Secondary Butterflies removal review

[sixpack577]

I never changed fuel map after removing them and loved the difference it made.

I think that your bike may be suffering from being too lean on low end now that there is just too much air.

The secondary throttle plates are not there to optimize performance, they are there to limit and not to increase.

Do you know why the Gen 1 had no STP´s? Because it had an ignition timing retarder on the first gears to emulate the STP effect - it could be easily tweaked by a device that fooled the gear position sensor, the famous TRE. It does not work on Gen II Busas.

I think we all can come to the following conclusion, after Brad´s report:

More air flow from down low means the POSSIBILITY for more power to be made - however if it results in a lean or rich mixture, it will result in less performance.

Kind like a situation where one introduces forced induction with high pressure, but the stock injectors cannot cope with so much fuel needs and the end result is unoptimal power because of a too poor mixture.

With that said, I am surprised Brad did not report that even with less power, the throttle response (resolution in low rpm) difference is amazing. I still think that the throttle response difference alone is worth the mod, even if it made slightly less power (not the case with mine, guessing mine did not result being lean on low rpms after STP removal).

I agree, the performance of my bike isn't bad by any stretch, I can just tell it does need more fuel. But according to my sparkplugs, it's not too lean either.
So you're still running the stock fuel map? You do have ECU Editor too right?
You should try changing the stp settings and see how much it improves, and then let us know!

 

[bradbusa]

i did notice a difference in throttle response, but it wasnt what i would call a positive difference. like i said, i felt the bike was sluggish in the lower rev range. my guess is this is because there is more air quantity being dumped into the cylinders now (lean mixture like you said) but the air isnt flowing as fast as it does when the STP's are installed. this is a trick manufacturers use to increase lower end power. yes they can be used to restrict power as seen in the B and C modes of the s-dms, but it's not as drastic in A mode. it didnt really seem like suzuki was limiting power, rather than improving drivability and keeping the low end grunt available.
the bike just falls on its face down low without the STP's. keep in mind, i have a completely stock k8, other than a bmc street filter. no power commanders, no tre's, no ecu editor(yet!).
yes, i think removing the plates does change the way the bike makes and delivers power but i dont feel it's a positive improvement - as was stated in the original post.
i think you would need either a full exhaust or air/fuel adjustments to be able to take advantage of the extra volume of air now being delivered to the cylinders, but there would still be a sacrifice of low end torque because of the loss of air speed(velocity).

i would still like to see a dyno sheet of the same bike with and without the STPs. without adjustments in the ECU.

 

[smithabusa]

richard ironically enough 1st gear isn't really limited, its just 2nd and 3rd,

gears 1,4,5,6 and pretty much the same regarding stp opening at WOT

 

[smithabusa]

I never changed fuel map after removing them and loved the difference it made.

I think that your bike may be suffering from being too lean on low end now that there is just too much air.

The secondary throttle plates are not there to optimize performance, they are there to limit and not to increase.

Do you know why the Gen 1 had no STP´s? Because it had an ignition timing retarder on the first gears to emulate the STP effect - it could be easily tweaked by a device that fooled the gear position sensor, the famous TRE. It does not work on Gen II Busas.

I think we all can come to the following conclusion, after Brad´s report:

More air flow from down low means the POSSIBILITY for more power to be made - however if it results in a lean or rich mixture, it will result in less performance.

Kind like a situation where one introduces forced induction with high pressure, but the stock injectors cannot cope with so much fuel needs and the end result is unoptimal power because of a too poor mixture.

With that said, I am surprised Brad did not report that even with less power, the throttle response (resolution in low rpm) difference is amazing. I still think that the throttle response difference alone is worth the mod, even if it made slightly less power (not the case with mine, guessing mine did not result being lean on low rpms after STP removal).

timing is only retarded in the lower gears at very low rpm, low throttle. wide open performance regarding timing is pretty much the same in all gears

 

[2wicked]

but the air isnt flowing as fast as it does when the STP's are installed.

I am curious why the air would flow faster with the STPs installed?

Richard

 

[bradbusa]

i'm gonna use the water hose example here because air and water have similar properties.
you have a determined size opening for the water to flow through (a hose)
you turn the faucet on full blast, similar to WOT.
when you let the water run out of the hose on it's own it is flowing a large amount of volume. it's flowing a high quantity of water but it's not necessarily flowing at a high rate of speed(velocity).
when you put your thumb over the end of the hose, not only does it spray farther, but it increases pressure and causes the water to come out at a higher velocity(faster).
yes it is a restriction of sorts, but air follows the same physical principles.
one way manufacturers use this to their advantage is that a higher velocity air flow increases torque, and this is a good thing a lower rpms. but when the engine is increasing in revs and starting to make power, you want more volume.. which is why the STP is "restricting" air flow at lower rpms, and opens up once the bike gets to higher revs.

the throttle bodies fitted to the gen2 are large enough for high rpm operation but it's not the best for building torque at lower rpms, thus by restricting the air flow until it is needed, manufacturers are able to tune the output of the engine for max torque down low and max hp up high. the minute amount of blockage done by the STP at 94% is negligible enough that the difference is more than likely not noticable without serious mods to displacement, forced induction, or other head flow work..
rant over

 

[POWERHOUSE]

i'm gonna use the water hose example here because air and water have similar properties.
you have a determined size opening for the water to flow through (a hose)
you turn the faucet on full blast, similar to WOT.
when you let the water run out of the hose on it's own it is flowing a large amount of volume. it's flowing a high quantity of water but it's not necessarily flowing at a high rate of speed(velocity).
when you put your thumb over the end of the hose, not only does it spray farther, but it increases pressure and causes the water to come out at a higher velocity(faster).
yes it is a restriction of sorts, but air follows the same physical principles.
one way manufacturers use this to their advantage is that a higher velocity air flow increases torque, and this is a good thing a lower rpms. but when the engine is increasing in revs and starting to make power, you want more volume.. which is why the STP is "restricting" air flow at lower rpms, and opens up once the bike gets to higher revs.

the throttle bodies fitted to the gen2 are large enough for high rpm operation but it's not the best for building torque at lower rpms, thus by restricting the air flow until it is needed, manufacturers are able to tune the output of the engine for max torque down low and max hp up high. the minute amount of blockage done by the STP at 94% is negligible enough that the difference is more than likely not noticable without serious mods to displacement, forced induction, or other head flow work..
rant over

Your analysis using water as an example is correct, however, with your water example, you are dealing with pressure, i.e., water pressure. What we are dealing with here is vacuum, a little different, I would think.
Wouldn't anything that impedes the flow of vacuum indeed be a restriction? Would a vacuum pump flow more with a smaller diameter hose? Somebody on this board must be an engineer . . . either that, or we need some dyno charts to validate all of this . . .

Whatever the case, every set of butterflies we removed was always accompanied by some dyno mapping, and all we saw was improvement everywhere, especially on the bottom. Never did one with stock pipes, though . . .

 

[smithabusa]

whats a stock pipe?

Regarding the 94%, this was the pic from petrik i was looking for.

You can put them to 100% if you want in ecu editor.

 

[Amode]

The throttle percentages I stated were for a powercommander, as an example. In ECU editor, you would again tune at different throttle percentages (9,11,16,21, etc.) versus rpm . . the point being that tuning isn't just done at WOT thereby making dynos useless, because you can never get it right, as you said originally. On carbed bikes it would main, needle and bottom end, much less precise than fuel injection, but tuning would again occur at less than WOT.

As far as you tuning since I've been in diapers, I have well over 35 years tuning, so you can whistle all you want grandpa, I'm probably old enough to be your older brother!

Anyway, lets not jack this thread about removing butterflies with this, what I will say is that I still think the Busa head flows well enough to remove the butterflies. And with proper tuning, you will see big improvements all over.

Well Frank at least we agree we are about the same age, just diff opinon's on tunning. I just want to say this, since i got my ECU i have been all over that thing.I know all about the diff maps, Timming, Fuel, Gears. My settings are changed some much from the stock settings. I started with the Ign 1.2 to 4.4, Fuel 1-2 to 4.4, And then the STP's. There is nothing set at stock settings. Then i went from there, And i will tell you i will think nothing of throwing 50 + at some places in the top end when i get there. Right now every thing is at the lower end and Mid. The STP settings are the interesting ones i have now. I started with the Ign every weekend keep putting more into it, the fuel i hit pretty close except at 1.2 up to 3.7 that took several adjustments. The timming was the real problam. Now the top end a little at a time. timming???.

 

[POWERHOUSE]

Well Frank at least we agree we are about the same age, just diff opinon's on tunning. I just want to say this, since i got my ECU i have been all over that thing.I know all about the diff maps, Timming, Fuel, Gears. My settings are changed some much from the stock settings. I started with the Ign 1.2 to 4.4, Fuel 1-2 to 4.4, And then the STP's. There is nothing set at stock settings. Then i went from there, And i will tell you i will think nothing of throwing 50 + at some places in the top end when i get there. Right now every thing is at the lower end and Mid. The STP settings are the interesting ones i have now. I started with the Ign every weekend keep putting more into it, the fuel i hit pretty close except at 1.2 up to 3.7 that took several adjustments. The timming was the real problam. Now the top end a little at a time. timming???.

Actually, I think we agree on more than that . . . I never said it was all about fuel, and nothing else. Timing plays a big part as well . . . dynos are not all about just WOT, there is much more going on . . . and it will be interesting to see how the whole STP thing plays into actual response and horsepower. Please share your results . . .

 

[2wicked]

A water hose is a poor comparison, as most household water suplies are around 40 psi of pressure, and there is no pressure in the airbox of the busa, unless it is turbo charged or supercharged.

Using water as your comparison why not use the suction side of your water pump, as the engine is sucking on the intake side not pumping pressure, by your theory, restricting the suction side should increase the flow of the water, good luck with that.

Also by your analysis, is one to beleive that in a gen 1 busa with a single set of throttle blades that air is moving quicker through the throttle bodies at 5-10% throttle then at 80-100% throttle?

Richard

 

[BLUR]

FYI, this is from Suzuki's 08 hayabusa brochure:

"The latest Hayabusa engine is fitted with a pair
of tapered, 44mm double-barrel Suzuki Dual
Throttle Valve (SDTV) throttle bodies, one for
the left-side cylinders and one for the rightside
cylinders, each cylinder served by its own
barrel and each barrel carrying two fine-spray
injectors. Unlike conventional fuel injection
systems, the SDTV system has two butterfly
valves in each throttle-body barrel, the primary
valve controlled by the rider via the twist grip
and the secondary valve controlled by
the engine management system, which opens
the valve incrementally to maintain optimum
intake charge velocity based on engine rpm,
gear position and primary valve opening.
Maintaining the optimum intake charge
velocity improves cylinder charging, in turn
improving combustion efficiency and low-andmid-
range torque and making throttle
response more linear.
The two compact, fine-spray injectors located in
each throttle body barrel each have 12 holes
versus a more conventional 4 holes, improving
fuel atomization, again improving combustion
efficiency with the added benefit of reducing fuel
consumption. The primary injector is aimed at
a steep, 30-degree angle down the intake port to
improve atomization and throttle response,
and operates under all conditions. The secondary
injector is aimed at the secondary throttle valve
and adds fuel under high-rpm, high-load
conditions. The quantity of fuel delivered to
the engine depends upon the length of time
the injector sprays fuel, or injector on-time;
primary injector on-time is controlled by
the engine management system based on engine
rpm, intake pressure and throttle position.
Secondary injector on-time is determined based
on engine rpm and throttle position."

 

[BusaDudeBrazil]

FYI, this is from Suzuki's 08 hayabusa brochure:

"The latest Hayabusa engine is fitted with a pair
of tapered, 44mm double-barrel Suzuki Dual
Throttle Valve (SDTV) throttle bodies, one for
the left-side cylinders and one for the rightside
cylinders, each cylinder served by its own
barrel and each barrel carrying two fine-spray
injectors. Unlike conventional fuel injection
systems, the SDTV system has two butterfly
valves in each throttle-body barrel, the primary
valve controlled by the rider via the twist grip
and the secondary valve controlled by
the engine management system, which opens
the valve incrementally to maintain optimum
intake charge velocity based on engine rpm,
gear position and primary valve opening.
Maintaining the optimum intake charge
velocity improves cylinder charging, in turn
improving combustion efficiency and low-andmid-
range torque and making throttle
response more linear.
The two compact, fine-spray injectors located in
each throttle body barrel each have 12 holes
versus a more conventional 4 holes, improving
fuel atomization, again improving combustion
efficiency with the added benefit of reducing fuel
consumption. The primary injector is aimed at
a steep, 30-degree angle down the intake port to
improve atomization and throttle response,
and operates under all conditions. The secondary
injector is aimed at the secondary throttle valve
and adds fuel under high-rpm, high-load
conditions. The quantity of fuel delivered to
the engine depends upon the length of time
the injector sprays fuel, or injector on-time;
primary injector on-time is controlled by
the engine management system based on engine
rpm, intake pressure and throttle position.
Secondary injector on-time is determined based
on engine rpm and throttle position."

Nice finding!

We have a tuner here that has first hand, empirical evidence of improvements removing the STPs and a couple of riders with reports on improvement on the bike feel, power down low and throttle response.

On the other hand, we have a marketing brochure excerpt, a negative report from one fellow rider and other people defending the logical sound theory on the existence of the STP.

Maybe what we have in our hands is a device that the engineers had a great idea in mind but executed poorly - I am sure that if it improved torque down low without impairing throttle response, no one would be reporting improvements on torque and response by removing the STP.

I am leaning towards the belief (mainly because the Gen I busas have no STP) that this is a device meant to restrict power down low so the Busa wouldnt become a wheelie machine that needed less teeth on the sprocket to keep it down, and to maintain emissions down low.

Still happy with mine removed.

 

[bradbusa]

Frank, when you were tuning the bike, once you reached your optimum level of tune with everything, did do you back to back dyno runs to see if there was a difference with the STP installed vs. removed?
there is only vacuum when the engine is cruising at a steady speed. not when yanking the throttle wide open. a smaller diameter hose would cause the air speed to increase. and that is what the STP do in lower rpm range, until the engine revs increase. by making the air flow at a higher velocity, cylinder pressures increase(versus the same engine without STP at lower rpms). when the valve closes the air kind of backs up on itself while waiting for the valve to open up again where it can then rush inside the cylinder. this happens normally but the effect is slightly increased when an STP or exhaust valves or variable length intake ducts are used. they all do roughly the same thing - just a little bit differently.


amode, when i used my water hose example i'm not talking about pressure. all we're talking about is velocity(speed) of the water flowing versus volume(quantity).
when you put your thumb over the nozzle the speed at which the water is flowing is faster. this is similar to having the STP partially closed. the air speed increases after a restriction. because the engine is operating at a lower rpm it doesnt need the large quantities of air that engines approaching redline do. suzuki admits to using this technique in the article BLUR posted about the k8+ hayabusa from their brochures. when the STP are more opened there is a greater quantity of air volume than when it is partially closed.

do not confuse flow with velocity(speed) and volume(quantity).

the tuner has only reported evidence of an increase in power when accompanied with other adjustments. there was no mention of comparing stock vs STP delete, or tuned with STP vs. tuned minus the STP.

 

[Amode]

Frank, when you were tuning the bike, once you reached your optimum level of tune with everything, did do you back to back dyno runs to see if there was a difference with the STP installed vs. removed?
there is only vacuum when the engine is cruising at a steady speed. not when yanking the throttle wide open. a smaller diameter hose would cause the air speed to increase. and that is what the STP do in lower rpm range, until the engine revs increase. by making the air flow at a higher velocity, cylinder pressures increase(versus the same engine without STP at lower rpms). when the valve closes the air kind of backs up on itself while waiting for the valve to open up again where it can then rush inside the cylinder. this happens normally but the effect is slightly increased when an STP or exhaust valves or variable length intake ducts are used. they all do roughly the same thing - just a little bit differently.


amode, when i used my water hose example i'm not talking about pressure. all we're talking about is velocity(speed) of the water flowing versus volume(quantity).
when you put your thumb over the nozzle the speed at which the water is flowing is faster. this is similar to having the STP partially closed. the air speed increases after a restriction. because the engine is operating at a lower rpm it doesnt need the large quantities of air that engines approaching redline do. suzuki admits to using this technique in the article BLUR posted about the k8+ hayabusa from their brochures. when the STP are more opened there is a greater quantity of air volume than when it is partially closed.

do not confuse flow with velocity(speed) and volume(quantity).

the tuner has only reported evidence of an increase in power when accompanied with other adjustments. there was no mention of comparing stock vs STP delete, or tuned with STP vs. tuned minus the STP.

Yes i have done comparisons with my adjustments. My settings
are in A mode, And the stock settings are in c mode. For one all my Ign, Fuel are the same in all gears the only diff is the STP settings and a whole lot of timming in areas. So i put the stock STP settings in c mode, So i can switch going down the road or from a start to tell the diff. You should try it then you will now. With the Vac, And all the other controls i would not remove the STP's with a stock bike. Throttle Respond is Great, I want to twist it not ease into it. Timming, STP opening, A little fuel. You will be happy going down the road from 60 up in 6 th a little throttle and how fast it pulls. 4- 4500 very smooth. Take your stock bike and roll on @ 60 in 6 th and see how fast it pulls.????

 

[Dozerdriver]

Here is a updated review... I was practicing launching and my bike would bog some then take off and wheelie badly with the STP's out. If I would just go from a slow roll it would wheelie fine and feel great but from the stop it didn't like it. I think it could of been adjusted out but I decided to put them back in. I put them in a month or so ago and ran some at the local track. It doesn't bog from the launch ( still learning and baby launches ) but the snappiness of the throttle is not there like it was. My opinion is that anything that blocks the airflow is a restriction...intake or exhaust, but there should be some tuning to make it all balanced again. If I decide to take them out or adjust them in the ECU editor I will have the bike retuned.

 

[sixpack577]

FYI, this is from Suzuki's 08 hayabusa brochure:

"The latest Hayabusa engine is fitted with a pair
of tapered, 44mm double-barrel Suzuki Dual
Throttle Valve (SDTV) throttle bodies, one for
the left-side cylinders and one for the rightside
cylinders, each cylinder served by its own
barrel and each barrel carrying two fine-spray
injectors. Unlike conventional fuel injection
systems, the SDTV system has two butterfly
valves in each throttle-body barrel, the primary
valve controlled by the rider via the twist grip
and the secondary valve controlled by
the engine management system, which opens
the valve incrementally to maintain optimum
intake charge velocity based on engine rpm,
gear position and primary valve opening.
Maintaining the optimum intake charge
velocity improves cylinder charging, in turn
improving combustion efficiency and low-andmid-
range torque and making throttle
response more linear.
The two compact, fine-spray injectors located in
each throttle body barrel each have 12 holes
versus a more conventional 4 holes, improving
fuel atomization, again improving combustion
efficiency with the added benefit of reducing fuel
consumption. The primary injector is aimed at
a steep, 30-degree angle down the intake port to
improve atomization and throttle response,
and operates under all conditions. The secondary
injector is aimed at the secondary throttle valve
and adds fuel under high-rpm, high-load
conditions. The quantity of fuel delivered to
the engine depends upon the length of time
the injector sprays fuel, or injector on-time;
primary injector on-time is controlled by
the engine management system based on engine
rpm, intake pressure and throttle position.
Secondary injector on-time is determined based
on engine rpm and throttle position."

"making throttle response more linear" they do exactly that
"reducing fuel consumption" my gas milage is Alot worse

 

[m_ridgeway]

this seems to be a comparison of carbs mech secondaries vs. vacuum secondaries. with one set of throttle plates you get the "toilet bowl" effect. i doubt you will gain any mph, but i also doubt anyone that races will try this and have positive results.........

which wasnt ever claimed with the op but has wondered there.....

 

[2wicked]

by making the air flow at a higher velocity, cylinder pressures increase(versus the same engine without STP at lower rpms).

do not confuse flow with velocity(speed) and volume(quantity).

I think you are doing exactly that, cylinder pressure will increase with more volume of air, not with higher velocity of air,

Richard

 

[bradbusa]

i've got a few pages im trying to scan over to help explain my point a little better. i know i dont have the best understanding of the concept. however, in lower rpm operations where a larger volume of air is not needed and air speed is not that high, the STP play the role of creating a lower pressure are behind the plates and keeping the air moving at a high speed( versus the same intake and engine speed without STP). this is what causes velocity of air entering the intake to increase. there is not a high demand for volume at lower rpm operation.
higher engine speeds dont need the STP the same way because velocity is maintained by the fact that you're hauling a$$. piston speed increases and this, in addition to the fact that air is being forced into the airbox by the ram air effect, are what maintains velocity at high rpm operation.
low engine speeds are different because the pistons arent moving fast enough to keep velocity up with a wide open throttle body. this engine does not need larger volumes of air and without the intake "restriction" (stp) air speed decreases because the throat of the throttle body flows so well. this is why the stp are mostly-partially closed at low rpm operation and they open up when the pistons start traveling faster.