AGBULLIT

It looks good! Great idea!

sqidd

Are you referring to the holes in the middle of the hood? If so those are not “Ram Air” inlets. They are in the boundary layer created by the aerodynamics of the cars nose. The air around those inlets is barely moving, the airstream is much higher off the surface of the hood than that. At best that could be described as a “Cold Air” inlet.

Here is a pic of a FR500 in the wind tunnel. You can clearly see the airstream is above the surface of the hood and it leaves a sizeable boundary layer. And this test was done at 35mph. The airstream gets pushed up a lot higher and the boundary layer gets thicker as speeds increase.






Cool airbox though

red454

Well, ok - the forward facing openings (on my hood) are likely much too low to register a true 'ram air' effect. Agreed. And I have seen the tests that show that even at 100 mph, the effect (even with a scoop that projects into the air stream) is minimal with regards to increased hp production.

It is, at best, a cold air inlet. Or perhaps a bug catcher. There is of course cowl induction, but not with the retro style hood of the '67 Shelby - which is really what I was going for with regard to aesthetics.

And as far as the old school ram air goes, other than a few Chryslers, I don't recall any Fords or GMs that had a hood scoop that was up very high. The old muscle cars perhaps used the psychological part of 'ram air' as a sales tool rather than the scientific facts.

It may be a misnomer - true, but I can say that this setup is far closer to 'ram air' than the factory setup.

Besides, I paid $1200 for a functional hood, and by golly I was going to make it work. I tried to keep my setup from looking home made. I need to find a better way to cut the foam sealing material. I used a razor blade, but the edges are still rough. I have a buddy with a LASER at a sheet metal shop. Maybe I can get him to cut one out for me.

One bonus that I noticed is that since I am using a factory box that is flipped over, the filter now faces the underside of the hood, and the intake sound when hammering on the throttle is much louder. Seems to really resonate through the hood.

sqidd

Yeah, the faster you go the thicker the boundary layer gets, especially with the “square” nose on the 05-09 S197. The oncoming air hits the nose and gets direct straight up! Not exactly ideal.

Oh, it looks cool and if it is sealed off it is far better to get air from there…instead of hair, or maybe a bear. But some just won’t care (a Dr Seuss moment, sorry). As far as cowl induction goes it is advertised a lot but an actual functional hood his rare and they really only work best when sealed to a carb/air cleaner.

Absolutely, I agree. Using a “scoop” for functional ram air involves a very, very tall scoop. You won’t see those on production cars. A perfect example of a scoop that works and how high it needs to be is on Pro Stock cars. Those suckers are way up there and they have little tiny pointy front ends that don’t direct the airflow up and effectively over the car. And the Pro Stock guys would be running a lot lower scoop if it worked. Aerodynamically they are horrible for the car.

The only way to truly pull off ram air is to have the opening in the front of the car. Taking into account that the actual upper grill opening is much smaller than the radiator (this creates a pressure front behind the grill and against the rad face) one could pull quite a bit of air through an opening where the foglight is or better yet where the foglight is and everything over to the edge of the grill and duct it to an airbox like yours. That would provide a massive amount of cold air and could possibly even pressurize the airbox a bit. I’m feeding my airbox/air filter through my RH foglight hole (GT500 nose), if not I would probably go for something fed by the grill. The 2010 GT500 grill feeds the airbox so Ford thinks it works. It could be done on a much larger scale because you have no need to pass noise emissions and it would be sure to “honk” quite a bit through the opening.


Absolutely!


From what I can see in the pictures it looks **** near factory. A very impressive job.

red454

The only factory cars I remember pulling (air) from the front were the Thunderbolts (which you could argue that they were not a street car) and the Olds 442s from the mid to late 60's. There may have been a few others.

The tall scoops on the Pro Stock cars - I figured they were as much to clear the tall tunnel ram intakes (and the like) and associated hardware as they were to get up into clean air.


As for my setup, I would like to be able to measure the air flow through the hood. After it enters the scoop on top, it has to make a 180 turn to dump into the air box, and I suspect that the path through the hood is rather restrictive. I can see the hood flex (suck down) briefly when I blip the throttle. I would guess that part of that is the delay in getting the air mass moving in response to the quick pressure drop in the duct work.

Really though, it is probably a moot point as I just drive it on warm sunny days. A few hp here and there at 6200 rpms won't be missed.

If you study the pic, you can see the path of the ducting.

Murph

Why not just bite the bullet and put in a CAI, then convert the hood not for RAM but use it for heat evacuation? You'd end up with a lot more air for the engine and the scoops could be augmented with a set of grills cut into the back of the hood to allow for air flow pulling out the hot air on city runs.

Just a thought...

Edited to add: love the lhood BTW - looks great!

red454

I thought about that. I bugged the guy who made to hood to add some heat extractors, but he said it was too big of a pain since the hood was finished and he decided not to make any more.

At the time I was looking (a couple years ago), there were other hoods that had heat extractors - but weren't functional. So I had to pick between functional and heat extraction. The functional part was more important, so that is the way I went. Although you are probably right about the CAI. And I suppose I could figure out how to incorporate some louvers / extractors without destroying the hood.

sqidd

I’ve talked to one of those guys. The tunnel rams are half there because the scoop needs to be that high. The crew chief I talked to said that if they could lower the inlet they would have no issue lowering the carb without worrying about loosing power.

I saw an article in Hot Rod where they went to Bonneville once and ran a Gen 2 Camaro with a silly huge big block with a massive blower on it that made something like 1500+hp. To run it in another class they removed the blower and ran just a carb. The car only slowed down by I think it was 10mph and they were dealing with half the power. There is aerodynamics for ya.


It’s easy to test. Buy a $20 vacuum/boost gauge and run it to the airbox to see what you get at 35-55-85-105-155mph. You can just run a rubber tube into the cabin and let the gauge flop around, not like you need to permanently mount it.

The first time I went to race at Daytona we did the same sort of thing on my “A” bike and played with the ram air ducts to see what kind of pressures we could get in the airbox while on the banking. It taught us a lot fast.

As long as you don’t see a vacuum the system works as a cold air inlet.

sqidd

The only effective placement for extractors on a S197 is where the GT500 ones are at which is between the radiator and the front of the motor. It makes sense, the air you want to evacuate is what is coming through the rad.

Here is a pick of the FR500GT. Clearly they placed the heat extractors there for a reason (and made the cool “duct” to them.





Here are some pretty cool louvers. They have different ones than in the link also:

http://www.hrpworld.com/googlebase.c...action=product

red454

- So, what did you learn? I do have a vacuum gage. I might try it out.

red454

Similar heat management that the Shelby Series 1 used...

sqidd

We learned that even though the ram air inlets were located at the furthest point forward on the fairing it was still hard to get any ram effect. Once we put some small “fences” at the openings and ran air ducts that tapered from small (inlet) to large (outlet) we saw about 1psi in the airbox. It was hard to tell exactly what the gain was because we were using a vacuum gauge which is about impossible to focus on while on the banking because you are doing 190mph and its Bumpy as he!! so your head is bouncing all over the place. Having it hooked up to a data acquisition system that you could download in the pits would have been ideal. We certainly made gains but nothing extraordinary.

Ghost

I also think this would be the best option, as it seems that the more HOT air you can evacuate from underhood, the cooler and denser your charge would be going into the intake, whether it was rammed in or not. If striving for ram air, I have to agree with Sqidd that the front of the car (either upper or lower grill) would give you more of an actual "ram effect"......I know on most sportbikes, the ram inlets are at the leading edge of the upper fairing, in order to be in the wind, and that they only really, truly add power once you get close to triple digit speeds.....don't know if that would be true for cars also. I will say that while maybe not perfect for ram air, hoods of that nature and CAI's in general that try to block off the intake from underhood heat still seems a worthy pursuit, IMO. Getting back to heat extraction, anyone here know of or heard of a test in which heat extraction hoods were put to the test to see how much lower the temps are with them installed?

red454

True - no argument that pulling air from the front is better. But still, for all the effort, the gains seem to be minimal. Same with my setup - not much of a real gain. And I don't race the car, so the high speed benefits (of ram air) aren't there for me.

Another thing I suspected is that the air flow though the hood at WOT was inadequate. I don't have a consistent way of measuring it, but you can see the hood draw down under the rapid vacuum of a wide open throttle. I had blocked off the factory inlet in my modified air box to keep any hot air from being drawn in. But I figure that some hot air in the mix is better than starving the engine for air when there is a high demand (load). So I made a bypass door that fits in the original air inlet. At some point, I may try to duct the bypass air to a cooler location, but for now it seems to work. Here is a short video - http://www.youtube.com/watch?v=ABo2WJ1EvEg I might try to seal it better. The gaps are there so that it will open and close smoothly. The screws are hard stops to control the open / close points. So when you hammer the throttle and the demand for air is high, the bypass door will open and allow additional air into the box. The hood does not draw down nearly as much now when you blip the throttle.

I put a thermometer in the air box to see what the temps are on my 'cold air inlet'. In the morning is was cool (around 70), so on the way in to work I checked and the temp in the box was 80. It was about 90 in the afternoon. I checked the temp after 1/2 hour of stop and go city driving, and it was a tick below 100. This setup (with my bypass door) seems to keep the air at about 10 degrees above ambient. I suppose I should put the factory box back on and see what the temp is under the same conditions.

And regarding heat extraction (I know it may not help much), I wired the fan relay so that any time the ignition is on, the radiator fan is running to keep air moving under the hood.