CAI data : open box vs close box. Data results

[Cobra Jet]

So as many of you knows I track on roadcourse my 18 10speed.
I'm also data driven for a lot of my choices.
I made 2 years ago a video about JLT CAI testing
On dyno. Pre and post (tune no cai vs tune with CAI) showing a major gain on HP.
However after years there is still the debate on
"Hood up hood down " or "real results are hoods down
Ive already share what i think about it:
Hood must be up. Cause you try to simulate energy and heat to reach 160mph...without the air at that speed to cool down.
And you heat soak.
But i accept the critics and the challenges and I always try to find an answer.. once again with data.
I went a step further.
i have big hood vents just above my CAI.
With my tuner we wanted to see if a closed airbox will increase pressure in the airbox (ram effect) while now the air coming from the front evacuates from the vent .
So
I made a airbox cover (plexiglass) seal everything and
I data log pulls with and without the cover. Same street. Same time( 20mins apart)
Well results were these:
Roughly 2 lbs/min LESS AIR FLOW IN THE CLOSE BOX VS open CAI
REMEMBER that 1 lb/min is approximately 10 bhp

So for me from now ,at least with my vents, i stick with OPEN CAI. At least for roadcourse.

I'm not sure for drag if makes sense. But the temps rise slower on a close system but also cool down slower too.
Open cai temps raise and cool extremely fast.
And more air moved.
Just food for thoughts.
Hope this can help
Alessandro

As always, excellent tech and details from you!!

Thanks for posting the info, it will definitely help those seeking similar tech regarding open or sealed CAI choices.

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[Dapepper9]

With the open box i run 2f max 3 above ambient.
Sealed is the same. But in strong acceleration the temps are decreasing way faster on the open one. (maybe cause it takes cooler air from the hood vents ? While otherwise is from the inside the box which is warmer?)

I think it has something to do with in a closed airbox, any ram-air effect or incoming air has a harder time displacing the hotter air already there. Yeah some of it will blend and some of it will be consumed by the engine but some of it should be displaced as well. The open element has a lot more area for that warmer air to evacuate from the cooler incoming air. At least that’s my theory.
As for your increased MAF with open filter, my theory there is that it doesn’t take long for the engine to consume the volume of air a closed airbox contains at any given time during low throttle demand. As engine speed increases and throttle demand goes up, that given volume of the airbox may be having a hard time replenishing from the box inlet. Conversely, open element setup has a much larger volume of air to draw from. If you look at IATs and gains to attributed to a reduction in them, you have to see a fairly substantial decrease in IAT to see any kind of appreciable power gain. However if you reduce overall air mass available by even as little as 3-4% you’re going to see quite a large power difference. If we assume you’re seeing around 45lb/min at peak, a reduction in 2lb/min is about 4.5% of that. For awhile I’ve had the thought that enclosing the airbox for temperature is often not the best decision even if you see as much as 10f in temp reduction vs a similarly sized open element due to reducing the pool you’re drawing from.
But that’s all just my theory on it so it very likely could be completely wrong and worthless

 

[Flyhalf]

I think it has something to do with in a closed airbox, any ram-air effect or incoming air has a harder time displacing the hotter air already there. Yeah some of it will blend and some of it will be consumed by the engine but some of it should be displaced as well. The open element has a lot more area for that warmer air to evacuate from the cooler incoming air. At least that’s my theory.
As for your increased MAF with open filter, my theory there is that it doesn’t take long for the engine to consume the volume of air a closed airbox contains at any given time during low throttle demand. As engine speed increases and throttle demand goes up, that given volume of the airbox may be having a hard time replenishing from the box inlet. Conversely, open element setup has a much larger volume of air to draw from. If you look at IATs and gains to attributed to a reduction in them, you have to see a fairly substantial decrease in IAT to see any kind of appreciable power gain. However if you reduce overall air mass available by even as little as 3-4% you’re going to see quite a large power difference. If we assume you’re seeing around 45lb/min at peak, a reduction in 2lb/min is about 4.5% of that. For awhile I’ve had the thought that enclosing the airbox for temperature is often not the best decision even if you see as much as 10f in temp reduction vs a similarly sized open element due to reducing the pool you’re drawing from.
But that’s all just my theory on it so it very likely could be completely wrong and worthless

They are good theories.
4.5% of 480whp is about 20 ish whp which is consistent with the statement i made before (2lb is about 20hp).

 

[GregO]

I think there’s over 20HP stuck in those two 2.25” exhaust connections and 2.5” Borla resonator.

 

[Flyhalf]

I think there’s over 20HP stuck in those two 2.25” exhaust connections and 2.5” Borla resonator.

I doubt it that big. The xpipe will need a connector anyway and the borla resonator is outlet 3"..maybe 5 max

 

[K4fxd]

I will not test the car with the cover cause a dyno test and a "real life test " with 100mph air pushed in , proved less air in the engine.so less power.
I also doubt laptime will be a effective test Cause so many variables are there.

Seems to me you could avg your laps over a 20 min session and that should show if one is better than the other.

What was the real life test?

 

[Flyhalf]

Seems to me you could avg your laps over a 20 min session and that should show if one is better than the other.

What was the real life test?

I could. Although i do time trials so is more about 2 super fast lap.

The test i did were dyno of course and 4th and 5th gear street pulls. 2k to 8k rpm.
2pulls in 4th and 1 in 5th for each situation (cover and not cover) . With interval of 20min in between.

 

[deanm11]

can you retrieve the fuel trims logged at/or near the peak MAF readings from each setup? If the MAF curve is not valid for both setups, the MAF PID will not be reporting the air flow equally on both setups.

 

[Ruckus50gt]

I will say the last section on temps, an open air does see higher temps sitting at a light but it drops so quick. Moving iat temps are identical . Open air as you said not ideal for sitting in staging lanes, but for driving and road course they work

 

[Evolvd]

I’m here for all the haters comments.

 

[Flyhalf]

I’m here for all the haters comments.

I will say the last section on temps, an open air does see higher temps sitting at a light but it drops so quick. Moving iat temps are identical . Open air as you said not ideal for sitting in staging lanes, but for driving and road course they work

IAT technically influences the volume of air (higher temps=less dense) but the fact that i have more volume on open CAI makes me think that the thinner air (warmer) might be compensate with the better breathing (so more air).
Those tests were from a crosslight after stopping 2mins.

 

[Flyhalf]

can you retrieve the fuel trims logged at/or near the peak MAF readings from each setup? If the MAF curve is not valid for both setups, the MAF PID will not be reporting the air flow equally on both setups.

I'll try to find them it would be interesting.
Busy at work.these days

 

[deanm11]

I really appreciate the testing and sharing you do. I try to do the same. The trims are not just interesting - it is essential to understanding your test results.

When evaluating performance by MAF readings ( I do it all the time) you HAVE to adjust by the trims. Otherwise you could be assuming a certain difference when it's just the MAF reading differently... even on the same setup sometimes, but particularly in your test where the airflow is taking a different path to the air sensor.

For example: Test 1, MAF reporting 50lb/min. 0% LT & ST trims. Test 2, MAF Reporting 52lb/min but -7% total trims (average left/right banks). Then the fair comparison is that Test 2 is really 48.36lb/min (52*.93) Separately, of course, you should adjust your observations by air density/conditions between the tests.

Dean

I'll try to find them it would be interesting.
Busy at work.these days

 

[tdstuart]

Banks Power did a video showing how to make an effective closed hood dyno test. Basically they bought some big ass fans from a car wash and use them when they dyno to simulate airflow.

They did a whole video calling out JLT and their inaccurate testing.

Very interesting if you can get the fuel trims to verify the comparison of the maf readings.

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