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Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
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Author:  Blackbird [ September 9, 2009, 10:03 pm ]
Post subject:  Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
While I haven't been much around lately nor had any progress on the car, the mind keeps on working :wink:

What I'm thinking about is the airbox and the ram air scoops that come on the R1.
My assumption is that they are tuned to maximize the engine's perfomance.
Unfortunately they can't go on the car, but, if I measured the volume of the airbox, the size of the inlet and the size of the standard panel filter and make my own to mimic the dimensions, would I be making more power in comparison to the normal way that it's being done?
Normally it's just a filter on top of the throttle bodies...

Anyways, if anyone has seen a comparison or better yet - a dyno sheet of both ways, I'll be happy to know about it.

TIA,

Moti
Author:  a.moore [ September 9, 2009, 10:35 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
The exact same thought has been going through my head recently and without shelling out money for dyno time, I don't have a much of an answer...only ideas on what is/is not important based on past experiences.

Will you be able to either keep the factory velocity stacks or make a set of your own in the same length so as to not change any resonance characteristics of the intake?

What sensors are on the R1's airbox? MAP and intake air temp?

Since there isn't a restrictor before the intake from the factory, the plenum's effect on throttle response and power is probably going to be pretty negligible. I wouldn't be too afraid of losing it.

Do you have access to a wideband O2 reader and some way to display the MAP reading? If no one has comparative dyno data, you could probably use these tools and do back to back acceleration runs with the factory intake and with a custom intake and see what sort of differences are noted across the RPM band.
Author:  Blackbird [ September 9, 2009, 11:37 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
I do have dyno access.
I'm not sure I want to spend the $100+ for a filter and the time and money to build my own airbox (yet) before I know if it's even worth it... I know I'll have to pick one eventually, but not at the moment.

The stock box has a temp sensor in it that will be incorporated to whatever solution I'll end up picking.

Moti
Author:  wyked [ September 10, 2009, 7:06 am ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
I'm in a similar position, only not out of necessity. My stock air box is bulky and ugly and I love the look of individual air filters on the throttle bodies. I've designed the frame such that it fits but it would look a lot cleaner to loose it. I've asked the same question on some of the GPz1100 boards and gotten no response. Similar to yours, mine only has a temp sensor which could easily be incorporated into one of the filters. My plan is what a.moore suggested, just collect some data with the stock air box and then switch to individual filters and see if there is a difference.
Author:  horizenjob [ September 10, 2009, 8:19 am ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
The air box is good to plumb cold air to the intakes. That's pretty much a given power boost. The engine gets really hot during competition and will warm large volumes of air under the hood. Dimensions don't seem too critical, but smaller then stock wouldn't be good. Considering space constraints on a motorcycle, the velocity stacks might be on the small side. For instance the exhausts, which are usually tuned, are much longer...

You can see how long they try to make them in car engines these days, they wrap and fold.

Building your own stuff from light gauge aluminium will save weight and shouldn't be too hard. Maybe you can build the box into the passenger side of your cowl. Then half the box comes for free...
Author:  Blackbird [ September 10, 2009, 10:06 am ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
My hood line is designed so that whatever the solution is it will stick out of the engine bay, so hot underhood temps are not a problem.
I need to take another look at the velocity stacks.

Moti
Author:  ldsgeek [ September 10, 2009, 10:42 am ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
Car intakes are indeed longer, but that is due to the lower RPM range most (all?) car engines operate in. Generally, the longer the tube the lower the resonant frequency (engine speed in our case). Some well sorted, high dollar engines actually end up with much better than 100% volumetric efficiency, in a very limited RPM range, whereas a street engine may struggle to get into the 90% range due to compromises.
Author:  TJF [ September 10, 2009, 11:13 am ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
Better than 100% volumetric efficiency? So that means more air/fuel in getting into the cylinder when operating than would fit in there statically right? Meaning that there is either forced induction or a ram air type effect going on. I've never thought about VE much and surprised that engines can achieve greater than 100% without forced induction. Cool. Do you have any examples with actual numbers? How is VE measured in practice?
Author:  horizenjob [ September 10, 2009, 1:03 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
It seems that the intake runners could be ( should be? ) a similar length to the exhaust primaries on the same engine. That would seem to make it hard for them to be too long. I'm just guessing here. I was at the race shop just the other day and could have asked. I'll ask next time I visit.

Getting better then %100 VE on a competition engine is not very hard. My FF does this and it uses a fairly stock intake manifold and 2 barrel carb. It does have proper headers though. The influence of the resonance is pretty strong. I think I remember a number like %106 for my FF engine.

I think the dyno measures the air input and compares it to displacement x rpm, to get a VE. It may not be hugely accurate, depending on well it can measure the airflow.
Author:  ldsgeek [ September 10, 2009, 7:15 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
Wikipedia has a good article on the subject.
Author:  SkinnyG [ September 10, 2009, 8:26 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
Datalogging my GSXR ITB's on my 4AGE shows a best of 101kPa manifold pressure when air pressure is 94.5kPa here.

No air box, just a set of K&N filters sticking through the hood.

G
Author:  olrowdy_01 [ September 10, 2009, 11:49 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
Blackbird wrote:
While I haven't been much around lately nor had any progress on the car, the mind keeps on working :wink:

What I'm thinking about is the airbox and the ram air scoops that come on the R1.
My assumption is that they are tuned to maximize the engine's perfomance.
Moti
On the Suzuki GSXR series of bikes the ram tubes aren't particularly "tuned" as much as they provide the passage way for the rammed air to the sealed air cleaner at higher speeds. This acts as a mild super charger.

The plenum created by the volume of air between the air filter and the velocity stacks provides the open space for the stacks to see the larger air volume to resonate against. The presence of the pleated air filter would probably cancel out any resonance affects through the tubes to the air cleaner box (plenum)..

My BEC has the large 1/2 loaf of bread looking foam air cleaner that is in the cool air stream. My engine runs way too rich above 5K RPM (~11.8:1 AFR). On the bike that would be ~75 MPH where the extra fuel would probably not result in as rich a mixture as I see without the ram affect.

I wonder how dyno tuners compensate for the lack of rammed air when the bike is running WOT in still air. Educated guess? I can just see somebody trying to build a fan to blow 180 MPH air into the air cleaner (as everything not tied down gets blown out of the shop into the street!).
Two leaf blowers perhaps? :idea:

The following link has a reference to the air tubes on the 2003 GSXR-1000.

http://www.sportrider.com/bikes/2003/14 ... index.html

This is a quote from that article that would be of interest.
"Relocated ram-air intake ducts are 20 mm closer to the center of the fairing increasing ram air pressure, charging efficiency and torque output."

The velocity stacks on my GSXR-1000 engine are rather strange looking creatures. There are 4 horizontal slots near the outer curved portion that (from what I've read on the net somewhere) serve to broaden the range where the stacks provide optimum resonance charging affect. I've never seen that done before. It also influence my decision to NOT change anything around the intakes. The Japanese engineers seemed to have really done their homework on these super bike engines.

a.moore asked: "What sensors are on the R1's airbox? MAP and intake air temp?"

The Suzuki the air cleaner box has the intake air temperature sensor (IAT) and the intake air pressure sensor (APS). There is another intake air pressure sensor (IAP) plumbed into the vacuum side of the four throttle bodies.

The ECU is constantly adjusting the fuel mixture in relation to the two pressure sensors, the engine speed and the gear it's in to compute the weight of the air being used by the engine. It seems that even though I don't have the rammed air the mixture is being made richer anyway.
Author:  Miatav8,MstrASE,A&P,F [ September 16, 2009, 2:13 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
Blackbird wrote:
While I haven't been much around lately nor had any progress on the car, the mind keeps on working :wink:

What I'm thinking about is the airbox and the ram air scoops that come on the R1.
My assumption is that they are tuned to maximize the engine's perfomance.
Unfortunately they can't go on the car, but, if I measured the volume of the airbox, the size of the inlet and the size of the standard panel filter and make my own to mimic the dimensions, would I be making more power in comparison to the normal way that it's being done?
Normally it's just a filter on top of the throttle bodies...

Anyways, if anyone has seen a comparison or better yet - a dyno sheet of both ways, I'll be happy to know about it.

TIA,

Moti


Air boxes are tuned to minimize resonance, noise, and fit a proprietary filter.
A power increase can be had by removing the restrictive box, opening up/smoothing the internal choke points, drawing in cooler air from insulating/routing, increasing the air pressure by drawing from a high pressure area, etc.

The more effective the method, the more likely you will need to adjust the mixture.

Realize that a small cone filter may be more restrictive than the original filter due to the filtered area being smaller.

Oiled cotton guaze is less restrictive than paper.

After the carb/tb, tunning runner lengths and box volume becomes effective. Steps in diameter (like antireversion cones in the exhaust or a throttle butterfly) stop the waves your trying to make the most of.

A stack smooths the air inlet for less turbulence and more flow.
On a Westfield, the air temp sensor is exposed, installed on the upper frame rail near the air intake.
Author:  nkw8181 [ September 16, 2009, 3:34 pm ]
Post subject:  Re: Anyone ever dyno'd a bike engine w/ the airbox and w/o one?
I am using a CBR1000RR motor and it has a primary and secondary fuel rail. this would be terible looking if I didn't build something. I have built a custom air box that I believe will look good sticking out of the hood. I doesn't have any exposed wires. there are a lot of pictures of it on the 2 page of my build. if someone whats the cad drawings of it let me know. I made it out of 22 gauge steel just so I could weld it.
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