doga-ot

iTrader: (1)

Right a mate of mine has a mk5 fiesta zetec S running turbo'd 1.7 puma engine (t25 turbo) @ 0.9bar using standard 1.7 puma box he gets up too 140mph and engine has lloads more to give but gearbox wont go past 140 what box does he need or any ideas how to cure this?

Cheers

gingerturbo

iTrader: (2)

I think the transit connect box is a good choice for an upgrade

Caddyshack

I don't get it, why wouldn't a gear box go past? Either the torque can't pull any more revs due to the gearing too high (or aero drag) or the engine hits max revs? Am I missing something? What do you mean the engine has "more to give"

gingerturbo

iTrader: (2)

It's not getting clutch slip is it at high revs?

doga-ot

iTrader: (1)

it pulls like a train then just stops when it hits 140mph and was bouncing off limiter (top of rev counter) it was like it needed another gear

GVK.

So you need a different final drive to extend all the gears, or a longer 5th/bigger wheels/higher profile tyres


1.7 PUMA gear ratios are :

1st 3.15
2nd 1.93
3rd 1.41
4th 1.11
5th 0.88
FD 3.82

doga-ot

iTrader: (1)

So what is recommended as surely if he fit transit connect box it will fuck the rest of the gearing up as I said before his box is perfect other than it wont let him go past 140mph?

I was thinking zetec s final drive as that's all the ford racing puma box is (just puma box with zs final drive)

GVK.

Transit connect box will be a MTX so completely different, need to convert to cable change etc etc.

I can check the zetec s ratios

GVK.

Can't see the zetec s ratios listed on ETIS

Out of all the other Fiestas 1996-2002 (1.25/1.3/1.4/1.8D)

Longest is a 3.82 as what he has already

doga-ot

iTrader: (1)

I know the zs ratios they're:
1st:3.58
2nd:1.93
3rd:1.28
4th:0.95
5th:0.76 final drive:4.25

doga-ot

iTrader: (1)

so if he fits the zs final drive how much difference will it make? changing this seems the better option cos if he fits the connect box yes he will gain top end but he'll lose a lot of his acceleration!

GVK.

Found a post on here that say that zetec s ratios are

1.6 zetec s

diff 4.25

1st:3.58
2nd:1.93
3rd:1.28
4th:0.95
5th:0.76

so a 4.25 FD will go even slower/hit rev limiter sooner.

Can fit the zetec s 0.76 5th gear that will help, but the zetec s final drive is a backwards step.

You really need to get a gear calculator tool and work it all out.

http://www.gearboxman.co.uk/inforatios.html

doga-ot

iTrader: (1)

what if he uses a zs box and fits 1.7 puma final drive?? Sorry I don't understand the gearing or calculator thing I don't understand how it all works

GVK.

http://www.jdmlegion.com/tools/gear_...alculator.aspx

I used this one and with 195/50x15 tyres and Puma ratios it said 140 mph at 7000rpm

With a 0.76 5th 7000 was 163 mph, that seems 'a big difference'

Be easier to fit the zetec s 5th into the Puma box (if the shaft sizes are the same)

doga-ot

iTrader: (1)

is a ka 1.6 duratec box any good its gear ratios are:
1st 3.583
2nd 2.038
3rd 1.414
4th 1.108
5th 0.876 Final Drive: 4.061

doga-ot

iTrader: (1)

he's running 185/45/15

GVK.

Ka 1.6 box - No, slightly worse.

If he has lower profile tyres than 195/50 ..Well he's not going 140 with those size tyres on then

134 according to the gear calculator.

jamie's

Fitting the zs diff will have the total opposite effect from what he's after, it will make it hit the limiter earlier but accelerate faster(as GVK has already said)
Fitting a taller final drive(lower 1st number) will give a higher top speed, but it will also directly affect all other gears and make them a bit longer so will accelerate a little slower
If he's happy with the way it goes thru all the other gears then he wants to be just getting 5th gear a little taller to give more top end
But to be honest topping out at 140 is quite respectable for that kinda car,
That kinda speed on a track is really going some, not many tracks you'd see that on,
That's why most track cars are geared highly, all about the acceleration

GVK.

Doesn't look like there's an off-the-shelf longer iB5 final drive than a 3.82 unless anyone knows different.

0.76 5th is the way to go providing it fits the shaft, you may find a bit of a drop and not accelerate as well initially in 5th, but if it's turbo'd will have plenty torque so that should ok.

doga-ot

iTrader: (1)

I just used the calculator:



Tyre Size (1st set) - 185 / 45 / 15

Diff Ratio (1st set) - 3.82

Tyre Size (2nd set) - 195 / 50 / 15

Diff Ratio (2nd set) - 3.82

Redline - 7000

Full Boost -


Gear Ratios (1st set)


1st 2nd 3rd 4th 5th 6th
3.15 1.93 1.41 1.11 0.88


Gear Ratios (2nd set)


1st 2nd 3rd 4th 5th 6th
3.15 1.93 1.41 1.11 0.76


edit data
RPM

1st Gear

2nd Gear

3rd Gear

4th Gear

5th Gear

6th Gear

500 3 3 4 5 6 6 8 8 10 12 - -
1000 5 6 9 9 12 13 15 16 19 23 - -
1500 8 8 13 14 18 19 23 24 29 35 - -
2000 11 11 17 18 24 25 30 32 38 46 - -
2500 13 14 22 23 30 31 38 40 48 58 - -
3000 16 17 26 27 36 38 45 48 57 70 - -
3500 19 20 30 32 42 44 53 56 67 81 - -
4000 21 22 35 37 48 50 60 64 76 93 - -
4500 24 25 39 41 54 56 68 72 86 105 - -
5000 27 28 43 46 60 63 76 80 95 116 - -
5500 29 31 48 50 65 69 83 88 105 128 - -
6000 32 34 52 55 71 75 91 95 114 139 - -
6500 35 36 57 59 77 81 98 103 124 151 - -
7000 37 39 61 64 83 88 106 111 134 163 - -
7500 40 42 65 69 89 94 113 119 143 174 - -
8000 43 45 70 73 95 100 121 127 153 186 - -
8500 45 48 74 78 101 106 129 135 162 198 - -
9000 48 50 78 82 107 113 136 143 172 209 - -
9500 51 53 83 87 113 119 144 151 181 221 - -
10000 53 56 87 92 119 125 151 159 191 232 - -

GVK.

You've put the wrong tyre size on 2nd set

doga-ot

iTrader: (1)

cheers guys looks like that's sorted change his tyres and 5th gear to zs 5th jobs a good one