Webers vs ITBs (e.g., Jenveys)

Webers vs ITBs (e.g., Jenveys)

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Discussion

MF35

Original Poster:

443 posts

28 months

Sunday 18th June 2023
quotequote all
For a fun weekend car (small 4-cylinder K11 Micra) used mainly for hooning around back roads, which would you prefer - Webers or ITBs/EFI? Assume all other engine work will be done.

I have an old 1997 k11 Micra which gets ragged on a near daily basis - it has custom headers and some other basic bits n bobs and, while not exactly fast, is faster and noisier than most people expect, and can be parkd anywhere without anyone wanting to steal it lol.

Anyway, I had been thinking about fitting Jenveys etc and getting some more engine work done. My engine builder rallies K11s and builds lots of engine using 40 webers, and is very much of the view that Webers are all you need, and has suggested, e.g.:

Original Italian Twin 40 Webers
New inlet manifold
Uprated pistons
Uprated camshafts
New ECU

Of course, Webers sound mega, but I've heard so many horror stories about them going out of tune, leaking etc. And undriveable through
town etc.

I suspect at least some of those horror stories are to do with inexpert installation in the first place. After all, all my parents' cars when I was growing up were on carbs, and I don't recall any major issues with them.

But Webers are something I have zero clue about.

I wondered what people in general terms think of them and whether they could be a fun thing to do on a little old runabout which, as
mentioned, tends to be driven enthusiastically anyway ...

Any experience of Webers / suggestions woulkd be great - ta.

Tye Green

796 posts

116 months

Sunday 18th June 2023
quotequote all
get a set of bike throttle bodies with injectors

200Plus Club

11,193 posts

285 months

Sunday 18th June 2023
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If you are fairly handy yourself and can learn/play with mapping then an ECU and TB project can be fun to learn and will save you a fortune in mapping and setup. If you've access to base maps already on same engine and ecu then that's half the problems solved immediately.
Don't believe anyone who says that it's plug n play, they never are.
Carbs are carbs, once setup you'll need to also tweak/keep an eye on but at Full throttle there will be bugger all real world difference in peak power between a properly set up pair of twin carbs and an ecu/TB setup on a smallish engine. Low speed/part throttle and cold starts in winter however are a different kettle of fish compared to a well tuned ECU setup.
Edit to add, cost of a pair of carbs vs TB/ECU also needs to be factored in,plus fuel pumps/regulator etc.

Edited by 200Plus Club on Sunday 18th June 22:59

shirt

23,491 posts

208 months

Sunday 18th June 2023
quotequote all
I was questioning the logic of using carb especially when you’d still need to retain the ignition of the ecu. So I googled and very quickly found that the 1.8 from the primera drops straight in, including retaining the existing gearbox and driveshafts, and gives 130bhp. Can’t fathom why you just wouldn’t just do that.

200Plus Club

11,193 posts

285 months

Sunday 18th June 2023
quotequote all
shirt said:
I was questioning the logic of using carb especially when you’d still need to retain the ignition of the ecu. So I googled and very quickly found that the 1.8 from the primera drops straight in, including retaining the existing gearbox and driveshafts, and gives 130bhp. Can’t fathom why you just wouldn’t just do that.
Job jobbed right there then !!!