gingerprince
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| posted on 7/9/05 at 08:39 AM |
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Carbs vs Injection
Can someone please explain to me the pro's and con's of running an engine on carbs vs injection, aiming the answer at someone who
isn't hugely mechanical.
As far as I understand the carbs is "easier" to setup but are there other advantages?
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mookaloid
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| posted on 7/9/05 at 08:40 AM |
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What engine do you have in mind?
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gingerprince
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| posted on 7/9/05 at 08:47 AM |
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quote:
Originally posted by mookaloid
What engine do you have in mind?
Was asking more "in general" really, didn't think that some engines were better one way than the other. However at the moment
I'll probably be looking towards R1 power (popular, reasonable power output without the dry-sumping requirement of the 'busa). So if
answer varies dependant on engine, then base it on this.
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mookaloid
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| posted on 7/9/05 at 08:58 AM |
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Sorry not sure what the best advice is for an R1 - I'm sure there are plenty of BEC users who will have an opinion though
Cheers
Mark
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Coose
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| posted on 7/9/05 at 09:06 AM |
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My carb'd R1 goes like stink and carburates beautifully on the TTS kit! 
Plus, I've got a set of Keihin CR41 flatslides to throw at it once I get bored.....
Comparing the two R1's, I don't think you'd notice much of a difference in the real world, so it's probably come down to which
package you could get for the best money! I don't think that one is more difficult to install than the other - just different!
Spin 'er off Well...
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smart51
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| posted on 7/9/05 at 09:07 AM |
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Fuel injection is generally better, that's why major companies all use it now. For a kit car, you can tune a FI engine using an aftermarket ECU
such as mega jolt for a car engine or power commander for a bike engine. You will need a computer with the apropriate software to programme these. I
am told it is not too dificult. The results can be excelent beacuse you can alter the ignition timing at 500 RPM intervals and alter it at every
engine speed according to load or throttle position. try doing that with a carb!
carbs don't need expensive electronics or computers. Screwdrivers do the job, except that they can't do it as well and you have to have a
general overall setting of the carb screws.
Carbs are cheap and simple where as fuel injection is good but expensive.
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Hellfire
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| posted on 7/9/05 at 09:12 AM |
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I'll probably stand corrected on this but I believe the only reason for going injection in the first place was to achieve ever tightening
emissions. As there are less moving parts; in theory it should be more reliable. There may also be a bias towards the injection for more mpg, but I
doubt this is at the top of your itinery!
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jimgiblett
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| posted on 7/9/05 at 09:38 AM |
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I am currently in the process of upgrading to FI (Yam R1 2001 carb to 2003 FI).
As far as absolute power is concerned I dont believe there is much in it. Power delivery is something else though. Although not impossible with
carbs it is much simpler to use FI mapping to clean up flat spots. Flatslides are a little special but at £500+ s/h but move the bar up a bit.
The smoothness of the FI power delivery was one of the main reasons why I have chosen this route.
Just my 2p 
[Edited on 7/9/05 by jimgiblett]
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Bob C
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| posted on 7/9/05 at 09:44 AM |
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No contest injection is better for power, economy, ease of setting up.
But it's harder to do the wiring & more expensive.
I've recently finished putting webers on a RV8 including making my own manifolds. I wish I'd gone the injection route - something like the
emerald system - the DIY tuning with a wideband 02 sensor gives you much better results in the end- plus the learning curve would have been more
interesting & more pertinent to the 21st century!
Bob
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Coose
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| posted on 7/9/05 at 10:11 AM |
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Various schools of thought - that's what I like to see!
As far as carbs are concerned, there are massive variations.... Webers are 40 year-old technology, certainly compared to a set of Mikuni CV's
off an R1 or a set of flatslides. Webers don't actually control the amount of fuel administered at part-throttle settings, whereas bike carbs do
via a tapered needle sliding in and out of an emulsion tube. These needles can be tapered to suit (even having negative tapers if required!!!).
I know of a chap who has fitted a set of bike carbs (off an R1) onto his S2 Twincam Lotus 7 and has witnessed a marvellous improvement! It cost him
around £250 in total (including manifolds and rolling road time to sort the jetting) and he's capped to bits!
So, my view is that injection is good and easier to set up (and get horribly and terminally wrong) for the average person, but a decent set of carbs
are very tuneable if you have an understanding...
Ok, I will admit that I'm a bit old-skool and like to tweak with tools as opposed to plugging in a piece of electronics, and my flatslides are a
gorgeous piece of kit, but considering that my R1 has never seen a rolling road and is fitted with a 4-2-1 exhaust to the Allbikes European
championship sidecar design with a TTS R1-car jet kit (needles raised one notch from stock) and a Pipercross filter it goes beautifully, with no
noticeable flatspots whatsoever!
[Edited on 7/9/05 by Coose]
Spin 'er off Well...
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Dillinger1977
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| posted on 7/9/05 at 10:20 AM |
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being a bit of a computer geek, i was tempted to the FI route, simply for the easy customisability. plug in laptop, upload new fuel map and go.
this sounded great for changing the car. one 'wimpy' map with clean emmissions for SVA, an average power map with decent(ish) fuel
economy for pootling around, and a balls-out power map for track use.
whereas i know nothing about carbs, and i'd have to get it rolling road tuned, and i'd be sticking with that one setup for everything.
(until i got the hang of fiddling with the screws)
there isnt a great deal in it if you only consider engine price, but dont forget the power commander which adds another 150-200 quid on top.
alas, i went for carbs in the end as there was an engine going quite cheap at the time and im now on a fairly tight budget. 
-Rog
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