i was wondering if there would be any advantages or drawbacks to installing a ram air hood and ram air box on my camaro.

 

Cold Air! Big benifit, TPI engines are very temperature sensitive due to their long intake tract. The cooler the better!

 

thx...i know it may have seemed like a dumb question but im new to cars and i didnt find an answer in the search, many thx for answering me though.

 

A Ram Air hood will give very little benefit over a good CAI pickup plumbed to pick up properly underneath and outside the engine bay.

However a hood will cost you 400$-500$ or more and and self made CAI might cost you at most 50$.

You can buy alot more power in other places with the money saved if you dont buy a Ram Air hood.

 

thanks for the advice

 

If you have a Camaro with the foglight cubbies, you can make a ramair setup quite cheap - and Ramair is better than cold air. Both are cold air, but the ramair will wake up at around 75mph and actually RAM AIR into your intake, resulting in a very small amount of forced induction.

 

please dont feed misinformation to the newbie.

 

Exactly right. Show us some proof to back up your hypothesis.

If you can provide some data logs from an ECM that has a 2BAR MAP sensor showing poitive manifold pressure at any speed then you will have made some believers.

Until then..............................................

 

to be fair his info isnt totally incorrect. there is a gain of like .3 horsepower at about 170 mph (both rough estimates give or take a little)

but its nowhere near his claim, a real "ram air" to give you REAL hp would be more along the lines of forced induction.

so yeah, as i said, dont give false info to the newbie kthx.

 

I can promise you my Ram Air Hood and CAI is MUCH better than your CAI setup.

1. I have 9 inches from Air cleaner to TB, you have several FEET. Lots of headloss, that means friction in different fluid dynamics sort of way.

2. Mine is a Direct shot, straight, uninterupted. Yours has several bends and turns in it. Big time restrictions.

3. I'm sucking in air from several feet off the pavement, cooler air. You're sucking air about a foot off the pavement, which is known to be up to 20 degrees hotter on dark asphalt in the summer.

So, I have less restriction and colder air. Plus my Ram Air hood looks WAY COOL!

 

OK my friend, next time you have your car in a wind tunnel be sure to post some vids demonstrating the proof of a direct shot of air down the air inlets in your hood. I would love to see the proof of what you claim, as the deflection of air off the front bumper cover will minimize any direct ram-effect with the turbulence that is produced.

Again, It would be nice to see some data logs that you have showing your MAT temps Vs. Coolant temps.

I heavy pleanty of logs showing a 60*-90* difference in temps of my MAT Vs. Coolant with my CAI, with a 180* t-stat. And my SR plenum is always cool to the touch due directly to the CAI.

Getting away from the bench racing theory sesssion, my car runs 113.55mph in the 1/4 mile, thats at 1300' elevation and 80* outside air temps, all through my CAI with filter in place, what does your car MPH in the 1/4???

 

Yeesh, sooo... perhaps then the avg 2 tenths gain people who install ram air see is from the true cold air and not a ram effect at all... tho I find it hard to think that 75+ mph isn't producing any ram effect.

Well, I don't have the equipment necessary to log the data required to prove what I understand. All I have is tons of heresay, from TGO members. Members who have done the camaro ramair mod... good enough for me, but fair is fair here you go for the newbie...


ALL INFORMATION PROVIDED ABOUT RAM AIR FROM D STROY H8 IS FOR ENTERTAINMENT PURPOSES ONLY

 

Ominous 87, Direct shot from air cleaner through MAF and into the TB, yours doesn't. What I'm saying is a Ram Air Hood will ALWAYS be better than a CAI through a fender or foglights or from under the car, ALWAYS! As for true performance, you have to measure the same car with CAI and then with a Ram Air setup and you know what, the Ram Air is going to win EVERY TIME! It's physics, fluid dynamics, you can't change that. You are obviously happy with your setup, fine, but it's not the best or optimum setup.

 

a wise man once taught me a lesson, can you comprehend it?:




"At no time did the car ever see an increase in pressure. In fact all the way to 140 mph the car was still sucking air in........

Also of note, the gm/sec readings.......one reason why the 165 ecm is such poo poo, a hard coded 255gm/sec limit.....

(this part i agreed with him on)
All intake on cars are CAI's. Period."

and as such, the reason a ram air works to increase performance is because its letting in cold air. therefore the term ram air is bogus, it DOES NOT ram air into the engine..dont believe me? go look at the above images again. the term ram air is simply a marketing ploy. i reiterate:

All intake on cars are CAI's. Period.

 

From everything I have seen, I've made the following observations:

1) A CAI and a functional Ram Air hood are good for roughly the same amount of power. Ram air hoods look great on F-bodies and if I owned an F-body, I might even spring for one. There is no way a RA hood is going on the Chevelle though.

2) The term Ram Air is bogus. There is no forced induction involved, though I don't really think this was a point Warbird was pushing.

Personally I think that strictly IN THEORY ONLY, a Ram Air hood on an F-body SHOULD perform better, based on what physics I have had (I am not a physics major or an engineer) and the various layouts I have seen. HOWEVER the real world results are that CAI's and functional R/A hoods produce roughly the same result......a colder, denser, charge to the intake tract.

 

To get a theoritical maximum stagnation pressure to boost the motor, lets assume that the inlet in your ram air hood is moving at V=0. Now lets assume that you're going 75mph as mentioned above. Lets assume standard air conditions at 59F. The change in pressure between atmospheric and the inlet, ignoring any frictional losses, is 0.5 * density of air * V^2

density of air = 0.00238 slugs/ft3

so..

0.5 * 0.00238 slugs/ft3 * 75^2 miles^2/hour^2 *
1/12.96E6 hour^2/s^2 * 1 lb s^2/slug ft * 27878400 ft^2/mile^2
* 1/144 ft^2/in^2 =

0.099 psi

Now keep in mind that we assumed zero inlet velocity which cannot be true if the motor is running. The actual inlet velocity depends on your RPM, VE, and displacement among other things. The inlet velocity is on the order of the vehicle speed or higher if we are racing (high rpm) so the delta velocity term turns negative (subtracts from positive boost). As you can see, the ram air can't do much for racing. But dang it sure looks cool! :hail:

I spent $500 on my cold air tube. That's just slightly dumber than expecting any boost from a ram air hood.

And there you go (from an engineer). Peace.

 

CbraKlr88 - If what you are saying is true then;

Q: Why do dragsters and Indy Cars and F1 cars have their air intakes up in the air stream facing forward?

A: Because you truly do get a Ram Air effect!

Put your hand out the window doing 140 and tell me theirs no way that can pressurize the air cleaner assembly.

Again it's physics and fluid dynamics. You can argue all you want and post all the data you want from your car or someone elses, but facts are facts. A properly designed and installed Ram Air system WILL give some pressurization to the air cleaner/air box. Most factory systems don't do this, they are mostly for looks, but they do allow cooler air in which is where the benifit really hits. The Dodge Challenger 440 six pack hood was truly functional even for Ram Air, though it pressurized a air cleaner and wasn't a straight in shot. That's because it puts the air intake above the boundary layer on the hood and into the air stream.

 

NO. because THEY truly MIGHT get a ram air effect. i doubt they do it for anything but a FEASABLE way to get colder air into the system, but if ANY benefit would be had, it would be had at the rate of speed at which they travel. You start doing 300mph in a 1/4 mile and then you come back to me stating how the ram air might have helped (hell even then i still say its for a source of cold air outside the car ONLY)

infact, you know what? the actual reason they all use a ram air hood style? THEY NEED THAT MUCH AIR INTAKE. they could use a cold air intake kit with a spherical k/n filter, but they wouldnt cuz it and the tubing are too small.

yeah facts ARE facts, see my above FACTS in the form of two nice tables. k thx.

no. read the above points.
exactly, the cooler air. period.


BTW go up a post and read the engineers explanation as well. justify the money spent all you want, you wasted money if you were looking for "ram air". you DID NOT waste money if you were looking for 1 ) looks 2) a way to get cooler air into your engine 3) a way to get cooler air into your engine bay to lower your engine temp (which btw is ANOTHER reason that pro stock/drag/f1/whatever use ram air style hoods)

 

 

RAM AIR is a huge lie, we have just been presented with all the hard proof needed to debunk that lie. But looking beyond the proof that is already on the table, I can offer further info to shootdown the RAM AIR lie. Cold Air is the only thing a RA hood gives a motor that is of any benefit.

The RA advocates claim a stright through shot to the motor, wrong!!!!!!!!!!!!!!!!!!!!!!!!! Nothing but lies.
1. Whatever air that might be "rammed" in the direction of the motor will first hit the air filter and stall causing imense deflection and a huge disruption in whatever benefit that might have ever existed from a "ram" effect, again this "ram" effect is only notional.

2. What is the function of a plenum? To stall the inlet charge and allow it to build density before being used by the motor. So even if the so called "ram" effect ever made it past the air filter it would stall in the plenum. Not to mention TPI is built on the priciple of predictable reversion where the intake charge is actually bounced back into the plenum when the intake valve closes. This in effect causes a positve pressure wave that jump starts air movement down the cylinders that are next in the firing order waiting to fill causing a higher velocity than normal charge when the intake valve timing event occurs. This becomes extremly difficult to maintain at high RPM hence the reason the TPI falls on its face so early no matter how you mod it out. GET IT NOW!!!

So no matter what any of these RAM AIR lovers and defenders offer you, THERE WILL NEVER AT ANY TIME BE ANY POSITVE PRESSURE ON THE BACK OF AN INTAKE VALVE DUE TO A RAM AIR HOOD, BOTTOM LINE...............................ITS ALL JUST BENCH RACING........................

I dont think it is terribly difficult here to see who is right and who is unable to accept the facts of reality.

 

I dont care what my 50$ CAI does or doesnt do in your opinion, because in reality it allows my car to MPH @113.55 in the 1/4. Again I ask, what does your car MPH in the 1/4? If you know so much then you should know how to make your car MPH in the 100 plus teens range and should be proud to tell us all about it and show a time slip.

If I really wanted bang for my 500$ then I would most certainly fab from scratch a DRY N2O system for my car and remap the fuel and timing timing curves in my chip and put another 100HP to the rear wheels. I most certainly wouldnt spend it on a RA Hood and hope to pick up a tenth.

Not to mention that I think the RA hoods totally kill the natural lines of a 3rd gen firebird, I think they look absolutely terrible. I dont think they look all that much better on a 3rd gen Camaro either, although slightly more acceptable depending on the paint and wheels.

 

WOW i didnt realize that this thread would have such a heated discusion, but you guys are helping me understand cars much more, many thanks for responding.

 

Another disadvantage of the cold air tube is that has a greater exposed area than does the ram air box. The heat flux through the tube/box is proportional to the exposed area of the tube/box (to warm underhood temps) if we assume that the heat xfer properties of the CAI and the RA box are similar, no convective heat transfer, etc. The tubes tend to pick up more heat than do the ram air boxes. Ya, hoods can get hot too. There are many many variables. The difference is probably very small, but still reality. Summit carries CAI insulation 'sock' to help shield the tube from heat, costing around $50.

 

Ok, I thought I might add my $.02 in here. A little on my background.....I'm an electrical and environmental specialist for the F-16 fighter jet in the Air Force. I deal directly with pressurization, ram air, etc. I've learned through extensive training that short distances are needed with regards to ram air/cold air. The reason being is that once cold air is being run through any ducting it will do two things. That is 1. gain temperature and 2. lose pressure. Forced air induction (turbo or supercharger) uses these principles by ramming air through a short amount of ducting into the engine for combustion. Engines need 3 things to produce power, fuel, spark, and air. The forced air requires more fuel to combust thereby creating more power. A cold air intake that has several bends will not see the best amount of power possible for this application. It will however benefit from the cold air furthest away from the engine, and everyone knows colder air is more dense and will ignite much faster. Ram air on the otherhand utilizes a psuedo-supercharger method. Air coming at higher velocities will be forcibly pushed into a ram air intake. This high pressure will force more air down each individual runner, as much as the cam will allow during it's intake open stage. The more air will create more horsepower. During my training, our instructors went over ram air and it's application on cars so it would better explain its use on the F-16 which uses several ram air intakes (not just including the engine intake). In each of these intake areas, the air travels minimal distance through as few bends as possible. Bottom line....ram air hoods with the ram air intake will NOT benefit from a standstill, only at speeds where air is going to be forced into the intake. Although this is true, it is the best setup for these cars with the exception of a turbo or supercharger. Camaro ram air with the ducts coming from the foglight area is not as effective due to the bends and longer distance it must travel. Cold air is all that is....cold air. Air cannot be forced into the cold air, the engine only takes what it needs from the cone filter; the rest is just passing on by.

And one other thing. Nitrous utilizes these same principles. the oxygen is very highly concetrated and extremely cold. It is forcibly rammed into the runners and sucked into each head where it is ignited thereby increasing hp by a great deal. If you were to have nothing but pure oxygen used in each of these setups, ram air would produce most of the power. Honestly, you can take what I say as heresay, but I just wanted to let you know, I work with this stuff everyday and have been trained very extensively on this subject matter.

 

:werd:

However, Pontiacs with the Turbo Buldge Hood can greatly minizmize this problem. If you open the exhaust panel in the buldge and rip out the insulation, the positve underhood pressure will force hot air out as cool air enters through the radiator.

I run a 180* t-stat, ceramic coated LT headers, have the insulation out, and the exhaust panel opened. My under hood temps are very cool and it takes my motor alot longer than usuall to warm up to temp. Often at night on the highway the motor drops below t-stat temps. If I pull out of the garage and hit the highway right away I can go for miles and miles before the damn thing gets up to temp.

And as stated previously my SR plenum and cast runners are always cool to the touch.

FYI

 

pat12spe

Thats a nice contribution and nobody will argue with your training or knowledge.

However: and as always.

1. We have never seen the RA hoods in a wind tunnel, so we dont know where the openings are in relation to the boundary layer. For any ram to actually occur we would need to be in a laminar flow environment with the opening above the boundary layer.

2. It is not a direct shot as the filter is a massive obstruction casusing any possible ram-effect to stall, deflect, and enter into a highly turbulent state forcing the boundary layer up and over the turbulance and cutting velocity tremendously.

3. A plenum is designed to stall the incoming intake charge, so even if the air was coming in fast and hard it would stall in the plenum.

4. There is substantial reversion occuring within the intake sytem every time a intake valve closes in a TPI intake. The reversion alone would counter effect any velocity left in the "ram air" charge if it actually ever made it past above points 1-3 with any substantial velocity left.

THERE WILL NEVER BE ANY POSITVE PRESSURE ON THE BACK OF AN INTAKE VALVE DUE TO THE EFFECT OF A RAM AIR HOOD.............................................

 

Fair enough. What about other areas. Is there no benefit to having a positive pressure on the air filter? On a camaro ramair mod, there must exist a positive pressure area in the air filter housing. That is - right underneath the lid. Even tho the plenum stalls air to store it, wouldn't a positive pressure area underneath the filters (first area of induction) result in an easier inhalation by the engine? Furthermore, even tho the engines breath overpowers ramair function, wouldn't ramair function still aid in the force that air is sucked in?

 

Your point on number 2.
Filters have been greatly modified to have a high flow of air pass through them. K&N among others all have high performance air filters that flow much better than the stock counterparts. Any ram air, whether on a car or a plane, must have a filter of some sort. The ram air isn't negated by the filter. I agree that it may be slowed down some, but who in their right minds would run his car without any filters of any sort? It still has a ram air effect to it. If this were true, than the incoming charge of ram air would cause such a severe back pressure that it would explode the weakest point of the system (this is on jets). Granted those speeds cannot be reached in a car but you face even more restriction on the outside of the vehicle. Air will take the path with the least amount of restriction, so that huge charge of air in the front of the car will shoot directly through the ram air intakes and pass through the filter.

Your point on number 3.
This is not true. If this were true then dry nitrous kits wouldn't make nearly the amount of hp that they do. They shoot directly into the plenum from the TB, causing a huge charge of concentrated oxygen pressure to go down into the runners. Also, if this were true, there would be no point in having a supercharger or turbo. If the plenum would stall the air, then it would negate the air coming from the supercharger or turbo. I agree that it may slow it down, but it won't stall it out. Plus if the car is speeding at a constant rate, more air will be forced into the plenum to constantly refresh any vaccuum that may have caused from any intake valve opening. There will always be a constant pressure on the plenum caused by this. There is one truth to what you are saying. The plenum can only hold a certain amount of air, but as each valve opens, more air will be pushed in against the constant air to fill the void of any that has left (i dunno if that is clear, i'm sorry but i'm tired as hell right now). If there is no such thing than GM and other car companies must have told the biggest fib in automotive history. The LS1's use this ram air technology. The third gen version is just a little more crude than the newer models.

 

Almost forgot to mention this. An instructor gave us this example as a kind of reference to ram air. Imagine a vaccuum cleaner with just a tube on the end. You turn it on and it starts to suck air through just like an intake valve would. Now imagine putting a giant aerosol can on the end. This aerosol can could shoot 1000psi. There would be more air forced through the vaccuum. The main thing that governs how much air is used in an engine is the cam. It regulates how long each valve is opened for in one revolution. Now, when the car is running at a high rpm, the valve is only opened for a split second. The valve will not take in as much air as it possibly could. If you force fed it air, then the valve will take on much more air and compress that air causing a bigger explosion inside the valve. This would give you more hp. It also helps to picture a deisel engine. There are no spark plugs, it solely relies on air being force fed into each valve. The air becomes compressed so much by the piston that it causes the temp to rise drastically enough that it ignites and therefore does not need a spark from a spark plug. It goes along these same principles with ram air. A supercharger or a turbo is a stepped of version of ram air.

 

Great they do flow better hence a benefit, however it is an obstruction none the less. The obstruction creates deflection wich creates turbulence resulting in a movement of the boudary layer to be pushed up and above the tubulence.



Well thats pretty much common knowledge, however there is no positive pressure within the intake provided by a RA Hood.

I would suggest you look further into this matter.

 

The reduction in velocity due to the sudden expansion in the plenum chamber does not alter the chemical makeup of nitrous oxide. Nitrous aids the combustion process because of its chemical nature and it's cooling nature due to changing states.

"huge charge of concentrated oxygen pressure"

Partially right. Larger concentration of oxygen, yes. Extra pressure that develops positive manifold pressure? No. You may be referencing bottle pressure which is a means to estimate nitrous flow rate and spray pattern. Or it may just have been a poor choice in words.

We are also beginning to confuse the terms velocity ('stall' as ominous used) and pressure. They are indeed related terms, but your arguements for ominous's #3 being wrong are entirely misinformed.

To Ominous-
The reduction in velocity, or "stall" in the plenum will not decrease the (pseudo) stagnation pressure at the throttle body/plenum inlet. Therefore the "boost" pressure will not be lost and the air density within the plenum will increase. Perhaps you are well versed on the subject and can provide an expanded discussion on the topic. Perhaps you could point us to some online literature that addresses the theory behind your explaination #3. I look forward to the discussion!

 

JMatlock88

My use of stall may very well be incorect in the spirit of using perfectly accurate terms. Correct as you feel to be necassary. As being well versed, I only know what the internet has to offer coupled with common sense. My B.S is in Finance with elective concentration in International Econimcs, thats the meat and potatoes of my formal education and it is not engineering.

There are a ton of good reads at the NASA site.

Here though is a read very relative to cars though.

http://www.grapeaperacing.com/GrapeA...ionsystems.pdf