147 replies to this topic

[l_jonez]

Have you worked out the mpg?

I was getting 45-50mpg with the ITB's

[Shingler4596]

I haven't speedos not reading right. I wonder whether it's had a gearbox done before and had a 1l box. Very high revs I barely have to touch the throttle. That would explain why it loves to spin the wheels and not have a good top end

[l_jonez]

I did think of that as an option, the 98-99 1ltr box was physically the same as the 1.3 ( so a straight swap) but it had a lower FD which the hill climb boys like as it offers good acceleration but no top end

[Shingler4596]

That sound like mine as it's fantastic off lights and off roundabouts. Wheels pins for days in first and into second but as I get up the gears it starts to drop off at about 80-90 and nothing beyond that. I'll have to take it for another run and see again.

[alaskanow0]

The Micra can pull 100mph at a push. So I'm sure the Mini would be able to pull 90-100mph no problem, bearing in mind the mini is not the most aerodynamic.

I also have a 1.3 Micra, in standard form (870kg) and can say top end acceleration is poor, but what do you expect for 75bhp. From about 80mph acceleration is pretty slow. The higher the speed, the more drag, hence you need more power.

What power do you think your running?

I'm surprised your comments about the gear ratios. They look spot on, on paper, with expection to maybe 1st is a little short with the 3.895 Final drive. I'm considering putting the 3.895 crownwheel & pinion into the facelift 1998 - 2000 998 box, to create a closer ratio box, ie

1275 V 998

3.331st. 3.062 1st
1.955 2nd 1.826 2nd
1.286 3rd 1.207 3rd
0.927 4th 0.902 4th
0.756 5th 0.756 5th

[alaskanow0]

Even with the 4.4FD 998 box, you would still pull 90mph at 5000prm and theoretically 107mph at 6000prm

Compared to 3.895 box

100mph at 5000pm & 120mph @ 6000rpm

All based on 175-50-13

[alaskanow0]

The 998 box with its 4.47 final drive would be my choice for a trackday project, but for road use I'd choose the 1275 3.895 box everyday. With the 998 box your never going to exceed 6500rpm in 5th ( 114mph ), unless you have some serious engine mods and a very weight car or a big hill. Therefore it's should perform better everywhere and allow a higher top speed as the engine can operate closer to peak bhp window. Certainly will not limit speed, just make it unpleasant at much higher revs. Factory Rev limit is 6900prm anyway. So Theoretically 120mph is possible.

There very little difference between the 998 and 1275 box in 1st gear terms, as the gear ratio and Final drive cancel each other out to a degree. Both are going to wheel spin.

Again, the 998 box with 1275 FD may be the answer.

[fuzzy-hair-man]

The Micra can pull 100mph at a push. So I'm sure the Mini would be able to pull 90-100mph no problem, bearing in mind the mini is not the most aerodynamic.

I also have a 1.3 Micra, in standard form (870kg) and can say top end acceleration is poor, but what do you expect for 75bhp. From about 80mph acceleration is pretty slow. The higher the speed, the more drag, hence you need more power.

 

CdA of Micra is 6.89

CdA of mini is 8.415

 

Strangely enough (I thought it would be better) the Modern VW Beetle is 8.64 apparently.

 

CdA takes into account drag co-efficient and frontal area

 

It's all academic anyway my mini isn't going to be going that quick even if it could.

[Shingler4596]

Cars been on the dyno today. Considering it's pretty standard, only inlet and exhaust it got 103bhp at the flywheel and 83 at the wheels... plenty of potential left... mmmmmmmmmmm turbo................

[fuzzy-hair-man]

Cars been on the dyno today. Considering it's pretty standard, only inlet and exhaust it got 103bhp at the flywheel and 83 at the wheels... plenty of potential left... mmmmmmmmmmm turbo................

Nice, sounds like a similar output to mine...

 

Do you have a dyno graph? what RPMs did it achieve peak hp? Torque figures?

 

I'm considering cams for mine, but I'm a little afraid the Green Cotton filter which is supposed to top out at around 100hp / 110hp is the bottleneck. Legally I must have a covered air filter (ie in some sort of box) for noise regulations.

 

I'll have to talk to Matt Humphries to see what they have got the filters etc up to...

[Shingler4596]

Have a graph will post it later when I'm home, does its best about 5500 rpm to 6000 after that it drops off a cliff in terms of power

[Shingler4596]

That's the graph I was given

Attached Files

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[Mike_Y]

Great conversion Shingler, impressive work. Just got myself a Micra to do the same but don't think I'll get mine done as quickly as you.

Edited by Mike_Y, 17 July 2016 - 10:10 PM.