'Cuda vs Hellcat Sound Wars - Page 5 - Dodge Challenger Forum: Challenger & SRT8 Forums
SRT Hellcat 6.2L Supercharged (2015 - ) Would you like the BLACK KEY or the RED KEY?

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post #41 of 50 (permalink) Old 06-17-2018, 10:06 AM
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[quote=TA 392 YJ;8329953]
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Originally Posted by Cuda340 View Post
The whole idea of the modern shaker is a really just a RETRO appearance package thing anyway.

It really doesn't work at all as it did in the past. The plumbing required to hook it into the intake is too long and restricted to truly call it a functional piece today in the way it was in the early 1970s. It was a much more "functional" piece when it was attached to the carburetor on top of an engine.
The ram air effect of the shaker hoods on the 1970-1971 Challengers and 'Cudas were good for 5 hp. on the top end.


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post #42 of 50 (permalink) Old 06-17-2018, 12:13 PM
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[quote=Cuda340;8330033]
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Originally Posted by TA 392 YJ View Post

The ram air effect of the shaker hoods on the 1970-1971 Challengers and 'Cudas were good for 5 hp. on the top end.
MAYBE......but doing so would require it to be sealed and it wasn't. Race cars, actual race cars have shown a SMALL bump higher at high speeds with SEALED UP air boxes and scoops that get a REALLY CLEAN path of air at really high speeds.

The original Hemi Shaker scoops don't meet any of the requirements to get a real BUMP in Horse power from a "ram air" effect.

That said there is the colder air ABOVE the hood as opposed to high heat under hood air.....a very direct path to the air cleaner ensures it makes it to the engine without any restrictions or chance to warm up. This is where any horse power increase is far more likely achieved.

People talk about "Ram Air" as if it was easy to achieve. In a street car it really isn't easy. The box is almost never sealed (if it was what would you do when GOD FORBID it actually RAINS and the water has no-where to go but into your engine......YIKES!!!

Then there is the problem of finding a clean air stream.......inches above the hood isn't that spot.....check out INDY cars for how high above body inspired turbulence you might have to get and keep in mind you'd probably have to be a lot higher. The front end of a '70 e-body is a virtual BRICK WALL in comparison to a modern open wheel INDY car.
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post #43 of 50 (permalink) Old 06-17-2018, 12:45 PM
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Originally Posted by TA 392 YJ View Post

MAYBE......but doing so would require it to be sealed and it wasn't. Race cars, actual race cars have shown a SMALL bump higher at high speeds with SEALED UP air boxes and scoops that get a REALLY CLEAN path of air at really high speeds.
People talk aboutld you do when GOD FORBID it actually RAINS and the water has no-where to go but into your engine......YIKES!!!
I had a shaker hood on my 1971 'Cuda. It was nicely constructed. It had a large metal mounting plate, with a circular opening in the middle, that slipped tightly on top of the carburetor. The fiberglass shaker scoop, itself, had a manually controlled flap (activated by a cable under the dash) that could be closed for warm ups or rain. If that occurred, the air would be pulled from a lower flap in the mounting plate. Also, the scoop had two exterior drainage holes to get rid of water.
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post #44 of 50 (permalink) Old 06-18-2018, 05:11 AM Thread Starter
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On posts 2-5 on this thread, we briefly addressed how modern engines are reluctant to settle back down to idle...
Ha... I was just thinking how quickly we get off track. I'm not offended or complaining, hey I do it too. But I just came up with a term for it: THE DIGRESS ADRESS. How 'bout that??? This would be a great term to describe a post that jumps off topic.

Anyway, getting back to the subject at hand, I was doing some research on a german car forum where they were addressing this. Apparently the phenomenon I was trying to describe is known as "REV HANG." The following are just opinions from forum members. I copied and pasted a few of their comments below:
--From what I understand it helps emissions because while it's slowly climbing down in revs it's consuming any unburnt fuel.
--A free RPM drop releases unburnt fuel into the exhaust (hence the pops) which is bad for co2 emissions.
--What he said. It is emissions related to help burn left over fuel before it enters the catalytic converter.
--Rev-hang is when the rpm tends to hold steady without decelerating. As mentioned, it is to keep the catalyst lit for emissions. When people say they reduce the rev-hang, they generally made adjustments at high RPM/WOT and kept the OEM parameters intact during normal cruising conditions.
--If they "did it right" the new APR tune should also have eliminated the rev hang... The rev hang is most noticeable at low RPM city driving, anyway.
--Stock rev hang should annoy just about everybody.
--This has been discussed quite a bit in the past. Yes it is emissions related. I hated the rev-hang when I got my R. I ended up with a UM Stage 1 flash that has pretty much eliminated it. I am not sure other tuners will represent that they can eliminate it but UM advertises it. Now it's much more fun when blipping on downshifts.

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post #45 of 50 (permalink) Old 06-18-2018, 05:21 AM Thread Starter
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Then I googled the terms "rev hang delete." OH YEAH... Now we're getting somewhere. I am finally finding some actual data on the subject. Apparently this has been an issue for gear-heads for some time. From an article found here CLICKY I gained some actual evidence about just why we have rev-hang. No doubt there is much more available on the web, but this is good enough for me.

Beginning with paragraph four of this article, the author states, "The cause of rev-hang can be put down to the war on emissions. Recently, manufacturers have been intentionally implementing rev hang within ECU programming to save themselves from a potential emissions scandal. When the throttle is released an ECU with rev hang is programmed to leave the throttle slightly more open than usual.

This strategy is used because it was found that suddenly closing the throttle produced a sudden spike in gas pressure within the crankcase which emphasised the rate of oil vaporization, thus adding to emissions from the engine." (I'D LIKE TO INJECT THAT A CATCH CAN SHOULD CURE MOST OF THIS ISSUE.) "Also, when the throttle is suddenly shut, the fuel mixture suddenly becomes lean which creates NOx (oxides of Nitrogen) which also contributes to emissions."

He goes on for a couple more paragraphs, but that answered the question for me. Now, that said, there is also a great deal of info online in the world of tuners to eliminate rev-lag. Now I'm wondering if this has ever been addressed with our modern HEMI's???


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post #46 of 50 (permalink) Old 06-18-2018, 08:26 AM
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[quote=Cuda340;8330185]
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Originally Posted by TA 392 YJ View Post

I had a shaker hood on my 1971 'Cuda. It was nicely constructed. It had a large metal mounting plate, with a circular opening in the middle, that slipped tightly on top of the carburetor. The fiberglass shaker scoop, itself, had a manually controlled flap (activated by a cable under the dash) that could be closed for warm ups or rain. If that occurred, the air would be pulled from a lower flap in the mounting plate. Also, the scoop had two exterior drainage holes to get rid of water.
Yeah.....they all had some way to avoid the water entering the intake......that wouldn't end well in street car.......but it also means there were no real RAM AIR intakes......even Pontiac's cold air access called "Ram Air" wasn't. I had a '70 GTO for a few years with a Hood that had decals stating "Ram Air" but...... it wasn't or at least the effect was so very small as to be pretty much insignificant.

Ram Air is real though and can make a difference assuming you can seal up the box to pressurize it at high speeds, you have access to non-turbulent air and your speeds are high enough to actually do something to pressurize the intake.

Again I think of those Formula on cars as the best example of Ram Air used to full advantage.......or maybe a top fuel dragster that will have those forward facing scoops on a super charged engine that will achieve 200MPH or more by the end of a run.

There is a great book of "tips" and solid information for using Holley Carburetors out there that devotes a few pages to this topic.......after reading it you quickly realize that in a street car what you really want to do with any intake you might choose is to optimize the "Cold air" and smooth out and unrestricted path as much as possible......at least that's what I got out of the read. What I took away from the pages devoted to the topic. The idea of RAM AIR isn't worth much or even achievable as a performance gainer on a street car.......it's straight out race car stuff only.
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post #47 of 50 (permalink) Old 06-18-2018, 09:53 PM
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Quote:
Originally Posted by Cuda340

The ram air effect of the shaker hoods on the 1970-1971 Challengers and 'Cudas were good for 5 hp. on the top end.
Another reason why... Chrysler didn't mount them backwards like GM did.
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post #48 of 50 (permalink) Old 06-18-2018, 09:58 PM
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Originally Posted by TA 392 YJ

MAYBE......but doing so would require it to be sealed and it wasn't.

They were sealed.
Your right about it being too low though.
Still a lot better than cowl induction.
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post #49 of 50 (permalink) Old 06-24-2018, 11:08 AM
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Another reason why... Chrysler didn't mount them backwards like GM did.
Uh......no! Chysler's choice was purely styling over function.

Backwards is the way to do it on a street car.

Again.....it's all about the aero-dynamics.

Read up, pick a reliable source rather than silly banter among BIASED car guys......there is still so much miss-information on this topic.

The rear facing Cowl induction systems are still mostly a race car piece but even so......if there is an effect worth having here don't be so quick to embrace your Preference for the styling choice of a forward facing scoop over a rear facing scoop as a performance enhancement to prefer as well.

There is actually an aero- advantage to the rear facing scoop that makes it PREFERABLE to the forward facing scoop that ISN'T high enough to grab air outside the turbulence created as the car slices through the air at high speeds.

Winston cup cars use the area ahead of the windshield as preferred area to grab air too. The area just ahead of the windshield is a higher pressure area that actually makes a rear facing scoop the way to go if it's a low profile scoop only a few inches above the hood.

Again.....look at the formula one cars and how high those forward facing scoops are in the effort to find unrestricted turbulence free air.

On a street car.........there is a lot to recommended the rear facing scoop over the forward facing scoop.

That said a Trans Am style Shaker mid way down the length of the hood wouldn't be nearly as effective as the L88 Corvette Hood or the similarly close the windshield cowl induction hoods on Chevelles and 1rst Gen Camaros.



To avoid the Chevy vs Dodge BIAS.......I chose a photo of a Toyota "cup car".......but rest assured this how the Chevy, Dodge and Ford guys all do it too.
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post #50 of 50 (permalink) Old 06-24-2018, 11:29 AM
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They were sealed.
No they were NOT sealed... at least not "air tight" as they would need to be to create an actual RAM AIR effect. They were mostly sealed up to prevent heat from under the hood to enter and ruin the cold air advantage they created regardless of whether they faced forward or backward.
Quote:
Your right about it being too low though.
Still a lot better than cowl induction.
If you like how the forward facing scoop looks better to your eye......there is no argument to be made that's your opinion......it's just a subjective opinion you have and it's neither right nor wrong.

.....on the other hand if you're suggesting forward facing low profile, middle of the hood is the better way to go for a performance advantage.......then race teams in drag racing and Winston Cup say you're not just a bit wrong.......you're completely wrong.

Drag cars, Winston cup cars and just about any race car that doesn't run a true ram air set up the right way through a forward facing scoop that can grab air well above turbulence created by the car itself as it passes through the air .....most all of them grab air just ahead of the windshield. This is the reason GM chose those rear facing cowl induction hoods. How much a Corvette, Chevelle or early model Camaro gets for an advantage is probably minimal but it is the better way to go in a street car that isn't going to run something that would be a pretty big obstruction to the driver's view of the road in an older car with the lousy aero-dynamics all makes had back in the 1960s and 70s. An old Baracuda or Camaro going through the air is a virtual BRICK WALL vs modern cars. The steep "rake" of the windshields back then were horrible for aero-but they did create a high pressure area at the base of the windshield for an air intake to take advantage of as a cold air supply. An opportunity to make lemon-aid out of your lemon situation if there ever was one.

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