Ram Air Intake Scoop on Hood
 

I want a small scoop on my hood directly above an air box that seals to the hood from the inside such that I get COLD RAM AIR. I know most would generically not like the looks of this, but my concern is more functional. That said, I'd like it to look as good as possible.

Would such a direct flow of air be hazardous to the filter (water or debris)?

Anyone seen a setup like this? Pics? Testimonials?

Where can I get a scoop that might fit the FD look?

Could an existing cold air box be modified for this purpose?

No need to debate the effectiveness of cold air on IAT. Been there done that in other threads.:o:

The sealed airbox your suggesting, while functional in design becomes more of a hinderance at speed. When you fill up a air box with velocity pressurized air like that it eventually fills, then a hig pressure area forms right infront of the scoop itself. Once the enigine suckes in enough air to reduce the pressure the cycle starts all over again(it actually can get to near vacuum at times depending on speed and a ton of other variables). It creates a pulsing effect that can have an ill effect on performance as well as aerodynamics. The F1 guys have spent alot of time developing airboxes with sort of trap doors that will keep the pressure constant and optimized at all the speed their cars travel at.

Your idea would be great if you didn't seal the box. I'd suggest just an open air fillament with a heat shield that makes them only suck air from around the radiator.

The stock, Racing Beat, and PFS intakes all get air rammed into them from the front of the car. The turbos get plenty of cold air (well, with the Racing Beat and PFS setups anyway). Why destroy your hood with a nasty looking off-center scoop .in the hopes of gaining a few more hp at high speeds?

Easy, do what I did. Put the filter under a non popup headlight and remove the combo light. You'll have to cut a little sheet metal to make the opening large enough for a 3" tube or whatever size you use. Your opening is then at the leading edge of the front of the car, a far better option than up on the front of the hood which is actually a lower pressure area. No real visual impact either.

Kevin T. Wyum

The Feed fresh air headlight cover here http://www.jt-imports.com/FEED_FD_Parts_List.htm or the Border NASA air ducts set here http://www.jt-imports.com/Border_FD_Aero_Kits.htm may compliment a heat shielded intake kit like one FDreaming suggested.

I guess I could see that happening. While it kicks my idea in the ass, I appreciate the scientific feedback.

My theory was that the hood scoop would provide more direct ram air at higher volume than the traditional boxes. I wouldn't do this unless it could be shown to have a measurable impact on performance at moderate speeds. And, not to spend too much time on subjective opinions, I don't think an offset scoop would necessarily look nasty. If Photoshop proved that, I'd back off.

I'm intrigued with your solution, but I'm not quite sure I get it. Can you post some pics?

As a compromise, I could consider the headlight cover option, but the opening looks pretty small. While the NASA option is more in line with my idea, it looked pretty bad.

Does anyone want to comment on the fact that you can't "ram" air into a forced induction engine, or shall I? :D

Anyone ever seen Vinny Ten's hood on his Supra. He has a hole in his hood so that you can actually see his turbo from the outside. He doesn't even have a filter on there since he's just dragging. The air is guided right into his compressor by the hood

His turbo still can't take in any more air than the rpm of the compressor wheel will allow. You're not going to shove more air past the blades.

The only benefit of this arrangement is that it's drawing directly from ambient air and not underhood air.

Jimlab is right
There are factors that limit the amount of air that comes in - Some can be improved, i.e. by improving the way the air comes in removing possible hinderances (ps. pipes with corners - the manufacturer might have put these in for noise restriction etc etc.) - but there is a limit to this, and the only other improvement factor is guetting cooler air in (ambient vs. underhood)

It seems logical to me that higher pressure on the intake side of the turbo will allow for quicker spooling and more efficient operation.

Right?:confused:

Higher inlet side pressure means the turbos have to do less work to obtain the limit boost level, and below that value higher inlet pressure should provide higher boost pressure.
So, I agree with you.

I think Jim LaBreck summed it up nicely.
In addition: The headlight scoops offered by some vendors are more for looks, as the opening is too small to do any real good.

The "remove the foam next to the radiator" trick offers an opening that is larger than the turbo inlets (i.e.- the pipes going from the airbox...), therefore works in terms of not offering a restriction. So a sealed airbox will work just fine.

Cheers,

So you're saying that because the turbo can spool more quickly, that you'll reach higher boost levels more quickly? True, but you won't increase boost levels beyond the preset limit without other changes.

While removing all restriction in front of the turbo (i.e. no intake piping, no filter) will allow it to spool as quickly as it possibly can (assuming the exhaust system is not a restriction either), it will not allow any additional air past the compressor wheel than it can ingest at a given rpm. You may hit your boost level sooner because of the lack of restriction, but unless you change boost level physically with a controller or wastegate spring, you're not going to see an increase in boost level. In other words, you can starve a turbo with restrictions in the intake path, but you can't feed it more than it can eat at a given rpm, even with no restriction whatsoever. You can only make it reach that rpm sooner.

"Ram air" works on naturally aspirated engines because they have to rely on cylinder/chamber vacuum to fill themselves. If you can pressurize the intake path even slightly by using the vehicle's movement to "ram" air in to the intake, you may see an increase in power because you're filling each cylinder more completely on each cycle. However, if you place a mechanical restriction (turbocharger, supercharger) in the intake path between the outside air and the engine, there is no "ram air" effect possible from the intake arrangement. Obviously a turbocharger or supercharger also forces air into the engine, but the vehicle's movement is not a requirement, so it is not, by definition, "ram air".

Bottom line, you can have a "cold air" intake on any type of car, but you can only have a "cold ram air" intake on a naturally aspirated car. If the car is turbocharged or supercharged, all you've got is a "cold air" intake with very little restriction. The term "ram air" no longer applies.

Actually Jim, some friends and I have found that (at least on a larger frame turbo) placing a length of tubing (essentially a venturi, but of constant diameter) before the compressor housing allows for quicker/better spool. We tested this statically (sitting still, using anti-lag) also and found that we would create on the order of 7-8 psi with no tubing and ~15 psi with the tubing. This screamed to me that the length/diameters used could essentially be optimized with some surely lengthy calculations and real world testing, but is interesting/useful none the less. After we found this out, I did some research and found a few examples of people running what I can best describe as a monster "air horn". They were ~4 inch O.D. peices of different lengths belled out at the end much like you'd see on a set of webber carbs or something of that nature. I had enough trouble at school making these out of ~2" O.D. 16 gauge aluminum for an FSAE car and never tried making one for my turbo. I also liked the idea of having a filter on a street car to help keep out the dirt :)

Anyways, just FYI :)

I plan to do a setup similar to what Kevin described, but am still attempting to save up enough money to buy the needed sleek lights. I'll definitely post pictures when I get around to it.

FD seeker, I would also advise not placing the intake source on your hood.

Damian also made a pretty nice ram air intake using dryer ducting and some piece its connected inside his heat shiel. Pretty dam nice if you ask me. Search for it.

intakes aside, would it be beneficial at speed to create some kind of ducting from a nacel inlet in the front of the hood (similar to the Scoot design) to push more air through the venting on the IC? i'm assuming yes, but has it been done to any success yet?

here go read all of this fd seeker will help you out alot. http://www.autospeed.com/cms/A_0629/article.html
read 1 rigth to the end of 5. it inforative.
joel

Thanks all for the input.

Jim: I appreciate your technical definition of ram air. I can live with omitting that specific designation from the description of my idea, but I think that concept needs to remain as it provides benefits that you mentioned yourself.

Because of the buffeting problem mentioned, I will probably not purse this anyway.

Just cuz I own a firebird I get to make this comment. There is no such thing as "Ram air" even trans am owners know this. The Ram air system on a trans am only added horsepower because it accomplished the same things as a cold air intake with improved piping. If you want I'll dig up a scientific article on why "ram air" is impossible.

But apparently didn't understand it... :p:

"Ram air" only works on naturally aspirated engines, and only when the vehicle is in motion. Using that term to refer to an intake on a forced induction car is not only technically incorrect, it makes you look like you picked up all your car knowledge from watching The Fast and the Furious. Are you with me now? :D

You did not say so BUT if you were planing on using the stock air box another problem is that in the stock airbox the TOP of the filter is the CLEAN side, So you need to ram the air in from the bottom.

Doesn't the same physics involved in a true "Ram Air" system, ...already exist in our FD turbo(s) function and application??? That is, to provide a "forced" air flow into any given intake to fuel supplied type design??

Not to go off on a tangent here, but the effect you're referring to is mostly present on NA engines, and really only with the ultra-high rpm that the extremely oversquare (big bore/short stroke) engines that currently populate F1 run at. All of today's sportbikes use ram-air to excellent effect, with no real problematic side effects.

Okay, so I'm ignorant for using those specific words to describe my idea. You've now pointed that out again, only more colorfully. Thanks.

I don't care what you call a direct flow of positive pressure air to the turbo, but if it has a positive effect on the system it should be considered.

Can we focus on whether or not the quicker spooling or potentially higher sustainable boost levels are worth the effort?

Really? That'd be interesting. Then read this article and let me know what you think...

http://www.sportrider.com/tech/146_9508_ram/

Now that's an authoritative site, Jim :) .

(too bad we haven't posted the dyno ram-air comparison article that we did back in Oct 99 yet... :D)

You're missing the point. There is no positive effect with ram-air on a forced induction motor, at least at the speeds a street-driven FD is capable of. While Suganuma's post is interesting, it refers to directing the airflow into the compressor impeller using a venturi. It has nothing to do with ram-air. I do know that simply having an open compressor housing without any type of directed airflow will cause significant turbulence right at the impeller, although I find it difficult to believe that it would affect ultimate boost that much. I can see a venturi having an affect on spooling from lower rpms, however.

I cannot see ram-air having any effect on "potentially higher sustainable boost levels", because even if you were traveling at 150 mph, the airbox pressure would be in negative numbers even with a NA engine, and would have a negligible effect on the intake impeller's ability to take in air while spinning at 70K rpm.

http://www.anodized.com/~clayne/fd3s/simple.01.sm.jpg

You know what's interesting is that with an ambient of around 10-15C (50-60F) and with completely "wrong" heat-suspectible intake locations and *stock* IC, I see an average of around 18-22C charge temps (IAT located on IC outlet tank) while not on boost, and a rise of anywhere between 3-10C while on sustained boost (.75 - .85 kg/cm^2). It takes about a minute for charge temperatures to drop back down again.

But I also have a lot of things removed from under the hood.

Never said it could.

:withstupi

it would be better to call it a "cold air intake" not "ram air" your not going to be able to "ram" more air into your engine than a turbo will.

so no one read the link eh. because it helps alont on this topic. if you to lazy to read it shame on you.
joel

I think the theory is quite simple, Intake - cooling - extraction. So as long as all this is balanced and optimal cooling is acheived, it should work fine.

p.s. extraction is often overlooked

I honestly don't know as much about sport bikes as I should so I won't enter into that one. But, comparing an NA F1 engine to an NA street motor is a bad idea the amount of air that they move is much more comparable to that of a turbo'd vehicle. Think of it this way, that F1 motor at idle(about 7k) is moving as much air as a forced induction motor of the same size at twice atmospheric pressure 3500 rpm at 1.0bar. so when the engine is wide open and in it's power band(usually around 20k) that engine is moving as much air as a 3liter motor would be moving at 7k rpm and 3bar.

To compare that to an RX7 motor to move as much air as an F1 motor is at 20k rpm a third gen RX-7 (2.6liter) would have to be pushing more than 32psi at 7k rpm.

this is from F1techinical.com:
"Just above the driver's head there is a large opening that supplies the engine with air. It is commonly thought that the purpose of this is to 'ram' air into the engine like a supercharger, but the airbox does the opposite. Between the airbox and the engine there is a carbon-fibre duct that gradually widens out as it approaches the engine. As the volume increases, it makes the air flow slow down. The shape of this must be carefullly designed to both fill all cylinders equally and not harm the exterior aerodynaimcs of the engine cover, this all to optimize the volumetric efficiency."

Yes, I read the article. I've actually read it before. But I must still be confused because it appears to make my idea sound more feasible/effective.

If you can increase boost by eliminating or redusing negative pressure within the intake, why can't you increase boost further by creating positive pressure in the intake box? :confused:

Alright already!
 

It's not one or the other (ram or turbo). I'm talking about creating positive pressure on the inlet side of the turbo (ramming air to it), thereby *possibly* making the turbo more efficient.

Re: Alright already!
 

Well, then let's just say that your goal, while well-intentioned, is probably beyond your technical capabilities. Unless you've got the equipment to monitor pressure levels at various points on the car, all you're doing is guessing, and you may harm performance more than you help it.

Re: Re: Alright already!
 

I don't think it's beyond my technical capabilities. Making a home-made manometer and routing it to various parts of the intake or exterior of the car appears easy enough. Unfortunately, I don't have the time for all the testing necessary.

I was hoping someone else may have done this already.;)

My car already has ram-air, it's called the turbo. Works just fine.

Thanks for contributing. :rolleyes:

I don't now what I was thinking. This thread can be retired now.

Well, that makes two of us...

I agree that you cannot ram air into a turbo. I also agree that you can make the turbo more efficient by providing more air to it. Zerobanger did some extensive testing with a modified airbox at the 1/4 mile track. He used at least one hose to force air into the airbox, and found the trap speeds were increased by about 3-4 mph. This was in comparison to the hoses being routed in a fashion without the speed of the car forcing air into them. It's possible that ZB was just providing more air.

Anyway, I don't think you can go wrong by providing more available cold air to the intake. Setting up a sealed "ram" duct could actually restrict intake at lower speeds.

That sounds contradictory to me.

I remember reading about his tests. Did he confirm that the 'non forced' position was not also a negative pressure zone? I'll have to find the original post.

Assuming that the "ram" duct is no smaller than the intake pipe, and that it is positioned in a positive pressure zone, this shouldn't be a problem.

I'd take any testing that he did with a grain of salt. He also thought water injection was going to increase his trap speed, and he claimed that just the addition of a strut tower brace vastly improved his car's handling.

:rolleyes:

Your F1 technical treatise was a nice try, but you completely missed my point. Airflow and aerodynamics behave the same way in any scale; that's why smaller scale models are often used in wind tunnels to demonstrate aerodynamic ideas without going through the expense and labor of fabricating a full scale model. That's why I used modern sportbikes as an example. Their airbox airflow characteristics are very similar to the F1 3.0L V10s you originally referred to; it's the same in any scale. And you're comparing the intake pulsations of a forced induction motor to a NA motor; they're not the same, because the turbo sitting in the intake tract negates that aspect.

The quote from the F1 techie site deals with slowing down ramair intake airflow as it enters the airbox. This reduces the turbulence that can occur around the velocity stacks at speed, which severely impedes flow (suganuma's post findings are a partial example of this). By opening up the volume, it slows down the airflow into the airbox. Virtually all modern sportbikes with ram-air systems use this technique inside their intake ducts/airboxes (especially the Kawasakis, since the company also builds aircraft).

By the way: no one outside of the race engineer dept of various F1 teams really knew for sure what the current V10 engines revved to. But a new book by Peter Wright (where he was incredibly allowed access to much of Ferrari's technical data on their F1-2000 car) reveals that they are redlining at around 20K rpm; that particular engine put out around (I forget the exact numbers) 800 hp @ (about) 19,500 rpm. So the "in its powerband at 20K rpm" figure may be a bit off. It's a fantastic book, incredibly detailed.

OK, enough of this technical ego dick-boxing.

It's not contradictory at all. Providing more available air or removing restriction on air intake is a proven performance enhancement. Don't be so defensive.


** I remember reading about his tests. Did he confirm that the 'non forced' position was not also a negative pressure zone? I'll have to find the original post. **

As I recall, the hoses were initially placed in a neutral pressure zone.


**Assuming that the "ram" duct is no smaller than the intake pipe, and that it is positioned in a positive pressure zone, this shouldn't be a problem.**

This assumes an intake pipe at all. I had not assumed that. Many people are running open intakes. However, your assertion is correct.