6 six speed swap mk7 1.6 zetec s

[bazzatrazza]

Hey guys, i currently own a 2009 mk7 zetec s 1.6 and am thinking about selling it due to high fuel consumption during daily long dual carriageway/motorway journeys where my rpm sits at around 3400 whilst going 70mph.

But i was wondering if it were possible or how hard it would be to six speed swap my gearbox (5 speed currently) any help or advice appreciated.

[Luke4efc]

The cost of doing such a change would outweigh any fuel savings for a good few years.

What MPG are you actually getting?

[bazzatrazza]

3 hours ago, Luke4efc said:

The cost of doing such a change would outweigh any fuel savings for a good few years.

What MPG are you actually getting?

around 40mpg

[bazzatrazza]

Ive seen fiesta st six speed gear boxes on eBay for around 150-200 but i assume i would need to change other components too, its also more of a fun project which some practical use 😄

 

[Bobr]

3 hours ago, bazzatrazza said:

around 40mpg

Even if you do change the box I doubt very much if you'd make much of an improvement on 40 mpg.   And even if you did, it would take years to make it worth while.

[alanfp]

Decreasing revs would decrease fuel use somewhat, but not perhaps by all that much.  Pushing the car through air at 70 mph is where most of the energy is going, and you'll still be doing that even with lower engine revs.

As an experiment, you could try driving a few days at 60mph instead of 70 and see if that makes a difference (drag proportional to square of the speed and all that) though that will add time to your commute.  

Personally I wouldn't entertain a second hand gearbox without knowing its history. I'd value known reliability over a few mpg.

Having said that, if you like the idea of doing it as a fun project (and my definition of fun is clearly different to yours!!!) then do go ahead and let us know how you get on.  

An interesting idea, though, and good luck whichever way you decide to go.

PS  For economy, you really need to change the ENGINE (to diesel), not the gearbox 😉

[bazzatrazza]

1 hour ago, alanfp said:

Decreasing revs would decrease fuel use somewhat, but not perhaps by all that much.  Pushing the car through air at 70 mph is where most of the energy is going, and you'll still be doing that even with lower engine revs.

As an experiment, you could try driving a few days at 60mph instead of 70 and see if that makes a difference (drag proportional to square of the speed and all that) though that will add time to your commute.  

Personally I wouldn't entertain a second hand gearbox without knowing its history. I'd value known reliability over a few mpg.

Having said that, if you like the idea of doing it as a fun project (and my definition of fun is clearly different to yours!!!) then do go ahead and let us know how you get on.  

An interesting idea, though, and good luck whichever way you decide to go.

PS  For economy, you really need to change the ENGINE (to diesel), not the gearbox 😉

I appreciate your detailed response, and switching to diesel was my first idea but i made the mistake of modding my car whilst i was trying to sell it which has made me slightly more reluctant to sell it  (luckily havent named her yet though) 😄

[isetta]

That’s pretty low gearing. My 2015 1.5tdci econetic does 2350rpm at 70mph in top5th gear and still pulls when I put my foot down.    My 2007 1.6 tdci was 2650 rpm.  I know a zetec s would be lower geared to make it feel more sporty but I didn’t expect it to be that low. A cheaper way, I’m not saying I recommend it, would maybe a 5 speed out of a car with higher gearing.   I don’t know how interchangeable they are.

[Eric Bloodaxe]

1 hour ago, isetta said:

I know a zetec s would be lower geared to make it feel more sporty but I didn’t expect it to be that low.

Yes, it is pretty low- that's about 20.5 mph per 1,000 rpm. I wondered about clutch slip until I remembered contemporary road tests mentioning the gearing was very low when the car came out - about 20 mph per 1,000 rpm was mentioned, so it sounds about right.

Different car I know, but I where I drive I rarely get chance to use 6th, I'm more often in 4th/5th and still average mid-40s. 

 

[Bobr]

51 minutes ago, Eric Bloodaxe said:

 Different car I know, but I where I drive I rarely get chance to use 6th, I'm more often in 4th/5th and still average mid-40s. 

At a steady 50 mph my car is always in 6th and I'm getting 44 mpg.

[Lorenzo Laagland]

But it would make it faster I think. I have a zetec s.  And I can only go 193km/h because I'm at the limit of my revs. Do if you would have a extra gear I think I could get 220kp/h

[Eric Bloodaxe]

1 hour ago, Lorenzo Laagland said:

But it would make it faster I think. I have a zetec s.  And I can only go 193km/h because I'm at the limit of my revs.

Hi, Lorenzo,

The later 125ps 1.0 ecoboost with 6 speed box had higher 5th and 6th ratios (24.6mph/1,000rpm and 29.3mph/1,000) but achieved its top speed of 121mph in 4th as it was unable to pull higher revs in 5th and 6th on the flat.

It did of course, allow lower revs and better economy when cruising.

So it's unlikely that the earlier 1.6 would have the power/torque to pull higher gears also, except downhill! 

 

[OvEr_KiLL]

try this is in a full tank

https://www.eurocarparts.com/p/stp-petrol-fuel-injector-cleaner-200ml-549771791

usually when i am doing 70 like that my mpg is better for some reason..no idea why..think its because its a not a short journey and im not changing gear much