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Fuel injection 'carbs'

Posted: Mon Oct 01, 18 1:43 pm
by morgan
Anyone tried this stuff ?
I mean not cheap but I gotta say I am wondering... Any experience ?
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Re: Fuel injection 'carbs'

Posted: Mon Oct 01, 18 6:26 pm
by Blue
No personal experience but from what I hear they work well. I like the Fitech because all the gubbins are inside the "carb" so there isn't miles of wiring like some others. You could hide it under a stock air cleaner as well. You would also need a high pressure return line fuel system for that clean look, unless you want their big swirl pot thing under the bonnet. I would like to try it, instant modern car starting and idling really appeal.

Re: Fuel injection 'carbs'

Posted: Mon Oct 01, 18 9:29 pm
by lough3969
As you say Blue, it is appealing for ease of starting etc. Engine Masters have done a couple of programs comparing these EFI and Carbs, carbs come out on top, but only just. One problem may be your intake manifold, some dual plane intakes and or internal plenums hinder the thing working properly...

Re: Fuel injection 'carbs'

Posted: Mon Oct 01, 18 10:18 pm
by db
I imagine they're a lot more efficient at low rpms, around town etc so would probably improve mpg quite a bit?

Re: Fuel injection 'carbs'

Posted: Tue Oct 02, 18 8:19 am
by DaveB
Watch Engine masters on EFI vs Carb,really interesting,I thought it might of converted me,but No,im still running a carburator :lol:

Re: Fuel injection 'carbs'

Posted: Tue Oct 02, 18 12:15 pm
by morgan
Blue wrote: Mon Oct 01, 18 6:26 pm No personal experience but from what I hear they work well. I like the Fitech because all the gubbins are inside the "carb" so there isn't miles of wiring like some others. You could hide it under a stock air cleaner as well. You would also need a high pressure return line fuel system for that clean look, unless you want their big swirl pot thing under the bonnet. I would like to try it, instant modern car starting and idling really appeal.
I've am replacing the fuel tank and running new lines in anyway, so wouldnt be the worst time to do it.
Modern car starting, idling and tuning itself on the fly really appeals...

Re: Fuel injection 'carbs'

Posted: Tue Oct 02, 18 12:47 pm
by MrNorm
I do think these are a real option now. Technically these are TBI (throttle body injection) or we used to call them CFI (central...) before we went to full port fuel injection decades ago in the industry :) . I always took the view that if you were going to switch to FI, do it 'properly' and do full port injection, and this is an available option too to retrofit to our cars. You have more control over the fuel that way, the distribution is better and you can even tune for cylinder to cylinder AFR variation etc if you want. with a 'wet' system like a carb or TBI (where the fuel goes through the intake as well as air) you get fuel droput, puddling etc that you don't get with port FI. Just a better setup.

However.....the aftermarket TBI systems like that FITech, Holly (super)Sniper, FAST etc etc, are now pretty good. For me a reason to consider one of these rather that the full port injection is that the price is pretty good, it doesn't require much of a tear-up of your existing system (mainly just fuel system and there are straightforward options for that), and now that they give you the proper tuning programmes even for TBI you can use the laptop and tune to your hearts content. Or just use the self-learning which if you don't have a radical motor works pretty well.
It's not news that FI does not make any more power than a carb but it's really similar, and what you do get is much better part load efficiency (i.e. fuel economy 'around town'), better starting, better driveability etc. And really quick to make tuning changes (no swapping jets etc), you can even have a track tune and a street tune if you want.
One reason why ultimately carbs can offer slight more power is that the fuel charge cools the intake air as it vapourises, so you get a cooler, denser charge. In theory I assume the same would apply to a TBI FI setup! However, we are splitting hairs, and quite possibly the better fuel distribution etc would outweigh that.

One other reason.....whatever is theoretically possible, I think the truth is that most people with carb'd muscle cars have not optimally tuned the carb at all - they are running around with the wrong jets, the driveability is poor etc (yep I included myself in that demographic). I think it's easier to get a better tune with a self learning TBI than a stock carb, so in truth I think most people would indeed get more power as well as the other benefits. Just my opinion!

Re: Fuel injection 'carbs'

Posted: Tue Oct 02, 18 6:07 pm
by Scooby
I seem to remember Anton ( not sure if he's still on here) went down this route and was well impressed said worked well on his charger a complete difference in running - fuel delivery and all round the motor behaved so much better with this set up.
Prob the way to go I guess eventually the saving made re poor running costs of an old carb and unreliability will make it worth it plus much improved mpg .

Re: Fuel injection 'carbs'

Posted: Sat Oct 06, 18 8:45 pm
by MattH
I definitely like this idea.

Re: Fuel injection 'carbs'

Posted: Wed Oct 10, 18 2:22 am
by Rebel
Have to say, I quite like this idea as well

Re: Fuel injection 'carbs'

Posted: Wed Oct 10, 18 7:54 am
by RobTwin
MrNorm wrote: Tue Oct 02, 18 12:47 pm I do think these are a real option now. Technically these are TBI (throttle body injection) or we used to call them CFI (central...) before we went to full port fuel injection decades ago in the industry :) . I always took the view that if you were going to switch to FI, do it 'properly' and do full port injection, and this is an available option too to retrofit to our cars. You have more control over the fuel that way, the distribution is better and you can even tune for cylinder to cylinder AFR variation etc if you want. with a 'wet' system like a carb or TBI (where the fuel goes through the intake as well as air) you get fuel droput, puddling etc that you don't get with port FI. Just a better setup.

However.....the aftermarket TBI systems like that FITech, Holly (super)Sniper, FAST etc etc, are now pretty good. For me a reason to consider one of these rather that the full port injection is that the price is pretty good, it doesn't require much of a tear-up of your existing system (mainly just fuel system and there are straightforward options for that), and now that they give you the proper tuning programmes even for TBI you can use the laptop and tune to your hearts content. Or just use the self-learning which if you don't have a radical motor works pretty well.
It's not news that FI does not make any more power than a carb but it's really similar, and what you do get is much better part load efficiency (i.e. fuel economy 'around town'), better starting, better driveability etc. And really quick to make tuning changes (no swapping jets etc), you can even have a track tune and a street tune if you want.
One reason why ultimately carbs can offer slight more power is that the fuel charge cools the intake air as it vapourises, so you get a cooler, denser charge. In theory I assume the same would apply to a TBI FI setup! However, we are splitting hairs, and quite possibly the better fuel distribution etc would outweigh that.

One other reason.....whatever is theoretically possible, I think the truth is that most people with carb'd muscle cars have not optimally tuned the carb at all - they are running around with the wrong jets, the driveability is poor etc (yep I included myself in that demographic). I think it's easier to get a better tune with a self learning TBI than a stock carb, so in truth I think most people would indeed get more power as well as the other benefits. Just my opinion!
Great explanation and info there Gavin :thumbright:

Re: Fuel injection 'carbs'

Posted: Tue Oct 16, 18 11:11 pm
by JinxJay
although my runs spot on, I keep looking at this and being tempted...


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Re: Fuel injection 'carbs'

Posted: Wed Oct 17, 18 8:30 am
by duncan scott
I’ve been looking into this for a friend on his biscayne. It boils down to this. If you can afford it do it. Then it’s a choice of manufacturers and after a bit of comparison I’d go with the Holley sniper. Much better piece in my book.


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