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What function does a cowl induction hood serve?

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Old 08-23-2002, 05:04 PM   #21
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Default Re: What function does a cowl induction hood serve? (OlGeezer)

The aircleaner for the 73 has the rubber seal on top which mates onto the hood and it has dual snorks so the possibility of positive atmospheres is essentially nil.

I believe the purpose of the flapper door is to deliver cold air directly to the air filter as opposed to air which has been heated by passing through the radiator. I like the idea of having the flapper wired to something other than WOT and a vacuum switch would serve well.

At the end of the road, the performance gains from this system wouldn't be huge but the GeeWhiz factor is great!! :lol:
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Old 08-23-2002, 07:06 PM   #22
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Default Re: What function does a cowl induction hood serve? (Mike Ward)

Well Mikey, about time you finally got back. I forgot to ask...How were you traveling, by rail? Did'ja git back all tired and cranky? :D :D :D

Yeah, yer right mikey. The theory is perfect, and I doubt if there was ANY boost until you were at least at highway speeds. It wouldn't take much; a few inches of water at the carb intake would deliver better performance. About the same order of magnitude as polishing the intake ports maybe.

I don't know why they even bothered with that stoopid flapper door; seems like cool air at idle and low speeds would have been a good objective. Most likely the flapper was to minimize engine noise inside the car when you weren't lettin' the hammer down.

Can we agree that hood scoops are strictly for display? Any hood scoop large enough to provide any benefit would be unattractive and would never get past the designers. :D
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Old 08-24-2002, 02:47 AM   #23
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

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I don't know why they even bothered with that stoopid flapper door;
You can't overlook that GeeWhiz factor. It's gotta be worth more hp than, say, underdrive pulleys. :eek:
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Old 08-25-2002, 01:12 AM   #24
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

On second thought, no wait, third thought, I think I'll add some flow indicators to the inside of the ducting. It's very possible that under certain conditions the air actually flows BACKWARDS and takes hot engine compartment air and dumps it into the plenum at the base of the windshield. This then flows into the cabin via the ashore ventilation system and explains why C3s are so farquing hot inside.

Didn't GM add the gills to C3s to reduce front end lift at high speed? Did they get it right? How do we know that there isn't positive pressure inside the engine compartment, high enough that it exceeds the dynamic pressure in the air filter housing and actually causes a flow reversal?

Hey Chuckie, was nice seeing you and Jan again! The rest of our vacation went great. Might take the rest of my life to pay it off, but it's only money. We took your recommendation and had ciopinno in SF on the wharf. It was great.

Yes we agree that cowl induction is light years ahead of hood scoops (don't forget what line of work I'm in and the GIANT hood scoops I get to play with) but my point is that GM's execution of the concept on the mid 70's sharks sux big time. Shudawudacuda.Dinna. :seeya


[Modified by Mike Ward, 10:14 PM 8/24/2002]
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Old 08-25-2002, 02:03 AM   #25
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Default Re: What function does a cowl induction hood serve? (Mike Ward)

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Hey Chuckie, was nice seeing you and Jan again! The rest of our vacation went great. Might take the rest of my life to pay it off, but it's only money. We took your recommendation and had ciopinno in SF on the wharf. It was great.
What did ya'll do in SF? Did you do Chinatown? Trolley ride to downtown? Did Karin have ciopinno too, or did she just do salad? Ciopinno is pretty messy eating, and the ladies are not big on dripping red greasy stew on their clothes and methodically picking the crab out of the shell. :D :D

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Yes we agree that cowl induction is light years ahead of hood scoops (don't forget what line of work I'm in and the GIANT hood scoops I get to play with) but my point is that GM's execution of the concept on the mid 70's sharks sux big time.
Me too, I worked on inlets at General Electric, but the inlets for industrial gas turbines are nothing like those for aircraft: First of all, the airflow comes in from 90 degrees to the centerline of the turbine, so after that, you are "just doing the best you can with what you got" using a huge rectangular duct with a rounded end at the machine.

I never will forget the worst problem in inlet design and personalities I ever encountered at GE. Schenectady was designing the inlet for the MS1000?, a 100MW gas turbine that was in development. Actual production was to be done at Greenville, SC, and I was trying to interface to some bone-headed redneck that wanted to put a 10" bearing oil return right through the dam inlet plenum. "You can't do that", I tried to explain to him, "it's a wonder these things run even when they are clean, let alone putting 10" pipes through the middle of the air path!!!"

GE turbines had an external front bearing, so the drain header had to start up front and slope all the way to the rear. The inlet duct had to be either right-handed or left-handed, but with the inlet on one side of the base, this drain header went right through the inlet plenum. According to this skid builder, there was no changing their design. They had their way of doing things, only one way, and that was that...the inlet air would just have to live with it.

Well, that isn't the only reason graduate school was looking real good right then. I decided not to stay around to see who was sweating and shrugging when the turbine performance wasn't up to snuff. :seeya
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Old 08-25-2002, 02:56 AM   #26
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

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According to this skid builder, there was no changing their design. They had their way of doing things, only one way, and that was that...the inlet air would just have to live with it.
You mean to tell me that an engineer was a curmudgeon, Chuckles? I canna believe it!

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I decided not to stay around to see who was sweating and shrugging when the turbine performance wasn't up to snuff. :seeya
I'm willing to be dollars to donuts that I know who got blamed! :D To paraphrase the old saying; "Absence makes the blame grow stronger." :lol:
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Old 08-25-2002, 06:02 PM   #27
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Default Re: What function does a cowl induction hood serve? (Mac)

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You mean to tell me that an engineer was a curmudgeon, Chuckles? I canna believe it!
Uhhhh...that I would SAY it, or that they actually EXIST??? :D Are you kidding me??!!...Virtually all engineers are ashores (present company not excluded). They are highly intelligent or they wouldn't be engineers. Most have an ego to go with their brains, and they are convinced only THEY have the only answer to every problem. (I bet ole Hvn would be smiling right now...not believing what he was hearing, but smiling. :D )

It was only through divine intervention that the United States put men on the moon (and back) without getting someone killed...uh, wait a minute, we did get three astronauts killed, didn't we?! It would be interesting to see the transcripts of all the arguments that went on about the dangers of using a pure oxygen atmosphere inside Apollo versus the absolute impossibility of any electrical ignition points. Someone finally won the argument...unfortunately, he was not the one with the right answer.

But then, ego is not the exclusive province of engineers either. I remember one of those corporate "team-building" seminars that I attended, where they take engineers, accountants, personnel employees, clerical workers, and whatever and try to demonstrate that a TEAM can come up with better solutions than the separate individuals...dealing with adversity and all that clap trap...what a bunch of bull sh#t!!!

I practically had to come to blows with a freakin' bean counter about the best way to build an innovative, strong bridge with free popsicle sticks and string. Actually, the real motivation for the bean counter was that he wanted to be Chairman someday, and what better way than to demonstrate leadership skills by deciding how the bridge was going to be built. Me...I just wanted to win the contest, had a very good idea, and was pretty sure I knew more about building bridges than a freakin' accountant.

I finally beat this ashore into submission (by screaming the loudest). We had the best bridge by far, but we lost the "team-building" competition. Awww ____! There went the old career! You learn to be a slick politician or you "Do not pass go, Do not collect $200". :cuss :cuss :cuss

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I'm willing to be dollars to donuts that I know who got blamed! :D To paraphrase the old saying; "Absence makes the blame grow stronger."
Well, I guess my reputation was spared (Like I cared; I started a new career in another industry :D ): After I was comfortably established in grad school learning about flow regimes and use of partial differential mathematics to describe three dimensional flow, the MS10000 project was cancelled when the A-rhabs turned off the oil spigot. The relative low thermal efficiency of gas turbines could not compete in the new world of higher oil prices; quick manufacture, fast set-up and portability not withstanding. :D :D :D


[Modified by Chuck Sangerhausen, 2:12 PM 8/25/2002]
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Old 08-25-2002, 06:21 PM   #28
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

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But then, ego is not the exclusive province of engineers either.
Remember what 'industry' I work in, Chuck. Ego is definitely not the exclusive province of engineers or doctors or other professionals. While there isn't the same educational requirements for police officers as other professionals, the 'working knowledge' takes years to accumulate. The old saying 'a bit of knowledge is a dangerous thing' is tailor-made for cops. Police have certain powers which are necessary to do their jobs but all the balances & checks are there as well. In their first few years, most cops wield police powers like a hammer. After a while, most (not all) figure out this simple truth- just because you have a hammer, that doesn't make every problem a nail.
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Old 08-25-2002, 06:41 PM   #29
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Default Re: What function does a cowl induction hood serve? (Mac)

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While there isn't the same educational requirements for police officers as other professionals, the 'working knowledge' takes years to accumulate.
When dealing with the real bad guys, it must be for cops somewhat like the new draftee in Vietnam: The accumulation of "In Country" experience was vitally important to their survival.

I think I have heard that if their sargeant could keep them out of harm's way for the first month, then they would have learned enough about the dangers that probability of survival to the end of their tour was greatly improved.

Of course, the "checks and balances" can also end the careers of those prone to overzealous application of the HAMMER. :D
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Old 08-25-2002, 08:57 PM   #30
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

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When dealing with the real bad guys, it must be for cops somewhat like the new draftee in Vietnam: The accumulation of "In Country" experience was vitally important to their survival.
Amen but the real bad guys aren't always as dangerous as Joe and Jane Q. Public when they're having a domestic dispute because you expect the bad guy to be dangerous whereas Joe and Jane are a nice couple until they get fighting and then things get unpredictible.

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I think I have heard that if their sargeant could keep them out of harm's way for the first month, then they would have learned enough about the dangers that probability of survival to the end of their tour was greatly improved.
Room for a 'war' story here? That's what we call them too. Along with my co-workers, I attended at a basement suite where a suicidal male was holding a knife to his forearm. His roommate called us for help. The senior police officer on scene was a trained negotiator so he was standing in the doorway, talking to the guy. The rest of us were arranged around the house to ensure the guy didn't bolt. The junior guy decided to watch the action inside through the window- directly behind our crazy guy, in the line of fire if the crazy guy rushed our negotiator. When I noticed, I signalled to him to move (I didn't radio as the negotiator's radio was still on) and he waved back with a smile. I walked over and whispered "I need you over here" and, once I got him out of danger, I explained why I wanted him to move. He turned bright red, then white (which was a good trick, since he was of East Indian descent) but he got to stay alive.

The negotiator talked the crazy guy into leaving the knife behind and coming out but once he got outside, he tried to run which didn't work since I was in the way. Like I said, he was crazy.

Quote:
Of course, the "checks and balances" can also end the careers of those prone to overzealous application of the HAMMER. :D
I think that along with teaching the classes about law and it's practical applications, arrest powers, search and seizure, etc., the Powers That Be should also teach professional ethics and accountability. That way the proper application of the hammer might alliviate the need for the checks and balances.

Training has always been an issue. All of our basic training is done at our Training Academy in Regina, Sask., and the instructors provide only the basics because there's a six month field training which follows basic training. The field training is provided at the detachment level and is supposed to be uniform across the country. With the RCMP, one can be called upon to serve anywhere in Canada and most of our detachments are in rural areas or, at the most, small urban centres. We only have a few large municipal detachments and most of those are here in the Greater Vancouver area. The volume and diversity of work available at a three horse town isn't matched by that at a large municipality. That's not to say the large centre provides better training, because they're chronically understaffed so time for training is usually limited.

Anyway you look at it, it's gotta be better than my training which was being handed a set of keys for the detachment and a police car. My first post was to a smaller detachment which was understaffed by more than 50% (three men per shift instead of seven) and my trainer, after a week, said "You seem like a smart kid. Don't get in trouble." and that was the end of my training.

(EDIT FOR JULIET) To my knowledge, the effectiveness of the Vette's cowl induction was never independently tested.
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Old 08-25-2002, 09:31 PM   #31
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Default Re: What function does a cowl induction hood serve? (Mac)

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(EDIT FOR JULIET) To my knowledge, the effectiveness of the Vette's cowl induction was never independently tested.
Hee, hee :lol: :lol: ...You still messin' wid Miz Juliet??!!!...You bettah stay up dere in the North Country, cuz when she gits back from Carlisle, she will be ready to whup you! :jester
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Old 08-26-2002, 03:54 AM   #32
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

A while back, Juliet pointed out that several posts made by myself and another prominant Canajun were of the 'Odd Topic' variety and did not necessarily contain any Corvette information which, according to the Book Of Moderators, can result in removal of percentage points.

When I notice a post is going that way, I sometimes add an edit of Vette related information to ensure my relevence. Since it was Juliet who pointed out this tendency, I show my respect for her by including her name in the edit. Me mess with Juliet? Not on my best day!! :lol:
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Old 08-28-2002, 09:19 PM   #33
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Default Re: What function does a cowl induction hood serve? (Mac)

I can't believe this post is still alive!!
haha, anyways, another query,....
Aero's, those BIG kissin' hoodscoops you see on the drags, assuming they use a blower under there, why not just, put the blower on backwards(obviously easier said than done..) and run a cowl induction hood, best of both worlds? I know you would need a BIG cowl like 5 inches, but those draggers are usually huge anyway, so why the hell not?
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Old 08-28-2002, 11:02 PM   #34
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Default Re: What function does a cowl induction hood serve? (tom10167)

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I can't believe this post is still alive!!
It seems to me that you are pounding on it's chest and doing CPR to try and keep it alive here.

The boost provided by blowers is measured in pounds per square inch. The incidental boost provided by cowl induction is probably only a few inches of water at best, and is negligible by comparison. The problem with using a blower IS NOT getting too little boost such that you need help from cowl induction...the problem is getting TOO MUCH boost.
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Old 08-28-2002, 11:15 PM   #35
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Default Re: What function does a cowl induction hood serve? (Chuck Sangerhausen)

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...the problem is getting TOO MUCH boost.
Chuck,

Now that I'm sproutin' little grey hairs (not many, but they're determined little devils), there's no such thing as TOO MUCH boost. :D


[Modified by 67HEAVEN, 9:15 PM 8/28/2002]
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Old 07-26-2016, 01:27 PM   #36
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Originally Posted by Mike Ward View Post
All of this theory is 100% on the mark, but in practice (at least on mid-70's Corvettes) it's all show but no go-
1) The flapper valve is only open at WOT- how often does someone do that?
2) How often does some one drive fast enough to actually create positive pressure at the base of the windshield? And at WOT?
3) The crossectional area of the duct couldn't feed a Chevette, never mind a Corvette
4) The plenum at the base of the windshield that the system feeds from is also vented to the interior of the car as part of the Ashore Ventilation system. Any pressure built in the plenum is bled into the cabin of the car.
5) The air cleaner outer housing has two large diameter snorkels that open directly into the engine compartment. Any pressure built in the duct would be relieved by these snorkels.

Talk about building a self defeating system.

One day, I'll block off the Ashore vents, remove the flapper valve, install one way doors on the snorkel and go for a midnight WOT drive on Route 30 between Ste. Julie and Sorel. I'll borrow a few pressure transducers and a data recorder from work and analyse the delta P trace on the way to jail.

You're the funniest Engineer/Scientist I've ever seen... and Yes, Chevrolet in the 70s were that stupid... CHEVROLET is an acronym which stands for: Constantly Having Every Vehicle Recalled Over Lousy Engineering Techniques.
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