Hood Scoop Opinions....

[fredvance]

Better too many than not enough.

[Rex Schimmer]

Sabat,
Maybe Kawasaki is only trying to get fresh air to the engine and pressure recover is not their goal.

Rex

[interested bystander]

Could that be why Suzuki's rule?

Kawis - plenty, but disturbed, bad air !

Seriously, I'm amazed with all the physical obstacles crosswise MC engines have to go through to get good air that they perform as awesomely as they do.

Bud Hare, back in the day, turned the head of his Triumph around (or changed intake  for exhaust) to put the (probably) Amals out front.

[sabat]

I haven't measured it myself, but I was told that there is almost 1psi pressure in the ZX10 airbox over 120mph. There were probably all kinds of compromises made in the design of the air intake, especially considering the path around the steering head, so I'm not going to take too much from the design, but clearly they some control over the shape of the snout. Maybe they oversized it for market reasons, what self respecting 18 year old wants a itty bitty looking air intake?

I think Kawasaki was the first to use ramair, in the ZX11. The ZX12 snout was very pronounced, extending ahead of the nose to "clean" air.

Dean

[Rchop]

I haven't measured it myself, but I was told that there is almost 1psi pressure in the ZX10 airbox over 120mph.
Dean

I built a simple ram air intake system for my last bike and it worked too well when I ran it the first time at Bonneville. My engine was capable of around 8100 rpm on the salt, but the first time I ran it with the new intake, the engine wouldn't go past 7K at 114 mph. The A/F ration jumped to around 17:1 and the engine was cutting out. It was obvious I was building a positive pressure in the carb throat and I didn't have airbox pressure in the float bowls. I removed the intake bellmouth and intake tubes and it ran just fine. I was really suprised I could build the pressure I did with such a small intake track...

[sabat]

Cool, why not tie the bowl vents to the intake?  I used a pitot tube in the charge pipe to pressurize the fuel bowls on a blow-thru carb turbo setup, worked well. Guess it's academic now.

[Rchop]

I was going to do that next, but I sold the bike and have moved on to another build.
Looking back at IB's intake data diagram, it seem that my design "loosely followed that design. It started with a small opening that split into 2 runners (making it larger) which connected to a larger box that had two bellmouth tubes laying side by side that fed into each carb. So, it got progressively bigger as it fed back to the carb intakes...




hmmm, so that's why it worked

[836dstr]

I was looking on the SCTA website the other day looking for implimentation dates on some of the new safety stuff and found this rule change for 2009:


"20. Non-functional hood scoops being used as aero devices.
Define air scoop to become functional.
4.R HOOD SCOOPS
A hood scoop is a functional air intake device used on full body, un-blown vehicles, where allowed. No part of a forward facing
hood scoop can extend forward of the leading edge of the hood, be more than 11" above the surface of the hood at the
centerline or extend past the trailing edge of the hood more than 11". Clearance between the scoop and the windshield
must be a minimum of 1/2". On rearward facing scoops they can not be more than 11" above the surface of the hood
at the centerline. They can extend past the trailing edge of the hood but the rear must be totally open and clearance
between the scoop and the windshield must be a minimum of 2". No foam sealing is allowed between the scoop and
windshield."

The part that got my attention was about no part of a forward facing hood scoop can extend past the front hood line. So much for one of my systems to get to clean air on my Street Roadster.

I guess by definition that "functional air intake device" does not pertain to air intakes of Gas/Fuel Roadsters that duct air from radiator blanking plates??

Dan Warner, is this correct?

Tom

[Stan Back]

Hey Tom!

I sent you a couple PMs, but they're not logged on my machine -- which means I didn't send them or I don't know how to run the machine.  Like to chat with you about air coming in.

Stan

[dwarner]

Tom,

On Fuel/Gas roadsters the intake that protrudes from the grille cover is called an Air Intake, section 4.B. A hood scoop sits on top of the hood as shown on your Street Roadster.

DW

[28rpu]

Can we assume that roadsters are not full body vehicles? Nick

[interested bystander]

STAN's scoop is the    benchmark for St Rdstr, otherwise look for TROUBLE from him!

Or most anything else, Street Roadster.

[Stainless1]

This may loop this thread back to the beginning... I was in Denver just before the NWR and shot a couple of pictures of the NACA duct.  Everyone that is reading the NACA report should note it was published in 1951 and it was not the end of the research, it was the result of the governments research.  Before you design or buy a NACA duct, re-read the entrance lip part. 

[836dstr]

Stan,

Got your PM's. Replied to the second one. I'll phone you tonight.

Thanks Dan, I was pretty sure that would be your response. Any insights on the reason for the rule change?  It's hard to get clean air coming off the front end of a Street Roadster.

Tom

[Rick Byrnes]

Interestingly enough after all this discussion, we are looking now at a NACA duct.  Just a feasibility study so to speak, but looking at do we have enough realestate to do the rather large duct, and correct air box/plenum for my requirements.  This car now has no plans for being boosted, so for the engine configuration I should have to do this only once.  I hope.
Again, I have real aero help with good credentials and lots of practical experience.  Even after 30years he still does the math first.  We will do our best.  After being jabbed by Rex a little we have had some serious discussions about trying this.
The fact that the duct Stainless has installed does work where it is located is pretty indicative of the potential.

How much air box pressure did you say Stainless?   

See Rex, it just takes some time

Digitizing of the bodywork to be saved and chassis happened last week and body design is beginning. 
Preview is attached.  This is not the laser scan, but rather digitizing with many identifiable targets and special software that allows the surface to be established.  The body designer can then work with this as a "so called solid model".
We are wayyyyy out of my knowledge base so we shall see....meanwhile, back to the chassis for me