MFactory Final Drive Kits in stock at Tuning Developments for GT86 and BRZ

[Mike@TD.co.uk 467]

I'll have some on display on the open day so people can check the quality for themselves. Certainly a smart piece of kit.

 

For quotes on fitting and so forth please drop me a message  

 

Thanks

 

Mike

[Deacon 1357]

Can you supply the ACT Prolite flywheels @Mike@TD.co.uk?

[Mike@TD.co.uk 467]

4 minutes ago, Deacon said:

Can you supply the ACT Prolite flywheels @Mike@TD.co.uk?

Got lightweight flywheels in stock Jeff, dropped you a PM with details.

 

Thanks

 

Mike

[Paul 442]

Can someone explain to me exactly what this mod is, does it work on N/A, what are the benefits, and how it works vs. pros/cons etc?

Not familiar with any of the terminology in this thread but has piqued my interest.

[Deacon 1357]

15 minutes ago, CanaryWundaboy said:

Can someone explain to me exactly what this mod is, does it work on N/A, what are the benefits, and how it works vs. pros/cons etc?

Not familiar with any of the terminology in this thread but has piqued my interest.

In terms of the final drive the advantage should be quicker acceleration. The downside will be higher revs which could be annoying on the motorway and will use more fuel.

[Rich 378]

18 minutes ago, Deacon said:

In terms of the final drive the advantage should be quicker acceleration. The downside will be higher revs which could be annoying on the motorway and will use more fuel.

To expand on this, it alters the gear ratios of every gear at once. The basic transmission setup is: Engine - Gearbox - Propshaft - Final Drive - Wheels. The gear ratio is determined by the gearbox and the final drive (and to an extent the wheels). Changing the ratio of the final drive will make gears longer (lower revs for same speed), or shorter (higher revs for same speed).

In the case of these, they shorten the gears, since instead of the wheels turning once for each 4.1 rotations of the propshaft, they turn once for each 4.44 or 4.67 rotations of the propshaft. This means higher revs for the same speed, but also due to increased mechanical advantage, more torque at the wheels. They should work out as around 8% or 14% increased torque for the 4.44 and 4.67 respectively.

[Ade 517]

It worth pointing out you wont get the same advantage as adding 14% more power.

Its all about keeping the engine as close to possible to outputting maximum power (area under the curve). By having closer gearing you are essentially increasing the average power output by the engine as you go through the gears. 

Dan's spreadsheet showing tractive effort shows how it works nicely.

Looking at 65mph with the 4.67 FD you are in 3rd and putting down 4700N. With the 4.1 FD (stock) you are in 3rd putting down 4100N. 15% more torque than stock.

But the shorter gearing has the consequence of having to shift up early.

Looking at 100mph with the 4.67 FD you are in 5th and you are putting about 3100N whereas with the 4.1 FD you are in 4th putting down 3500N. 11% less torque than stock.

Other pros and cons include the right gear selection on certain corners and the power delivery of the engine itself. Plenty of times I've wanted slightly shorter or longer gearing on track. 

 

[Nicebiscuit 655]

So... For the sake of argument - why wouldn't a longer FD be better? Then 1st gear would effectively be a shorter second etc etc. It's rare first is needed for anything...

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[Ade 517]

21 minutes ago, Nicebiscuit said:

So... For the sake of argument - why wouldn't a longer FD be better? Then 1st gear would effectively be a shorter second etc etc. It's rare first is needed for anything...

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Area under the curve. Putting the gears closer together increases the average power output by the engine closer to max power. 

[Deacon 1357]

Although this video is of s2000's watch from about 2.55 and you'll see a pretty clear illustration of the difference a shortened final drive can make on the mcr s2k

 

[Ade 517]

The MCR car has more power, semi slicks and rear down force though! 

 

[Deacon 1357]

It's only very lightly tuned (exhaust, etc) and the tyres and rear wing don't make much difference on the straight acceleration. They even state in the video that the big difference is the final drive.

[Ade 517]

1 minute ago, Deacon said:

It's only very lightly tuned (exhaust, etc) and the tyres and rear wing don't make much difference on the straight acceleration. They even state in the video that the big difference is the final drive.

I agree but they all contribute. Its 20hp more according to the video. The semis and wing contribute because of power out of the corner. I had the trouble at Bedford. I spent most of the straights catching up to slower cars just because they were able to get on the power much earlier. 

Anyway, hopefully Dan and I will be able to see at Snet. Harrop and Cosworth are similar power so if it makes that much difference as per the video he'll be able to drive past me down Bentley. I'm very interested

[Deacon 1357]

Yeah definitely all helps. 

It's only 10ps more though (260 compared to 250) isn't it?

It will be very interesting to see how your cars compare that's for sure 👍

[DanJ 374]

Indeed it will! I should be able to borrow the VBox from work so we can have some proper data to review and try to normalise for corner exit speeds etc.

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[Ade 517]

6 minutes ago, DanJ said:

Indeed it will! I should be able to borrow the VBox from work so we can have some proper data to review and try to normalise for corner exit speeds etc.

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That would be perfect as if I go for AD08R I might be cornering a bit faster or slower depending if it rains or shines 

I can use torque with a high sampling rate, but its not great as the Chinese knock off scan tool isnt that fast. 

[DanJ 374]

Given how lucky we were at Bedford I'm expecting it to piss it down all day!

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[Nicebiscuit 655]

21 minutes ago, Nicebiscuit said: So... For the sake of argument - why wouldn't a longer FD be better? Then 1st gear would effectively be a shorter second etc etc. It's rare first is needed for anything...

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Area under the curve. Putting the gears closer together increases the average power output by the engine closer to max power. 

Ah yes - of course - it closes up the ratios not just shortens them... Makes sense.

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[Kodename47 446]

3 hours ago, Nicebiscuit said:

So... For the sake of argument - why wouldn't a longer FD be better?

It may well be on an FI car. If you have load of torque you'd likely be able to use it better with something like a 3.9. That's why I think anything over a ~4.56 on a manual FI car will just be too much. Autos tend to favour a shorter FD for obvious reasons.

[Ade 517]

3 hours ago, Nicebiscuit said: So... For the sake of argument - why wouldn't a longer FD be better?

It may well be on an FI car. If you have load of torque you'd likely be able to use it better with something like a 3.9. That's why I think anything over a ~4.56 on a manual FI car will just be too much. Autos tend to favour a shorter FD for obvious reasons.

On a dry day I struggle to wheel spin in second, so with grippy tyres I cant see how you wouldn't benefit. sure with 350whp it a different beast. its only 14% more torque after all.

Proof will be in the pudding at snet when Dan drives past me down bentley.

[Nicebiscuit 655]

Yup - used to long legged ratios on turboed cars where you can pretty much pick a gear and accelerate from 2500rpm up to the redline.

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[MikeB 79]

The issue is is not to be to wrapped in the figures it's how you want your car to perform and what you are using it for. It's the same when changing exhaust and air filter for the ecu map to match so you get the best from upgrades working together.

I have noticed in sport mode with auto (4.67) you are changing down a lot earlier than you might want to so its gaining in accelerating but losing out in braking. Which would be fine in tight track/road but keep in normal mode for longer less twisty track.

It will be interesting to see how performs on the first two sprints at Blyton.

[DanJ 374]

4 minutes ago, MikeB said:

The issue is is not to be to wrapped in the figures it's how you want your car to perform and what you are using it for. It's the same when changing exhaust and air filter for the ecu map to match so you get the best from upgrades working together.

I have noticed in sport mode with auto (4.67) you are changing down a lot earlier than you might want to so its gaining in accelerating but losing out in braking. Which would be fine in tight track/road but keep in normal mode for longer less twisty track.

It will be interesting to see how performs on the first two sprints at Blyton.

Agreed, its all "horses for courses", I spent a lot of time playing about with my various spreadsheets before deciding that the 4.67 would be fine for how I use my car, but its definitely not a "no brainer" mod for everyone.

The two graphs are based on Abbey dyno plots for the Harrop and Cosworth with different final drive combos.

 

[Kodename47 446]

What I'd be interested in is seeing graphs of just the Harrop 4.1/4.44/4.67. The top graph suggests that 3rd-5th gear there is little in it between 4.1 and 4.67 but then the Cossie has a little extra torque at the top end based on the dyno plots.

[Foulsmell 120]

It worth pointing out you wont get the same advantage as adding 14% more power. 

 

Also for those who don't know whatever extra torque you add through engine mods, the FD will add 14%.