuum gauge.

[miker]

Thanks for the hard work, your net worth around here just went up!

Question: If you remove the box around the air filter doesn't that expose it to hot air off the engine? In which case the induction would suffer from hot air wash and you would be doing more harm than good. I'm not trying to contradict your "research" here, but maybe you could post a picture and show us what you removed for clarification. Did you test on a warm or cold engine?

Thanks.

[LarryS]

miker,

Yes, taking the cold air intake assembly off does expose the inlet air intake to hot air. Just as most of the aftermarket intakes with the cone type filters.

I don't know if the improved flow with zero vacuum will offset the gains of having restricted cold air. Depends on how much restriction the cold air intake creates. All I am saying is that with the cold air intake assembly off there is less restriction and that the cold air assembly is the restriction. There is no restriction based on my tests resultant from the factory filter assembly. With 1/2" of Mercury at full throttle I feel that you would see more hp/tq on a dyno at the point where the gauge starts rising even though it is warm air. Below that rpm you would see more hp with the cold air intake on.

I don't have a pic taken of the cold air intake assembly off but if you look under your hood you will see where they connect is square and forms a square inlet when disconnected. This is where my engine got its intake with the cold air box removed.

My engine was warmed to normal operating temperature for both tests.

Glad I have some worth on this forum now! Hope to be even more worthy as I continue to test and post my results.

[miker]

Thanks Larry. I'll be sticking my nose under her bonnet this afternoon (get your minds out of the gutter gentlemen). I will probably get a K&N filter just for the hell of it.

As far as forums go there is a small handful of people on these boards that actually contribute something other than the "should I get a standard or an automatic, my mom won't let me get a stick..." A lot of the topics are redundant so it's good to see something we can all benefit from.

TTYL

[LarryS]

Your welcome miker!

I really think you should consider getting an alignment based on what I can determine from your cars picture in your signature.

[miker]

You like that? I lifted it off someone elses site, Windows XP makes that so easy.

Actually I need to get both cars in one real picture but that's impossible these days with two small kids and a wife who has a whole list of projects for me every weekend.

I'm still catching flak from neighbors and people who know me for buying a japanese car. We where (& still are come to think of it, bought a new Windstar this month) Ford people, but when it came time to replace my F-150 with a car, the SHO taurus and SVT contour where discontinued. That Crown Vic Sport is a lame duck at 220 HP and I knew that a Marauder would be hard to get and pricey. So here we are...

But I love my new Maxima, I say that every morning I when I start it and I don't give a damn what anyone thinks.

[LarryS]

Here are my other rides that you don't see in my signature. I do own American as well as Japanese.

http://www.fbody.com/members/LarryS/6.0Chevy.JPG
http://www.fbody.com/members/LarryS/maxima.JPG

I don't own the Mustang in my web site as I wrecked it a couple weeks ago. I only have the Camaro to race now.

By the way, the Maxima replaces a Buick LeSabre that we had nothing but trouble with. So far the Maxima is a much nicer car but don't know yet about its longevity capability.

[miker]

I like the color, mine is sterling mist as well. I like it because you can't see the dirt and it's not too flashy which is good for not attracting unwanted attention from Houston's finest.

I was looking at your site earlier, sorry to hear that the notch is gone. I miss my 91 LX so badly that I will probably get another one. Perhaps a nice convertable or I have my eye on that teal green 93 Cobra at Performance Mustangs.

Too many cars and too much money but not enough garage space...

[LarryS]

I have modified my cool air intake to see if my vacuum lowers. The following pics show how I have cut out the center pillar and added a small pillar of my own made from hard wood dowel. As you can see, I contoured the leading and trailer edges to allow better flow.

http://www.fbody.com/members/LarryS/intakeI.JPG
http://www.fbody.com/members/LarryS/IntakeII.JPG

My initial tests indicate I have improved flow. On the 1-2 shift I got just flicker on the gauge, maybe 1/4" of Mercury, on the 2-3 zero. Previously I got about 1/2" on both. I can't explain the 1-2 flutter although I believe my transmission shifts lightly higher on the 1-2. If this is the case then perhaps my modification is marginal but improved. I am reasonably sure that with a good flowing exhaust system I will have mountains of vacuum to rid.