ArcticMax

I just installed the PR CAI yesterday, and i'm trying to shed some light on the issue of the CAI hurting high end.

While it probably is true to some extent, CAI cannot get any more restrictive than the factory intake was, right?

Factory intake has long tubing itself, and with the flat rectangular shape, it looked pretty bottled up.

So even if the CAI loses topend relative to the hybrid setup, my thought is that it cannot get any worse than factory intake already was.

Am I right?

We really need to have a dyno shootout. If someone in the DC area with a 5-speed 2k or 2k1 with a HAI wants to go dyno with me, let me know.

Y2KSESteve

iTrader: (22)

The factory airbox is waaay more restrictive than any intake. The main thing is getting rid of it and getting an aftermarket one. Gains between all of the aftermarket ones are minimal, 1-4 HP usually.

thebigsadler

iTrader: (4)

air has to travel further in the CAI, therefore hindering top end.

Stock is more restrictive, but air travels about a foot instead of 2 feet with angles.

That's why some people wet themselves or Hybrid setups, only using the upper intake piping and a filter (and they are lazy).

T-bone

iTrader: (1)

how about we just "dyno" on the beltway?

Hmmm, I am curious about how true dyno's are with these intakes. I would not be reluctant to dyno polished ports or exhaust mods, but an intake is designed to allow more air to flow into the engine. The problem with restive tubing and bends vs a HAI has been discussed to death. A CAI has more trouble taking in air at high speeds that a HAI. Regardless, BOTH benefit from MOVING air. As for the CAI beeing just as 'bad' as the factory setup, I'm not sure. The factory setup IS a CAI, but there are far more bends and restrictions. Also, it seems the intake hole for the place racing is smaller than the factory design and smaller than the Injen. I think that a CAI may perform better on a dyno than a HAI due to the fact that it can take in air easier. This MAY be especially true with the place racing since the tires will stir up the air in the fender wall. I think that the track may be a better test, but something is better than nothing.
Blah blah blah....
I have a 2K 5 speed with a Berk. I live in Arlington. Maybe we should give it a shot.

ArcticMax

let's go get some dynos.


I used to have Berk too.


Let's find out the truth, so we will be freed from this neve ending debate.

Let's go to EIP tuning in Maryland. That's where I went last year.

T-bone

iTrader: (1)

well if you used to have one, what do you have to say about the two? Where is EIP and how much $$$$?
I think the DC memebers wanted to have a dyno day (at autothority in Fairfax?) .

ArcticMax

it'a about 70 miles from Virgnia.


When I had the Berk, I couldn't really tell the difference.

I'm not even sure if I can tell the difference with the CAI.

The only way to find out is to go to the track, or the dyno.

1MAX2NV

iTrader: (5)

We are setting up a dyno session at Swift Racing in Beltsville MD in the next few weeks. It will be during the weekday so if anyone is interested. Let me know.

DTR Maxima

i would be more interested in seeing some track times. I say we get 2 auto (because with 5speed driver affects times) and one with just PR cai and one with just injen, and run them. this is probably more work than its worth but im just so d*mn curious

JAIMECBR900

I don't know which CAI you guys are referring to that has so many bends, but the PR CAI only has 1 bend. The CAI MAY have trouble on the top end not due to air passing thru, but possibly because the overall length of the tube and available engine vaccum at that point. How is the factory and injen's intake "hole" any bigger when the factory sucks air thru an opening in the bottom of the airbox that is probably 2-2.5" wide and injen sucks air in thru the same diameter as PR which is 3"?

As for testing, we have argued this point to death in other threads. The dyno would not be an accurate way to test because of several reasons: 1. The dyno uses a big fan to keep the car from overheating, which in turn (when the hood is open) gives the HAI an unfair advantage it doesn't have on the road; 2. The ecu in our cars uses diff sensors and readings to map timing/fuel/air curves based on those readings. It does not make the changes or takes the readings in an on-going and immidiet basis. Therefore, if you drive in with a CAI and then test, switch to a HAI or any other, you can possibly get inaccurate results due NOT to the intake but to the fact that the ecu still thinks that it has the CAI because last time it checked thru it's sensors it did, so the fuel/air/timing curve will reflect the CAI and not the actual setup; 3. It would be very difficult to test two cars side by side with only the intakes as the difference because there are no such beasts. The cars would have to be "identical" in every respect except for the intake being used for the results to be considered remotely accurate.

The only way to really see the difference between A, B, or C intake is to take measurements for what the intake was designed to do...take in cooler air, more of it, and faster. The only way to test those things is probably by using a temp probe both at the point of intake (filter) and at the TB; Using a vaccum gauge to check how much vaccum is created by the engine at different RPM's; and finally, Flow testing the intake piping itself and it's varying lengths and bends to see which one allows more "flow" without using vaccum as a driving force.

ArcticMax

It IS possible to dyno for differences betweeen cai and hai.


It is not possible to detect the difference down to the last horsepower, but dyno WILL give us accurate data as to the overall shape of the power curve.

(whether it levels off with a CAI on the top end, or if it continues going up with a HAI).

It is true that no two cars are identical, and that there are way too many variables that alter dyno#s.

but,

CAI is supposed to level the power curve on the high end, as opposed to the HAI which is supposed to continue sloping upward.

The dyno WILL detect big differences like that in spite of the variables between test cars and other conditions.

Str8ridin

Please do not forget to take into consideration that when the car is in motion, air flows very efficiently through the engine bay to match the temperature in the wheel well.

So, for you to be up to speed to realize the 'weak top end' of a CAI, the air temperature entering the throttle body will be the SAME for both HAI and CAI.

Unless the radiant heat from the engine heats up the CAI pipe enough to influence the temperature....

hmmmm, then it would be safe to assume, the HAI is more effecient when in motion.

JAIMECBR900

At a sustained highway speed, yes air does flow thru the engine bay. Is it cooler than in the fender well? Doubtful. Which location has a substantially faster rise and sustained temp reading, especially in traffic? The HAI and it's derivatives. Is the temp of the air that reaches the TB lower with one or the other? Noone has done that test yet. Someone did test with a simple thermometer the temp of incoming air at the filter and showed that at sustained speeds the incoming air temps were similar (the CAI still showed lower temps in the beginning AND the end), but noone has shown temps at the TB where it counts the most. As for radiant heat, the same heat would heat up a hybrid/HAI/Injen or any other intake using an aluminum intake tubing. If you are saying that because the CAI would have longer to travel and thereby give more time to heat up, it's an understandable assumption and good educated guess but unproven (would be proven if someone placed a probe at the TB instead of the filter).

BTW, whoever said the measly fender well covered by all the .00001 mm thick plastic, push in screws, and holes in it is a sealed enclosure? Air moves thru I'm sure. Probably the same amount of air that "rushes" over the HAI sitting between the battery and fender.

If our cars were Nascar race cars that run at speed for super extended periods of time, I would say go Hybrid with some kind of scoop to channel fresh air in that way getting the best of both worlds. Since our cars are not like that at all and we have to be in traffic, take off and slow down, and speed up and stop for the majority of the time, I say go with the intake that gives you the most amount of time, volume, and coolest intake air temps.

The only test that came close showed that the underhood temps were substantially higher, took several miles to "cool down" to temps approaching the CAI (never lower even then), and rose very quickly as soon as you came to a stop. So to be honest, the only argument that has really held any credible negative points towards the CAI is the flow issue due to length of piping. And even that point hasn't been proven yet.

Street Reeper

I am scheduling an OKC meet. Hopefully we can get together and test a variety of intakes on the dyno. To test these though I will request that the hood remain closed, and the fan be put in front of the car, this I think will be the most accurate way to test the intakes. I know one person coming out their has a stillen intake so that will probably be the first to be tested. I will warm up the car with the stock intake, put it on the dyno (with the hood closed), and do a run. After this I will switch to the stillen, reset the ecu, drive around until the car is warm, and put it on the dyno with the hood closed. Hopefully this will clear up some debate.

Check your regional locations on the Org, and try and get members togther in your area, some of these people will have different mods that you can test on the same car. IF it's an intake, please keep the hood closed, this is the major factor in determining the advantages and disadvantges of an intake.

03BlkSETE

iTrader: (3)

I new to the Maxima world and have been trying to read everything I can about this issue. I know the guys on the 5th Gen board were trying to get a dyno test done but it needed more support to get done.

In trying to get some knowledge I wondered what people were doing with other cars. My brother, a mechanic, is building a turbo PT Cruiser with a complete engine buildup believes CAI is the only way to go.

I also came across a Honda Tuning mag which should be on the shelves now. They were testing several intakes on a Acura RSX. I only skimmed the article but I noted a some things of interest.
First of all, a drop in K&N did not produce any power gains.
The HAI's which looked similiar to the Berk and Franken produced around 8-9 horsepower. They tested several.
The two CAI's they tested produced 19-20 horsepower. They both looked similiar to the Injen intake.

I'm writing these results from memory so keep that in mind.

The mag guys were shocked at the power increase from the CAI.

Just some food for thought.

JsL

iTrader: (5)

Totally my speculation:

CAI usually cost more than HAI because of the longer piping. Honda tuning wants people to buy the more expensive intake, so they say the CAI produces more hp.

T-bone

iTrader: (1)

This is getting wayyyy to complicated. In the end, we're probably talking about a diffence of < 5hp. I think the best way to 'test' is to race; however, real data will not be produced (unless you use a clock). Yes there are a lot of variables when you race, but I say we do it and see how it goes. I don't really care about the tiny details. As for the best choice, I spend most of my time on the highway and it's cold out now so I am sticking with the Berk. It cost 1/4 the price of a CAI.

We should get SteVTEC to help out; he lives in Tysons and he's an Engineer.

Anachronism

Does the fan that a dyno shop would use move as much air as when the car is actually moving? Wouldn't it be more acurrate to dyno both and then test the intake temp and use the correction factor (1% per 10 deg) for HP.

I tested the intake temperature on my hybrid setup not to long ago and was satisfied that I would see very little temperature improvement from a CAI. However I did not record the results detailed enough to make a full report, but maybe I will do it again and record my results. I put the temperature sensor just inside the filter, just in front of the MAF. If somebody did this test on a CAI they could also put the sensor just in front of the MAF. If the end of the temp probe broke off at least the MAF screen would probably stop it. I personally think the air is moving through the intake tube to fast to gain any temperature between the MAF and throttle body, but even if there was a temp gain it would be the same between the CAI and hybrid.

SteVTEC

The only way to conclusively prove anything on this debate is with back-to-back dynos with different intake setups on the same car. Two different cars (same generation), but the same for mods otherwise would probably be good enough too, though. Racing on the highway is only going to introduce more variables (driver, different cars, different intakes, many other things), and the power differences that you're going to have won't be enough to draw any sort of conclusion. All of those "tiny differences" will add up. Even 1/4 mile racing probably wouldn't be able to accurately compare the different setups, other than obvious differences between stock and non-stock.

I forget the exact equations, but a longer tube will be more restrictive than a shorter tube. I know that much. This is why you gain more top-end with a POP, and it's also why all the new VQ engines with VIM's open up a secondary shorter runner at high-RPM's. Because it's less restrictive than the longer runners. So why not use a short runner all the time? I don't know exactly (forget the equations), but probably to promote smoother running and cleaner (less turbulent) intake air for better overall flow than a short runner. If the air flowing into the intake manifold isn't very smooth, then it'll mess up your low end power and decrease the efficiency of the intake manifold, and in turn give you less power.

So now apply this to intakes...

A CAI (long tube, filter down near bumper) will theoretically give you low-end simply because it'll be less restrictive than the factory setup. But at high-RPM's your gains would (in theory) be limited because you're still stuck with a long and restrictive tube.

A hybrid intake (medium tube length, filter in engine bay), will give you the added benefit of still having a less restrictive intake than stock but with a medium tube length that promotes mid-range the best. You'll still gain low-end and top-end, but you'll feel it the most in the mid-range.

A JWT POP charger intake (short tube, filter almost directly on throttle body) will promote the best top-end power (almost no tube to act as a restrictor), but because the intake charge flowing into the manifold won't be as smooth, perhaps this is why people with these intakes report lost low-end. The pop charger decreases the overall efficiency of the intake manifold at the low-end, but because there's almost no tubing, you get the best gains at the top-end.

This is all in theory of course. Theories need real-world results to back them up, and butt-dynos are not always that accurate

As for the CAI vs under-hood intake temperature debate, a buddy of mine did a test and he found that the intake air temperature at the filter of a hybrid-style intake was identical to the outside air once you were moving at more than a few MPH. Also consider that when you're at WOT, the engine is bringing in 3.0L of air every 2 engine cycles. At 5000rpm WOT, that comes out to 124.8 L/sec!!

It'll be bringing in air so fast that it would hardly have any time to heat up at all from engine bay components before it's ingested. This is why I think all of these intake heat shield products are a complete waste of money.

I don't think even a CAI will cause you to lose top-end power vs stock, though. I've never seen a dyno that showed that. You might gain more at the low/mid-range and then feel it much less at the top-end thinking that you "lost" power, even though you still gained it. This is why butt-dyno's can't always be trusted.

I haven't checked enough of the dynos here, but at least from the AccordV6 guys (my ex-ride), you can see a trend of power dropping off more at the top-end with a CAI than with a hybrid style intake. This would suggest that a CAI doesn't give as much top-end gains as a hybrid or POP, even though all intakes were making more power than stock at the top-end.

Hopefully this will help some

MaxSE2k

You'll find that in the link I've provided below, I voluteered to run my car on a dyno with various intakes. However, the time needed to run 3 different intakes, allowing ample time for cooldown in between runs, costs $$$... SO, if y'all are in need of a guinea pig to pound on his car for a few hours, I'll do it, but I'm not forking over the $160 I need for 2 hours of dyno time.
http://forums.maxima.org/showthread....ntake+shootout

03BlkSETE

iTrader: (3)

I'm good for $20. Anyone else?

Nismo87SE

It seems like this happens at least every year. Here is the end all test, log the MAF voltage with both intakes. Which ever intake makes the maf read more voltage makes more power. However I'm sure with one of those OBD-II loggers someone can take a maf volt vs rpm plot of a CAI and WAI. Hell that same person (assuming proper funds) could test different diameters to see the effect on the powerband. Also I must point out that I've dynoed/drag raced my old maxima before and after the CAI from WAI. I gained 13hp/11tq at the peaks and an average of 11hp/9tq from 4000-5500rpm. But then again I drove a VG .

03BlkSETE

iTrader: (3)

I'm confused about your horsepower/torque gains. Was CAI over stock or CAI over WAI? or something else

Y2KSESteve

iTrader: (22)

Definitely over stock, its debatable over WAI. Both have advantages to them.

ArcticMax

i'll gladly chip in $20 for the dyno.

I really want to find out the truth.

MaxSE2k

Any other takers? I'm hoping to be able to go within the next few weeks...

03BlkSETE

iTrader: (3)

Checked out your car on your website, nice ride. I noticed you listed a custom ram air in your signature. Can you explain what that is and how helpful you think it is?

Street Reeper

If the throttle body is the same size as the tube it connects to would the tube be restrictive, or the throttle body? Wouldn't the size of the throttle body really be the last point of restriction? IF you have a 3inch throttle body connected to a 3inch pipe, wouldn't they flow constant. IF you had a three inch water faucet, connected to a three inch hose, wouldn't the flow of water only be restricted by the faucet since the hose is the same size, would you be able to fill a bucket up with water faster from one to the other?
How much air can flow through the throttle body, and how big does the intake pipe have to be to compensate this? Would a CAI still be restrictive if it were a a 4inch pipe connected to a 3inch throttle body?

ArcticMax

this is Hokiemax. I'll chip in $20 too. set up a paypal account so we can start putting in $5, $10, $20 or whatever.

JAIMECBR900

Can you explain how you're going to override the ecu's original settings to whatever intake it rides in on?

MaxSE2k

That is a good point, however I don't believe that there would be that big a change... The flow of the air isn't going to change, it's only going to be a matter of sucking power, and air temp right?

MaxSE2k

Paypal account: rcaron@maine.rr.com

I'll leave the funds there until the testing commences. I'd like to see if Frankencar or someone independent is willing to supply a WAI setup of their own w/ Apexi filter. Of course, it'll be returned upon completion.

Remi

JAIMECBR900

The thing is that our ecu's have the ability, thru different sensor readings, to "change" the air/fuel maps to fit the particular situation (i.e. more air coming in due to better intake, colder air, etc.). The bad thing is that the ecu does not make those changes instantaneously. In other words, say you drive in with the CAI installed. The ecu may have already taken readings and adjusted to fit the characteristics of the CAI. You do a dyno run. Then you change to a hybrid/HAI to do your other dyno run. The computer may still "think" it has a CAI in because it has not taken it's readings yet and therefore skew the outcome.

Again, another point to consider about dyno testing is the fan/hood open scenario. This scenario gives the hybrid/HAI an unfair advantage it does not have in the "real" world because it will give them "fresh" air it does not normally get.

So, we're back to where we started. In my opinion, the only way to accurately test intakes head to head is to flow test the piping itself (to find restriction numbers), to temp test the intake installed both at the filter AND the TB (to find and factor air temp the car is taking in), and vaccum test with intake installed (to find volume numbers). As I said before, the intakes job is simple....suck in cooler air, faster, and more of it. The more air, coming in faster, and colder (as long as the fuel volume comes up to match) the more power the engine will make during each stroke. Period.

If you have an intake that can do all three better than the next, you will find the BEST intake. If one intake does 2 out of 3 good, it's not as "good" as the one that does all 3. See the logic? If all the intakes do 2 out of 3 good, then you have to decide which one does the best at which point of the powerband (low end, middle, or top) to suit your needs.

MaxSE2k

Ahh, I get your point and have a solution! Maybe what I can do is actually make 2 trips to the shop - and @ $75 each trip, they can gather a boat load of info. See the link below for details of their "Tuning Package", which adds the ability to put sensors nearly everywhere. This would still keep the price @ $150 for the complete test, it would just take longer doing it in 2 visits.

http://www.cmperformance.com/dyno.shtml

03BlkSETE

iTrader: (3)

This is sounding pretty good. So what your saying is that after the first dyno day, install the new intake and let the ECU adapt to it for a few days and then go back for another run at the dyno. Sounds like this should work. We might not get the perfect answer but we should get plenty of good information so we can make a more informed decision.

Dave B

I think this all getting a little rediculous. I use to think there was a difference in performance between the hybrid and a CAI, but now I've come to realize there's not much difference, even with a modified stock airbox. All this talk about laminer flow, velocity stacks, pipe length & diameter, etc probably applies to an F1 car that winds to 12000rpms and makes 600+hp. But on a low revving V6 that makes between 150-290fwhp (depending on power adders), I don't think the difference in intake style (POP/hybrid and CAI) will make a huge difference.

Recently I swapped back in my Poorman's CAI just for comparison. The Poorman's CAI consists of removing all resonators, running a mid pipe, and K&N filter panel. I also cut a 2.5" hole in the lower box on the drivers side for a little more airflow. Honestly, I can't tell any difference in WOT acceleration vs the HKS. With the Poorman's CAI, intake noise is significantly quieter, initial off the line acceleration is better, acceleration into succesive gears is better, and tip-in acceleration is better. I dynoed my Poorman's CAI vs my HKS about 1.5 years ago. The Poorman's CAI made the same exact power from 2000-5400rpms with the same peak power (174fwhp and 192 fwtq). The only difference was the HKS held on to power better after peak HP. At 6000rpms, the HKS made 5fwhp over the Poorman's (150fwhp vs 145fwhp). With a y-pipe, Poorman's CAI, and B-pipe I ran 14.73@93.9mph. With the HKS, I ran 14.80@94.5mph.

You can decide for yourself, but I think the biggest restriction in the intake pathway of the VQ is the resonators, filter, and the airbox. All of these problems can be remedied quite easily by either modifying the stock intake or getting a CAI or POP/hybrid. IMO, the differences are minimal at best.


Dave

MaxSE2k

bump - worthwhile discussion & test results if we get the necessary support

JAIMECBR900

Correct me if I'm wrong, but your description of a "poorman's CAI" sounds a lot like a hybrid??? Is that correct or am I picturing something else? Not flaming, just not clear.

Dave B

Nope. It uses the factory airbox and factory intake snorkel along with a K&N filter panel and no resonators.


Dave

JAIMECBR900

Using that setup, you are saying the difference between that and a HAI is 5 HP at the wheels?