Secondary air door/A.K.A Flapper door Experiment

[Ram Air]

I thought I would start a new thread because we were getting a little off topic in the Dead Pedal issue. To summarize my last post, I tried to prove, using math, that the the demands of the engine were greater than what the under-hood induction system (UHIS) could provide.Hence, the need for a secondary air door (flapper door) Some speculated that I didn't take into account enough factors to make the data valid. To a certain extent that was true. The air ingestion rates were based on a 100% efficient system with no bends, leaks or obstructions. I thought that it was much less efficient than the numbers suggested. But, I had no way of proving whether it was 50% or 90% efficient without a flowmeter. Some speculated that ram air pressure would be great enough to close the flapper door at speed. I thought not!
So I set out to do a little experiment with the flapper door. It's a simple electrical continuity test that others should do to validate the results. Here goes.
Purpose: To determine if the flapper door closes at any time during wide open throttle (on a 5.0).
Materials: 15 feet of wire, 12 volt bulb, two contacts, a 12 volt power supply.
See pictures that show bulb on when flapper door is closed. Bulb off when flapper is open.
Method: Accelerate from 35 mph to about 105 mph. Do 2 runs; each one in opposite directions. Also, accelerate at part throttle to determine when flapper door opens. Note: Ram air pressure is negligible below 35 mph. I picked 105 because our trap speeds in the 1/4 mile are about that.
Observation: When throttle was opened the light immediately went out and stayed out up to 105mph.The light came back on when lifting. This was repeated in the second run.
At 2/3 to 3/4 throttle the light would go out at 4000 rpm...until lifting off.
Conclusion: The engine needs more air than the under hood induction (UHIS) can provide.That's why we have a flapper door. Vacuum overcomes the magnet, spring and any ram air pressure that may be in the system.
"THERE IS NO RAM AIR GOING ON HERE!" Sluggo, you were right!

 

[amartz]

Observation: When throttle was opened the light immediately went out and stayed out up to 105mph.The light came back on when lifting. This was repeated in the second run.
At 2/3 to 3/4 throttle the light would go out at 4000 rpm...until lifting off.
Conclusion: The engine needs more air than the under hood induction (UHIS) can provide.

I'm not one to argue with emperical evidence! So you are saying at 2/3-3/4 throttle the door staying closed until the engine hit 4K rpm? At which speeds? But any time you went to WOT the engine sucks the door open at any speed. So, at normal steady state highway cruising it's drawing from the front scoops only? And if you floor it at, say 70mph, the door immedialy opens? It would be interesing to see if a 3.8 has similar results. Regardless, nice job!

 

[Ram Air]

The answer to your first question is: speed did not matter. It would do this in any gear so long as it was pulling enough vacuum. As to your other two questions the answer is yes to both of them.

 

[zielritter]

Good work. I always like when people take the time to apply procedure to demonstrate results rather than relying on subjective feelings.

Keep these results in mind if you decide to build or buy an aftermarket intake. I went with 3.5" OD pipe after starting initially with 3" and then 4" pipe. I think, at least for the V6 engine, 3.5" inches is the best compromise for retaining some low-end torque and not choking the engine at the top of the rev range.

 

[daviderle]

Ram Air, Nicely done my man... as the old adage goes: ''the proof is in the pudding'...

..And thank for allowing the other thread to resume its intended course as well as running with the sensor idea and making it a reality in a short time frame..

 

[daviderle]

Love this (and the other) thread on the flapper door. I did the Gorilla tape method and have improved throttle response. You guys deserve lifetime memberships to this forum.

But..

Poor use of that phrase, as the "old" phase is "The proof of the pudding is in the eating!", which means you need to eat the pudding to know what's inside of it. Modern English has hacked it into the "proof is in the pudding".

Educational session is over. Back to the topic.

I was hoping no one would catch that one!

I spent an agonizing half hour debating which one I should use!? But being across the pond for fifteen years, I asked myself is it about time I should be embracing my "Modern" heritage without the risk of abandoning the 'old'?

Next time I will reference both and thank you in bringing back such fond memories of being scolded by my old A-Level English teacher for butchering a beautiful language!!

 

[craigt]

Half an hour? Proper English isn't worth it.

 

[daviderle]

Half an hour? Proper English isn't worth it.

I am surprised 'young man'! , I know how old habits die hard and thirty years ago, you too may have endured the constant reminder of the importance of using 'proper English'?

Apologizes Ram Air, back to the subject...

 

[QCTLG]

Ram Air,

Thanks for doing this test...just awesome...
Pardon my English but should we remove the flapper door assembly completely?
What's the best thing to do with the flapper valve?

thanks

 

[daviderle]

I would add 'theoretically';

- Extending the life of the air filter especially in city traffic.
- Constantly sucking hot air from the engine bay, again only may be applicable to city stop and go traffic.

All marginal in the grand scheme of things...

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[amartz]

Maybe that is the dreaded dead pedal issue!
If anyone can prove to me what purpose it has, beyond suppressing sound, please tell me . Then I will put it back on.

That's exactly what I'm thinking. Which screws up the tranny trying to figure out what gear to be in. I would guess (of course, 'yall proved my last guesses totally wrong, so fwiw), that normal highway cruising would benefit "some" from cooler outside air being pulled in from in front of the radiator, as opposed to from in the engine compartment.

 

[Youseethefight]

I thought I would start a new thread because we were getting a little off topic in the Dead Pedal issue. To summarize my last post, I tried to prove, using math, that the the demands of the engine were greater than what the under-hood induction system (UHIS) could provide.Hence, the need for a secondary air door (flapper door) Some speculated that I didn't take into account enough factors to make the data valid. To a certain extent that was true. The air ingestion rates were based on a 100% efficient system with no bends, leaks or obstructions. I thought that it was much less efficient than the numbers suggested. But, I had no way of proving whether it was 50% or 90% efficient without a flowmeter. Some speculated that ram air pressure would be great enough to close the flapper door at speed. I thought not!
So I set out to do a little experiment with the flapper door. It's a simple electrical continuity test that others should do to validate the results. Here goes.
Purpose: To determine if the flapper door closes at any time during wide open throttle (on a 5.0).
Materials: 15 feet of wire, 12 volt bulb, two contacts, a 12 volt power supply.
See pictures that show bulb on when flapper door is closed. Bulb off when flapper is open.
Method: Accelerate from 35 mph to about 105 mph. Do 2 runs; each one in opposite directions. Also, accelerate at part throttle to determine when flapper door opens. Note: Ram air pressure is negligible below 35 mph. I picked 105 because our trap speeds in the 1/4 mile are about that.
Observation: When throttle was opened the light immediately went out and stayed out up to 105mph.The light came back on when lifting. This was repeated in the second run.
At 2/3 to 3/4 throttle the light would go out at 4000 rpm...until lifting off.
Conclusion: The engine needs more air than the under hood induction (UHIS) can provide.That's why we have a flapper door. Vacuum overcomes the magnet, spring and any ram air pressure that may be in the system.
"THERE IS NO RAM AIR GOING ON HERE!" Sluggo, you were right!

Genius!!!

Is there any other conclusive info you can provide about this experiment?

Is the flapper door necessary?

Are the (stick on padding) on the magnets a good idea like in the other thread about responsiveness and WOT from a dead stop?



Thanks

Joe

 

[Ram Air]

Joe: See post #11

 

[Youseethefight]

Thanks for the info Ram Air.

 

[amartz]

Did the sticky pads over the magnets provide any improvement in responsiveness, especially WOT from a stop?

I noticed a delay when I go WOT from a stop. Very annoying.

Check out the thread at http://genesisowners.com/hyundai-genesis-forum/showthread.php?t=13828

 

[DRS]

Great stuff Ram-Air. Appreciate your time at this. It looks like to me on the 5.0 I have, the flap leads to air duct that goes in front of the sub assembly cage. Forward of the radiator, and behind the lights. It does not open directly to inside the engine compartment? Therefore not so much hot air when the flapper is taken out, some are thinking about?

 

[Ram Air]

I agree. I have known about this cavity for some time now. I can't see any down side to drawing air in from this source full time.

 

[sluggo]

Nice job Ram Air. Really good solution to the question of "when does this thing open?". I was dreaming up a similar test but mission creep took over and had me thinking up all sorts of embellishments.

My other question, the one that drove me to complicate the test setup, is still this: Why did they put a variable air source in an engine that's designed to be fuel throttled?

I don't understand. Carb engines have venturis and butterflys to control the amount of air available to the engine. Port-injected engines have a throttle body that does the same. A GDI engine, on the other hand, doesn't need any throttling on the airflow to keep the engine from running away - the fuel injection is metered so that the power produced by the engine is no more than what's called for by the accelerator position, velocity, and other sensed inputs.

Why don't they just give the engine all the air it wants? Why have a variable air intake?

GDI engines, in contrast to earlier induction methods, run with little to no vacuum in the manifold. Because the engine is drawing in only air (and not an air-fuel mixture) there's no danger of it running away if you give it all the air it wants. So why restrict the airflow into the manifold with a flapper and a magnet?

I suppose the PCV system works better with a little vacuum on the manifold side, but it should work just fine as long as there's positive crankcase pressure. There's the resonator. I honestly don't know if it relies on vacuum to work, but my guess would be no. Then there's a hose to the EHPS system (electro-hydraulic power steering). Maybe there's sone non-critical function in that system that requires (and permits) variable vacuum. Drawing a blank here as well.

Anyone know why they would use this flapper arrangement?

 

[OneFunGenesis]

^ This is a simple answer actually. The 09-2011 were not GDI engines yet the intake runner is still the same...why retool? They would have to redesign the intake or leave a hole in it when they dont have to. Seems to be a cost cutting measure to me

 

[Tailwalker]

Given all of this testing, and overflow of information (some of which is beyond me), what are your thoughts on the removal of the assembly for an open intake system like 'CAI' on the 09-11?