anyone converted their NA to twin carb?

[Blue94t]

Sounds like none of you guys have ever had a Weber fed car.

Under WOT throttle conditions, as long as carbs are set up correctly, EFI will make no more power. The main advantages with efi are cold start, economy, more precise ignition mapping and drivability on partial throttle openings. That said I am sure a pair of 45's would flow considerably better than the standard MX5 manifold but no more than the same sized irtb's.

A well tuned Weber will make great power and drive beautifully.
The myths that they need to be retuned constantly are rubbish, they just need to be setup correctly the first time.

My old Datsun 1600 with a SOHC 2 litre made ~95rwkw with twin 45's and was very easy to drive. I drove it daily to work and used it for club sprints on the weekend. It was relatively economical (considering the cam it ran) and would pull cleanly in 4th all the way from it's 700rpm idle to it's 7500rpm redline. It did take a fair bit of dyno time and a bit of refining on the street to get the tune spot on. Once the tune was sorted I didn't touch the jets for 2 years, just put fuel in it serviced it and thrashed it regularly.

[GP]

Very true, I had an XU1 with 3 dellortos. Once I had it tuned it was fine, Still can't think of any good reasons for doing it to a 5 though

[Rob E]

People do it for the character.......in Japan, there is quite a scene where guys modify the NA in a retro roadster style. Companies like Pit Crew and Zoom Engineering specialise in this style.......Carbs are part of this. I dont have a problem with it, but you will never be able to get Carbs legal/engineered in OZ on an MX-5.

[Mr Morlock]

A bloke told me yesterday that ( he is a "tuner" builder of British sports cars) the MX5 , did not have any character and after a pause explained that this was because they did not break down.

Many British cars had SU's and these things can be a big pain. They need regular tuning, maintenance for wear ( shafts needles) and they are not really that easy to tune. If you make changes to the engine then getting the right needles is not always easy. Webers were fitted to Alfa's and these had a good reputation. Incidentally older cars often ran better at night and you noticed quite considerable differences at elevation due to mixture changes- fuel injection is far less cantankerous .

But many still prefer older cars and older technology with "more character" and repairing and breaking down is part of the fun.

[Benny]

How would the ECU handle carbs?

[bruce]

How would the ECU handle carbs?

It can't. (was that a question?)

[philz]

The reason for people going Carbs is, because it's cheaper than an ITB setup.

And it's debateable, that you can tune it easier.

[bruce]

We're sounding more and more like an MG forum! "I need a refill of the Lucas smoke".

[Fatty]

How would the ECU handle carbs?

It can't. (was that a question?)

i suppose the ecu just goes about it's business sending pulse signals to the non existant injectors. i doubt the ecu would even notice that the injectors aren't doing anything, so it should just continue to operate normally, only controlling the timing / ignition. i suppose you could even fit an aftermarket timing / ignition device and do away with the ecu alltogether!?

[Fatty]

actually i knew i'd read about this before, and a quick check of the miata performance handbook shows a 1.6 with a pair of mgb carbs on page 79, and dual webers on page 82. it seems that there is some electronic trickery required to fool the ecu, but it's fairly basic stuff and it's all explained in the text.

[broady]

A bloke told me yesterday that ( he is a "tuner" builder of British sports cars) the MX5 , did not have any character and after a pause explained that this was because they did not break down.

Gold!

[Adam_NAclubman]

Many British cars had SU's and these things can be a big pain. They need regular tuning, maintenance for wear ( shafts needles) and they are not really that easy to tune. If you make changes to the engine then getting the right needles is not always easy.

Theres nothing wrong with SU's, they don't go out of tune very quickly and they're actually reasonably easy to retune. The only real problem with them is that the shafts on the linkages start to wear out where they connect and it makes the throttle stick a bit at low revs

[silvermx5]

having used modified 51 ida webber then upgrading to throttle body injection i can relate to the nostalgic value
of them old carbs altho i have never played with dcoe being from a rotary back ground . while i am confidant that my tuner
new exactly what he was doing with both efi an carb the webber made a sharper touqe curve but 2 more hores power while it was hotter while on the dyno with efi .efi seem to smooth the power thruout the rev range i did feel it lost a lot of car pazzaz my two cents !

[fastfreddygassit]

***OFF TOPIC***

Incidentally older cars often ran better at night and you noticed quite considerable differences at elevation due to mixture changes- fuel injection is far less cantankerous .

It may surprise you that new efi cars aren't that much better.
Mate has a 3 month old XR6T. It runs like all powers of pi$$ at night and early cool mornings.
Give it a hot day and it loses soooo much power.
Now, we all know why this is but is this that much different to the old carby cars "cantankerous" nature?
***BACK ON TOPIC***

[wun911]

Does it save weight??

Can we just have one carb??