Making the move to fuel injection?

[jackh707]

Just wondering if making the move to fuel injection is worth it?

Currently running a 1.8 raceline zetec on weber 40s. We think we are getting just under 150 hp at the moment, but we wouldn't mind some more power and better fuel consumption.

Is fuel injection the best route to go down?
What benefits are we likely to see?

[Aeroscreens]

I guess it depends what you really want from the car.

When my x/flow 'let go' I invested in a 2.0l Raceline Zetec with modified head and RL200 cams but ran it on 40DCOEs. This produced 170bhp. 'Twas a great car to drive but nevertheless the engine was being held back by the carbs.

A change of finances allowed me over the winter to make the change to fuel injection, Jenvey 45s, Emerald K6 EMS etc. I now have 190bhp, there are no flat spots, instant acceleration, better mpg (not that I've checked) and all round better 'driveability'.

Just my 2p worth....

[Supra Chewie]

With a 1.8 litre Zetec you're never going to be up there with the 2.0 litres. I swapped 40 DCOEs for an OMEX 600 & Jenvey TBs on my 2.0 litre Silvertop. Cost of the kit, hoses, clips, fasteners, fuel pump, electrics incl wiring, relays, swirl pot, various widgets and rolling road mapping must be close to £2.6K and gave an extra 15 BHP at 160 BHP. Now I could have got more BHP/£ from a gas flowed cylinder head and 280 duration cams at probably £1.5K and sticking me in the 180-190 BHP. Admittedly I've done it back to front as when I eventually get round to doing the head and cams, I'll only have to get the ECU remapped.

[russelli]

transformed my 2L VX.
i had the car on carbs for at least 12 years before i could afford the tb upgrade, but best upgrade of many in the 20 years i have had the car. cost was around £2000 back then.

[Alistair1537]

Stay with the Webers - fuel injection is too complicated - and look at the cost!!! If you want more power you won't get it from fuel injection alone - carburetors can push as much fuel into an engine as you like - first get the engine breathing better - work the ports - get Verniers and decent cams - all cheaper than changing to fuel injection and you'll get the power you want.

[Yellow 7]

I was lucky to get a job lot of all that was needed to take my Redtop from 45's with 3d mapping to Jenveys.
Loom, ECU, TP, Fuel rail, injectors, the lot. Also included 2 freeflow 2.5" bore manifolds.
The kit was said to be off a certain well know blue VX that had been converted to a bike engine. That was back in 2002/2003.

Combined they completely transformed the car. Throttle pick up, power down at any RPM was much better.

Economy - hehe (who cares) was also much better.

I had hours of fun mapping with lambda fitted and learning about Easymap and it was a great experience.

[jackh707]

Sounds positive. We do like the induction noise and simplicity(well...) of carbs. I've been reading a few books and websites on jetting carbs, for the past few days, and I reckon from the state of tune it's in and the jets that are in it, the jetting is out. I'm going to buy some bigger main jets and fit them, while my dad is away (his car and drives it most of the time), and not tell him, then see if he notices a difference.
I also Like the pops and bangs on the overun with carbs, lovely little blue flames flashing out of the exhaust at night.
Do you still get this with FI?

[Aeroscreens]

You must be doing something wrong if you're only getting little blue flames! You need proper flames like this

Just a thought but isn't the car currently mapped to run on the existing jets? Not sure that just changing jets will achieve much, but I'm no expert.

Still get loads of popping, banging and flames on my current set-up, but then again I do have switchable mapping and on one setting the fuel overrun setting is turned off.

As for costs excluding the RR session the net cost of purchasing all the necessart bits and selling off the bits I removed was just £1300.

[jackh707]

I'm fairly new to carbs, but I am quite sure there is no "mapping" involved.
I thought tuning them just involves the dark art of synchronising them and swapping various jets/emulsion tubes until you reach the perfect combination that produces the best drivability and power.
Or am I missing something?

Awesome photo, that's definitely a bigger flame than we have.

[Aeroscreens]

The photo, to be fair, is from my x/flow days. However, all the Zetecs I know that are running on carbs also have an ECU, so assumed yours would too. Happy to be be told otherwise.

[DVandrews]

jackh707 said:

Sounds positive. We do like the induction noise and simplicity(well...) of carbs. I've been reading a few books and websites on jetting carbs, for the past few days, and I reckon from the state of tune it's in and the jets that are in it, the jetting is out. I'm going to buy some bigger main jets and fit them, while my dad is away (his car and drives it most of the time), and not tell him, then see if he notices a difference.
I also Like the pops and bangs on the overun with carbs, lovely little blue flames flashing out of the exhaust at night.
Do you still get this with FI?

You get the same induction bark with throttle bodies, sometimes better as there is no choke or aux Venturi to dampen it. It's a myth that injected engines dont have induction bark, it's just that most modern injected engines run on a plenum in their original installations which attentuates most of the induction noise.

You will never match the drivability or perfect calibration of fuel injection with carbs, they are a box of compromises with three discrete fuel slopes tha intersect. This is especially true when the engine is off cam and suffering with reversion as a carb relies on airflow to draw the fuel in whereas the correct fuel is metered by injection regardless of how intermitent the airlfow may be.

You can have flames on overrun with injection if you wish, but it is also possible to reduce the fuelling on overrun and suppress this, somehting that is next to impossible on a carburettor.

Mapped ignition will also bring the sort of drivability and part throttle performance that a distributor equipped engine cannot approach.

Some time ago I wrote an article about engine management with a chapter on the change from carbs to EFI, it has been reproduced on the Emerald website, but the orignal is here www.dvapower.com/ems.


Dave

Edited by DVandrews on Monday 9th April 17:26

[jackh707]

Wow thanks for that post^. A lot of very good information. I've got too admit, I am having some difficulty in understanding carb tuning. Seems as much art as it is science. I am picking up the new 140 main jets tomorrow to replace the 135s that are in it. That's a reasonably educated guess as to what the engine should be running best on, hopefully will be good.
Next lot of money is going on a decent set of tyres before fuel injection is considered. Although, hotter cams and some serious head-work is the direction I would like to go in the future, whether it goes in the direction I want or not is a different matter.

[Eugene7]

I have a Raceline 2L Zetec on 45 Webers with 210BHP.

Omex 200 ECU, and it goes like stink, with no flat spots, etc, and delivers good MPG.

It's great

I have spent a lot of time with the ECU map, so it is well sorted, and the Webers are 5 progression hole versions.

But I would not go TBs...

[jackh707]

Okay, I am being stupid here, someone previously mentioned it, how and why does your carbed engine have an ECU? Is it to control ignition timing? Also, our engine was built in 1994 ish, so is it likely to have an ECU too? Thanks.

[Supra Chewie]

The carbs control the fuel into the engine cylinders and the spark plugs ignite it BUT what controls the point of ignition. In the old days it was a distributor driven off the engine and powered by a coil. Now fast forward back to the future and the dizzy and coil has been replaced by a compact igntion pack but you still need magic box of tricks to control the point of ignition. That's the ECU.

If you're doing a carb to TB conversion you would need a new ECU and whole lot more, HP injection pump, maybe a swirl pot, miles of HP injection hose, wiring sundries, relays, blah blah... The one that was fitted to the donor car you can bin it.

Edited by Supra Chewie on Friday 13th April 19:00