The only problem I see w/ removing the rear hood seal is that hot and slightly stinky engine compartment air is sucked into the cabin if you have the vents on, which for most of us is most of the time. If we remove the bottom plastic pan under engine like many of us have, is the heat sucked out from below when we're driving?

 

I agree and that is my point about the location of Francs CAI, it is OK for cooling but a bad point for a CAI.

I think if you reread my post you will see that is the point being made.

 

Thanks for the input gents. This has confirmed my belief that there would be interest in such a mod, and I will be working on it. As soon as I have it designed and installed I will be back to post some pics. As stated before, this will be up to three months from now. Any continued input and advice is welcome please! I'd still love to hear from Squirrel Crusher on the reasons for the steel vs aluminum. And not to beat a dead horse, but while I understand the sceptism of some, I'm hopeful that once I get this produced and demonstrated it will speak for itself. Thanks for the good wishes!

Peter

 

Please do. And I am serious about the CAI adaption. Having tested for a negative pressure last summer during the infamaous ram Air tests I did not find a pressure difference between the fake vents and the current site of my CAI intake.
Since Eurpocharged has me at almost 200HP at the wheel, I imagine there are no issues with "negative air presure' and would not be so from this new position.

Any improvements would be from removing the CAI away from the hot valve cover of the engine causing a loss of power when idling at the stop light. I could stop burping my engine which seems to invite unwanted challenges from neighboring ricers, Mustangs and Cobalts

Frankly the low performance of Squirrelcrusher's open side vents suggest that the natural outward airflow would not be that great. And my vacuum tests affirm that theory. There simply is not that much negative AP at the side wall of the car.

Look;
We have guys here that actually wrench on their cars, like Waldig and Boiler Up. Then we have armchair engineers who suppose what would happen but don't really apply these mystical concepts as serious mods to their Crossies.

Unless others have tried and proven them.

I like Wally's hood vents for simpliscity and actual function. In point of fact, he proves his theories before he proposes them here. One has to respect that.

But. that said, most of us would prefer more aestheticaly pleasing mods like what you have suggested.

Go for it.


roadster with a stick

 

The reason air comes out of Squirrels side vent so little is because it is much easier for the air to go out a bigger hole, and the air that comes out of those vents is only being sucked out in an effort to balance air pressure. Air that is going into the engine bay will come out all exits from under the hood, but most of that will go out the largest gap, down the tunnel if the pan is on.

To test the venturi effect on a blind cavity stick your head out the window of a moving car and open your mouth while facing at right angles to the direction of travel, you will find the air sucked out of your mouth and nose. Face rearward and it is worse. You could not expect a CAI to operate well in such conditions. Face the direction of travel and you have too much air. The faster you go the more evident are the effects.
Do not do this while driving.

Burping your engine at the lights would do very little to cool the CAI as air is very poor as a coolant when it passes over a smooth surface, that's why a multitude of fins are used in actual cooling practice. Turbulent air is much better, lamina flowing air as in a CAI tube is poor. Turbulent air causes all or most of the air to be used not just some. The slower moving boundary layer of air in the tube gets hot and the air above that remains the same. Turbulence in a CAI is prejudicial to the cause and minimizing the thickness of the boundary layer gives more efficient air flow. The inside of the boundary layer causes turbulence at the edge of the lamina flowing air and that is not wanted either as this turbulence cools nothing. The boundary layer is caused by friction and the more polished or slippery the surface the thinner the boundary layer will be, it will also reduce the cooling effect as well as it will depend on radiant heat loss more.
It is a quite complex area and I know little about it. Although I have been involved somewhat with water cooling and the principles are similar.
That's my take on it anyway.

 

Dave I have patents and proprietary devices in vacuum technology but that doesn't mean I know what I am saying here. We could expand this t!t for tat sillyness into more nonsense but...

The reason burping my engine cools is because it brings in fresh colder air into the engine.. That is just too simple Dave not complex at all.
After all your nay saying about positive pressure air flow, now you say it matters in reverse. Seems you just want to knaw on a bone. Well have at it, but not with me.

Bringing cold air from the side of the vehicle is not a novel idea. Take it up with the engineers at Volvo, Peterbuilt and Diamler Mercedes.

roadster with a stick

BTW we did all those excercises with the ram experiments. I reported on the detrimental effects of the turbulence remember?
I get it OKay?

 

Air breathers on the sides of big rigs have been around for ages....turbos come to mind...lol... But, here's the deal...of all the mods that are out there, why take on this mod? I would think, if looking for HP, there are plenty of other things to do before we get here, but, I know, I am all about HP....just sayin'....

 

My interest is based on the issues I have had with the inlet of my CAI. Drawing air down low instead of from behind the grill seemed like a good plan.. Since we have concluded there is not a beneficial "ram air effect" there then the option to place the inlet low, where the air is less disturbed and cooler makes sense.

But, from inside the fender box, I have had issues with puddle water and rain. Plus the 3" CAI traverses over the right valve cover and picks up a lot of heat when the car is not moving.

Coming from the side may well eliminate these two issues.

My "ram air " testing proved the air pressures inside my Fender box were no different than where the fake "gills" are located, suggests that I would not have a difference in available air. Just less likely to be waterlogged. And, of course, a shorter pipe run, inside the engine bay, to the throttle body.

I might even get to use my MB engine cover without modifications.


roadster with a stick

 

Franc, you are a car guy, I know that, and as a car guy you know air has been taken from all sorts of locations, and certainly the side is doable...there have been cow vents, hood vents, spoiler vents, frontal vents in all sorts of locations, and certainly sucking air from the sides is doable...non of these were ever "RAM" air...we have beaten that dog before...lol...good luck, and I was actually shooting my comment at the OP...

 

Geez doc not you too. I said we gave up on the ram idea. It's 180 that keeps bringing it into the coversation. OKAY!!!!!!!!!!!! Reread my posts here. I am not advocating RAM AIR. But,when we did the tests I used a compound gauge and tested for positive and negative pressures, all over the car.


What I would like is to drive in the rain without losing another engine.
What I would like is to retain the HP my engine now produces.
What I would like is for the CAI not to heat up when I am at idle in the summer heat.
What I would like is for the fake "gills" on the side of my Crossie to actually be functional
What I would like is to use my MB engine cover without major surgery

This mod may present those solutions.

What I would like most of all is for the nay sayers to give the idea a chance to breathe. Because there is nothing inherently wrong with any of those goals.

 

The point is why take air from an area with lower than ambient air pressure? The air in the CAI would be a lower pressure than if it was taken from in front of the rad.
The turbo or SC would see much less of a loss percentage wise because it is sucking more air. Delta p would have much less, if any effect. That's it in a nutshell.

 

Dave, One more time.

Because testing has shown, it isn't lower. And because where I now have my CAI inlet, is dangerous.

I have always considered the "vents" to be a possible place for CAI intake. I tested the air pressure there with the compound gauge. It was no different than from the place I now take it, the fender box. It was also not significantly different than behind the front grill. Or from inside the passenger compartment.

Therefore I would not likely see a difference. In the end, if it were detrimental to engine performance, I would simply abandon the inlet and use the now active vent to cool the engine compartment.

But sitting in our easy chairs, cannot prove the case.


I'm sure there are significant negative AP points all over the Crossfire. There are also positive pressure points, significantly the base of the windshield. But these three points points in question did not register significant deviations from ambient unless the pitot inlet was aimed directly forward or backward to the moving air stream. Your "boundry layer" at the vents seems to be non turbulent and rather stable.


So, while it doesn't really apply here,,,,,,,
I still do not see how you can argue so hotly against the benefit of a positive pressure air flow, as you did last year, and then now suggest it matters when the air flow is a negative pressure
Perhaps the laws of physics have been amended in some way.
And,,,,,,
Perhaps I'll stop being a butthead when you can logicaly explain that reasoning.

 

You twist things around too much, I never answered negatively to positive air flow, I argued against ram air.

I am not talking about the surface of the car, I am talking about a cavity behind the strakes, open only to the side of the car with an inlet to the CAI in it. That area will be partially evacuated by the air running down the side of the car due to the Venturi effect. As a result the faster the car goes the lower the air pressure in it, that would be like running the car at higher elevations, not a hard principle to grasp I would have thought.

 

Franc, I hate to say it, but not a single vehicle you mentioned earlier, to my knowledge, has a CAI that gets air from the side vents. They are simply to let air escape, cool brake components (higher end), and many times, they are not functional at all.

After hearing the Chrysler project head for the XF speak at Woodward, he told us all about the aerodynamic testing the XF underwent. I have to believe that the grille is still the best place to draw air, especially if you open it up with mesh or the like. IMHO that open scoop of a grille is going to channel air into those filters better, especially at speed - I have to believe the engineers did something right here, just needed something a little less restrictive than stock tubing or materials, enter the traditional XF CAI.

If you are worried about cooling, I think you are going to need to trade in the XF you know these Merc V6s are notorious for heat. Personally, I am not willing to spend thousands on cooling mods for my NA, when I can run it for 2 hours straight at the track in 95 degree heat and see little loss comparatively....

 

1) Heat really isn't a problem in the NA's. Except, it would appear, on my CAI application. I'll be happy to demo it for you at the Dragon.

2) I'm not going to argue the superiority of the MERC engineers. I mean, geez no body here ever has, right? Everyone has accepted their cars just as the are, right? No one makes improvements or mods, right?

3) Cold air intakes from the side are not uncommon and can be found on those manufactures"vehicles" Most of them have18 wheels.

4) I want to draw air from down low as I do now. And honestly, I may very well be currently in the best place to do it. But it has had consequences.

5) I do want to solve the heated CAI issue and a front scoop won't do that.

6) While I like the look of our "fake" vents, real ones would be cool. This, whether they actually create an improvement or not. As it is they are just cheap jewelry bling, ,,,,,,useless appendages anyway.

7) My stubborness with Dave has to do with his negativity on most any new idea presented here

8) In case you have not noticed, I truly like to be differ't.

In the end,the original poster here, CFForever, has an idea. He is willing to go the distance with his own resources. Your response to him was on the mark and respectful. But,,,,, Mostly he got razzed.

Not many companies out there are doing stuff for our Crossies. Seems to me, anyone willing to put in the time, effort and money to try something for our orphans ought to be encouraged.

Jus sayin'

 

Working for Nissan, I've learned that the GT-R's fender vents are opened for one purpose: lower drag. By allowing the air to escape the fenderwell, the pressures are lowered and witchcraft happens, allowing teh car to slip through the air more efficiently. They're not tied in with the engine bay at all.

Regarding the heat aspect -- if we could somehow tastefully incorporate NACA ducts into the hood, and line these up with a perforated tube linked to the side vents, it would provide a low-pressure slipstream to assist drawing the hot air out.

Now if we could only get the hot air out of this thread...

Ram-air or not, there are definite advantages to facing the air inlet as directly forward as possible, as unimpeded as possible. Otherwise, you wouldn't see F-1 teams place a saucer-sized inlet above the driver's helmet. Skeptics of ram-air abound, but the air ingested into an engine with a forward-facing scoop is always going to be at a greater volume/pressure than a rearward-facing scoop.

F-1 teams have millions of dollars, countless hours, and endless resources to play with. We don't. They build cars based on what works; anything more detracts from performance, anything less undermines it.

Brake ducts, air inlets, radiator cooling surfaces -- all face forward.

The only thing opened towards the rear is the underbody diffuser, and that's to scavenge (remove) air from underneath the vehicle as quickly as possible.

Which, brings me back to my GT-R point.

 

I am not negative to new ideas, but I am negative to poor ones. I spent my working life designing and I did not waste my time considering bad ideas, I spent my time on good ideas not ideas that were based on poor physics. A forward facing scoop where the strakes are would work, but would fail as it would be a danger to pedestrians and you would be banned from the road.

The strakes are fakes for air vents not intakes and you cannot alter the dynamics of the geometry with out adding forward facing scoops.

When you look at the volume of air that enters the engine you realize that the air in the intake does not stay in there too long and hence it will not get heated too much at all. The faster the engine runs the less the air gets heated. That's simple thermal engineering basics.

Probably more heat is picked up by the air in the intake manifold as the airways are smaller and the metal surrounding the air is at or about engine temperature. Whereas the air around the CAI is not at engine temperature.

I am not against the OPs idea, it is your idea of using his vents as an intake that fails the test of logical analysis.

 

I never said, 'do not modify', I said that ON THIS PARTICULAR POINT that I, personally, think that the grille best place to source air.

I never said anything negative to the poster, and am all for new parts for the car, useless (in some people's mind) or not. I just tried to supply guidance to a new comer the best way I could.

Have you ever wondered why they are only on 18 wheelers? I have not seen your setup, so who knows, it may be the best flowing thing the XF has ever seen, but after being around for 7+ years, I think someone would have done it by now, or tried and realized Benz got it right. Most of those 18 wheelers are running a little different setup than your crossie, hardly apples to apples.

Name me one car that definitively uses side scoops exclusively for air intake and I will not post on this thread again.

I mean no disrecpect, just stating my opinions on the matter.

 

The simplest way to keep the CAI cooler inside is to use a double wall pipe with insulation in between the two pipes just like stove chimneys and chimney liners, what works inside to out will work outside to in. A bit cumbersome and not worth the effort really.

Good points JHM2K and Boiler, I agree with the points made.

 

Guys, I am going to make one point here from experience, I am not an engineer nor do I claim to be one.

I just finished 30 years in the transit maintenance industry. Along those years we have been always fighting engine cooling issues in the summer time with hot temperatures. All the coaches I dealt with had a side mounted radiator, and sometimes even an AC condensor in front of that. Early versions had an engine gear driven radiator fan. Around town doing slow speeds, it worked fine.

Now on the highway, it was a different story. At highway speeds, you could see the engine temperature rise quite quickly. Even running down hill, the engine would not cool off.

My opinion was that the air running down the side of the coach was causing "low air pressure" in front of the radiator opening or what I often call vacuum. With the vacuum in front of the radiator, and the fan causing vacuum on the back side of the radiator, the air required for cooling was stalled or had very little movement toward the stronger side.

Get the coach down to 35mph and the engine immediately cooled down because now the fan could overtake the vacuum on the outside of the radiator causing air to flow through the radiator.

Yes we did try a large air scoup. And it helped. But to get it to be really effective, it would stick out to far from the coach, snatching potential passenger right off the side walk.

Today, the transit industry is still using side mount radiators & charged air coolers. But they are using hydralic fan drives now that are so powerful, they can do the job to overtake the "low air pressure issues" at the side mounted heat exhangers.

With all this in my mind, I don't think a CAI would do well from a side opening of any sorts, at least at high speeds when you need it most.

I am not here for an argument, just letting others know what I have delt with over the years.

James