evo.rocks
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| posted on 23/11/09 at 09:43 PM |
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how to manage fuelling on carbs
Over all the excitement of buying my bits for the turbo set up, i have not give a thaught for fuelling of the car.
My zx9r engine is run on carbs, i will have stock internals and will be running 6psi of boost.
Will i need to mess about with the fuelling or will it be ok??
What do i need to buy if i do have to do something??
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Macbeast
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| posted on 24/11/09 at 08:18 AM |
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What do i need to buy if i do have to do something??
Petrol (lots of ) 
I'm addicted to brake fluid, but I can stop anytime.
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bigpig
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| posted on 24/11/09 at 08:57 AM |
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I expect you will need to get the carbs set up and re-jetted.
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evo.rocks
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| posted on 24/11/09 at 10:29 AM |
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the carbs have had a TTS dynojet kit in already so in that department i am already done.
I was just wondering if the carbs would sense if there was more air being thrown in that the fuel would automatically alter aswell to give the correct
ratio???
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Steve G
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| posted on 24/11/09 at 10:30 AM |
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and most importantly, a rising rate fuel pressure regulator.
This increases the fuel pressure as the boost increases via a feed line running from the pressurised side to the regulator. Your fuel pressure always
has to be higher than the boost pressure otherwise you wont get fuel flowing through the carbs.
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Steve G
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| posted on 24/11/09 at 10:50 AM |
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quote:
Originally posted by evo.rocks
the carbs have had a TTS dynojet kit in already so in that department i am already done.
You'll need to start your tuning pretty much from scratch with regards to jets and needles once it's turbo'd.
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will121
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| posted on 24/11/09 at 11:49 AM |
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i thought there was issues potentially with bike carbs on different pressures externally and internal with boost? fuel pressure will need some link to
rising pressure against boost too
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Steve G
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| posted on 24/11/09 at 12:57 PM |
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quote:
Originally posted by will121
i thought there was issues potentially with bike carbs on different pressures externally and internal with boost? fuel pressure will need some link to
rising pressure against boost too
The carbs need modifying to ensure they are pressurised internally to the same pressure yes. I'll have a look for a link i used to have on how
this is done.
http://www.turbo-bike.net/Pressurize%20carbs.htm
[Edited on 24/11/09 by Steve G]
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RAYLEE29
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| posted on 24/11/09 at 01:03 PM |
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hi, inmho you would need to get rid of the carbs and run throttle bodies and have it mapped
cant realisticly see it running right on carbs without a real load of hassle but basically as atmospheric pressure is 14.7 psi and your gonna run 6psi
boost youll need a 50 to 60 percent fuel increase on boost so your dynojet kit and jets will be way off
also not sure how the diaphrams will react to having boost instead of vacum to lift the slides
Ray
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Steve G
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| posted on 24/11/09 at 01:14 PM |
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quote:
Originally posted by RAYLEE29
hi, inmho you would need to get rid of the carbs and run throttle bodies and have it mapped
cant realisticly see it running right on carbs without a real load of hassle but basically as atmospheric pressure is 14.7 psi and your gonna run 6psi
boost youll need a 50 to 60 percent fuel increase on boost so your dynojet kit and jets will be way off
also not sure how the diaphrams will react to having boost instead of vacum to lift the slides
Ray
Plenty have done it with carbs......... but i agree that injection and megasquirt would be a better option. This would mean looking at the whole fuel
system from the tank forwards though - maybe use a swirl pot fed via a low pressure line from the tank to allow a high pressure circuit to feed the
throttle bodies.
With carbs, the slides still work as normal so long as the pressure is equalised both above and below the diaphram. Think of it as less pressure
(rather than vacuum) that causes the slides to lift.
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