Improving Cold Air Set Up - Reviews Comments Suggestions please

[Kmrumedy]

Hi,

Getting some items to do my first upgrades to the car. I have a 1997 B/W GTS completely stock.

Did a lot of research on the forum. Some info is dated and contradictory so just want to make sure I have the latest and greatest info. Your help as always is greatly appreciated.

I terms of improving air intake:

I read about Performance by Joe (PBJ) - Cold Air Set Up. Is this set up worth the additional $$ as compared to the regular upgrade of buying smooth tubes and K&N filters? Yes - PBJ solution looks very cool but is performance better? What are the advantages of PBJ?

There are 2 versions of the PBJ solutions
Fully Powdercoated Short Cold Air Setup: $415 - draws air from the NACA duct
Fully Powdercoated Long Cold Air Setup: $550 - draws air from the NACA duct and the front fascia

vs. $85 for smooth tubes.

Is there anything new that others have used to improve this area?

OR......do I just keep the airbox stock and not put smooth tubes or PBJ? Is this upgrade worth the $$?

All upgrades/modifications I make to the car must be easy to return car to stock.

 

[puma]

John i have some smooth tubes if you want to save money.

 

[-FROG-]

I have a Gen I, so smoothe tube / cone filters is what I chose. If I had a GTS, I would ptrobably go with a PBJ type setup.

 

[Purdue_Boiler_Viper]

Since you are drawing all of your air through the NACA duct, cold air should not be an issue. Since you are bone stock, the NACA duct is more than sufficient to deliver enough air. There are lots of claims about HP increase with smooth tubes and high flow filters, but any increase is so small that it is hard to quantify since the repeatability on a dyno varies as much as the gain you are trying to measure.

All that said, everyone you show your smooth tubes to will think you gained 50HP.

 

[01ACR/VIPER]

vipair. 50 plus hp.

 

[FE 065]

1. The NACA duct opening alone does not supply adequate air to a stock engine.

2. Air flows out of the NACA duct at speeds as low as 45mph.

 

[ViperTony]

vipair. 50 plus hp.

...you beat me to it.

 

[JohnnyBravo]

I have the PBJ intake on my Roe blower car and absolutely love it. I opted for the long cold air setup that also draws air from the fascia. Well worth the money. I had smooth tubes and K&N's on the Roe for a year before switching to the PBJ unit. It was difficult to quantify the results on the dyno because the fan they use doesn't move enough air to showcase the difference. However, the car seems to run much cooler on the road and my trap speeds at the track are higher with the PBJ than with the smooth tubes. The hard pipes were also easier (and safer) to plumb for the water/methanol injection.

One of the other big advantages to the PBJ unit is that it relocates the IAC to the center of the air box, directly behind the NACA duct. This ensures that the IAC is constantly supplied with fresh, ambient air so that it doesn't get heat soaked and start making screw ball fuel corrections.

It also looks very cool.

 

[Purdue_Boiler_Viper]

1. The NACA duct opening alone does not supply adequate air to a stock engine.

2. Air flows out of the NACA duct at speeds as low as 45mph.

Do you have any data to support this? Even if you have 70mm throttle bodies, I only get about 12 sq. inches of area into the engine. I measured the opening of my NACA duct on my 01 GTS, and it has an area of over 16 sq. inches. So, unless the NACA duct effectively cuts down on effective surface area, it would not seem to be the "bottleneck".

 

[Tom F&L GoR]

PBV, I don't have data, but it's the location of the opening that matters. The grille is the high pressure area and the front of the hood is not. People that found the fog light openings not to be good for brake ducting for the same reason.

I found these images to show what may happen:

http://www.gmecca.com/byorc/dtipsaerodynamics.html
look at first and third image and where the green lift arrows are.

http://www.csiro.au/news/ach9697/CAR_PATH.JPG
red in front is higher pressure than yellow or green on hood.

Arguably the Gen 1 system that pulls air from the grille should work well.

 

[dave6666]

PBV, I don't have data, but it's the location of the opening that matters. The grille is the high pressure area and the front of the hood is not. People that found the fog light openings not to be good for brake ducting for the same reason.

I found these images to show what may happen:

http://www.gmecca.com/byorc/dtipsaerodynamics.html
look at first and third image and where the green lift arrows are.

http://www.csiro.au/news/ach9697/CAR_PATH.JPG
red in front is higher pressure than yellow or green on hood.

Arguably the Gen 1 system that pulls air from the grille should work well.

So Tom... I'm going to have an extended moment of stupidity... If the fog light openings are high pressure, assuming Vipers have their fog light on the front of the car, then why are they not good for brake cooling? Wouldn't that force air in if that is a high pressure area?

Great info BTW. I read it all.

 

[Purdue_Boiler_Viper]

Tom,

Thanks for the links. But, It's not clear to me that the images shown model the Viper case. For instance, one could easily make the case that the duct is in the frontal area vs. on the hood looking at the image. The very curved Viper front end makes it ambiguous where the front area stops and the "hood" begins. So, it is not clear to me that the duct is in a low pressure area.

I think we agree that the only way there is airflow out of the NACA duct at 45 mph is if there is high pressure in the airbox relative to the air pressure at the duct opening. Assuming the engine is creating a significant vacuum, then there would have to be an even bigger vacuum created by the airflow over the car for air to flow out of the duct. Even though I have not measured it, I find this hard to believe. In fact, I would guess that if this did happen, the car would have to stall.

Am I missing something?

PBV

 

[dave6666]

Tom,

Thanks for the links. But, It's not clear to me that the images shown model the Viper case. For instance, one could easily make the case that the duct is in the frontal area vs. on the hood looking at the image. The very curved Viper front end makes it ambiguous where the front area stops and the "hood" begins. So, it is not clear to me that the duct is in a low pressure area.

I think we agree that the only way there is airflow out of the NACA duct at 45 mph is if there is high pressure in the airbox relative to the air pressure at the duct opening. Assuming the engine is creating a significant vacuum, then there would have to be an even bigger vacuum created by the airflow over the car for air to flow out of the duct. Even though I have not measured it, I find this hard to believe. In fact, I would guess that if this did happen, the car would have to stall.

Am I missing something?

PBV

The only other air path would be the seal around the air intake to the NACA duct.

Otherwise, you are correct. Seeing as I can do 45mph without the engine imploding, I find the 45mph note by FE 065 to be confusing.

 

[Tom F&L GoR]

So Tom... I'm going to have an extended moment of stupidity... If the fog light openings are high pressure, assuming Vipers have their fog light on the front of the car, then why are they not good for brake cooling? Wouldn't that force air in if that is a high pressure area?

Great info BTW. I read it all.

Sorry, Dave, I see was unclear. I think what people have found is that the fog light openings are not high pressure areas and did not provide good air flow when ducted to the brakes. If accurate, then it demonstrates that you don't have to be too far from the center of pressure (in the center of the grille area) before you are in a low (or relatively lower) pressure area. Therefore I didn't see it as too much of a stretch to think that the NACA opening was also too far away from the center of pressure and may not bleed air "in" and could actually bleed air "out" at higher vehicle speeds.

 

[Tom F&L GoR]

Tom,

Thanks for the links. But, It's not clear to me that the images shown model the Viper case. For instance, one could easily make the case that the duct is in the frontal area vs. on the hood looking at the image. The very curved Viper front end makes it ambiguous where the front area stops and the "hood" begins. So, it is not clear to me that the duct is in a low pressure area.

I think we agree that the only way there is airflow out of the NACA duct at 45 mph is if there is high pressure in the airbox relative to the air pressure at the duct opening. Assuming the engine is creating a significant vacuum, then there would have to be an even bigger vacuum created by the airflow over the car for air to flow out of the duct. Even though I have not measured it, I find this hard to believe. In fact, I would guess that if this did happen, the car would have to stall.

Am I missing something?

PBV

I'm sure the blue car doesn't represent the Viper outline, and yes, it is very ambiguous where the "edge" of the Viper hood would be. That was simply to visually explain the possible effect described at 45MPH.

Since I have a Gen 1, I can't comment intelligently on how well the NACA duct is sealed to the intake system, but am guessing it is still going to allow air from in front of the radiator. Therefore, air entering the grille could exit into the engine and also out the duct. The engine won't ever be sucked out of air.

You and a friend can test this. Old fashioned aerodynamics were evaluated by taping short lengths of yarn onto the bodywork. With enough tufts, you can see the air flow pattern over the fenders. Pictures I have seen shown maybe 4" lengths every six inches. If you tape a few in front of the duct opening and have your friend drive in front of you, they will see if the yarn is pointing into the duct or out of the duct. In fact, I bet if your Viper is close to the car in front, it will more likely be pointing out (drafting) so maybe you want to occupy two lanes.

If you try this, take pictures.

http://www.cleanmpg.com/forums/fuel-economy/t-93-civic-aerodynamics-test-2854.html

http://www.aoe.vt.edu/~devenpor/aoe3054/manual/app3/text.html
http://www.aoe.vt.edu/~devenpor/aoe3054/manual/app3/text.html

 

[GTSnake]

This has been discussed many times before. Check out the Viper race cars. Do any of them have a NACA duct opening? I'm looking at a picture right now and it's blocked off.

 

[dave6666]

This has been discussed many times before. Check out the Viper race cars. Do any of them have a NACA duct opening? I'm looking at a picture right now and it's blocked off.

I work in the chemical industry. Every year they re-train us on not to use the top step of the ladder and not to eat with your products on your hands.

Sometimes, a review is useful.

Soooo, we are just reviewing things, eh?

 

[Purdue_Boiler_Viper]

This has been discussed many times before. Check out the Viper race cars. Do any of them have a NACA duct opening? I'm looking at a picture right now and it's blocked off.

Yeah, but remember this thread is about what to do for a stock Gen2.

 

[dave6666]

Yeah, but remember this thread is about what to do for a stock Gen2.

Well said PBV.

 

[outtahand]

Hi,

Getting some items to do my first upgrades to the car. I have a 1997 B/W GTS completely stock.

Did a lot of research on the forum. Some info is dated and contradictory so just want to make sure I have the latest and greatest info. Your help as always is greatly appreciated.

I terms of improving air intake:

I read about Performance by Joe (PBJ) - Cold Air Set Up. Is this set up worth the additional $$ as compared to the regular upgrade of buying smooth tubes and K&N filters? Yes - PBJ solution looks very cool but is performance better? What are the advantages of PBJ?

There are 2 versions of the PBJ solutions
Fully Powdercoated Short Cold Air Setup: $415 - draws air from the NACA duct
Fully Powdercoated Long Cold Air Setup: $550 - draws air from the NACA duct and the front fascia

vs. $85 for smooth tubes.

Is there anything new that others have used to improve this area?

OR......do I just keep the airbox stock and not put smooth tubes or PBJ? Is this upgrade worth the $$?

All upgrades/modifications I make to the car must be easy to return car to stock.

I went with a PBJ CAI. Its looks great and seems to be have a bit more noticeable HP'S at the rear.

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[Kmrumedy]

Thanks for all the input. I learn so much each time I post.

I should add.... I'm a simple man looking for a simple solution.

I have decided to keep the original air box stock and upgrade the air filters and install smooth tubes.

I'll start with that.

 

[Jack B]

Do you have any data to support this? Even if you have 70mm throttle bodies, I only get about 12 sq. inches of area into the engine. I measured the opening of my NACA duct on my 01 GTS, and it has an area of over 16 sq. inches. So, unless the NACA duct effectively cuts down on effective surface area, it would not seem to be the "bottleneck".

The hood opening actually stops flowing at about 100 mph. I believe the orca race cars actually blocked it off. Take a look at the Gen 1 air box and the method they use to get the air from the high pressure area behind the grill. I built a air box that grabs both the air from the duct and the grill - look in the media section at the pictures of the custom air box.

 

[FE 065]

The only other air path would be the seal around the air intake to the NACA duct. Otherwise, you are correct. Seeing as I can do 45mph without the engine imploding, I find the 45mph note by FE 065 to be confusing.

I'm just now getting back to this thread after seeing it pop up while doing a search.

Twice I fastened a long piece of string deep inside my airbox (no rain dam) right in front of the K&Ns, and at approx 45mph the string was out of the airbox and bouncing around on top of my hood.

That could have been partially due to the TBs not being open much at all at only 45 mph, but none the less, something had pulled the string out.

Confusing-yes, but it did happen 2x.

Your engine wouldn't have to implode due to this amount reverse flow for it to be true, just have its' HP production impeded by it.