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Posted: Mon Feb 05, 2007 3:53 am
by MX Quad Dad
You know I really dont think there is any swirling going on in the chamber.Remember when Wistech had one bad injector how only one pipe of two was glowing red on his exhaust same side?I couldnt believe that would happen but it did.This throttlebody experiment could be really interesting.
Well, this has been eating at me since you posted it. so I have a few questions swirling in my head now
How well are the injectors matched? They are controled as one, correct? Only one flow rate setting on the D&M.
seems to me if the automotive injectors come in a set of 4,6or 8, they would be a matched set? Is there any way we can assume Cannondale used matched sets? Performance shops must be able to check flow rates tomake sure they are matched?
If one runner is rich and the other is lean, and they tend to stay on thier own side (so to speak) of the cumbustion chamber. would this not effect HP? I think they refer to the way the flame travels across the top of the piston as the flame front. Spark plug in the center suposedably, starts the explosion in the center of the cumbustion chamber and travels evenly across the top of the piston for maximum eficensy (sp?). Now if one side is lean and the other rich, would this not rob you of HP? After all most racer index spark plugs for a efficent burn.
Did't the Rapter run two carbs? I am pretty sure they ran two differant size main jets. Did they run two differant size carbs? What was Yam. reason for it if they did?
Would it be better to add the fuel to the air charge before the split?
Maybe forcing the air flow to one side may cause a swirl effect in the chamber, Making a more perferable burn?
Do the new Cannondale injectors come in a set of two? What about the Harley's?
I got more swilling around in my head but this is all I can handle in one sitting
Posted: Mon Feb 05, 2007 12:56 pm
by cannondale27
Raptor did run two different jets.Hmm
When we got injectors new they always came in sets were matched and flowtested by Cannondale there is a right and left injector plug so they very well could have slight diffs between two.Would be somewhere in magical HEX code .You are right would be worthwhile to get them flow tested but then you threw Raptor into mix.All I can think of is like a snowmobile often depending on coolant routing the jetting will be different among the cylinders.
Posted: Mon Feb 05, 2007 10:16 pm
by hogman
The raptor did run 2 carbs. They were both 33mm mikunis but they were jetted differently, because one carb feed 2 intake valves and the other only feed one valve.
Posted: Tue Feb 06, 2007 1:34 am
by cannondale27
Good info Hogman.I also know the same motor DS650 has is used in a bunch of motorcycles.Some of those had twocarbs.Also DS is 4valve head I wonder if jetting is same in that example?
Posted: Mon Feb 12, 2007 4:56 pm
by wayneschofield
Running a different mix in each port is called 'Stratified charge'. It's normally only used on 'bias-ported' engines to concentrate a richer mix around the plug to help it fire, then the mix gets ever leaner as the flame front travles out from the plug. It's an emissions thing to help lean-burn motors run without misfiring.
Nearly all the three-valve-per-cyl (two In, one Ex) Honda, Mazda and Toyota motors employed some degree of stratified charge to help then burn cleaner when not using a Cat, and thus allowing them to run as high as 18:1 AFR rather than stoichiometric (14.7-8:1) that a Cat needs to do to work efficiently....
Not a lot of use for going faster though I'm afraid guys....
Any marginal difference between injector flows down each port will make three-fifths of bugger-all difference in the real world on our motors. There'll be a bigger variation in fuel pressure regulators than there is likely to be between injector flows....
BTW...
When it comes to dynoing mine I'll be experimenting with a secondary (third) injector pointing down the end of the trumpet set to inject at higher rpms... I'll replace the Sagem ECU with something else that will run closed-loop to speed the dyno process up a heap. That will just take fuelling quantity variations out of the equation....
Posted: Mon Feb 12, 2007 9:04 pm
by claas900
BTW...
When it comes to dynoing mine I'll be experimenting with a secondary (third) injector pointing down the end of the trumpet set to inject at higher rpms... I'll replace the Sagem ECU with something else that will run closed-loop to speed the dyno process up a heap. That will just take fuelling quantity variations out of the equation....
[/quote]
This might help.
http://forums.cannondaler.com/viewtopic.ph...9fa865aa8df3c05
Posted: Mon Feb 12, 2007 11:54 pm
by cannondale27
Thats a very good idea and something that has thrown a wrench into tuning on more than one occasion.All we have been able to do is get conditions as close to same as possible in dyno room.I wish Scooter or someone who knows would tell us the variables.I believe % capable of self correcting is alot greater than thought.
Baro=?%
Air Temp=?%
Coolant Temp=?%
Ignition,RPM=?%
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Total %