Snorkel pull before/after dyno results

Another oldie but a goodie pulled from the dusty archives of the Big VFR List:

-----Original Message-----
From: DynoWorks@aol.com [mailto:DynoWorks@aol.com]
Sent: Monday, 29 March 1999 5:20 PM
To: vfr@cs.wisc.edu
Subject: 800 snorkel dyno test (mostly data)


Hello list ...

Had the opportunity to do a back to back dyno test on the VFR800. We'll let
the numbers tell the story.

Dynojet Model 150 Chassis Dynamometer
Eastside Harley Davidson, Bellevue, Washington
DYNORUN #1, baseline, 4th gear roll-on - 3-27-99, 3:17PM
DYNORUN #5, no snorkel, 4th gear roll-on - 3-27-99, 3:22PM

DYNORUN #1                    DYNORUN #5
RPM      SAE hp                SAE hp
3500        28.3                    28.8
4000        32.1                    31.7
4500        35.4                    35.4
5000        39.8                    40.3
5500        45.2                    46.1
6000        54.4                    55.3
6500        62.6                    63.2
7000        69.6                    69.9
7500        75.6                    75.5
8000        81.1                    information not available
8500        86.6                    87.1
9000        90.0                    91.0
9500        91.6                    92.7
10000      93.2                    93.8
10500      92.9                    94.2
11000      90.3                    91.6
11500      88.8                    89.6

Magnifying the resolution of the 500 rpms nearest the hp peak follows

10000      93.2                    93.8
10100      93.4                    94.1
10200      93.5                    94.3
10300      93.6                    94.6
10400      93.3                    94.6
10500      92.9                    94.2

Magnifying the resolution of the 1000 rpm range nearest torque peak follows

RPM        SAE ft-lb            SAE ft-lb
8100        53.4                    53.3
8200        53.4                    53.4
8300        53.6                    53.6
8400        53.6                    53.7
8500        53.5                    53.8
8600        53.4                    53.8
8700        53.2                    53.7
8800        53.0                    53.6
8900        52.8                    53.4
9000        52.5                    53.1

Testing conditions: 29.66 in.Hg. absolute barometric pressure, Vapor
pressure .44 in. hg., ambient air temperature 49.5 deg. F. Partly cloudy.
All stock '98VFR800FI, 3,273 miles.

Subjective comment: Noticeably louder intake noise. Doesn't  sound like a
sewing machine anymore. Changes the character of the engine. Feels raw,
sharper edged. I will be leaving the snorkel out for now.

Wayne Chan, WMRRA/OMRRA #326

So, basically other than enhanced noise removing the flapper does nothing. A 1.3 hp peak increase is not even noticeable. I may unplug mine though just hear what it sounds like.

veefer800canuck, Oct 30 2005, 09:46 AM
Another oldie but a goodie pulled from the dusty archives of the Big VFR List:

Live by the dyno... die by the dyno... it is the last word...

I'd like to see one more run to eliminate rising temp as the factor... that is to install the
snorkel back and run a third time...

I removed Mr.RC45's snorkel once and it felt like I lost a few seat of the pants horse
power... but I never did confirm my impression on a dyno...

Flightar, Oct 30 2005, 12:33 PMSo, basically other than enhanced noise removing the flapper does nothing. A 1.3 hp peak increase is not even noticeable. I may unplug mine though just hear what it sounds like.

It wasn't the flapper valve they removed, just the rubber intake snorkel.

But Honda designed the flapper valve to help the bike meet noise standards in the EPA mandated drive-by test. At that speed/RPM, the flapper valve is conveniently closed. Hmmm. comp13.gif

veefer800canuck, Oct 30 2005, 12:21 PMIt wasn't the flapper valve they removed, just the rubber intake snorkel.

But Honda designed the flapper valve to help the bike meet noise standards in the EPA mandated drive-by test. At that speed/RPM, the flapper valve is conveniently closed. Hmmm.  comp13.gif

My seat-of-the-pants-ometer said removing the snorkel and plastic-welding the flapper in the open position did nothing but add noise (but I liked it...). I'm kind of surprised anyone would expect useful gains in horsepower and torque without a higher-flow filter element.

Hi magellan,

There is no solid unbiased evidence (that I am aware of) that a non OEM air filter (such as a K&N) is a *consequentially* higher-flow filter than a new OEM filter on a new VFR.

Also as has been said here and elsewhere (better them I can) Father Honda would not leave such easy HP behind if all it took was a higher surface area OEM air filter.

Chumly, Nov 4 2005, 06:56 PMHi magellan,

There is no solid unbiased evidence (that I am aware of) that a non OEM air filter (such as a K&N) is a *consequentially* higher-flow filter than a new OEM filter on a new VFR.

Also as has been said here and elsewhere (better them I can) Father Honda� would not leave such easy HP behind if all it took was a higher surface area OEM air filter.

The stock Honda filter has more surface area than the K&N any way, the other brand after market filter is much larger than the K&N (BMC???)
Someone somewhere had a stock VFR filter and K&N filter dyno tested back to back and the K&N showed no gain over stock. unsure.gif

baileyrock, Nov 4 2005, 07:27 PMThe stock Honda filter has more surface area than the K&N any way, the other brand after market filter is much larger than the K&N (BCK???)

I believe that's the BMC filter you're talking about.

MFP-2241, Nov 4 2005, 09:09 PMI believe that's the BMC filter you're talking about.

That's the one, thanks ! beer.gif

Thanks Chumly and Baileyrock. I agree completely. It's just slightly amusing how often people post and say things like, "DUUUUUDE, I just removed my rear fender and now I can pull wheelies in 6th gear!!"

Snorkel and flapper removal makes sense if you like the noise and want to play with the possibility that there isn't enough air getting to the filter in the first place, but I would have thought that a larger-area filter (the BMC if not the K&N) would be a better means to introduce a few real HP.

Thanks for killing the dream goofy.gif

Flightar, Oct 30 2005, 01:33 PMSo, basically other than enhanced noise removing the flapper does nothing. A 1.3 hp peak increase is not even noticeable. I may unplug mine though just hear what it sounds like.

??? I agree with BLS, 1.3 is almost 1.5% more on this engine, that's alot in my book. What does a slip on add to any bike ? There is hardly anything that adds alot unless we are talking turbo, blower, nitrous, more cc's, so every 1 hp here and there adds up.

Oh and it was free ! And save weight too ! That's bang for the buck Bro.

Has anyone managed to plumb some sort of ram air setup for 5th gen VFR's? The ZX9R snorkel "looks" like it might be modifiable but the trick is to get the air from the nose to the airbox.

Since this thread has developed a sub-plot centered around the surface area of various brands of air filters, I thought I'd throw in this bit for thought: if the VTEC is mapped too lean at almost all points from the factory (which we've pretty much verified), in order to increase horsepower by getting the fuel/air mixture closer to optimal, wouldn't a filter with a smaller element make more sense? When fiddling with carburetion, we used to cover up part of the filter element if we thought the bike was running a bit lean, just to see if that helped.

If someone has dyno results that show the K&N filter doesn't add gains, that's fine. I'm not arguing with evidence. I just think that before we all sell our souls to a bigger filter element, we should remember that our bikes are already too lean; therefore, more air might be a bad thing.

Begin "theory disassembly" in five . . . four . . . three . . . goofy.gif

BusyLittleShop, Oct 30 2005, 11:54 AMLive by the dyno... die by the dyno... it is the last word... 

I'd like to see one more run to eliminate rising temp as the factor... that is to install the
snorkel back and run a third time... 

I removed Mr.RC45's snorkel once and it felt like I lost a few seat of the pants horse
power... but I never did confirm my impression on a dyno...

Dyno doenst give you those few extra ponies that ram air scoop gives you moving either? RC45 has ram air correct?

viridicyana, Nov 26 2005, 08:16 AMSince this thread has developed a sub-plot centered around the surface area of various brands of air filters, I thought I'd throw in this bit for thought: if the VTEC is mapped too lean at almost all points from the factory (which we've pretty much verified), in order to increase horsepower by getting the fuel/air mixture closer to optimal, wouldn't a filter with a smaller element make more sense? When fiddling with carburetion, we used to cover up part of the filter element if we thought the bike was running a bit lean, just to see if that helped.

If someone has dyno results that show the K&N filter doesn't add gains, that's fine. I'm not arguing with evidence. I just think that before we all sell our souls to a bigger filter element, we should remember that our bikes are already too lean; therefore, more air might be a bad thing.

Begin "theory disassembly" in five . . . four . . . three . . .  goofy.gif

Add a BMC airfilter with increased surface area plus a Turbo City fuel pressure regulator and all should be well.

I'd like to see some Dyno runs with an A/F ratio curve thrown in so I could see the before/after effects of an airfilter/modded FPR together.

veefer800canuck, Nov 26 2005, 09:28 AMAdd a BMC airfilter with increased surface area plus a Turbo City fuel pressure regulator and all should be well.

I'd like to see some Dyno runs with an A/F ratio curve thrown in so I could see the before/after effects of an airfilter/modded FPR together.

Canuck, you forgot to say, "...two... one....!"
But I agree, adding a larger filter should only be one of several steps toward proper A/F ratio under all loads, something Honda is literally not allowed to provide by law.

The only things I would add to the list would be a PCIII, which is now available for both 5th and 6th gens, and Innovate's Air-Fuel Ratio Meter LM-1 http://www.innovatemotorsports.com/
...which I should have in my shop anyway.

veefer800canuck, Nov 26 2005, 12:28 PMAdd a BMC airfilter with increased surface area plus a Turbo City fuel pressure regulator and all should be well.

I'd like to see some Dyno runs with an A/F ratio curve thrown in so I could see the before/after effects of an airfilter/modded FPR together.

...and make sure the dyno is installed in a wind tunnel. Hanging your hat on dyno results without replicating actual operating conditions can lead one to incorrect conclusions. Especially if the main intent is to objectively determine the effect of an air flow path modification.

Stan sbei
02 VFR800

All this air filter talk has me wondering if anyone has tried to do the most extreme jet kit available from FactoryPro(?) for the carbed VFRs which requires mounting 4 individual K&N style clamp-on filters, one to each carb... the website says they have no clues on HOW to mount the filters but say that if you can do it, this is the biggest gain in HP from jetting and an air-filter change (also said you had to have aftermarket high flow exhaust)... Anybody do this or heard of someone who has???

ssbei, Feb 24 2006, 02:30 PM...and make sure the dyno is installed in a wind tunnel.  Hanging your hat on dyno results without replicating actual operating conditions can lead one to incorrect conclusions.  Especially if the main intent is to objectively determine the effect of an air flow path modification.

Stan sbei
02 VFR800

Agree 100%. I too am rather suspect of a lot of dyno tests.

Putting in a BMC filter hardly qualifies as a path modification, though the point is more valid regarding snorkel and flapper removal. Fact is, even a wind tunnel will give false readings unless wind velocity matches the appropriate vehicle speed through each gear (it'll never happen).

However, our bikes - with their well-hidden airboxes - benefit from almost no ram air effect anyway (you're not pushing air into the airbox in a VFR, you're mostly sucking it in by creating negative pressure below the plane of the air filter), so increasing velocity of the intake charge by improving exhaust flow, providing optimal A/F ratios, and installing a less-restrictive air filter will absolutely show measurable gains at the dyno unless no gains were actually achieved by the mod.

When it's all said and done, comparing my dyno run in Oregon with Joe Blow's dyno run in Denver for bragging rights is stupid. Dyno results are best used to compare modifications against a baseline, and you can still do that sans wind tunnel with your VFR. If you want to go hog wild though, bring a box fan and set it up in front of the bike. Your idle and low-gear readings will be false because airflow will be too great, and in higher gears airflow will be insufficient, but maybe you'll feel like the results are more authentic??

Magellan is absolutely correct, actually the dyno is probably friendly to the vfr, because where the airbox is at is in a bit of negative atmosphere being behind the fairing and windscreen, so it is not even 1atm on the top side of the airbox while riding. Standing still the ambient pressure would be close to 1atm on the top side of the airbox.

But if you look at the RR bikes, they all have ram air tubes on the nose of the bike, I have read on the R6 that they see upwards of 1.4 atm on the top side of the box. On the dyno with no airflow, this would be a huge loss on the top end.

It always amazes me that people expect big gains or any gains at all from de-snorkeling and other similar mods.

Hi magellan,
You�re right I should not have been agreeing �bout the wind tunnel part with Stan sbei and the VFR in particular!

benSV, Feb 24 2006, 09:20 PMIt always amazes me that people expect big gains or any gains at all from de-snorkeling and other similar mods.

It is odd isn�t as they well may make good sense with other aspects and then boom...........they�re convinced that more noise = more power or an uneven power-band is a hotter engine.

benSV, Feb 25 2006, 07:20 AMIt always amazes me that people expect big gains or any gains at all from de-snorkeling and other similar mods.

Every vehicle on the road, and especially performance-oriented vehicles,
has compromises designed in. These compromises are necessary to meet
cost limits, assembly-time targets and regulatory constraints for all markets
that the vehicle is sold in.

The VFR's intake/exhaust set-up is as good an example as any. One of the
key functions of the snorkel is to keep intake noise down so the bike can
meet noise targets. The air filter design is finalised by Honda (actually the
little Japanese company that supplies Honda) based on cost/ease of materials,
cost of manufacturing, and whether it meets the Honda design target for
airflow.

The airbox does have some serious engineering behind it as do the carbs,
which is why very few people mess with this area.

The exhaust is designed to maximise gas flow whilst meeting said noise
limitations. This is achieve through capacity, which is why more powerful
bikes have even larger OEM canisters than the VFR. For example, Ducati
found that by combining the dual canisters of the 996 into the single
canister of the 999, they could make a little more power while meeting
exactly the same dB reading. The single canister utilises the previously
wasted space between the dual canisters to allow more baffle volume, so
the engineers could rework the internals for more efficient gas flow.

Even the OEM sprocket has a rubber damper to help the bike meet noise
targets - it can be ditched with no ill-effect, and combined with other
seemingly insignificant weight loss measures can add up to a pretty decent
improvement in overall vehicle dynamics.

So, seeing as there are clear compromises in these areas, it makes perfect
sense to me for an owner to exploit the lost gains and make their bike a more enjoyable ride. To wit - ditching the snorkel, replacing the airfilter (I replaced
mine as much for long-term value as for any possible airflow gain) and
replacing the exhaust. Then tune the whole plot for the changed parameters
(jetting on carbs, PC on FI) and you will have a bike that is far closer to the
original design spec of the engineers (who must hate the beancounters and legislators!).

Blueprinting an engine is just the same thing - simply ensuring that all
tolerances meet exactly the original design spec, rather than the 'near
enough' manufacturing spec that is required to keep the product affordable.

Every little bit helps... and if you're not interested in tinkering, that's fine
too (although it always amazes me that people aren't interested in
tinkering goofy.gif )

The Phantom, Feb 25 2006, 01:15 AMEvery little bit helps... and if you're not interested in tinkering, that's fine too (although it always amazes me that people aren't interested in tinkering  goofy.gif   )

Weight-wise for racing yes, every little bit helps, but for the street modest weight changes +/- are rather insignificant.

The sporting 1000�s are a vastly better platform for the type of endeavors you refer to, but then the sporting 1000�s or the Blackbirds / Busas have such a higher performance envelope than the VFR, I again ask what�s the point from a street / cost / performance perspective?

As for VFR engine mods, there are no easy HP gains left without extensive before and after testing to know if you really have made any real world overall improvements for the street.

Finally IMHO the VFR is too idiosyncratic and the displacement is too small to lend itself well to noticeable, real world effective, performance mods for the street.

As for the fun and interest factor, I think that�s great and I�m all for noddling.

Chumly, Feb 24 2006, 09:44 PMWeight-wise for racing yes, every little bit helps, but for the street modest weight changes +/- are rather insignificant.�

The sporting 1000�s are a vastly better platform for the type of endeavors you refer to, but then the sporting 1000�s or the Blackbirds / Busas have such a higher performance envelope than the VFR, I again ask what�s the point from a street / cost / performance perspective?

As for VFR engine mods, there are no easy HP gains left without extensive before and after testing to know if you really have made any real world overall improvements for the street.

Finally IMHO the VFR is too idiosyncratic and the displacement is too small to lend itself well to noticeable, real world effective, performance mods for the street.

As for the fun and interest factor, I think that�s great and I�m all for noddling.

how do you figure this? re the 600's not worth modding then? if removing a snorkel allows 1.5 more horse power to a bike, which one experiences the greater percent of change? the 99 hp vfr or the 140 hp gxr? if math still serves me i would figure the vfr shows a greater percent of improvement on a percentage basis...mods being equal. to prove my point i assume we would need to see a desnorkled cbr. but a one hp gain on a lower hp bike will always have a larger % change than a higher hp bike. imagine what your little scooter would do desnorkled

Hi 767fixer,

How are you, these days?

I am not disagreeing with your points but perhaps you are not talking about the same things in the same way as I am.

You say: �if removing a snorkel allows 1.5 more horse power to a bike, which one experiences the greater percent of change? the 99 hp vfr or the 140 hp gxr?�
I was not responding to snorkel mods per se but to The Phantom�s post about a gamut of mods including blueprinting, exhaust, rubber dampers, weight loss, airfilters ect. as they pertain to my views on the VFR for street use.

As to you and your VFR, and snorkel mods specifically, you don�t have to satisfy me if you want to justify your mods, only yourself. But for me here are some of the criteria I would need to confirm prior to a snorkel mod:

a. that I actually get 1.5 *usable* HP in a *useable* RPM range
b. that I have proven this with accurate back to back dynos testing
c. that the time and money I spent is worth it
d. that there is no detracting from the bike�s abilities in other areas such as noise or warranty or tractability or component service life etc.
e. that I believe this 1.5 more horsepower will actually *improve* my ridging experience for the street

The 600's were not in the topic of my conversation. I did not mention anything about 600�s nor make any referencing or comparisons to them. It was the VFR for the street, and then a comparison of the VFR to the more sporting 1000�s + for the street.

But since you brought it up here�s my views on the sporting 600�s. If you seriously feel that the 600�s do not have enough power for the street, then by far your best bet is to buy a bigger displacement bike. If you want to spend all the time and costs modding your 600 bike as per a) to e) or whatever floats yer boat great, have fun!

here we go lol....you mentioned

Finally IMHO the VFR is too idiosyncratic and the displacement is too small to lend itself well to noticeable, real world effective, performance mods for the street.

hence my reference to 600 cc displacement bikes.

as far as:

a. that I actually get 1.5 *usable* HP in a *useable* RPM range
b. that I have proven this with accurate back to back dynos testing
c. that the time and money I spent is worth it
d. that there is no detracting from the bike�s abilities in other areas such as noise or warranty or tractability or component service life etc.
e. that I believe this 1.5 more horsepower will actually *improve* my ridging experience for the street

someone posted a dyno run....it may not satisfy you, but a report none the less. that covers a and b.
c- its free! and it takes minutes to try
as far as d goes. i assume you run stock pipes (your noise comment). trust me, this wont be louder than your pipes. and you can install it just as easily so no warranty concerns.
e. you wont know until you try it, no?

Hi 767fixer,

All good points and an interesting chat as always! Me I don't care about a few HP +/- even if a) to d) are addressed. Why? Because of e)

I have ridden more powerful and less powerful bikes and the better times had nothing to do with moderate power to weight ratio differences. This is not meant as a judgment on anyone else�s road to happiness.