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Author Topic: Carburetor vs Fuel Injection by FortNine  (Read 266 times)

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Offline Dustbiter

Carburetor vs Fuel Injection by FortNine
« on: November 07, 2021, 10:04:14 am »
He explains things simply, and will give many riders a better understanding of both systems, I hope!

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Offline Fransw

Re: Carburetor vs Fuel Injection by FortNine
« Reply #1 on: November 07, 2021, 10:23:25 am »
After seeing this I don't understand why most bikes are fi, even Lyndon Poskitt swears by carbs I n his designs...
 

Offline BuRP

Re: Carburetor vs Fuel Injection by FortNine
« Reply #2 on: November 07, 2021, 11:02:25 am »
So, Ryan, Direct Injection FI works on cars to increase performance (whilst keeping enviro etc in check yeah...) but it does not on bikes because they "rev higher"?

Yeah, sortof true-ish, but that's not the whole picture I'm afraid.
High revs prevent direct injection yeah, because 'time' is at an essence here: at high revs there's no time enough for injection, thorough mixing of air & hopefully-fully-evaporated-now fuel so that the charge will ignite (for which a sortof homogeneous stochiometric mixture is required!) and combust completely.
There's simply not enough time for all this - but this CAN be the case in cars, with their engines revving lower .... but, those engines are almost always also bigger!

Bigger cylinders hence pistons in cars, so more space - plus more time due to lower revolutions per minute, and also, as a coup de grace, a bigger differential in cylinder-diameter and effective combustion chamber (squish dome)!
Hell, the clever dicks at Mazda (the forerunners currently in ICE development, not Honda, Toyota or Yamaha!) even go as far to create a layered charge in their SkyActive engines (these are DI !), in doing to running as lean as 38:1 instead of approximate stochio ratios - that's super lean! Yeah, only at partial engine loads but google this, very clever indeed  :thumleft:
Oh, yip, only at low revs and with relatively big pistons is this possible, not with a 600cc four cylinder revving to 18000 rpm.... or this same engine revving to only 7000rpm!
Size does matter Gents, and revs do too - and keep in mind we're talking Direct Injection here, so no filthy remarks please!


Oh wait, perhaps some editing will not go amiss here.....  :P
Bottom line here Ryan, you're right, but only sortof!
« Last Edit: November 07, 2021, 11:04:16 am by BuRP »
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Offline Grunder

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Re: Carburetor vs Fuel Injection by FortNine
« Reply #3 on: November 07, 2021, 01:49:50 pm »
So, Ryan, Direct Injection FI works on cars to increase performance (whilst keeping enviro etc in check yeah...) but it does not on bikes because they "rev higher"?

Yeah, sortof true-ish, but that's not the whole picture I'm afraid.
High revs prevent direct injection yeah, because 'time' is at an essence here: at high revs there's no time enough for injection, thorough mixing of air & hopefully-fully-evaporated-now fuel so that the charge will ignite (for which a sortof homogeneous stochiometric mixture is required!) and combust completely.
There's simply not enough time for all this...

He did mention the time factor

Very informative video.

« Last Edit: November 07, 2021, 01:50:15 pm by Grunder »
the Truth will offend at first
 

Offline BuRP

Re: Carburetor vs Fuel Injection by FortNine
« Reply #4 on: November 07, 2021, 01:57:58 pm »
He did mention the time factor

He did indeed, but related this to 'lower revs' only - which is only part of the reason.

Agree, I like his vids too!  :thumleft:
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Offline Cracker

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Re: Carburetor vs Fuel Injection by FortNine
« Reply #5 on: November 07, 2021, 06:04:08 pm »
After seeing this I don't understand why most bikes are fi, even Lyndon Poskitt swears by carbs I n his designs...

It's about the fuel, not the mechanics of the delivery. FI is the future because fuel development is moving beyond carbs.

Same thing happening in human fuel too ..................
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Offline 2StrokeDan

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Re: Carburetor vs Fuel Injection by FortNine
« Reply #6 on: November 07, 2021, 07:32:21 pm »
After seeing this I don't understand why most bikes are fi, even Lyndon Poskitt swears by carbs I n his designs...

It's about the fuel, not the mechanics of the delivery. FI is the future because fuel development is moving beyond carbs.

Same thing happening in human fuel too ..................


Yes, fuel development is going towards batteries.
 

Offline Cracker

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Re: Carburetor vs Fuel Injection by FortNine
« Reply #7 on: November 07, 2021, 07:50:02 pm »
Did you see his vid about the electric bike - that old Suz AC? (whatever) with no engine?

That was also a good one ..............  :thumleft:
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