Acceleration

[Hammy]

Hi as some of you know I have increased the rolling radius on my MX5 donor and was wandering what I can do to regain the acceleration lost because of it. Any ideas??

[WorldClassAccident]

Change gear ratios or possibly something in the rear diff?

Or the Clarkson solution MORE POWERRRRRRRRRRRRRRRRRRRRRRRRRRRRR!

[Hammy]

previous experience tells me diff but waiting for expert...

[WorldClassAccident]

[img]but waiting for expert...[/img]

then please don't wait for me but I would have thought the diff would be easiest although more power wouldn't hurt...

[Hammy]

power wont change the ratio and apart from forced induction Ive done every other mod

[WorldClassAccident]

Won't change the ratio, agreed, but will provide more power to spin the ratio you have but then it sounds like you have done that already. I shall step down and await an engineer.

Have a great weekend!

[oxford1360]

Acceleration may have gone, but the theoretical top speed with those rears must now be about 500mph.

[tonyt]

I looked into turbos awhile ago, but its expensive, around £2000 but I did find a self contained unit with no oil feed, not sure how they get away with this but it would be easier to fit.

[redratbike]

Change the diff i'd say find a different ratio one...must be different ratio's available....go pick the brains of the guys on the mx5 forum

[landmannnn]

Yeah, I think there are 4 different ratios, 1.6 engines the lowest.

[mx5teo@planet.nl]

Use the diff from the NB 6 gear but then you need the axles as well.

[Mister Towed]

Is the gearing so tall that it's undriveable?

Unless the motor is so peaky that it can't comfortably pull away from a standstill I'd be tempted to live with it.

If you're planning on drag racing or short circuit track days perhaps a second set of (smaller?) wheels with lower profile, sticky track rubber would address the issue, but on the road I wouldn't worry about 0-60 acceleration.

Once you're on the move just use a lower gear for overtaking, leave the boy racers to spin their wheels away from the lights outside Tesco and revel in just looking cool cruising in your stunning ride.

[Hammy]

Originally Posted by Mister Towed

Is the gearing so tall that it's undriveable?

Unless the motor is so peaky that it can't comfortably pull away from a standstill I'd be tempted to live with it.

If you're planning on drag racing or short circuit track days perhaps a second set of (smaller?) wheels with lower profile, sticky track rubber would address the issue, but on the road I wouldn't worry about 0-60 acceleration.

Once you're on the move just use a lower gear for overtaking, leave the boy racers to spin their wheels away from the lights outside Tesco and revel in just looking cool cruising in your stunning ride.

No its still very drivable but I know from building my 7 that this is fixable and I like the challenge

[Mister Towed]

Originally Posted by Hammy

No its still very drivable but I know from building my 7 that this is fixable and I like the challenge

OK, I share that philosophy. For a bit of (very) old school tuning you could try methanol/water injection. That'll provide more power and torque throughout the rev range without breaking the bank. Or the engine. After all, it was good enough for the Supermarine Spitfire.

[fatbloke]

Just a thought, could you fit a 6 speed box to the car? Found this with some details on the different ratios of the 5 and 6 speed boxes.

http://www.miata.net/garage/KnowYourCar/S8_Gears.html