Review of Digi-tec 125i tune

[Drawn05]

Now that I have some comparisons with another almost identical spec'd 125i (with auto + sunroof) I will post my observations of the tune I got from digi-tec gmbh. I met with chylld earlier today and we utilised my new g-tech pro SS. The only diffrence between our cars is that chylld has 18" wheels, while I have the stock 17".

So the most important issue is that it does have more power, but does it have the 200ish kw that was advertised? I cant verify that yet, but using 0-100km/seconds times it shaves at least 1 second off the stock times (i.e. BMW claims an auto 125i can do 0-100 in 7.0 seconds (6.4 manual).

The best time I have managed today was 6.01, a few 6.1-6.6 but also some 6.9/7.1 times with 2 people in the car. Launching was very difficult, the best times I got were just by hitting the gas from standstill, so getting better traction would certainly improve times. When I did try to launch I was getting 7ish.

Chyllds times were around the 7.1+ mark (from memory), so the tune certainly makes a difference over stock.

This is the dyno chart supplied by Tino at digi-tec



On one of the last runs, it did feel as though the tranmission was struggling under the load. Also, the shift from 2nd to 3rd is another issue that stops the car from breaking into 5 seconds. A manual 125i would be fantastic with this tune, or a better torque converter for the auto.

My car also has the Perf. Exhaust and intake, which I assume add nothing if not minimal improvement over stock. Some 18" wheels and non-rft tyres coupled with this tune would see certainly see mid/high 5 seconds times (launch seems to have traction issues that make under 6 seconds hard).

Overall, having the GM auto and a sunroof isnt going to help anyone be fast, but I think 6 seconds 0-100 is pretty good for the 125i. Thats faster than a stock auto 130i or 128i, so not bad at all.

(many thanks jonathan, hope it didnt take too long to get home).

[Jeef Beef]

18" wheels instead of 17s will make you slower due to higher unsprung weight and rolling diameter. Also, I'm quite certain all autos in Aus-spec BMWs are made by ZF, only the American x28i's get the GM unit.

6 flat sounds pretty good for an auto, what does your butt dyno tell you?

[Drawn05]

going off realoem, I dont have the zf option, just the GA6L45R which is the french gm version.

The main problem is the launch, which I have far from perfrected. The 18" tyres are wider and should give more grip, but we shall see (they certainly look better).

[Jeef Beef]

Originally Posted by Drawn05

going off realoem, I dont have the zf option, just the GA6L45R which is the french gm version.

The main problem is the launch, which I have far from perfrected. The 18" tyres are wider and should give more grip, but we shall see (they certainly look better).

realoem shows two transmissions for the 125i - GA6HP19Z which is the ZF 6spd and GA6L45R which is like you said the GM unit. Not sure which one is the correct one...I just always though Euro-spec models had ZF transmissions.

I don't see why a 118i hatch would get the ZF transmission while your 125i gets the GM.

[dr.bmw]

call me a skeptic....

[jksgoh]

Originally Posted by Drawn05

going off realoem, I dont have the zf option, just the GA6L45R which is the french gm version.

The main problem is the launch, which I have far from perfrected. The 18" tyres are wider and should give more grip, but we shall see (they certainly look better).

Good work with getting the tune!

I duno much bout launching but just from a physics pov shouldn't thinner tyres give more grip? ( assuming the road doesn't have too many inconsistencies)

[Dackelone]

What happens when you race your "almost identical spec'd 125i (with auto + sunroof)" side by side, in say a rolling start? Or at speed???

[Drawn05]

Originally Posted by Dackelone

What happens when you race your "almost identical spec'd 125i (with auto + sunroof)" side by side, in say a rolling start? Or at speed???

Neither location we used was totally devoid of traffic and doing 0-100 runs didnt attract much attention. Racing each other might have been possible at the last location but as I was able to get faster 0-100 times, didnt seem necessary.

[Taymaishu]

Originally Posted by Drawn05

Neither location we used was totally devoid of traffic and doing 0-100 runs didnt attract much attention. Racing each other might have been possible at the last location but as I was able to get faster 0-100 times, didnt seem necessary.

Happy to help as I have a location. PM me :-)

[Taymaishu]

Edit - auto and sunroof with 17s too :-)

[Drawn05]

PM sent

[MrBlonde]

Take the two cars to WSID and do several runs against each other, will give good info and you can go balls out legally.

[Drawn05]

I havent been out there before. My instincts tell me that it is for seriously modded cars, not lower spec'd euro cars. But I am keen if anyone else wants to head out there. Shame its only on wednesdays, would have to get off work early to get out there in time.

Back to the wheel size issue. With the 'bigger is slower' reasoning, a 135 should run faster 0-100 times if it drops down to 17x7 wheels? The wheels I have ordered (have the fronts and just waiting on the rears) are the 18x8 313s, which I think are lighter than my 17". Plus I would be using non-rfts, so I would think this could only help.

[Dackelone]

Originally Posted by Drawn05

Back to the wheel size issue. With the 'bigger is slower' reasoning, a 135 should run faster 0-100 times if it drops down to 17x7 wheels? The wheels I have ordered (have the fronts and just waiting on the rears) are the 18x8 313s, which I think are lighter than my 17". Plus I would be using non-rfts, so I would think this could only help.

Yes, 17's are faster on a 135i - accelerartion wise. At least that is what several 1er forum guys have said. There must be some drag racing guys on our forum!?

[MrBlonde]

Originally Posted by Drawn05

I havent been out there before. My instincts tell me that it is for seriously modded cars, not lower spec'd euro cars. But I am keen if anyone else wants to head out there. Shame its only on wednesdays, would have to get off work early to get out there in time.

Back to the wheel size issue. With the 'bigger is slower' reasoning, a 135 should run faster 0-100 times if it drops down to 17x7 wheels? The wheels I have ordered (have the fronts and just waiting on the rears) are the 18x8 313s, which I think are lighter than my 17". Plus I would be using non-rfts, so I would think this could only help.

There are all sorts of cars at a street meet, from seriously modded cars to factory stock cars. There are more modded cars than stockers but really it makes no difference to you and your run.

If you can organise a group of BMW car owners to go out one night together then it can become a lot more fun.

I hold an ANDRA race licence since 2003 and have been to WSID many many times. I'm happy to come out and how any newbies the ropes. I understand it can be a bit confronting the first time but believe me when I tell you it is very simple and a lot of fun.

[minijet]

Originally Posted by MrBlonde

There are all sorts of cars at a street meet, from seriously modded cars to factory stock cars. There are more modded cars than stockers but really it makes no difference to you and your run.

If you can organise a group of BMW car owners to go out one night together then it can become a lot more fun.

I hold an ANDRA race licence since 2003 and have been to WSID many many times. I'm happy to come out and how any newbies the ropes. I understand it can be a bit confronting the first time but believe me when I tell you it is very simple and a lot of fun.

Yea im up for that if anyone else is.

[Drawn05]

Originally Posted by dr.bmw

call me a skeptic....

This is a vid that was shot last night of a 0-100 run. Its running time is consistant with the times stated by the gtech

Thats pretty quick for a auto 125i.

Edit: not sure why i get all those haircut vids associated with mine

[Taymaishu]

You get those haircut vids because your vid name is 5 967 - those haircut vids have 967 on them too

Nice and smooth. Car sounds great, too!

[Drawn05]

Originally Posted by Dackelone

Yes, 17's are faster on a 135i - accelerartion wise. At least that is what several 1er forum guys have said. There must be some drag racing guys on our forum!?

If 17" wheels are preferable over 18", why does the 135, S3, S4, TTS, TTRS, Golf R and Evo all come standard with 18"? Why would these manufacturers want to a). offer a wheel that would cost more and b). offer lower performance)? Hell, even the mazda 3 mps comes with 18s.

Originally Posted by minijet

Yea im up for that if anyone else is.

+1. Start a thread and see if we can get numbers

[MrBlonde]

Originally Posted by Drawn05

If 17" wheels are preferable over 18", why does the 135, S3, S4, TTS, TTRS, Golf R and Evo all come standard with 18"? Why would these manufacturers want to a). offer a wheel that would cost more and b). offer lower performance)? Hell, even the mazda 3 mps comes with 18s.

He didn't say they offer lower performance, he said they result in slower acceleration figures.

The larger diameter results in longer gearing overall compared to 17" wheels/tyres. Kinda like putting a longer diff ratio in rather than a shorter one.

[QSH17Z]

Very good to know you got your ECU back albeit later than expected. I'm very keen to hear about any further evidence that your car is now around 130i numbers. It would appear to be so far but I would love to see a dyno of yours against another similar 125i (would of course have been even better if you dynoed yours first ) and likewise a 1/4 mile time. I've already done the latter in mine and was not at all impressed with my times. Given my really rough guesstimate I reckon I was only getting 7 seconds flat for 0 - 100kph. But I do have a manual and it's a delicate art getting off the line. I know we've had discussions already about tunes via PM so how does this one compare from the point of view of potentially being wiped after a service at the dealer? Do they offer to reflash the ECU (at the expense of shipping it back again?) or is it once off? I think you know I still have two years warranty left and still two free services to go which I plan to take advantage of. I have read a little on their site but my German is hopeless haha. How much was the total cost (Tuning, shipping, duty? etc)? I've got no idea where the ECU even is but how difficult is it to remove? I still live in hope of realising my dream of a 130i coupe . Please PM me if you don't want to discuss here.

[chylld]

Originally Posted by Drawn05

(many thanks jonathan, hope it didnt take too long to get home).

no worries, got home in about half an hour. could have saved both of us a lot of time though by asking you for a location first!

Originally Posted by Taymaishu

Happy to help as I have a location. PM me :-)

is this the 'usual' spot alex? that one's no good anymore as its crawling with cops and construction vehicles (lots of dirt on the road too)

Originally Posted by MrBlonde

The larger diameter results in longer gearing overall compared to 17" wheels/tyres.

the tyres are thinner to maintain a relatively similar overall rolling diameter, aren't they?