I am putting a 2.0 silvertop into a mk3 Fiesta Si, I want to use an ib5 box but don't know which one to go for.

My first thought was an Escort RS Turbo series 1 or 2 to get an LSD, but apparently the ratios may be too tall.

There seem to be quite a choice of boxes as follows:

1. The standard 1.6 already fitted to the Fiesta

2. 1.8 Fiesta Diesel

3. Ka

5. Puma racing (probably too expensive)

No doubt a number of others I'm not aware of.

I want some close ratios for good acceleration plus a tall 5th gear for more relaxed motorway driving.

I know that ideally the LS diff should be fitted to whichever box is used, and I could get one of these from an RS Turbo box, I don't know if the S1 or S2 would be the more suitable LSD donor?

In any event I don't feel particularly confident in trying to fit the diff as I have never stripped a gearbox before!

All advice greatly appreciated!

the standard box, diesel box and RST boxes are BC boxes not IB5

S2 ERST Box with LSD would do you good!

if you can get a Erst box id go for that !

i found the ratio's spot on when i had one in my 2.0'd mk2 fez

Standard gearbox will be fairly quick on acceleration, sits at about 3-3.5k at 70mph, cant remember exactly, and it'll top out at about 130mph sat nav speed.

For a more relaxed approach to motorway driving, a diesel box would probably be better as they are meant to have a really long 5th so it'll keep the revs down.

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I agree with Danny, the 1.6 box is pretty fast up to about 110 but is really noisy cruising. If you sit at 80 it's closer to 4k
Not sure how good diesel box is at acceleration but people have said it tops out off the clock so good for top speed and comfortable cruising.
I want to do a hybrid with the 1.6 box and diesel 5th gear. Just need to find a gear puller for uner a hundred quid first to save having to get the blow torch out and heating gears.

Paul

yep - 80 is 4000rpm as confirmed by Si Turbo

diesel box isn't bad on acceleration -happypaul will confirm this! but it is much better for cruising

2.5k at 70 with a erst lsd box, I got 44mpg on a long run once as well, perfect box imo

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