1990 g50 Q45 stock air filter box restrictive?

[subtle_driver]

Hey all, I just got back from the Dyno, And I have some interesting info with concerning the stock air box. I was going to just tell you, but I wanted to have some of you guess or if anyone knows how much RWHP is gained or lost from removing the stock air box?

Here is a basic history of my car:My 1990 q45 has a baseline (not-dialed in) e-mance tune. Deleted the suitcase muffler and i made a dual 2.5" strait pipe from the resonators back, and installed a 20mm rear sway bar from a q45a I also Just installed some 94-96 injectors, removed the fuel dampener, and installed a Walbro 255 LPH pump, and Just converted back to gasoline, (I was running e85 with a tuned ECU) Getting ready to sell the car, or if i keep it, install a 5-speed and install my Espelir Lowering springs with some tokicos. I have run 10 passes with this car down my local drag strip, and I have run a few Autocross events with it. Alot of fun!

Give me some guesses, I'll check back and post the link to the dyno results in a little bit!
Modified by subtle_driver at 12:22 AM 12/29/2009

[Q45tech]

OLD NEWS since we did detailed chassis dyno tests back in 1993 and 1994.

The problem is 99.9% of dyno are not repeatable nor are their operators to achieve the necessary resolution accuracy to say even a 5 lb'ft or 5 HP variance is meaningful.

All that counts after all is aceleration time and it takes 10 units improve to create a 0.1 secomd change.

Depending on situations most people think they see a 3HP improvement over oem air filtration system.

Mathematics says <1.23% improvement might be optainable so the upper limit is 3.9 HP.

Many replacement system actually make lower than stock HP due to their design and higher underhood air temperature leaking into engine.

Many chassis Dynos are not very useful in real world since the vehicle is sitting sit and not loaded with wind resistance so the engine accelerates faster than possible especially above 60 mph.

[1QIKQ45]

NICE SETUP!!!Sounds like ur building a BAD@$$ G50!!!When you removed the stock air box, what did you replace it with?A standard cone filter, or did you run a true cold air?And also, what did you gain from the fuel motifications? Millage, Hp, TQ, Ect?Keep us posted on prformance things! Nothing wrong with making a nice big pair of Q balls, Bigger!

[1QIKQ45]

Oh, the guess. hahaIf you just replaced the box with a filter, then probably lost 1-2 HPBut if you fabed up a true cold air then gain 3-4 on the street, 1-2 on dyno.

[subtle_driver]

nice guess people. but to my surprise nearly 10hp gained to the wheels. i repeated the test 4 times, and it was within a 1/4 of a hp or less on each run.i just took the air filter housing off the maf, removed the 4 bolts and ran it like that.

Whoops. looks like i had the run with the vacuum lines after the maf disconnected to artificially lean it out. I will have to get the other runs i did with the richer AFR's posted sometime.


Modified by subtle_driver at 12:17 AM 12/29/2009

[Q45tech]

Something is wrong with your dynojet graph as it does not follow the multi-hundreds I've seen especially in the torque presentation below 4,000 rpm.

Good luck on your modifications. Carefull about removing or recalibrating the fuel damper reference hose [after MAF] as this is a very necessary item to stablize the fuel pulses around and above 4,000 rpm.

Your AF chart varies significantly and is extremely lean for any power gains probably the result of Walboro.

What was tire roller interface temperature before and after runs? Tire brand, size, and psi to derive a frictional correction factor.

The rub is a chassis dyno accelerated faster than possible on street due to mass difference in roller and lack of air friction.

When you reach 14.8/98 mph in a sea level quarter mile with stock diff you know you have reached nirvanna.

Over 8 years here I've seen lots of dyno runs very few are accurate presentations of what is really occuring, but it gives some something to talk about.

All in all I like quarter mile tickets better as they are significantly more reliable [unless substitution occurs].

[1QIKQ45]

Wow, IF those are accurate, then i wonder what HP gains there are with a TRUE cold air on the street. I can feel a differience between hot days and cold nghts in HP. So with this added to it... HMMM.. Thinky thinky thinky

[subtle_driver]

Something is wrong with your dynojet graph as it does not follow the multi-hundreds I've seen especially in the torque presentation below 4,000 rpm.

Good luck on your modifications. Carefull about removing or recalibrating the fuel damper reference hose [after MAF] as this is a very necessary item to stablize the fuel pulses around and above 4,000 rpm.

Your AF chart varies significantly and is extremely lean for any power gains probably the result of Walboro.

What was tire roller interface temperature before and after runs? Tire brand, size, and psi to derive a frictional correction factor.

The rub is a chassis dyno accelerated faster than possible on street due to mass difference in roller and lack of air friction.

When you reach 14.8/98 mph in a sea level quarter mile with stock diff you know you have reached nirvanna.

Over 8 years here I've seen lots of dyno runs very few are accurate presentations of what is really occuring, but it gives some something to talk about.

All in all I like quarter mile tickets better as they are significantly more reliable [unless substitution occurs].

thank you for your comments! the lean afrs are due to tuning not the Walbero fuel pump, thank you.the 255lph walbero can do over 450 on e85. more on 91octane gas. I will go back when i have some time, and acually tune the car and see what numbers i get. Like i said, that was one of the runs i pulled off vacuum lines after the maf to artificially raise the afr's, and it worked. haha. i need to get the other dyno sheets with the normal afr's. but it would mean i would have to drive an hour to do that. im lazy and broke.

btw, what are your hundreds of dyno torque representations? my car is the only one i have seen, so i really am curious to see what differences you are talking about.

anyways, i'm gonna get going to work.

[maxnix]

... HMMM.. Thinky thinky thinky

If you really want to "thinky thinky", read Q45tech's earlier posts on this and other subjects.

[1QIKQ45]

If you really want to "thinky thinky", read Q45tech's earlier posts on this and other subjects.

I have been reading up on all of the old posts.Now i know that all of you are WAY ahead of me in knowledge, but i just find it hard to believe that Nissan made the intake for the VH Perfect for the amout of air it needs to breath.And even if they did do that, when you start upgrading the exhaust, ECU, fuel, then the intake most deffinatly wont be able to flow what the new mod's need. Nothing is perfect, there is always somebody/ something out there beter, faster, stronger, Ect.So if you ran a 90mm+ intake tube, perfectly smooth on the inside, that slowly grows in size as it get lower to the ground, allowing a bigger space for the air to "ram" into, then y wouldnt that function beter than the factory?Not that i dont believe you guys, but the OP has a graph that shows increase in HP and he says all he did was remove the Air box, and i believe him.A pixture is worth a 1000 words.

[Q45tech]

Since the engine is already supercharged/pressurized by the 14.7 psi atmospheric pressure, intake restriction is a minor component at best.

Incrementally Measure the pressure loss to the plenum and you will find that the MAF and Airbox intake filter system are approximately equal at ~ 7 " H2O EACH.

Mathematics usually tracks real world conditions except when you use variables like a chassis dyno which can be so very easily tweaked to make the paying customer happy.

As to dyno charts look back over the past 8 years [300,000 post] and you will find many posted.

[maxnix]

I have been reading up on all of the old posts.

So if you ran a 90mm+ intake tube, perfectly smooth on the inside, that slowly grows in size as it get lower to the ground, allowing a bigger space for the air to "ram" into, then y wouldnt that function beter than the factory?

You need to read more.

the distance of the intake from the ground has nothing to do with inlet pressure. Locating it in a high pressure area does. "Ram effect" is an advertising gimminck under 125 mph. Even then there isn't that much of an effect until you get closer to 200 mph.

[1QIKQ45]

the distance of the intake from the ground has nothing to do with inlet pressure. Locating it in a high pressure area does.

Thats what i meant. Lower to the ground meaning into the path of larger amounts of colder air. Im not saying that the increase will be astronomical, it just seams that there would have to be benifets of some form. (other than sound)

[Q45tech]

Obviously the closer to the road surface the hotter the air is! Also consider the hot exhaust gases from forward vehicles except semis.

Each 11F changes air density by 1%.............a sensitive accurate thermistor will provide useful info.

Don't be confused by measuring the temperature of plastic ducts, housings, or even the TB or plenum since at WOT the air is flowing pretty fast, too fast for much heat to be transferred to air.

Calculate how fast the 400CFM [6.66 CFSec] is moving thru a 3" pipe.

[1QIKQ45]

Ok then, This seems to be a never ending battle. HAHA. If your not to big on the OP's Dyno Answers. Then what whould be the best way to answer this question?What test should be proformed? Find someone who is as close to perfectly consistant as possible and have him run 10 pass's down the 1320?5 with a stock box and 5 with a cold air?

[qship96]

Tough to accurately measure as even if it added 10 hp, the change in 0-60 or 1/4 mile would be tiny

[maxnix]

Ok then, Find someone who is as close to perfectly consistant as possible and have him run 10 pass's down the 1320?5 with a stock box and 5 with a cold air?

In both directions with a stabilized engine temperature, you might get an indication.

10 runs is not going to yield statistically significant results. 100 in each direction will, provided the fuel is the same and you compensate for barometric pressure, temperature and humidity and keep the engine and transmission thermally stable.

[subtle_driver]

I thought I would mention one of the cats was melted almost completely shut. I took it out and replaced it with a magnaflow unit. I'll post more results, but i want to install the updated timing chain guides first.

I will do two baseline pulls first, then remove the box and do two more again. then I will remap the ecu and see what happens to my hp numbers. all i can say is the stock air box is a restriction at some point. I was bored and had no way to change the hp, so i just started pulling things off, starting with the factory air box. and it has a lot of muffling to keep the Luxury car customers from having to hear that horrible v8 sound.

[elwesso]

Since i have a 94 and thus a grille, i took the air horn from a 90-93 and put it on the front, so ive got this nice cold air thing right behind the grille... I also took off one of the baffles off the bottom and sealed it up..

Im not sure I gained any HP but i might have gained an MPG.

Dyno is also misleading because the air profile over the front of the car is at a constant lower rate, vs when you're driving you actually have air flowing over the car at 30-50-etc MPH...

Also most of the time people still use metal which conducts heat much better, making the air flowing hotter...

[subtle_driver]

well, under 30mph it gained 10hp. if that's the argument you want to make. Does anyone have any dyno sheets to back up what they are saying? I don't know why people are comparing my results with CAI? my results are from HOT air intake with no filter. unbolt the filter housing from the maf, and let it ingest the air from the surrounding area some cold air, from the bottom half of the air box, some hot air from the radiator and header and little to no pressure/ velocity you would gain from ram-air effect with the stock sealed unit.

Since the Q45 stock box is so great and flows so well, why doesn't everyone adapt this restrictive unit to their race car's and make more power? : remember, they designed this unit with stock efficiency, and noise dampening in mind, not all out performance. the smaller the hole, the quieter the intake is gonna be. I work at a high-end luxury service shop, and you wouldn't believe the stupid things they complain about and spend thousands of dollars fixing the tiny little noises they hear from the weather strip, and... i mean the most ridiculous things. if you read TSB's on luxury cars, there are alot of lame comfort/noise related ones, compared to say Toyota corrolla or Nissan altima.

anyways, I still think this is interesting to see what everyone's opinion is after a dyno result is posted. I can't wait to see what numbers i get when i get another set of runs with a dialed in tune and a non-blocked cat.
Modified by subtle_driver at 10:12 AM 1/3/2010

[elwesso]

well you just said that you removed the vacuum lines too...

in my opinion it seems like there are too many different variables that make your comparison kind of sketchy... You say stuff about pulling vacuum lines, melted cats, and so on...

[subtle_driver]

with the vacuum lines removed, it didn't gain anything worth mentioning, .1 hp. the other 2 runs without the air filter were the same as this run. but you can safely say this. One cat almost completely blocked, with filter housing makes 233, same setup with no filter box makes 242.

[Trumpkin]

You have struck a nerve here with all the "big boys". They all have proven this before-long before you got here. Or so they say. best to leave it alone! You are rocking their forum!

[elwesso]

You have struck a nerve here with all the "big boys". They all have proven this before-long before you got here. Or so they say. best to leave it alone! You are rocking their forum!

i like your sig....

Anyway, here is what I honestly think.. I think there are secondary effects causing the effects to be more pronounced than you think... You even said yourself that the AFR's are quite a bit lean, and for a stock car they are...

I think that whats happening is since you were running an "open MAF" is that the MAF was not getting an accurate reading, causing the lean condition.. no doubt that leaning out the mix will give you more HP and I think thats whats happening..

Read up on "entrance length" in fluid dynamics, you want fully developed flow at the MAF because, the velocity is maximum at the centerline of the pipe. The MAF is reading the velocity of the air going through it, since that is the only thing changing as the mass flow rate of the air increases (for the most part)



If you consider the head loss from the front of the air box to the TB, the air filter and air box is so insignificant for a 4.5L engine N/A that it becomes iffy if its worth messing with. This has been, and can be, proved theoretically and experimentally..

[subtle_driver]

the open maf can possibly read inaccurate depending on the velocity yes. My car does not have a stock tune. also, the afr's are lean on this dyno sheet because i pulled vacuum lines, it was a bit more rich before when i ran it as is and left the lines alone. But, they produced basically the same results in hp. i can get you the complete sheet later on, the next time i'm near the dyno shop.

[Q45tech]

Those of us who have been using chassis dyno for the past 25+ years* and engine dynos since the early 1970"s [I'm 62] always take published dyno charts with a grain of salt.

Especially SINCE MOST DYNO MANUFACTURERS STATE REPEATABILITY is +- 3 HP at best in operating manual. Why we laugh at decimal points or some promising 3 HP gain.

If things make you happy why not. My Q LIVES on the mistakes of others [junker parts].

* First personal Q dyno runs were in 1993 thats when I learned different 15" rear tires can change numbers by more than 10 HP due to wear index.160 vs 340.

[maxnix]

* First personal Q dyno runs were in 1993 thats when I learned different 15" rear tires can change numbers by more than 10 HP due to wear index.160 vs 340.

Back to the 100 bidirectional timed runs!

[elwesso]

If things make you happy why not. My Q LIVES on the mistakes of others [junker parts].

so true!

[maxnix]

so true!

Yes, experience is an education earned dearly!

[1QIKQ45]

I know its off topic, but speaking about HP gains, Have you dyno'd the q sence u put in the 5 speed? I wonder how much Less drivetain loss there is.