fiestaturbo.com

[dellboy]

Hello,
I have a Fiesta Rs Turbo. 186bhp on a T2 turbo.

Well I was wondering if I can replace the Escort Rs gearbox with LSD I have on my fiesta Rs for one which will give me more top end. Can this be done ??
I heard you could put a diesel one on ????? but not sure what one the guy said ?
I have 15” tyres and am going to uprate the springs to coilover’s and put 17” tyres on. This should help a bit.
I drive this car a lot, more now on motorways, I have noticed that @ 90mph I’m hitting 4000 rpm, @ 100mph I’m hitting around 5000 rpm. i hate screaming the arse off it but most days i'm late for work !
So I would think my car is only good for 125 on current tyres ??
Need more speed guys, I also really want to stick with the engine I have for now.

thanks

Gerome (AKA Dellboy)

[Oranoco]

How fast do you really need to go?

I ran my S2 on stock ratios up to 149.7 and that didn't hit the limiter in top with 260bhp (hit the limiter on the S1 box that's in it no though and only managed a verified 146mph ). You really don't need to dick about with ratios with 186bhp.

Diesel box is a no go as it's no tougher dispite the myth always doing the rounds.

If you want to drive the car and enjoy it I would recomend against the fitment of 17's but it's your car

[heeman10]

If you're hitting 90mph at 4,000rpm in fifth, that equates to 22.5mph per 1,000rpm. If that's the case, you'd be hitting 112.5mph at 5,000rpm, 135mph at 6,000rpm and 151mph at the 6,750rpm limiter.

What profile are the 17" tyres? I'd calculate the rolling radii of your 15" and 17" tyres before you start assuming big top speeds as a result of fitting larger wheels.

[dellboy]

thanks guy for the advice.
17" are going on the car.. so should see some improvment there then.

[heeman10]

What profile are the 17" tyres? I'd calculate the rolling radii of your 15" and 17" tyres before you start assuming big top speeds as a result of fitting larger wheels.

[Superal]

If you want speed stick with 15s!

[dellboy]

Why stick with the 15".
i am going for the 17" as i think they will look a lot better, my friend has them on his and they look good and not too bad to drive ?

why is everyone against putting bigger wheels on ?
my Mrs looks great in high heels but she cant walk that well and they give her pain !!! but she still wares them !!

[Oranoco]

Becaue those of us actually in the know know that 17's complete arse the handling of the car. 17's are just too damn big if you intend on using the car for performance. 15's are imho and extensive experience perfect. 16's are an acceptable compromise but not one I'm prepared to make.

Look at the Fiesta's used in competition they certainly aren't rolling on 17's

[heeman10]

why is everyone against putting bigger wheels on ?

Who said they're against it? Up until Oranoco's reply (which I'll come to!) we're all just questioning your reasons. If you have a 195/45/15 tyre on your 15s at the moment, that gives you a rolling circumference of around 1.747m. Fitting 205/35/17s, for example, would give you a rolling circumference of 1.806m. That means you gain 60cm in rolling circumference (1.9cm in diameter).

At the 6,750rpm rev limiter on the 15s, if you'd be doing 151mph as calculated above, on the 17s used in these calcs you'd be doing 156mph. We're talking about a 5mph increase on the rev limiter in top gear - hardly enormous!

[heeman10]

Oh, I didn't comment on 17s! As Steve says, 15s tend to be a very useful size on the Mk3. They have lower inertia than most bigger wheels of similar design, and as space isn't all that available in the wheel arches, smaller tyres mean there's less chance of scrubbing on full suspension travels and on cornering. That said, Rawli's car's been on 17s for years and only scrubs on hard corners when there's a passanger in the car.

[xrsi]

unless you get what are branded as motorsport wheels 17's will give a far higher unsprung mass and hence not only effect acceleration but also the handling characteristics of the whole car.

yes a slight top end speed gain can be obtained when using larger diameter wheels due to what heeman has mentioned above, but i think as well that it would be wise that for this gain to become apparent that you can infact get the car to pull round to the limiter in 5th with load on the engine (not jacked up on stands as many do to try to get their car to read off the speedo).

i have gone for 16's on mine but the pro race from team dynamics, there are about half the weight of the oz super t's that were on the car last so should help alot when accelerating.

could be worth considering dropping a wheel size and getting a lot lighter wheel that will be more benificial to the performance and handling of the car.

[BLOGGY]

The only way you could get higher gearing is to change the box for one out of a 1.6S or something like. They had alot higher 5th gear.
The gearbox ratios are as follows:

RS
turbo 1.6S

2.95 3.15
1.94 1.91
1.34 1.28
1.00 0.95
0.81 0.76
They both have the same diff ratios, so you get higher gearing with the fact that the ratios are higher. You have to remember though that the pick up won't be quite as good with the higher gearing. The only down side is that first is lower.

[jdfiesta]

i wouldnt say 17's make that much of a difference to handling or acceleration.
i recently raced a friends 2.0si, very similar mods to mine but minus the cossie brakes and 17's, he uses the standard 14's. and there was nothing in it. i got a slightly better start, but we remained pretty much the same distance appart. if anything i started pulling away at higher speeds.

i think the only issue with handling is that they can occasionally catch the arches, which puts you off a tad bit
JJ

[dellboy]

I know about the tyres catching the arches, i get the wheels next week, has anyone got a good way of getting them to fit ?
i dont suppose it will pose much of a problem. i was going to go the whole hog and get 18" on but that would mean a lot of work and i can't be arsed !

I think the only reason i'm going for the 17" as they look better on.

I'll post some pics of the cat once i have bolted everything new bit on.

thanks guys.

gerome

[Jay]

you'll have a HUGE amount of work..

I personally have had to do it and its just a load of ballache and fucks up your cars ride.

[Oranoco]

i wouldnt say 17's make that much of a difference to handling or acceleration.
i recently raced a friends 2.0si, very similar mods to mine but minus the cossie brakes and 17's, he uses the standard 14's. and there was nothing in it. i got a slightly better start, but we remained pretty much the same distance appart. if anything i started pulling away at higher speeds.

i think the only issue with handling is that they can occasionally catch the arches, which puts you off a tad bit
JJ

If you really beleive that you really don't know anything about handling. Why do you think they didn't slap on a set of 17's to the competition cars? grip and handling are not the same thing. I've driven on every size wheel from 13's through to 17's and the best I have found is a 15" 7J ET35 rim with a quality 195/45/15 tyre. The only benefit of larger wheels that I've found is it allows the fitment of larger brakes. Cossie brakes fit nicely under most 15's and will stop pretty much anything you wish to build.

That's from my experience of 10 years performance driving on and off track not racing up the local High Street