600RR Injectors

[TG]

We are using a 600RR motor. I'm wondering if anybody else is using this motor and if they are using both sets of injectors or just one. There would be the advantage of weight and simplicity of a single set. With the second set, you place the first down by the head for fast response at low rpm's. But when we will be racing, the rev's will always be high enough that both sets of injectors will be firing all the time.
Another option to consider is moving both sets of injectors up the intake to allow proper atomization of the fuel at high rpm's. I know the injected fuel amount has to be considered.
If anybody has anything to say about this, please comment.

For those unfamiliar with the 600RR's injectors (as indicated in other threads about the 600RR), the lower set are always on and are positioned just above the head for fast response. The second set of injectors come on above 5500 rpm. They are aimed down over the throttle bodies in the airbox. The height of the injectors allows for sufficient time for the fuel to atomize in the faster moving air at higher rpm's.

[Dan Deussen @ Weber Motor]

The primary CBR600RR inectors will support aproximately 75hp at 12k rpm and 80% ducty cycle in a sequential injection with 3.3bar fuel pressure. So to answer your question: Yes you should be able to use just a single set of injectors.

In my oppinion, 80% duty cycle is quite high and it is the recommended limit, so if you are really just gonna use a single stage I would probably step up the fuel pressure a little bit (maybe 3.5 to 3.8 bar) to reduce duty cycle. Be aware that some injectors do not respond properly anymore with too much fuel pressure and at some level they might not even open at all anymore. It is something that might be worth testing.

If you want the easy way out, you might just be better off buying a set of F4i injectors from ebay.

[Cody the Genius]

The 600RR injectors are very nice, 12 orifice laser cut beauties. The only thing that I can find wrong with them is that the lower ones are pink. We are using them this year, however we do run staged injection any so it is not that much different from tuning a set of four injectors, just 2 more fuel maps and the
M800 tuns them loose. You can also get them off ebay for really cheap, cheaper than the stock f4i injectors and way cheaper than any bosches while still being a better fit (flow rate wise) for our motors.
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The staged injection really does help a lot with both transient response and broadening out the power curve although the concepts you mentioned above are a little off.
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The reason you want lower injectors at lower rpm (idle-9000) is because that smaller cross-section as it goes into the intake port is the only place to find any velocity down there in the rev range, and because you can still get better atomization by squirting a hot valve than simply wetting down the walls trying to inject into the lower velocities up the runner. The quick response isn't really a feasible arguement as the amount of time it takes the fuel to enter the chamber fom even the longest runner is still too small to be noticed by any driver we're going to have in the cars. That then parles into the reason for upper injectors, a high velocity (at high rpm), long, straight, chasm of swirling fuel death awaits to smash up the droplets as they scream through a well tapered runner. However this affect only becomes really noticible above 10 grand where the air is really honkin' down through there. The staged injection is a great advantage to anyone who is capable of running it (takes a ton of dyno time to get right)because atomization means low BSFCs means free hp and you can tell everyone else you doing it for fuel economy and driveability.

[Dan Deussen @ Weber Motor]

I have to concur with Cody on the staged setup. It is essentially free power in the upper rpm range. The keyword here is charge-cooling. When you inject the fuel upstream in the intake you essentially use the fuel to densify the incoming air by cooling it which results in more power. It also allows the use of slightly longer runners for good low end torque, which usually causes a rapid drop of HP past the power peak. With the second stage of injectors you gain anywhere from 1 to 3 hp above 8k an you can rev the engine past the power peak just a little higher without hitting the big power drop too early. I have done this with a special Walbro ECU version that has already been used in the World Superbike Chnampionship on two bikes. It controls four inductive coils and eight high impedance injectors with individual trim tables for each output. The best feature of this ECU is the closed loop lampda tuning function with individual lambda inputs for each individual cylinder. This allows a quick and painless balancing of the fueling for each individual cylinder which results in improved performance, fuel economy, throttle response and durability. A lot of development work and dyno time needs to be put into a system like this, but the results are well worth the effort.

http://cs.svsu.edu/~dsdeusse/dyno.jpg

[TG]

Dan, Cody,

Thanks for the advise. I'll show it to our engine team leader when we meet up tomorrow. Sounds pretty sweet.
Dan FYI:
Honda recommends the block to be tilted 38 degrees forward for maximum performance. So if you're looking for that last bit of hp...

[Dan Deussen @ Weber Motor]

Tim,

What does Suzuki recommend??? http://fsae.com/groupee_common/emoticons/icon_confused.gif http://fsae.com/groupee_common/emoticons/icon_razz.gif http://fsae.com/groupee_common/emoticons/icon_wink.gif

[TG]

Oh, don't know. We found that in the 600RR engine service manual. Sorry about that.

[Kirk Feldkamp]

Hey Dan,

Why the modification to the oil filter? Looks like you turned it sideways. Care to share any "before and after" dyno charts with the hi/lo setup?

That's a bunch of Lambda sensors... whew.

I feel sorry for the guy that had to bore the inside of that LONG tapered restrictor exit.

-Kirk

[Dan Deussen @ Weber Motor]

The actual secondary injector position in the picture above did not quite work out. Most of the fuel got blown to the last cylinder so the secondary injectors got repositioned to the runners.

The final setup that was run in the car with the right exhaust looked like this (with the headers mounte upside-down):
http://cs.svsu.edu/~dsdeusse/final.jpg


Here is the power comparison you asked for on an old beat up engine that was kind of low on power:
http://cs.svsu.edu/~dsdeusse/inj.jpg


The final dyno graph with a freshly rebuilt engine looked like this:
http://cs.svsu.edu/~dsdeusse/dynochart.JPG