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Carbs v Fuel Injection: is it worth the extra expense for old dubs?

5K views 31 replies 18 participants last post by  Sigi 
#1 ·
being technically challenged on the subject :crazy:, I'm aware that adding a fuel injection system to an old dub is not a cheap option, but is it really a option worth consideration or saving up for, or are you better off in the long term with a decent set of twin carbs?
 
#2 ·
I'd go for fi over carbs any day of the week.

Infinitely more tunable, more efficient and better for future upgrades IMO.

fact of the matter is, with BOTH you're better off taking them to a decent rolling road to have em set up right.
 
#5 ·
I was thinking about this but the only one that I could find (read: get linked to from here) was £1000+

I know that the later mexican beetles had a FI 1600. could you chance it to suite a 1776 d'ya think?

Just out of interest....
 
#6 ·
you can do FI on the cheap; but there's a bit of learning to be done too.

there's a massive DIY EFi community though.

Some people will tell you it's shit.. some rolling roads won't set it up because of some really shitty installations by people doing it REALLY cheap, and because they don't want to touch the software...

but if you do the research...
 
#10 ·
Really depends if you have the money or knowlege to do the job properly.

I'd say that the set-up in Prawnstar's race car is the best money i've spent on fast VW's. it makes it driveable all across the rev range despite the FK89 cam and being able to flow FAR more air than twin 48IDA's. And it is designed to be able to cope easily when the bigger heads and capacity get built.

For Drag Racing it's a no brainer. If you are building a really fast but really streetable car, then i don't think there is really an alternative despite what some will tell you. but it's a diminishing return on cars that are less highly developed.

But it depends on many things, including how attatched you are to tradition and the 48 IDA ;)
 
#13 ·
i'm going to be using FI on my pepped up 1600 when I can afford it. ECU will probably be a kronenburg unit, and will run it on a closed loop, so will only need to download a pretty safe map, and it will do the hard work for me ;) it can control the ignition, and will even handle twin spark of I could be arsed to do the machine work on the heads.

good thing is that I can transplant it onto a bigger motor when I get the funds to build such a thing :)
 
#14 ·
so do injection solutions give you the best bang for your buck when more applied to race/drag applications then? What about normal larger sized engines for vans with daily usage or touring aspirations? Is it a bit overkill here or are there other advantages/disadvantages to be considered?
 
#15 ·
a carb can only be tuned to one rev range ie; give its oeak performance in one place. pretty much the same for a dizzy even with vacum advance.
a well set up efi will control the fuel and timing at any rpm and load thus giving you a perfect mixture and timing.
you can set them up for max power or best drivabilty/ econemy.
my race car went from a all or nothing screamer to a much smoother and more powerfull motor that will now has a much wider spread of torque and better hp.
its not cheap but as with most things you get what you pay for.
on a street engine i dont see a problem of have just the one throttle body which cuts down on the cost and you can buy end castings with the injector bosses allready in them.
so buy the time you have brought your pair of 40's, manifolds, linkage, dizzy, msd you wont be that fair behind a efi set up.
both will take about the same amount of time to set up on a rolling road so the differance is not that great.
for any one that is concernerd about the envrioment efi is the only real soulution as you can run a lamda to control the misture better which also allows you to run a cat if you want.
dont see why you couldn't control the emissions enough to get it to relitivly recent emission laws.
cheers rob
 
#18 ·
carbs need adjusting to run at optimum.
injection doesnt .


thats the basic arguement , but its not that simple ;)

megasquirt using junkyard parts is the cheapest way i think .

hotVWs have been running a series of articles on there quest to get the best mpg .
iirc , there best upto now is the cb singlethrottlebody system .

its a rather crude test , they fill up at the same gas station , drive down the same road watching the speedo , then drive back and see how much it takes to fill back up .

the real differences with carbs would happen if they drove to somewhere out of state at a different altitude .

the latest interesting development is injection that looks like a set of idas (built in)

if you compare to your modern car , the ammount of extra sensors etc. have made the same basic engine design more economical , powerfull , and basically maintenence free .... yet a nightmare when you have to diagnose a problem ;)

costs ???
if your looking to buy new carbs , injection has gotta be worth looking at .
if your gonna be driving to different areas/countries too .

if your looking from a mpg viewpooiint , the savings will pay for the initial costs ...... eventually !! :D
 
#28 ·
'proper' ??

ok, lets say DTA with jenvey throttle bodies. 500 for the ecu. 500 for the TBs. then add on your inlet or manifolds, injectors, sensors, loom, maybe a wideband O2, etc etc
say £2k
very much an estimate but probably a reasonable guide.
 
#23 ·
it's got infinitely more potential and elements of control than running carbed engines, and in theory should need less maintanance...

it all depends on how you do it, how you build it, and how you set it up / tune it though.

its possible to cock it up to a great extreme.
 
#24 ·
but once set-up, does it stay that way? Is the re-mapping to different/changed requirements a difficult or expensive thing to get done? I've seen a few dubs with fuel injection sold on here that came with their own laptop?
 
#26 ·
sort of still on topic but, if you are running a "new" mexico engine, would it be essentially better to run...

option A. standard 1972 single carb.

option B. modified small twin carb set up.

option C. standard 2003 mexico injection set up.

or, something else?
 
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