How much power does it take to make a really quick 7?

[Dave J]

so in a 5 speed box, if 1st is too short and 3rd takes you to 100mph at 7500rpm, then in essence you would only ever use 2nd and third on the road.

I don't fancy a 2 speed box 😏

[Dave J]

so in a 5 speed box, if 1st is too short and 3rd takes you to 100mph at 7500rpm, then in essence you would only ever use 2nd and third on the road.

I don't fancy a 2 speed box 😏

[scubadude]

Dave J said:

so in a 5 speed box, if 1st is too short and 3rd takes you to 100mph at 7500rpm, then in essence you would only ever use 2nd and third on the road.

I don't fancy a 2 speed box ??

:-)

Do you want to cruise at 7500rpm?

5th of the 5 gives 60mph@3000rpm, 70mph@3500rpm and 80mph@4000rpm (may vary with type of gearbox, engine and wheel size obviously)

[Mario149]

Dave J said:

1st is too short and 3rd takes you to 100mph at 7500rpm, then in essence you would only ever use 2nd and third on the road.

When driving the t*ts off it yes. But at least it's a big improvement on 997 GT3 and 981 6sp Porsches where 2nd takes you to 84mph and 3rd to 115

[Eugene7]

I use a BGH 5 speed, with modified gearing - a close to perfect box to go with the Zetec.

Gear set: Ford Sierra Type 9/N BGH 2.0 Sporting Close 5 Speed
Gear 1 2 3 4 5 Final
Ratios: 2.920 1.860 1.295 1.000 0.850 3.890

RPM Limit: 7500
Tyre Size: 185/70 x 13
Tyre Diameter: 23.20 in
Tyre Circumference: 72.88 in


Gear Mph per 1000 RPM Mph @7500 RPM
----------------------------------------
1 6.08 46
2 9.54 72
3 13.70 103
4 17.74 133
5 20.87 157

[Mario149]

The first 3 in gear speeds look almost identical to the 5 sp in the 360R I drove

[Mario149]

To add, the best ratios I've come across have been in my Porsche 993 and my old F355: 2nd to about 65mph, 3rd to about 90mph and after that you don't care much for the road.

[Eugene7]

Obviously, I don't go to the full 7500rpm often on the road, so the change-up speeds are lower.
With the torque the Zetec provides the drivability is just about ideal.

It really does all fit as a great package

[KN02LEY]

Mario149 said:

The first 3 in gear speeds look almost identical to the 5 sp in the 360R I drove

I think the newer Mazda 5 sp box is better than the previous Ford. If I'm not pressing on in my Duratec, I often set off in 2nd as 1st is still a bit low. I guess its down to manufacturers having to allow for tin-top hill starts while towing a caravan

[coppice]

First time I drove my six speed I assumed I had mistakenly been given a gearbox with a longish first and five second gears ....But love it now.

[CycleSi]

[Mario149]

For peaky engines (maybe something like the F175/200 from Premier Power? Assume they're quite peaky!) I imagine a 6 sp works well and is indeed necessary so you don't bog down in the wrong part of the rev range.

[tankplanker]

Mine has very close ratios with it being a bike gearbox, I'd prefer slightly longer gaps between gears but I'd need more power to make the most of it.

I'm not massively impacted as I have paddle shifters, if I had to use a normal gear stick and clutch I'd be losing a lot more time shifting.

[bcr5784]

tankplanker said:

Mine has very close ratios with it being a bike gearbox, I'd prefer slightly longer gaps between gears but I'd need more power to make the most of it.

I'm not massively impacted as I have paddle shifters, if I had to use a normal gear stick and clutch I'd be losing a lot more time shifting.

+1. There does come a point with close ratios where the time lost in shifting can come close to (or even exceed) the gains made by staying closer to peak power - at least with vaguely sympathetic driver in an H pattern box, and especially with slower cross-plane shifts.

[jimmyVX]

I'm waiting for my Superlight 20 to arrive, essentially a 270R with a 6 speed box and for me personally the 6 speed transformed the Sigma engine experience, just felt so much more urgent and stayed within the power band when pressing on. Agree with other comments on here that at the 360 with a 5 speed box seems to be a better match and I can only put that down to the added torque the Duratec brings.

As with anything a lot of this comes down to personal preference, but I thought the 270 made a great road car and agree it might be lacking on the track in some areas. Being able to work the box rather than just driving on the torque is a plus for me and while I might not be the fastest out there, I'll have a huge grin on my face in the process!

[SKC]

"For peaky engines (maybe something like the F175/200 from Premier Power? Assume they're quite peaky!) I imagine a 6 sp works well and is indeed necessary so you don't bog down in the wrong part of the rev range".

Quite the contrary actually, these engines are not peaky but very smooth and very responsive compared to a standard or even 140 Caterham Sigma. We originally drove our F200 with a 3.9:1 BMW and a six speed box. For the road this was felt to be a bit noisy, 70mph, 13" wheels, 4200rpm. Since fitting the F200 Ti-VCT Sigma we've fitted a 3.6:1 BMW diff. I've yet to drive the car in the dry but this was done to make the car more comfortable to drive on the road, as well as to help the car on long circuits like Silverstone GP and Spa. We even found with the first F175 Sigma, fitted in a race car with 6 speed box and 3.9:1 diff that we were hitting the 7400rpm rev limit in top 1/3 of the way down hanger straight (that's 124mph). We then fitted the 3.6 diff and this then allowed him to just kiss the limiter going into Stow which calculates to 130mph.

SKC

[Mario149]

SKC said:

"For peaky engines (maybe something like the F175/200 from Premier Power? Assume they're quite peaky!) I imagine a 6 sp works well and is indeed necessary so you don't bog down in the wrong part of the rev range".

Quite the contrary actually, these engines are not peaky but very smooth and very responsive compared to a standard or even 140 Caterham Sigma.

SKC

Lovely

[bcr5784]

SKC said:

"For peaky engines (maybe something like the F175/200 from Premier Power? Assume they're quite peaky!) I imagine a 6 sp works well and is indeed necessary so you don't bog down in the wrong part of the rev range".

Quite the contrary actually, these engines are not peaky but very smooth and very responsive compared to a standard or even 140 Caterham Sigma. We originally drove our F200 with a 3.9:1 BMW and a six speed box. For the road this was felt to be a bit noisy, 70mph, 13" wheels, 4200rpm. Since fitting the F200 Ti-VCT Sigma we've fitted a 3.6:1 BMW diff. I've yet to drive the car in the dry but this was done to make the car more comfortable to drive on the road, as well as to help the car on long circuits like Silverstone GP and Spa. We even found with the first F175 Sigma, fitted in a race car with 6 speed box and 3.9:1 diff that we were hitting the 7400rpm rev limit in top 1/3 of the way down hanger straight (that's 124mph). We then fitted the 3.6 diff and this then allowed him to just kiss the limiter going into Stow which calculates to 130mph.

SKC

How much are the conversions? On a new car there are various options - a 270 with a 6 speed box vs a 360 with a 5 speed box or (perhaps) an F175 - depending on whether it needed a 6 speeder or not. I've not seen any dyno curves which would provide some useful info. I notice the (very impressive and attractive!) claim that the F175 produces nearly the same torque as the 360, but how that equates on the road depends on how broad that peak is.