steve m
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| posted on 10/8/09 at 12:10 PM |
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converting a 1700 xflow to a bec, whats involved ?
Its only a question at the moment, but as i am getting fed up with xflows, poor fuel economey, etc etc, i was just musing the BEC route (sorry James,
Bob etc)
so, questions, what is the prefered engine choice, and carb;d or injection
apart from no reverse any drawbacks ?
regards
steve
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omega0684
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| posted on 10/8/09 at 12:27 PM |
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if you want better fuel economy upgrade to a zetec
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adithorp
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| posted on 10/8/09 at 12:27 PM |
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I think this sticky just about covers it.
http://www.locostbuilders.co.uk/viewthread.php?tid=90943
I'd go injection. More power generally and with a PowerCommander easier to adjust the fueling. If you're thinking of a reverse, my choice
would be MNR's new box but I've had over a year without and not got stuck yet.
Biggest problem with a BEC is and go, stop and corner quicker...and it'll be loud. 
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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nstrug
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| posted on 10/8/09 at 12:30 PM |
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I haven't done a conversion, but can maybe address parts of your question.
Regarding carbs vs. injection, they both have their upsides and downsides. If you have a post-95 engine, it will be easier to get through the
emissions limits with an injected engine and a cat, however it can also be done with carbs and cat but its not as simple as just getting a known
working map and loading it into the PowerCommander.
If you have an injected engine, definitely get a PowerCommander so that it can be easily remapped to cope with your exhaust - also needed if you
replace the original airbox with a sausage filter. A carbed engine will probably need to be re-jetted.
The main advantage of carbs is that they pretty much halve the amount of wiring required in the engine compartment as you have no injectors, TPS, air
pressure/temp sensors etc to worry about.
Regarding the conversion, you'll need a suitable cradle - bike engines mount in cradles which are then solid bolted to the chassis. You will
also need two new prophafts, either with a centre bearing (about where your gearshift is in your current car) or a reverse box. One of these props
(usually the front one) needs to be a 'Torque Resistant Tube' (TRT) that uses a rubber sleeve to replicate the action of the cush drive
built into the rear wheel of a bike.
The front propshaft is connected to the engine using a flange adapter that replaces the drive sprocket.
You will also need a gearshift mechanism of some description. Paddles are the best way to go with a bike engine on the whole, either a solid mechnical
linkage or cables.
If you go injected, you will need an injection pump and possibly need to modify your fuel tank to support a return feed.
Regarding the diff, you _may_ need to go to a lower ratio, however for an R1 or 'blade engine, 3.62 is fine with 15" wheels.
You may also need softer suspension springs, particularly at the front as you are going to be losing a huge amount of weight (R1+gearbox = 75kg)
Cheers,
Nick
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nstrug
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| posted on 10/8/09 at 12:39 PM |
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I haven't done a conversion, but can maybe address parts of your question.
Regarding carbs vs. injection, they both have their upsides and downsides. If you have a post-95 engine, it will be easier to get through the
emissions limits with an injected engine and a cat, however it can also be done with carbs and cat but its not as simple as just getting a known
working map and loading it into the PowerCommander.
If you have an injected engine, definitely get a PowerCommander so that it can be easily remapped to cope with your exhaust - also needed if you
replace the original airbox with a sausage filter. A carbed engine will probably need to be re-jetted.
The main advantage of carbs is that they pretty much halve the amount of wiring required in the engine compartment as you have no injectors, TPS, air
pressure/temp sensors etc to worry about.
Regarding the conversion, you'll need a suitable cradle - bike engines mount in cradles which are then solid bolted to the chassis. You will
also need two new prophafts, either with a centre bearing (about where your gearshift is in your current car) or a reverse box. One of these props
(usually the front one) needs to be a 'Torque Resistant Tube' (TRT) that uses a rubber sleeve to replicate the action of the cush drive
built into the rear wheel of a bike.
The front propshaft is connected to the engine using a flange adapter that replaces the drive sprocket.
You will also need a gearshift mechanism of some description. Paddles are the best way to go with a bike engine on the whole, either a solid mechnical
linkage or cables.
If you go injected, you will need an injection pump and possibly need to modify your fuel tank to support a return feed.
Regarding the diff, you _may_ need to go to a lower ratio, however for an R1 or 'blade engine, 3.62 is fine with 15" wheels.
You may also need softer suspension springs, particularly at the front as you are going to be losing a huge amount of weight (R1+gearbox = 75kg)
The drawbacks to the BEC route are:
* Lack of reverse unless you have a revbox or electric reverse
* A bit 'stally' until you get used to it due to no flywheel effect and light clutch
* Not great in start/stop traffic
* Can be VERY loud
* Depending on diff ratio, can be at about 6-7k at 75mph, which makes motorways a bit of a chore
* No synchromesh on the gearbox so you will have to learn how to heel-and-toe/throttle blip on downshifts
Advantages:
* Huge weight saving over a car engine
* Very high specific power output (150hbp/litre)
* Six speed sequential gearbox+paddles give lightning fast changes
* Individual throttle bodies give instant throttle response
* No synchromesh gives incredibly quick clutchless upshifts
* Very high rev limit and broad power band + close ratio gearbox gives the ultimate flexibility on track
Cheers,
Nick
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bob
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| posted on 13/8/09 at 02:29 PM |
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Steve you have been blackballed from the fraternity just for having these BEC thoughts.
But if you really want my tupence worth ZX12
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sucksqueezebangblow
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| posted on 14/8/09 at 01:20 PM |
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quote:
Originally posted by steve m
Its only a question at the moment, but as i am getting fed up with xflows, poor fuel economey, etc etc, i was just musing the BEC route (sorry James,
Bob etc)
Come young Steven........Join us...... on the Dark side!!!!! Feel....... the dark side..... of the Force.  
[Edited on 14/8/09 by sucksqueezebangblow]
Better to Burnout than to Fade Away JET METAL ~ AndySparrow © 
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Major Stare
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| posted on 17/8/09 at 06:47 AM |
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Just done the very thing your after... x-flow to BEC.
Cant see me going back to a CEC.
Car is so much quicker, weight saving, better handling etc.
Sound of engine at 11,000rpm is addictive.
Do cost in the possibility of new shocks as the car weighs less, plus new dials/clocks.
Jon "FISH"
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