ram air boost levels

[OB_crazy bill]

maui , these specs are metric so bear with me . just remember 27 mb(millibar) = .4 psi .the specs are according to sportrider magazine october 99.100 mph=16mb , that seems to be a consistant pressure after 80 mph but the box pressure looks like it fluxuates drastically. the mag claims this is"due to the busas cylendr head gulping down tremendous amounts of air".

 

[OB_ducmanic]

Maui-
From what i have read max positive pressure is around .5psi. I think this is one area that Kawasaki has done their homework. Look for the "12" to have a much higher intake pressure. In my own race stuff i have found that cross wind over the intake opening can shutoff / seize motors at 100mph plus by leaning out the air flow.
ducmanic

[This message has been edited by ducmanic (edited 09 October 1999).]

 

[Guest]

Don't make the same basic mistake Sportrider did.

To find the boost pressure that the ramair provides, you need to measure the airbox vacuum (pressure BELOW atmospheric) when at revs on the dyno, then measure the airbox pressure (pressure ABOVE atmospheric) at speed, then find the pressure difference between the two.

If the airbox pressure is 3psi below on the dyno, and 0.5psi above with the ramair, the ramair is adding 3.5psi.

The Sportrider article is woefully incomplete, any engine that sucks more (like 'Busa) would show less ramair boost than a smaller sucking engine (like ZX-9) due to those idiots not being competent enough to compare airbox pressure before and after. Anyone versed in scientific methodology would have done the tests very different. The 'Busas ramair likely pumps more air than the ZX-9, so no more of this "Kawasaki did their homework" rubbish please! Suzuki did their homework too. The people that didn't do their homework are Sportrider, IMHO.

 

[Guest]

Another bit of information to think about here. It's not all about how much pressure you can put in the airbox, pressure in the airbox doesn't mean squatt if you can't get the air through the engine. Your intake and exhaust system has to be as efficient as your ram air system. The sport rider article left out a lot of information that you would need for a truly valid comparison. Just like on a turbo machine it's not how much boost you can make, it's how many cubic feet per minute you can cram through the engine.
Just my 02 cents worth.
Jim

 

[OB_Bob]

99TLR
SPORT RIDER did it right the best I can tell.

They placed the sensor in the air box and went for real rides with the test bikes. A speed sensor was also placed on the wheel to measure speed (MPH).
The vacuum in the airbox is shown on the graphs, and 0 on the graph represents atmospheric.

I agree that big pistons will suck or gulp more air out of the airbox, and thats why AIRBOX VOLUME is important. The ZX-12 is designed with a large airbox allowed by the framed design. This will probably minimize the effect of the vacuum or gulping effect of the pistons. Just think of it like an air compressor tank. The bigger the tank volume the better your air tools will work because the pressure decrease in the tank will happen slower.

The article even graphed a non ram air bike (ZRX1100) and the airbox stayed below -22mb for a long time, and it never went positive due to the lack of pressurized air into the airbox.

It also shows your TLR graph thats very eratic due to the big (over 450 cc's) two pistons in the V-Twin sucking huge amounts of air volume from the airbox with each stroke versus the relatively smaller 4 cylinder bikes taking quick bites of air volume.

I could be wrong but thats the way I remember the article. It would be interesting to know the airbox volumes of the different bikes as well.


Bob

[This message has been edited by Bob (edited 09 October 1999).]

 

[Guest]

Bob, the point I was trying to make is that you can't quantify the ramair effectiveness by measuring boost above atmospheric.

As part of one of my qualifications in electronics I was trained as an instrument technician for industry, and we did a LOT of training on pressure, what it is and how to measure it. We designed and maintained systems to measure pressure and flow.

Pressure is the difference between zone A and zone B. In this case, the ramair provides a boost in pressure, compared to what the motor normally gets.

The only sensible test, is one where you measure the airbox pressure without ramair and with ramair. The difference between the two is an indication of how well the ramair stuffs extra air into the system. Comparing the ramair pressure to atmospheric is silly, unless you want to measure the difference between ramair and say, no airbox at all. Or between ramair and velocity stacks (in a turbulence free zone on the bike). Bulldust figures!

To really compare the difference between the ramair effectiveness of two bikes, you need to test properly.

Of course, when the bikes are stationary, the Hayabusa has a lower pressure in the airbox than the ZX-9. That is because it's bigger motor is creating a larger vacuum to the box.
The fact that the 'Busa might have a lower figure compared to atmospheric than the ZX-9 is also to be expected!

Just for example, imagine the two bikes have IDENTICAL ramair systems, with identical supply of air at identical speeds. A controlled study. Now, if these identical systems are feeding a 900cc motor at full tilt, and a 1300cc motor at full tilt, what airbox would have the lower pressure in it?
The 'Busa of course, as its motor is draining more air from the system, even though we know the ramairs are identical! Now, would this prove that the system on the 'Busa was not as good? Hmmm.

Suzuki made a fuss about engineering the ramair on the 'Busa to new technology. I am sure they tested the nose/scoops combination in a windtunnel to get maximum pressure. Don't assume that the ZX-9 has a better system, just assume it has a smaller motor and that Sportbike didn't do their homework!

 

[OB_maui]

Is there any consensus to how much boost (actual manifold pressure) is provided via the ram air? At 100 mph, 150 ? 190?

 

[Guest]

Damn. I was hoping to start a good technical discussion with my "strong" opinion on the ram-air tests.

So nobody wants to argue? Does that mean that I am right on this one? (that might do the trick!)

 

[OB_Dirty Pete]

To paraphrase Kevin Cameron in his respected tech book "Sportbike Performance Handbook,"

-Forward-facing intakes have only one real purpose at less-than-race speeds, and that is to prevent engine-heated air from entering carburetors. Also, rad-looking scoops sell bikes.


Even IF the energy of moving air could be completely converted to pressure, the gain is only 3 percent at 150 mph.

Ram air is a velocity-squared effect. Double the speed and you get 4 times the pressure. Conversely if you halve the speed to 75 mph, you get 1/4 of the full effect. This is one or less horsepower on a big engine @ 75 mph.

End of paraphrase.

 

[OB_Bob]

The point IS they DON'T have Identical ram air systems, so your example at the end of your post is meaningless. They are comparing the different boxes between stock bikes. Their next magazine issue will pressurize the boxes on the dyno to different levels and see the effect. It may not mean crap. The GSXR750 did not have impressive pressure numbers, but accelerated like the devil.
The bigger the air box the better you will dampen the gulping effect from the pistons-FACT
NASCAR, and the performance auto industry is using ram air and has for years. They are wrong. They just wanted to add weight and look good. Cool pressurized air can help make more power. I am sure Suzuki did their "homework" and put in the biggest box they could and placed the air intakes in the best location they could given the aerodynamic/cosmetic compromises when making that decision.
S. Rider did include a non ramair bike for comparison.(but did not show the change with ram air) I agree with your point that it would good for comparison to run a test without an air box or ram air. But, the bike would have to be remapped or rejetted, its just an article for interest and they have a budget. Don't slam them for providing more information than we had before.
Take your air box off your bike and go for a ride. I did. Its crap.
They are testing the bikes as delivered.
AS far as a good tech discussion-
I will always stick to 1/4 mile times, top speed and dyno work anyway. This is just interesting info. and ramair is ONE piece of the total package.
With all of your instrument trainning you must realize why the ZX-12 has the air intake located where it is? Its for looks.

[This message has been edited by Bob (edited 10 October 1999).]

[This message has been edited by Bob (edited 10 October 1999).]

 

[OB_maui]

Actual manifold pressure, between the throttle blades and the intake valve. It's not the same thing as air box pressure. I don't give a rip about air box pressure (well, kinda). The difference between atmospheric and manifold pressure. Boost. On cars with blowers, or turbos, we put a check valve between the manifold and the boost gage. This way we get a max reading. Of course snapping the throttle shut on the ram air system would give you an erroneous reading at the air box. It would indicate boost where none was present. One more reason not to monitor your air box. The engine doesn't care about your air box, as far as it's concerned, there is nothing past the injector blade.

Velocity, the magic word. Objects in motion tend to stay in motion (I just made that up). V is how engine builders get more than 100% volumetric efficiency (VE). Intake port speeds are supersonic. Air and fuel have mass. It's one of the reasons that turbo engines surge. Increase velocity, and volume will follow.

 

[OB_Dirty Pete]

I am very leery of the results posted by Sport Rider in this month's Ram Air II.

They occlusively sealed their pressurized tubes to the bikes' ram air intakes and attached the other end to a hi-powered pneumatic pump.

We all accept that volume (and therefore pressure) of the air forced into the intakes in the real world is a function of the intake's placement within the total airflow picture of the bike and of the intake's size.

The artificial delivery of air from a pneumatic pump through sealed tubing is too perfect to have much relevance to real conditions, so the mag's reported figures are high.

 

[Frank Adams]

the question is....how far can we go with what we have?

the way i look at is, these boxes need to be modified by the setup you have.

i don't remember who said it further up the post, but i agree with them, you need to modify the your box to the application your currently using.

thats why i said in one of my post that i was doing something a little bit differant on my airbox.

differant setups have differant needs.

now back to the begining( how far can you go with it)

 

[Guest]

Lots of thought provoking material here. Sportbike really taking this thing seriously huh? Good on them.

Since I have not had the pleasure of reading the second article, I really should shut my mouth until I know more facts. Anyone care to enlighten me? Pete?

Did they really block the intake system and deliver air pressure from a controlled pump?? Although I am impressed by the work involved, I tend to agree with others here that it doesn't constitute an accurate test...

Really would like to see the figures they gained from that. I have a modded airbox on my TLR, and the main mod was to remove all the flappers and supports so that;
1. The airbox is now one big cavity instead of two smaller compartments (Bob likes the big airbox idea! - so do I)
2. The airflow from the intakes now has a much wider and more direct path to the intakes, ie more flow and more velocity. About 6 to 8hp gain on the dyno, probably more with the ramair doing its thing.

 

[OB_Dirty Pete]

99TLR, it's the December Sport Rider mag.

They pressurized the airboxes, using the method I described above, of a TL1000R, YZF-R6, Hayabusa, GSX-R750, CBR600F4, 1100XX and a ZX-6R.

The TLR got 7 hp @ 10,000 rpm; the R6 5hp in the mid-range; the Hayabusa about 3-4 hp in the mid range then little/none up top where the engine sucked more air than the 370 cfm (combined total) pneumatic jackhammer compressors could deliver.

[This message has been edited by Dirty Pete (edited 11 October 1999).]