Air box mod save $$$

[CB4ME_imp]

All I can say is this ! I got a friend with a gsxr1000 he put a new exhaust on it sounded great! But his drag strip times dropped. Put his stock pipe back on and his drag strip times went back up! Dyno don't lie. Lots of guys buy pipes, K&N filters thinking more power more speed when most bikes lose performance FACT

I could definitely see that happening. The stock ECU is set up for the stock airbox and exhaust. Altering those componets without an ECU reflash, tuned Power Commander etc. can mess things up.

Now you'll probably blow my mind by saying that GSXR had a properly tuned air/fuel controller and still lost power.

[rboe]

If the bike sounds louder or different the rider will tend to think there is a performance gain. Some of this is probably an unconscious desire to justify the work done or money spent, on the mod. Just human nature so something to be mindful of (and dyno does not care one way or the other)

No way to really tell until you dyno it. Nothing like cold hard facts.

[CIP57_imp]

Let me add to this:

I ran the following 0-100 times

Stock 9.1
Flashed 9.0
Yoshi Open Airbox 8.3
Yoshi Closed airbox 8.0

As i mentioned, these runs where all in the same place. The two Yoshi runs where on the same day and conditions.

Edit: I have documented these gains with video's.

[Greg_imp]

Let me add to this:

I ran the following 0-100 times

Stock 9.1
Flashed 9.0
Yoshi Open Airbox 8.3
Yoshi Closed airbox 8.0

As i mentioned, these runs where all in the same place. The two Yoshi runs where on the same day and conditions.

Edit: I have documented these gains with video's.

... um ... we're waiting ... haha

[CIP57_imp]

Let me add to this:

I ran the following 0-100 times

Stock 9.1
Flashed 9.0
Yoshi Open Airbox 8.3
Yoshi Closed airbox 8.0

As i mentioned, these runs where all in the same place. The two Yoshi runs where on the same day and conditions.

Edit: I have documented these gains with video's.

... um ... we're waiting ... haha

... um ... we're waiting ... haha Sorry, computer crash lol

[Greg_imp]

Ha, DAC.

I got spanked for my part in this kerfuffle but it occurred to me that even though this is an old thread, new members are coming in and reading what is old stuff for us.

I did the controlled testing after this dust-up and think my results are repeatable. After all we're talking real time and dollars and people should be informed.

If the mods are being done for aesthetic reasons or simply because it's there, then that's fine, but facts is facts.

(Don't taze me dude!)

Air box mods are very popular with the Bonneville crowd. Often referred to desnorkling the air box, this mod, combined with a less restrictive exhaust supposedly lets the engine breathe easier and produce more power.

Greg did dyno testing of various intake and exhaust configurations. I find the results interesting and worthy of follow-up. But the results seem to contradict the claims of aftermarket manufacturers and the experience of other riders.

I haven't done any dyno testing and can only go by seat-of-the-pants "testing". My first mod was a Staintune. I did not notice any increase in power. When I opened the intake with a TSR air funnel, the bike seemed a lot more lively.

Several other members have done intake and exhaust mods and seen significant HP gains, verified by dyno testing.

Greg, I’m not disputing your results, but I remain unconvinced that opened up air boxes and CAT free exhausts will only affect A/F ratios while HP numbers remain unchanged.

Now I've done it

Yes, it would be good to have some confirmation of these results which were done without a piggyback fuel controller.

[flynrider]

If the bike sounds louder or different the rider will tend to think there is a performance gain. Some of this is probably an unconscious desire to justify the work done or money spent, on the mod. Just human nature so something to be mindful of (and dyno does not care one way or the other)

No way to really tell until you dyno it. Nothing like cold hard facts.

That is so true. I used to operate the dyno at my friend's bike shop on the weekends (back in the 80s). There were a lot of folks that were certain they'd bumped up the hp by just slapping a pipe on their UJM and making no other changes . While their bikes were certainly much louder, invariably the dyno showed they had less power than before. Even after the proper tuning of intake and exhaust mods were done, the extra power usually showed up at rpms that the rider rarely saw on the street.

The shop had a race bike that we constantly tuned and retuned using both the dyno and a set of test pipes equipped with fast response EGT probes (fancy stuff back then!). Even with all that equipment it was often difficult to get the right combination of mods tweaked just right to produce more power.

Things are a bit easier these days with an ECM in charge, but even so, performance tuning is still a bit more art than science.

[Dengie Boy_imp]

I was doing some calculations on this very subject last night on my work bench! Having lost the plot on the PAIR valve mod subject (look up the thread) I decided this time to do my own research.
I measure the cross sectional area of the aperture in the end of the snorkel to be 31cm2, the diameter of the hole into the centre of the air filter element to be 20.5cm2 and the area of each throttle body venturi to be 10.05cm2.

7,500rpm is 125revs/sec and in the case of a 4 stroke 4 that equates to 250 intake strokes per second, which act like vacuum pulses in that massive sandwich box of an air cleaner. These individual pulses from each of the venturis in turn will probably appear as one by the time they get through the filter element, leaving the snorkel to act as a velocity stack? Just a thought.

Snorkels are usually fitted to internal combustion engines to silence intake roar. Just another thought.

Any way here it is:


And here it is with the strange rubber bung removed (32mm in diameter), increasing the intake area from 31.5cm2 to 41.5cm2:


I reckon this will just mess up some of the velocity stack effect. Dyno?
Shame you can't just turn the snorkel around to face the breeze!

Cheers
Dengie

[Greg_imp]

I didn't notice any difference in sound without the snorkel; and it's called that because it's designed to prevent the engine inhaling water. The rubber bung covers the place where an emission device not required in the USA is connected.

When you're figuring cross-sectional area you should also consider the potential restriction created where the opening of the duct (snorkel) meets the part called Fender B in the OEM parts catalogs.

Like I said, I sat with the Dyno operator: one run without the snorkel, the next run with - no difference.

The pictures are good. It's nice to know how things work.

[CB4ME_imp]

I swear I've heard intake noise with the TSR funnel and K&N filter. But then I'm probably imagining any performace gains with the Motogear headers and Staintune.

Hopefully dyno testing will confirm my apparent loss of HP over stock configuration (sarc)