Here's an interesting article regarding Fuel injection system and how it can be modified.
In short, it says that the amount of horsepower can be limited by the size of the injectors and the unit(s) used to calculate the amount of air going into the engine: Vane Air Flow(vaf) in conjonction with the Manifold air pressure (map sensor) and the air temp sensor or by a Mass Air Flow (MAF). According to this article, the best way to increase HPs is to replace the injectors with bigger ones, and replace the VAF or MAF with more power oriented ones. Just by curiosity, I checked on the VFR what we have for controlling the air flow. I cannot see a VAF nor a MAF, but there is a MAP and an air sensor. The second thing I checked is with what could replace it with. CBR1000RR? Perhaps. I looked up the injectors on the Ron Ayers website. I don't know if the electrical connections are the same, but the upper and lower O-rings share the same part # on both bikes. In other words, they would fit in the rail and in the intake. Because the CBR1000 is generates more HPs than the VFR, one have to assume the injectors are bigger. I saw that a few of you guys have modified the Fuel Pressure Regulator (FRP) which is kind of doing the same as having bigger injectors. Anyone with both bikes interested in trying this?
Here's what the writer of the articles had to say about the EFI of the VFR:
"St�phane:
You have what is called a speed-density EFI system. It calculates flow based on the pressure and temp, and maps showing the volumetric efficiency (or VE) at the various speeds and loads. You cannot just replace the injectors without remapping! If you did it would just be super rich everywhere, get less power, horrible fuel economy, and probably blow black smoke. Keep in mind that richer is not better. There is an optimum AF ratio to get the most power and response. Unless you have made other modifications, there is generally very little power you can add with tuning or fuel system modifications. So, if it is otherwise stock, you are best leaving it that way. However, if you have replaces the pipe, changed compression, used forced induction (turbo/supercharger), done some porting, or made any other modifications to the engine, then you need to modify the fuel system and calibrations to match. This will require access to the maps in the ECU and a wide band AF meter. If the modifications are major, you may need to install larger injectors and fuel pump.
You can get extra flow from your injectors by raising the fuel pressure (as you mentioned others had done). This is a cheezy fix for minor mods, like porting or a pipe. I have a spreadsheet online you can download and calculate everything you will need to properly modify your fuel system. Just go to my free software page. http://jroal.home.mchsi.com/ .
It seem to me that with a larger injector you could more precisely time the injector pulse because you would have to shorten the injector pulse width to compensate for the additional volume.
I know in most cars tuners shoot for right around 13.1/1 for an Air/Fuel Ratio.
Does anybody know what the duty cycle the stock injectors are running at WOT?
What I would like to know is whether the injectors from the VTec can be used on the 99-01 models. Apparently they're a New! Improved!! 12-hole injector. Dunno what difference it makes, but I'd still like to know.
Here's the latest e-mail from Jim regarding the increasing the size. The first part was from me.
" > Thank you so much Jim for the very quick reply. This is very informative stuff. I posted your reply and your website on the VFRD forum. > As for remapping, we can install what is called a Power Commander III which is a way of changing the mapping. On their website, I can download a variety of mappings for some standard modification (eg: air filter and slip-on pipes). > In my case, I will remove the catalytic converter on top of that (the 99 model did not have a cat. and the headers are straight bolt on). Since I will need to have a custom mapping anyway ($300), is it worth it to put new injectors at the same time? Or should I not bother? > > Thanks again, > St�phane. > > PS: I will definately have a look at the spreadsheet when my PC with windows is back and running(I using Linux right now)
St�phane:
Chances are very good that just changing the pipe will only need a remap and not new injectors. There is absolutely no benefit in upgrading injectors if you don't need to. In fact, larger injectors can become unstable at idle. Upgrade the injectors only if they are too small to support the airflows. You can determine this from my spreadsheet and confirm it with an AF meter at the dyno.
Jim Roal http://jroal.home.mchsi.com/ ----- Original Message ----- From: "stephane Gingras" <leyol@shaw.ca> To: "Jim Roal jroal@mchsi" <jroal@mchsi.com>"
As for knowing if the injectors would fit, check the top and bottom o-rings on both to see if they are similar. If so, they shoud fit in the hole. I don't know about the electrical connection though.
It seems the hot tip for fuel injected bikes is to get the injectors matched so they flow the same. A local racer with a ZX10R said the OEM injectors varied as much as 15%. He was able to dyno over 180hp with no engine rebuilds over a whole season, unlike the teams running in the U.S.
enzed_viffer, Jan 16 2006, 07:46 PMWhat I would like to know is whether the injectors from the VTec can be used on the 99-01 models. Apparently they're a New! Improved!! 12-hole injector. Dunno what difference it makes, but I'd still like to know.
Nope, I saw a graphic with dimensions of the old/new injectors when the Vtec first came out, and all the cruicial dimensions are nowhere near close.
I wish I'd saved that graphic, 'cause it's gone from the site now.
You guys sound like you're grasping at straws for extra horsepower.
If you need that much more horsepower just ditch the VFR and go buy a different bike.
You're talking serious serious mods IMO to need or want to bother with changing out injectors. If you're going to go to all that trouble you might as well be getting different cams, pistons, etc.. and go absolutely nuts.
benSV, Jan 18 2006, 09:39 AMYou guys sound like you're grasping at straws for extra horsepower.
If you need that much more horsepower just ditch the VFR and go buy a different bike.
You're talking serious serious mods IMO to need or want to bother with changing out injectors.� If you're going to go to all that trouble you might as well be getting different cams, pistons, etc.. and go absolutely nuts.
You're correct, indeed. I doubt that Honda left much on the table as far as inexpensive horsepower. It's just that it's fun to think about, and you never know what will spark someone into tinkering and....the next thing you know, some smart fella figures a method to change the PC maps and get good low-speed driveability! biggrin.gif
Oh, and yeah, we have a "dumb" FI system, at least as compared to Vette motors, which have MAF, AAP, MAP, IAT, knock sensors, variable FP, O2 (wideband) sensors, etc etc etc. It's like the Space Shuttle in there.
enzed_viffer, Jan 16 2006, 08:46 PM... New! Improved!! 12-hole injector. Dunno what difference it makes, but I'd still like to know.
The 'improvement' was better atomization, which makes the fuel more easily combustible and supposedly cleaner. It makes the fuel burn more efficiently inside the cylinder, makes it ignite quicker and more completely. Kinda like the difference between the 'Spray' and 'Stream' functions on the nozzle of some spray bottles of cleaning solution (like Simple Green)
veefer800canuck, Jan 18 2006, 09:42 PMNope, I saw a graphic with dimensions of the old/new injectors when the Vtec first came out, and all the cruicial dimensions are nowhere near close.
I wish I'd saved that graphic, 'cause it's gone from the site now.
I had the same idea Ian, but sorry, no-go.
Thanx for that, Rob. And benSV, it's not a question of going to buy another bike - the VFR has more than enough power for me, although more off-the-throttle wheelies would be fun. I'm just a born tinkerer.
I still like the idea of having or grinding up some different cam/cam profiles where the second set of valves(Vtec) have more lift or longer duration. Nice and smooth below 7k then Bam, let the fun(extra) fun begin. fing02.gif
baileyrock, Jan 18 2006, 04:09 PMI still like the idea of having or grinding up some different cam/cam profiles where the second set of valves(Vtec) have more lift or longer duration. Nice and smooth below 7k then Bam, let the fun(extra) fun begin. fing02.gif
How would that work? Two of the valves for each cylinder have different lift/duration than the other two, but all four are in operation simultaneously such that two open earlier than, and close later than, the other two? Wouldn't the two short duration valves still be the performance limiter in this situation?
kerplode, Jan 18 2006, 04:21 PMHow would that work?� Two of the valves for each cylinder have different lift/duration than the other two, but all four are in operation simultaneously such that two open earlier than, and close later than, the other two?� Wouldn't the two short duration valves still be the performance limiter in this situation?
Well having all four valves with more lift or duration would be best, but any extra fuel (if it can be used) would be an improvement. IMO unsure.gif If your cutting cam you might as well do them all ! fing02.gif