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... )

 

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.

 

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.

 

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?

 

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.

 

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.

 

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.

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.

 

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.