Custom intake on my NSX (my write up)

96cxt · 15 November 2008

Hi everyone, I've been a member here for a little over a year now and have read many debates on the intakes for the NSX. There are those that say the Stock box is perfect with just a UNI filter, and some that say you will not gain any power by putting a cone filter. After taking some measurements and doing some calculation I made my now CAI (cold air intake). Using the proper diameter piping and a filter that has more surface area than stock is what makes the differance.
The filter sits right behind the side vent so it's away and not in the engine bay. If you drive your car everyday and are worried about the filter getting wet in the rain then a shield can be made to block the filter from getting wet.

My car has DC sport exhaust, Top speed headers, cat eliminators (straight pipe/test pipe), and CAI.

We did 4 dyno runs with the CAI to get an average as each dyno will get different reading. Then changed to the stock box with the UNI filter and went thru the gears to let the car get use to the different intake so the ECU can adjust. With the stock box we made 3 dyno runs to get an average again.

As you will see on the dyno sheet below there was power gains thru out the rpm, and good tq at low to mid range. This is a NA1 car so the power difference isn't big so don't hope to get anything more than 5whp. On the NA2 and supercharged cars you'll see alot more gain.
So in conclusion using the proper diameter piping and filter there is power to be gained and the stock box is restrictive once you start doing bolt ons.

Thanks
Rahim Jamal

Here is the Video of the dyno. When I edited the video the audio is completely off and doesn't go alone with the video. This is my first time posting/editing video so please go easy on me.
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4AU4LIFE · 17 November 2008

What do you consider the 'proper diameter'?
What kind of material is the piping made out of? What kind of cone filter are you running? Is it a pipe that runs directly to the T-body from the filter? Are the bends in the pipe done on a pipe bender and create creases or is it mandrel bent? Did you have a fan blowing into the side scoop on all runs. Was there a cool down period after each run/modification? Wouldn't having a 'shield' to protect against water be counterproductive? With the amount of heat being generated in the engine compartment while car is running, wouldn't any water/moisture that was injected be dried/evaporated before making it all the way to the intake? Pics of your setup? Weather conditions during dyno runs....
Lots of questions.:smile:

davidf · 17 November 2008

Rahim we should have a dyno day at Carboy soon. Cool weather coming, now is the time. Maybe if we can get a bunch together we can get a discount. I'd like to get a base dyno soon. That would be a blast.:smile:

96cxt · 17 November 2008

92NSX said:
What do you consider the 'proper diameter'?
What kind of material is the piping made out of? What kind of cone filter are you running? Is it a pipe that runs directly to the T-body from the filter? Are the bends in the pipe done on a pipe bender and create creases or is it mandrel bent? Did you have a fan blowing into the side scoop on all runs. Was there a cool down period after each run/modification? Wouldn't having a 'shield' to protect against water be counterproductive? With the amount of heat being generated in the engine compartment while car is running, wouldn't any water/moisture that was injected be dried/evaporated before making it all the way to the intake? Pics of your setup? Weather conditions during dyno runs....
Lots of questions.:smile:

Well all of the above is a secret, you'll have to buy my intake.

J/K

I have videos and will be up soon.
Piping = 3.5" aluminum mandrel bend
filter = K&N cone
No fans blowing in any runs. There was a cool down time when I changed over to the stock box since I had to jack up the car and remove to rim to get the CAI out of the rear fender and put the stock box back in.
Wheater was nice and cool in Houston on friday, 11/14/2008, 76°F / 51°F.
The piping slips into the stock flixible coupler and the the stock hoses stay the same.

With the help of José (Alas-NSX) we should have dyno results from his car with the CAI. His car has the Comptech supercharger, etc...

I will be making these CAI kits available soon and the price should be right at $150+ shipping. Each 3.5" tubing is about $35-$45, you'll need 1 straight and 1 90° bend, a coupler, few clamps and a real K&N filter which is about $35-48. So I'm not making much profit on these and it would cost you about the same to do it yourself.

Just PM me if you want one.

Rahim

96cxt · 17 November 2008

davidf said:
Rahim we should have a dyno day at Carboy soon. Cool weather coming, now is the time. Maybe if we can get a bunch together we can get a discount. I'd like to get a base dyno soon. That would be a blast.:smile:

Yes sir, I already talked to Carboy about it and they said saturdays are good and they can do $50/car, 3 runs/per. Me and Jeff dynoed our cars past friday and it alway nice to know what your car is putting down.
I dynod my car when I first bought it and my base run was 239whp with just the DC sport exhaust. Now I'm up to 261whp.
I'm gonna be doing the throttle body and ported intake manifold next.

I'll make a thread for the dyno and see how many might be interested.

Rahim

4AU4LIFE · 18 November 2008

96cxt said:
I dynod my car when I first bought it and my base run was 239whp with just the DC sport exhaust. Now I'm up to 261whp.

22 RWHP with headers alone ?!?!?!

WOW

96cxt · 18 November 2008

92NSX said:
22 RWHP with headers alone ?!?!?!
WOW

96cxt said:
My car has DC sport exhaust, Top speed headers, cat eliminators (straight pipe/test pipe), and CAI.

The stock NA1 headers are very restrictive.

4AU4LIFE · 18 November 2008

96cxt said:
The stock NA1 headers are very restrictive.............My car has DC sport exhaust, Top speed headers, cat eliminators (straight pipe/test pipe), and CAI..

Guess I didn't read very well huh:frown:
I have Cantrell Concepts headers and they did make a difference. However, I just changed my exhaust back to OEM because I got tired of the sound of my Dali system.
Come to find out, the reason it sounded so bad is one of the cats had come unattached from the muffler and it was making a horrible sound. I figured this out AFTER I had already commited to taking it off.
I might get another exhaust in the future.

96cxt · 19 November 2008

yoojeankim · 9 February 2009

so whatever happened to this? was it a fail?

96cxt · 21 February 2009

yoojeankim said:
so whatever happened to this? was it a fail?

No, I have been to busy. I know it's not an excuse cause it's been along time. The parts have come in and I just have to send it José (Alas-NSX) to test it on his supercharged NSX.
Hopefully soon.

Next inline is the BBTB and a ported intake manifold.
Will Update soon.

thanks
Rahim

96cxt · 24 February 2009

Here is the write up to porting the intake manifold. Intake manifold

Rahim

Nero Tenebre · 17 February 2012

Put this link in your signature too Rahim. I didn't see any pics of the actual intake anywhere, did I miss them?

L_RAO · 17 February 2012

I wish we had a 2.75 vs. 3.00 vs. 3.25 vs. 3.50-inch cold air (filter in the fender) dyno comparison.

B-Line's 3.0 inch intake looks good, but the only hard data we have on that is 14 wHP on a supercharged application.

96cxt · 17 February 2012

Nero Tenebre said:
Put this link in your signature too Rahim. I didn't see any pics of the actual intake anywhere, did I miss them?

Will do.
No I don't have any pictures of it. In the video you can see the polished aluminum piping. There is not much to see it just the piping.

96cxt · 17 February 2012

L_RAO said:
I wish we had a 2.75 vs. 3.00 vs. 3.25 vs. 3.50-inch cold air (filter in the fender) dyno comparison.

B-Line's 3.0 inch intake looks good, but the only hard data we have on that is 14 wHP on a supercharged application.

Well I can't make a decision on the facts that were provided by the supercharged one because he said he switched from the old HKS one. It could be said that the old HKS one might have been hurting the performance to begin with. But like I said not enough data to come to a conclusion.
But it you are FI then if you increase the piping diameter you are increasing the volume of air available for the supercharger but if you don't get the BBTB then you are still restricting the volume by the opening of the stock throttle body.

HIJACKER · 18 February 2012

96cxt said:
Well I can't make a decision on the facts that were provided by the supercharged one because he said he switched from the old HKS one. It could be said that the old HKS one might have been hurting the performance to begin with. But like I said not enough data to come to a conclusion.
But it you are FI then if you increase the piping diameter you are increasing the volume of air available for the supercharger but if you don't get the BBTB then you are still restricting the volume by the opening of the stock throttle body.

I want to see a dyno graph of the B-Line intake with the OEM throttle body compared to the same intake with the BBTB.

greenberet · 19 February 2012

L_RAO said:
I wish we had a 2.75 vs. 3.00 vs. 3.25 vs. 3.50-inch cold air (filter in the fender) dyno comparison.

Given all the variables that impact dyno tests (engine temperature, air temperature, tire slip, etc.) measuring the pressure drop through the intake might be a more accurate and repeatable test. Differential pressure gauges like a Dwyer Magnehelic that measure differences in air pressure are cheap and then you wouldn’t need a dyno at all. You could do real world on the road tests. If you place one measurement hose against the driver’s side fender air intake garnish perpendicular to the airflow and the other measurement hose in the bellows just in front of the throttle body, you’d measure the pressure drop caused by the entire intake system in front of the throttle body. The only part you’d have to destroy is the bellows by cutting a hole in it and that costs about USD 120 new and surely less used. Once you know the pressure drop, you could estimate how many horsepower that cost you by using dyno correction factors and see which intake cost you the least horsepower.

Just for comparison, the NSX Club of Britain held a dyno day in 2008 at which the ambient air pressure was measured as was the pressure at the entrance to the intake manifold, after the throttle body. The pressure loss caused by the stock throttle body (which has a 2.5 inch diameter at the throttle plate), the stock airbox (which has a 3.4 inch exit towards the throttle body), the stock paper air filter, and the stock intake snorkel (which inhales cold air from the fender and is 3.2 inches in diameter at its smallest point if you leave the resonator in place) was as follows:

Using dyno correction factors, that pressure loss should have robbed the engines of this many horsepower:

gt_nfr · 19 February 2012

greenberet said:
Given all the variables that impact dyno tests (engine temperature, air temperature, tire slip, etc.) measuring the pressure drop through the intake might be a more accurate and repeatable test. Differential pressure gauges like a Dwyer Magnehelic that measure differences in air pressure are cheap and then you wouldn’t need a dyno at all. You could do real world on the road tests. If you place one measurement hose against the driver’s side fender air intake garnish perpendicular to the airflow and the other measurement hose in the bellows just in front of the throttle body, you’d measure the pressure drop caused by the entire intake system in front of the throttle body. The only part you’d have to destroy is the bellows by cutting a hole in it and that costs about USD 120 new and surely less used. Once you know the pressure drop, you could estimate how many horsepower that cost you by using dyno correction factors and see which intake cost you the least horsepower.

Just for comparison, the NSX Club of Britain held a dyno day in 2008 at which the ambient air pressure was measured as was the pressure at the entrance to the intake manifold, after the throttle body. The pressure loss caused by the stock throttle body (which has a 2.5 inch diameter at the throttle plate), the stock airbox (which has a 3.4 inch exit towards the throttle body), the stock paper air filter, and the stock intake snorkel (which inhales cold air from the fender and is 3.2 inches in diameter at its smallest point if you leave the resonator in place) was as follows:

Using dyno correction factors, that pressure loss should have robbed the engines of this many horsepower:

What's your transfer function for the delta_P to HP drop?

greenberet · 20 February 2012

gt_nfr said:
What's your transfer function for the delta_P to HP drop?

Basically, I corrected the rear wheel power measurement at every rpm to standard temperature and pressure twice. Once using the air pressure measured in the intake manifold at that rpm (which dropped as the revs rose) and once using the air pressure measured in the intake manifold at a baseline rpm (at 2000 rpm, where the measurement started. At that rpm, the pressure in the intake manifold was just about the same as the ambient measurement, by the way). The difference between the two calculations is the horsepower lost due to the drop in air pressure as the revs rise. As an equation, I used SAE J1349 JUN90.

Edit: I think I answered the wrong question. Let me try again. SAE J1349 JUN90 calculates the horsepower you would have gotten if you would have had an air temperature of 25° C and an air pressure of 990 mb when you put your car on a dyno. To calculate the horsepower lost due to the reduction in air pressure, I’d measure the pressure drop and assume you’ve gone that far below 990 mb.

The pressure portion of the correction factor formula is 1.18 x (990 / air pressure in millibar) - 0.18. So (1.18 x (990 / (990 – drop in air pressure in millibar at 7500 rpm)) – 0.18) – 1 will tell you how what % of horsepower you lost due to the restriction you measured in the intake system. Multiply that with how many horsepower you think your car has at 7500 rpm and it’ll tell you how many horsepower your intake restriction costs.

Custom intake on my NSX (my write up)

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