True Ram Air???

[vvv90]

Thanks Mike. I'm just to tired and grouchy I guess.

Anyway, Shawn and Izzy did a test with a flow meter and some ribbons taped to certain areas to determine airflow.

The short version is that the faster they went, the less air went into the hood scoop.

It's not a Ram Air.

Sorry for my earlier outburst.

Because of why? ..... Equalization in air pressure from underneath the truck? Was this test done actually using a sealed ram air system?

 

[Chuck B]

I think what Silver and others are stating is in stock configuration the hood scoop is low pressure area. If you install a true sealed CAI utilizing the hood scoop you would in fact have high pressure sitting at the scoop and thus forced air into the intake track. Question becomes if the scoop is now sealed and independantly working as ram air where does the high pressure air from under the truck now go? Worse case it acts similar to what happens in the bed of the truck....pillow of air forms and the air just flows by possibly creating high(er) heat in the engine compartment. Since Mopar makes a true closed system utilizing the hood scoop probably nothing to worry about as this was most likely explored/tested.

btw...in the motorcycle world just because you have a sealed intake track with an opening in the front does not mean you are taking full advantage of the increased pressure while at speed. One of the reason's Kawasaki dominated the top speed arena was better ram air configuration. Testing consistently showed major increased pressure from their ram air over the likes of other manufactures. Response from the factory was they had extensive expertise due to Kawasaki Heavy airplane manufacturing division. Our hood scoop may in fact be too far back to offer best use of Ram air. Kawasaki consistently placed the intake fartherest forward stating it was the only way to get best use of air velocity. :dontknow:

 

[Silverback]

Because of why? ..... Equalization in air pressure from underneath the truck? Was this test done actually using a sealed ram air system?

It's the difference between a low pressure area and a high pressure area. The front part of a hood is a low pressure area. The cowl area at the base of the windshield is a high pressure area.

Ever notice the NASCAR boys all draw their intake air from the cowl. Now look at the NHRA Pro Stock cars. Where is their hood scoop? It's up in the air stream. If they could reduce drag by getting the same ram air effect from low on the hood they would.

Okay, more proof. Almost all, if not all hoods slope down at the front. If this was a high pressure area hoods would not fly open when a hood latch fails.

Sorry, I did not answer your question did I. No, the test was not done with a sealed ram air system as that was not what was being tested.

Once again, what was found was that the faster you go the more air goes over the hood scoop, not into it. This was verified by the air speed actualy dropping the faster they went, and you could also see it by the ribbons lifting off of the surface of the hood in front of the hood scoop.

 

[Silverback]

I think what Silver and others are stating is in stock configuration the hood scoop is low pressure area. If you install a true sealed CAI utilizing the hood scoop you would in fact have high pressure sitting at the scoop and thus forced air into the intake track. Question becomes if the scoop is now sealed and independantly working as ram air where does the high pressure air from under the truck now go? Worse case it acts similar to what happens in the bed of the truck....pillow of air forms and the air just flows by possibly creating high(er) heat in the engine compartment. Since Mopar makes a true closed system utilizing the hood scoop probably nothing to worry about as this was most likely explored/tested.

btw...in the motorcycle world just because you have a sealed intake track with an opening in the front does not mean you are taking full advantage of the increased pressure while at speed. One of the reason's Kawasaki dominated the top speed arena was better ram air configuration. Testing consistently showed major increased pressure from their ram air over the likes of other manufactures. Response from the factory was they had extensive expertise due to Kawasaki Heavy airplane manufacturing division. Our hood scoop may in fact be too far back to offer best use of Ram air. Kawasaki consistently placed the intake fartherest forward stating it was the only way to get best use of air velocity. :dontknow:

Adding a ram air system will not turn this into a high pressure area.

 

[Nowwhat]

keep in mind...this is an air-flow issue at speed....the air is being deflected off the large grill area up and over the scoop...the scoop would have to be up higher or much closer to the leading edge of the hood....

this is one reason that the TSTM guys need to create a snorkle system that pics up air from the grill...

 

[Chuck B]

Adding a ram air system will not turn this into a high pressure area.

Agree....however, if you sealed the scoop from the high pressure area from below it can become a high pressure of its own. Again your comparing pressure at the leading edge of the air scoop to the intake track entering the engine with a sealed system. As you and I stated above I believe the air scoop is too far back to be of benefit regardless. Your testing with ribbon confirms air flow path in open stock configuration. The fact that Mopar made a true sealed CAI utilizing the hood scoop tells me they did get a positive pressure all though how much and was it consistent/linear with speeds?

That was my point mentioning Kawasaki and you mentioning Nazcrap. Dynamics in air flow are complex and not obvious. Another example....on my Honda Valkyrie the factory had 6 different "horns" inside the airbox. One for each cylinder. Each horn was turned slightly differently. Several of which were over 180' off from each other. I met one of the developing engineers and he stating they did that in order to equalized the amount of air for each cylinder. stating fluid dynamics etc within the airbox. Otherwise each carb (1 for each 6 cylinders) would have had to been jetted individually i.e. differently for each cylinder. Something the factory would not accept so engineers had to govern airflow within the airbox.

 

[Deibs]

this is one reason that the TSTM guys need to create a snorkle system that pics up air from the grill...

Phew, that's what I was wondering. This little discussion had me scared that the TSTM would be starved for air under WOT.

 

[vvv90]

It's the difference between a low pressure area and a high pressure area. The front part of a hood is a low pressure area. The cowl area at the base of the windshield is a high pressure area.

Ever notice the NASCAR boys all draw their intake air from the cowl. Now look at the NHRA Pro Stock cars. Where is their hood scoop? It's up in the air stream. If they could reduce drag by getting the same ram air effect from low on the hood they would.

Okay, more proof. Almost all, if not all hoods slope down at the front. If this was a high pressure area hoods would not fly open when a hood latch fails.

Sorry, I did not answer your question did I. No, the test was not done with a sealed ram air system as that was not what was being tested.

Once again, what was found was that the faster you go the more air goes over the hood scoop, not into it. This was verified by the air speed actualy dropping the faster they went, and you could also see it by the ribbons lifting off of the surface of the hood in front of the hood scoop.

Actually you've got it backwards. Cowl induction is located at a low pressure area on the hood enabling it to extract heat.

I agree about the front of the hood being a high pressure area, but the hood scoop sits back off the front so I'm curious as to the amount of pressure there.

I still think using a sealed system would provide a better test.

Let me be clear that I trust the SRT engineers to have designed the hood for it's fuction which is to cool the engine and NOT be a ram air intake. However, if it's a high pressure area (hence the reason for buffetting and causing the ribbons to dance about) it would serve no purpose of cooling the engine so I'm a little confused at this point.

Airplane instructor use the "ribbon test" or yarn test on airplane wings to show students how an airplane wing can stall from the buffetting affect cause by turbulence. I would really like to understand more how wind speed might be affecting the turbulence thus affecting air pressure.

Using a sealed ram air intake, and mercury barometer, and an air speed indicator would be more of a controlled test IMHO.

 

[Riff62]

this is one reason that the TSTM guys need to create a snorkle system that pics up air from the grill...

I was curious about that as I had seen the pictures with the filter box up near the top of the motor. If there is a low pressure area where the filter is located, and in essence these guys are taking air that is pretty hot, performance of the s/c would be what?..greatly reduced? or does it make so much power that it would overcome the decrease in performance due to feeding the motor hot air?
Forgive my silly questions, My fingers sometimes dont type what I am thinking..

 

[Nowwhat]

I was curious about that as I had seen the pictures with the filter box up near the top of the motor. If there is a low pressure area where the filter is located, and in essence these guys are taking air that is pretty hot, performance of the s/c would be what?..greatly reduced? or does it make so much power that it would overcome the decrease in performance due to feeding the motor hot air?
Forgive my silly questions, My fingers sometimes dont type what I am thinking..

the TSTM guys are still rocking a bunch o' power....but cool air helps....a lot...when I went to a sealed ram air system on the paxton I picked up significant hp....we already know these motors hate heat....

 

[Prof]

Actually you've got it backwards. Cowl induction is located at a low pressure area on the hood enabling it to extract heat.

I agree about the front of the hood being a high pressure area, but the hood scoop sits back off the front so I'm curious as to the amount of pressure there.

I still think using a sealed system would provide a better test.

Let me be clear that I trust the SRT engineers to have designed the hood for it's fuction which is to cool the engine and NOT be a ram air intake. However, if it's a high pressure area (hence the reason for buffetting and causing the ribbons to dance about) it would serve no purpose of cooling the engine so I'm a little confused at this point.

Airplane instructor use the "ribbon test" or yarn test on airplane wings to show students how an airplane wing can stall from the buffetting affect cause by turbulence. I would really like to understand more how wind speed might be affecting the turbulence thus affecting air pressure.

Using a sealed ram air intake, and mercury barometer, and an air speed indicator would be more of a controlled test IMHO.

I question your assumption that the DC SRT engineers have the ultimate decision in design...I would beg to differ...the marketing people reign supreme in a consumer product...i.e. the SRT 10.... the scoop is an appearance feature not an engineering mandate. DC could care less about where the flow of air goes...it looks sexy and might drive sales 5 or 6 percent is the decision criterion.

DC is a marketing/financial organization, not a racing entity. And it is for sale.

 

[Silverback]

Actually you've got it backwards. Cowl induction is located at a low pressure area on the hood enabling it to extract heat.

I agree about the front of the hood being a high pressure area, but the hood scoop sits back off the front so I'm curious as to the amount of pressure there.

I still think using a sealed system would provide a better test.

Let me be clear that I trust the SRT engineers to have designed the hood for it's fuction which is to cool the engine and NOT be a ram air intake. However, if it's a high pressure area (hence the reason for buffetting and causing the ribbons to dance about) it would serve no purpose of cooling the engine so I'm a little confused at this point.

Airplane instructor use the "ribbon test" or yarn test on airplane wings to show students how an airplane wing can stall from the buffetting affect cause by turbulence. I would really like to understand more how wind speed might be affecting the turbulence thus affecting air pressure.

Using a sealed ram air intake, and mercury barometer, and an air speed indicator would be more of a controlled test IMHO.

Roy.
This is the exact reason I did not want to get into this again.

And no, I do not have it backwards. The cowl is a high pressure area. Take a look at the early 70 Chevelles with Cowl Induction. It opened towards the rear out of the air stream. Why? Because it's a Fu*king high pressure area that forced air into the intake.

By the way, they did use a Air Flow Indicator in addition to the ribbons. As stated earlier, the faster they went the less air went into the hood scoop. This was verified by observing the ribbons also lifting off of the surface of the hood which is an indication of low pressure in that area.

If you don't like the results of what Shawn, Izzy, and myself did then run your own god damn test and post the results. Until such time as you have something to back up your claims STFU.

After all, you asked the original question right? If you knew all the answers why ask.

 

[belgiumbarry]

again... the windshield bottom is the high pressure area : on the vette's you can see crearly that they take the air there. Performance ones as the LT1 had a bigger scoop opened at that area. The air was funneld trough a box molded in the hood and ended above the air filter where a soft seal kept it closed between filter and hood.

Also don't over-estimate the build up pressure from "ram" air. Cannot find directly the info but remember me that only at very high speeds you can talk about a very,very small pressure above atmosferic.In no ways to compare with SC or turbo's....

 

[GILMO'S10]

ANY IDEAS ON HOW TO PLUG SNORKEL OPENING.
YOU GUYS GOT ME THINKING.I MAY TRY RUNNING WITHOUT
THE SNORKEL AND SEE IF IT MAKES ANY DIFF.WHEN I TAKE IT OFF,
LEAVE THE HOLE OPEN OR SHOULD I COVER IT.
DONT GET PISSED SILVERMAN!! JUST ASKING A ???

 

[Silverback]

ANY IDEAS ON HOW TO PLUG SNORKEL OPENING.
YOU GUYS GOT ME THINKING.I MAY TRY RUNNING WITHOUT
THE SNORKEL AND SEE IF IT MAKES ANY DIFF.WHEN I TAKE IT OFF,
LEAVE THE HOLE OPEN OR SHOULD I COVER IT.
DONT GET PISSED SILVERMAN!! JUST ASKING A ???

Me? Get pissed?:dontknow:

I was voted the most even tempered person when I was in college. I was constantly pissed off at someone.

 

[Prof]

Sure, duct tape...

Silverback, I love it when you kick ass! You are my idol. Except that Bone has posted pics of Amy at Roe Racing...something that has needed to be done for a long time! Ohhhh to be 20 again....hell just to be 50 again would be fine!

 

[Silverback]

Sure, duct tape...

Silverback, I love it when you kick ass! You are my idol. Except that Bone has posted pics of Amy at Roe Racing...something that has needed to be done for a long time! Ohhhh to be 20 again....hell just to be 50 again would be fine!

Well it has been a while since someone has ruffled my fur.

 

[Prof]

Well it has been a while since someone has ruffled my fur.

The drugs are a good thing....but you are much more exciting when you are off them, and only consuming beer:rock:

 

[GILMO'S10]

Me? Get pissed?:dontknow:

I was voted the most even tempered person when I was in college. I was constantly pissed off at someone.

WELL CALM TH F DOWN AND ANSWER MY ??? OLE WISE MAN. :rock:

 

[Silverback]

WELL CALM TH F DOWN AND ANSWER MY ??? OLE WISE MAN. :rock:

Calm down?:dontknow: Hell, I'm just getting started.

Work just went to hell in a hand basket here. I will get back to you just as soon as I can. Didn't want you to think I was ignoring you.