Nitrous Advice

[Commuta_Busa]

based on this few statements from you opening post I wouldn't suggest spraying until it's been tested & tunned properly on a dyno. You've invested time and money to build a good safe setup but you're willing to risk your engine just for some extra fun on the streets? So what's your plan if you go all the way down there just to hurt your engine? Is it really worth it?

~ figured I would have time to test run it and get it on the Dyno for some tuning.
~ so it won't be getting tuned.
~I don't trust them.
~ do want to spray it on the street.
~ I don't want to grenade my favorite bike. Thanks

 

[smithabusa]

adding 8% more fuel to the lower injectors only is going to be a good way to KABOOM the engine IMO.

The lower injectors on gen II busas only do 20% of the total fuel flow at high load high rpm, so increasing that 20% of total fuel flow by 8% is almost nothing in the grand scheme of things.

I have seen maps for just a pipe on power commander installed on the lower injectors with numbers much larger than that.

ECU would be killer for your NOS Setup.
ECU Flashing


Greg

 

[Mr Brown]

adding 8% more fuel to the lower injectors only is going to be a good way to KABOOM the engine IMO.

The lower injectors on gen II busas only do 20% of the total fuel flow at high load high rpm, so increasing that 20% of total fuel flow by 8% is almost nothing in the grand scheme of things.

I have seen maps for just a pipe on power commander installed on the lower injectors with numbers much larger than that.

ECU would be killer for your NOS Setup.
ECU Flashing


Greg

Adding 8% across the 100% throttle cells to an already mapped bike will cause it to go lean? How so?

 

[smithabusa]

no it will make it richer, but not much, if we are talking about spraying nitrous i dont think it will be nearly enough, if we are talking about 8% on a power commander.

Its not 8% more total fuel, its 8% more fuel out of the lower injectors, which aren't doing much of anything.

lets use simple numbers, lets say the bike currently has 10 milliseconds of injector flow, at wide open throttle, upper rpm, the lowers do 20% of the work, and uppers do 80%.

So out of 10 milliseconds of fuel pulsewidth, you are getting:
2 milliseconds from lower injectors
8 milliseconds from upper injectors.

So you want to add 8% increase to lower injectors, that will give you 1.08 X 2 = 2.16 milliseconds on lowers, uppers will still give exact same as power commander is only working on lowers.

So now for total fuel flow you have 2.16 + 8 = 10.16 milliseconds fuel flow.

So % increase in fuel = new fuel rate / old fuel rate = 10.16 / 10.00 = 1.6% increase in total fuel rate. So unless we are talking about the worlds smallest nitrous shot ever, I predict a KABOOM.


For example sake, a 50 shot of nitrous, 17% total fuel increase seems to be fairly common, in the case above that would require 10 X 1.17 = 11.7 milliseconds total.

Using a power commander the uppers will do just as they did stock so you need to get 11.7 - 8 = 3.7 milliseconds from the lowers.

New fuel rate / old fuel rate = 3.7 / 2.0 = 85% increase in fuel required on lower injectors to accomplish this.

See what i mean? Monster numbers are required if you are only controlling lower injectors.

All numbers above are for example purposes only, no idea what actual injector on time is required for a stock busa at wide open throttel and redline.

Greg

 

[smithabusa]

and since i am working on a small novel here LOL

Schnitz has a nice chart, and at the top clearly says valid for SINGLE injector per cylinder, for this very reason, anyhow it says:

*For Fuel Injected 4 Cylinder Motorcycles (one injector per cylinder) with Single Nitrous Jet.

Nitrous Jet Horsepower gain total fuel increase required
14 6hp 3%
16 9hp 3%
18 12hp 5%
20 15hp 5%
22 17hp 8%
24 20hp 8%
26 25hp 10%
28 30hp 10%
30 34hp 12%
32 38hp 12%
34 40hp 15%
36 45hp 15%
38 50hp 17%
40 55hp 20%
42 65hp 22%

I dont 100% agree with this comment listed below, but it does show you that you need a LOT more fuel added if only controlling the lower injectors

Note: If your motorcycle has 8 injectors (2 per cylinder), you will need to increase fuel by 3 times that of the chart. Example: 1000cc engine with 30 jet. Chart for 1 injector per cylinder show to add 12% more fuel. For an engine with 2 injectors per cylinder, 36% more fuel should be added. This is just a guide. Dyno tuning is the best way to ensure a safe fuel curve.

 

[Mr Brown]

I see what you are saying. I thought an 8% increase on the PC would supply an 8% increase in fuel, which seemed plenty for as small a shot as he was wanting. In fact I kinda wondered what the point of a shot jetted for 15hp was.....
And you are 100% correct, he needs an ECU edit.
Again Greg, thanks for educating me

 

[smithabusa]

To be honest 15 hp sprayed without tuning maybe it wont blow, but the reasoning behind it will melt a motor, because if people think thats how it works, then why can't i apply that to a 40/50/60 hp shot, sorry not trying to come off know it all, at all, just hate to see people melt expensive motors when could be prevented.

The nice thing about ecu editor, you want 8% more fuel, you add that in the fuel table, and you actually get 8% more total fuel.....crazy stuff LOL

 

[smithabusa]

This is how the injectors are controlled by Suzuki ECU on the Gen II Busa, notice at high engine load and rpm, lower injectors are doing very little in the grand scheme of things.

 

[Mr Brown]

I wasn't meaning you came off like a know it all, fact is you know way more about this stuff than me and most others. I appreciate you letting me know when and where I'm wrong. I told the OP that this is just a temporary fix, he seems bound and determined to spray it regardless.......

 

[smithabusa]

i understand we all need more hp HEHE, just do it safely

 

[Mr Brown]

The secondary injectors flow at a higher rate under light throttle/low rpm??

 

[smithabusa]

No, what you are looking at is LOWER injector contribution to total fuel flow.

From 0-30% Throttle, lowers do ALL the work, uppers do NONE of the work.

You can see at 40% throttle, 5600 RPM, is the very starting point of upper injectors being phased in.

 

[Mr Brown]

I see. Thought the lower injectors were the secondaries. Make way more sense now.....

 

[smithabusa]

you got it now

Primaries = Lower injectors = used mainly for idle, and light load conditions
Secondaries = Upper injectos = used mainly for high rpm, high load conditions

 

[jshtriumph]

So if I increase my 100% throttle opening settings at all RPM's via my Power Commander that doesn't actually increase the fuel I am applying at sya 10,00 rpm at 100% throttle??

 

[Mr Brown]

 

[smithabusa]

it increases LOWER injector flow.

a 100% increase in fueling on the lower injectors DOES NOT EQUAL 100% total fuel flow increase, it equals much much much smaller than that.

 

[Mr Brown]

It increases the fuel, but not by much. If you input a 10% increase it only adds 10% extra of the 20% the lowers are supplying, so it's really only a 2% increase.

 

[Mr Brown]

Gen ones only have 1 set of injectors, so the increase put in on the PC is an across the board addition.

 

[smithabusa]

Good point Mr Brown, my argument only applies to Gen 2 Busas that have 8 injectors.

Gen 1 bike has 1 set of injectors, so a 10% increase does equal a 10% increase in total fuel flow.

Anyone confused? HEHE