In Ā gear times measure by racelogic Vbox mini
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Point to note :Ā Auto gearbox in the MX5 is a lot longer geared in 5th / Ā 6th than the manual gearbox
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In gear times now added
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that 50-70 difference is INSANEā¦
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Thatās one VERY quick car now
There is a big difference between the normal sportshift and the BBR turbo in that range. Sadly when Mr Mazda did the auto version (whilst dressing it up as a Powershift which makes you think dual clutch, ho ho) he decided it should be a cruiser and so for all us poor sods who broke their back 20 years back on a motorbike we were lumbered with an NC 3.5 with interstellar gearing in 5th and 6th compared to the manual. 5th gear in the auto is 6th in the manual and 6th gear is geared for 195mph so could give the Millennium Falcon a run for its money at the Bonneville Salt flats. Maybe.
Luckily the BBR stage 1 is quite linear and starts to get in its stride at 2000 rpm before itās sweet spot between 3 and 4. So 5th and 6th are now proper gears. Thatās a real good point of this conversion for the auto in general driving, perhaps more so then just going bonkers on the odd time, if you think about it.
Note also for the 0-60 and 0-100 times being an auto I just moved my foot from the brake to the throttle, no holding it at revs on the brake as this is not something I do normally. So the car didnāt get up to speed as if you forced a bit of slip, so knock 0.2-0.4s off the 0-60 time if you have a manual and are considering this.
Note also the auto shifts up automatically at 6700 where as BBR on manuals go up to 7400+ and so have more top end power.
So this is a lower end all round performance wise compared to what a ānormalā manual MX5 driver could expect. I have not seen anyone put a racelogic databox on one of BBRās conversions so far so thought this would be of interest to everyone on this forum, so actual proper stats, even if at the lower end.
I will be posting a couple more posts shortly hopefully including a dynograph from third party and video of the optional BBR supersport exhaust backbox I got fitted so you can hear that. Thatās rather rare on youtube so I shall pop it up.
Dyno tested now at Surrey Rolling road. Charlie is a nice guy and fitted me in on a busy Saturday first thing so I got time to chat to him about dyno testing having never done it before. Learnt a lot of stuff and had an interesting time. Charlie has done a lot of MX5ās as you can imagine, lots of turbo ones too but this was the first auto box one for a turbo. At this point Iām starting feel slightly like Chuck Yeager about to meet some sound, or bhp, barrier
Ā Below is the calculated engine bhp. not wheel
So less than 200bhp when BBR stage 1 is normally around 250 to 270 on their dyno. Ā So I asked Charlie and he said my gearbox was slipping so losing a percentage, guessing wise he said add 20bhp, so up to 220bhp. Ā Unfortunately again my auto gearbox is slipping me a kipper. Ā Charlie also said the fueling was slightly rich as that was good for turboās, better than lean and he was happy with it, also the work was well done by BBR, all in order, as you would expect.Ā So Iāve done a dyno run and the minimum is 200 but I do not know the actual figure thanks to my gearbox. As BBR said, can of worms, hence why they did not do a dyno. But then again, Charlie did one to give a rough estimate. Hmmm. Low figures are never popular of course all round. Ā
I did some rough checking online for RWD bhp Ā per tonne v acceleration figures and in general to get my acceleration figures you would need about 200 bhp per tonne, so 230-240bhp for the weight of an auto lardy Mazda. I then used some online calculators also and it moved it down 225-230bhp at the engine.Ā
Scientifically then I have a large error range. Ā 220bhp +/- Ā 10bhp Ā as best estimate. Ā Thatās still a lot less than BBR claim, but they did those figures for the manual which has a lot different parameters such as rev limit and gearbox. I do think with the lack of other people testing with the auto box means they might have played it safe with me. Which is fair enough.
I will follow up with this in the future with hopefully another dyno from someone else to see how it compares.Ā
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20bhp is roughly 15KW of heat being generated in that torque converter. Where is all that waste heat going? Does it not lock-up when the in-out speed is matched?
Of course youāre most unlikely to ever be using max power for any great length of time on UK roads, but even so if about 10% of engine power is lost in there I would imagine it is getting pretty hot with CAT and exhaust close by.
Very interesting reading Andy, some very impressive figures there, 2.3 seconds faster to 60MPH and a massive 8 seconds quicker to 100MPH!! 
It would take far more than just an extra 40-60bhp for such time gains and 200bhp on a manual gets the 0-60 down to 6.1 seconds with just a single gear change so you have much more power than that 
Please be very careful if you run your car on a dyno and do not run with the inlet temps over 40 degrees, the graphs you see from us are all at 20-35 degrees inlet temp any more than this and power recorded will drop considerably due to the ignition and fuel corrections we put in place to protect the engine. We use two huge fans to keep things cool in our dyno and this is still not enough to simulate road conditions, remember with road use in just 5.6 seconds you have a 60MPH head wind!
Happy BBR turbo motoringĀ
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Hi
Yes the racelogic vbox Ā figures are a lot more accurate than my rolling road bhp figures due to the gearbox. Ā The standings starts are impressive, but being the auto Ā it still starts from idle of course rather than dumping the clutch at revs as a manual, so the in gear times are even better for me, the conversion has made 5th and 6th gear on the auto proper overtaking ratioās. Mazda screwed the auto gear wise Ā to be honest and a BBR turbo put it right.
Iām really enjoying the car, the linear nature of the power increase does not overwhelm the standard suspension and tyres I have. It can hook up well with Ā the smooth delivery.
I had a BBR supersports back box fitted as well at the same time. BBR do GT and Sports versions, but there are not many youtube videoās of either to allow you to judge, and as you know sound is very perceptive. So I guessed at the sports one and I really like it. I did a video so others have some guide.Ā
https://www.youtube.com/watch?v=er61656VFns
The mapping does the odd pop and bang which makes you feel years younger.Ā Ā 5Ā pops on the trot is my record up to now after I learnt the trick. Get funny looks from my daughter when I do that.Ā
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No idea and no idea in answer to your 2 questions to be honest. Itās still changing gear at the moment as it did before. Yes, as you can tell from my answers, I am not mechanic. 
I have a track day booked in at Brands Hatch in October. I will see how the gearbox performs there. Also the manifold seems to have caused issues on track days in the past so it will be interesting to see how that does also. BBR have made a change to them for track day users but not sure if mine has that. BBR donāt guarantee for track work as far as I can tell but then lend cars to Evo etc who do trackwork and then advertise it, so all in all a bit of a grey area.
But then track days are always a grey area even with the manufacturers when they are not busy with emissionsā¦
When you decide to modify your car you are modifying your car after all. Itās an adventure. This is my honest users log of the trip to help future folk taking the same path.
The torque converter is a fluid clutch that allows the engine and the input shaft to the gearbox to run at different speeds and yet still transmit lots of power for the smooth changes between gears. There is a good article on the Wiki
It mentions that modern systems allow the engine and input shaft of the gearbox to be locked together when at cruising speed to improve fuel economy. On my brother-in-lawās ancient Mercury Comet it used to cut in with a bang because the converterās vans were worn and the gearbox sometimes barely reached about 80% of the engine speed before the controller thought āOKā when the throttle was lifted. Low fluid levels can also show up as slippage.
If the TC has the ability to be ālocked-upā ie no slip in the fluid clutch, then the full power should go through with just some minor friction losses from stirring the fluids. The rev counter and speedo can help with observing this when driving normally.
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Thanks Richard for that, Ā you do tend to learn things when modifying cars. Went to work in it today, the M25 and A21 boring route, it just toodled along like the standard car. Ā Fuel consumption seems Ā better than before. Will have to investigate that, though thatās a pretty boring thing to investigate for my full summary of this conversion.
I have noticed there are not a lot of other automatic MX5 drivers hanging on my every thought on this BBR conversion before getting it themselves. Oh well. Itās now in the public domain.
Iāve got a Gopro arrived, so will try that out. Actually itās not a GoPro, itās from China. ahem
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Andy
As an MX5 MK 3.5 2.0 automatic owner I have followed this thread with interest. Ā I am amazed at the improvement especially at the high gears. Ā The high ratios are great for that motorway cruise, but i find myself having to reach for 4th if I need to get an extra move on into the fast lane. Ā 195 mph would be something though, wouldnāt it?
Unfortunately I will have to let you live the BBR fantasy lifestyle for me, as I have a kid at university and one hoping to go next year, which is keeping my feet firmly attached to the ground financially speaking, for sometime to come.
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I know what you mean, I saved up a long time for this, Ā£100 per month so to speak. In the meantime we had a new front wall, new roof, new this that and the other for the house. When you have a family other things always take priority. My daughter still has to go to University, it was different when I was young and it was free plus student grant 
The best thing about this conversion for the automatic is that it does make 5th and 6th gear usable.
I did my track day at Brands, probably the slowest thing out there even with BBR help, due to driver being duff and standard street tyres which are not much cop on circuit. No issues apart from the brakes started smoking on my last session and the tyres of course got overheated
Some onboard, my new Chinese cam did quite well considering no car mounting so I had to bodge it. Note how I am ok on the straights, just the corners slow
https://youtu.be/w0LiA-Yh8wU?t=295
Update
Been running the car now for 6 months now and found my first issue with this conversion, nothing major. After a warm December a few colder days in Jan Feb and with it around -1C to 0C on acceleration in 3rd from 3000 to redline wide open at these temps the cars hesitates and stutters. Must be a fueling / cold air issue on the map 2 for high octane, not tried it with the 95 standard map. Itās nothing major. It happened first time in Jan but I wanted to make sure it was not some dodgy fuel so ran the tank out and then waited for more cold weather. Maybe something for the BBR crew to look into. Itās not exactly a big deal though.
Considering the car is bog stock suspension and tyre wise it still puts the power down well. The rear Bridgestones were replaced and so those new ones were far more grippy than the 5 year old front ones so all I got was understeer. Fitted some Michelin Pilot Super Sports to the front recently and now they have more grip than the back and the car once more is not washing out. They might have a bit too much grip for the rather average Bridgestones once it gets warmer, we shall see.
Interesting that youāve said that, my map 2 is the high octane with launch control etc and I had the odd stutter with that , I assumed it was a RaceRom bug as Map 1 (high RON and 3 ( low RON) do not suffer likewise.
Thanks Steve for adding your input. Nice to see itās not just me. Itās nothing major, but just a point of note.
Note sure how my picture of my baking got into the thread for in gear times, now corrected. If anyone else wants to see my baking efforts though, PM me. I have a good one of a Victoria sponge cake.
Now, getting back to the car, the lack of LSD on the auto version of the MX5 is really bugging me. It makes the car spin an inside wheel. Whilst this is quite nice in that it gets rid of excess power over enthusiastic throttle prodding and so adds a safety net it does mean that the car does not accelerate as quick as it could or conversely if wanting to oversteer means it does not, then does, lucrching into it.
I have found Quaife do an LSD though
https://shop.quaife.co.uk/mazda-mx-5-nc-100d-quaife-atb-helical-lsd-differential
So that will be fitted.
I will get some anti roll bars fitted and Eiback lowering springs at the same time as though I donāt want the suspension to be much firmer and donāt mind some roll the amount of roll at the moment is a bit too much.
Ill report back when all that done.
Abbey Motorsports dyno at at the hub.
Consensus was that BBR didnāt do the full stage 1 because of the automatic gearbox, probably 240 at the engine rather than 270. Abbey thought this was probably a sensible decision considering lack of auto gearboxes doing turboās on MX5ās. Ā Me and my damn auto Ā grrrrĀ Ā sob sob ā¦
They fitted the Quaife LSD also and here is a photo of that hidden under itās casing along with a new exhaust to try and at least lose some weight after fitting all the extra bits. That weighs 4kg rather than 12kg for OEM dual twin pipe box.