1.8 NA Turbo 5 speed gearbox. Can it be strengthened?

[tickious]

Going for a little more power in my Turbo MX5 NA.
I think I'll be pushing the limits of the 5 speed box.
Is there anything that can be done to strengthen the 5 speed?
Or is it best to swap for 6 speed?

Thanks

(It's the one Harris slagged off in his infamous MX5 review)

[VladD]

According to BOFI the 5 speed will take up to 250 bhp, while the 6 Speed will take up to 320 bhp.

[tickious]

VladD said:

According to BOFI the 5 speed will take up to 250 bhp, while the 6 Speed will take up to 320 bhp.

Yes, found that too, and just found one on eBay. So going that route now.

Cheers

[griffdude]

After I fitted the 6 speed, I stopped having to change gearboxes, even though the 5 speeds are so cheap & easy to change. Make sure the 6 speed has the 4th gear mod.

[tickious]

griffdude said:

After I fitted the 6 speed, I stopped having to change gearboxes, even though the 5 speeds are so cheap & easy to change. Make sure the 6 speed has the 4th gear mod.

What's the 4th gear mod please?
Is now on a pallet, being collected tomorrow, for delivery later in the week.

[iguana]

I ran my NB turbo for about 7 yrs road & track on an NB 5 speed. Replaced box when I got the car with a used £30 one & it was good as gold with 240bhp.

Not long sold the car in bits & was happy to sell the box as a decent one.

Edited by iguana on Tuesday 22 September 22:36

[tickious]

iguana said:

I ran my NB turbo for about 7 yrs road & track on an NB 5 speed. Replaced box when I got the car with a used £30 one & it was good as gold with 240bhp.

Not long sold the car in bits & was happy to sell the box as a decent one.

Edited by iguana on Tuesday 22 September 22:36

I'm aiming for around 300 bhp

[iguana]

tickious said:

I'm aiming for around 300 bhp

Ah yeh probably a step too far. 6 speed & my dif, just the regular NB Torsen, wouldn't have been great tbh, just too close together, more suited to frisky NA power.

[muckyman]

Back in the day when I had my turbo NA it ran 245bhp and the gearbox was just fine - but I did blow a hole in the diff once 🤣🤣

[VladD]

tickious said:

griffdude said:

After I fitted the 6 speed, I stopped having to change gearboxes, even though the 5 speeds are so cheap & easy to change. Make sure the 6 speed has the 4th gear mod.

What's the 4th gear mod please?
Is now on a pallet, being collected tomorrow, for delivery later in the week.

This