Review of Digi-tec 125i tune

[MrBlonde]

Originally Posted by bmroxm5

He got the G Tech after the tune.. only comparo is against Chylld's stock 125i.

Argh! I guess the best bet then is running at WSID against a stck 125 with same tranny and wheel/tyres on the same day. Say over 4 passes against each other. Then compare average trap speeds.

[chylld]

Originally Posted by MrBlonde

Argh! I guess the best bet then is running at WSID against a stck 125 with same tranny and wheel/tyres on the same day. Say over 4 passes against each other. Then compare average trap speeds.

the times we're getting is fully indicative of a performance improvement close to the advertised gain. i'm not sure if drawn05 would have much use for more precise measurements...

best next move is to compare actual track laptimes (none of this straight line BS) on a fast circuit like EC or WP. it should slot nicely in between the x25 and x35 times, a 130i would also be a nice basis for comparison

[MrBlonde]

I don't agree at all. The way to do it would have been dynosheet before and then dynosheet after on same machine.

To measure power in a real world situation then a drag strip is hands down the best place to do it. The timing equipment and weight station is setup to easily get highly accurate information.

But each to their own. If you want a G tech toy and a "butt dyno" to be your purchase guide, then follow your bliss!

[1q2w3e4r]

You can't compare laps times unless you put the same drive in both cars. The best measure is 1/4 mile trap speed in the same or
similar conditions and/or dyno runs on the same machine in the same conditions, lap times won't tell you much due to all the variables

[chylld]

Originally Posted by MrBlonde

I don't agree at all. The way to do it would have been dynosheet before and then dynosheet after on same machine.

To measure power in a real world situation then a drag strip is hands down the best place to do it. The timing equipment and weight station is setup to easily get highly accurate information.

But each to their own. If you want a G tech toy and a "butt dyno" to be your purchase guide, then follow your bliss!

Do what exactly? If drawn05 only cares about precise quarter mile times and straight-line acceleration then yes, obviously you're correct. But if he only wants to make sure he's in the ballpark for the advertised output, and is instead interested in how that extra power helps around a track, then a G tech toy is more than adequate for now.

Also depends on what his definition of "real world" is - the whole track, or just the straight bit.

Originally Posted by 1q2w3e4r

You can't compare laps times unless you put the same drive in both cars. The best measure is 1/4 mile trap speed in the same or
similar conditions and/or dyno runs on the same machine in the same conditions, lap times won't tell you much due to all the variables

Then you put the same driver in both cars.

[MrBlonde]

Originally Posted by chylld

Do what exactly? If drawn05 only cares about precise quarter mile times and straight-line acceleration then yes, obviously you're correct. But if he only wants to make sure he's in the ballpark for the advertised output, and is instead interested in how that extra power helps around a track, then a G tech toy is more than adequate for now.

Also depends on what his definition of "real world" is - the whole track, or just the straight bit.

Then you put the same driver in both cars.

I don't understand, the Digi-Tec tune is advertised to improve the power delivered, correct? Given that a pass on a drag strip is pure acceleration, this will measure in real world verifiable terms any change in performance.

Driving around a circuit will measure so many more variables about a car and driver than altered engine performance.

The Digi-Tec tune does not advertise improvements around Eastern Creek or Wakefield. It advertises an increase in peak horsepower.

Edit: On second read of your comment I wondered if we aren't mixing topics here. I'm not commenting on the relative merit of drag racing a street BMW 1 series vs circuit racing a street BMW 1 series. I'm just talking about the best way to evaluate what you got for your money with a tune.

[chylld]

Originally Posted by MrBlonde

I don't understand, the Digi-Tec tune is advertised to improve the power delivered, correct? Given that a pass on a drag strip is pure acceleration, this will measure in real world verifiable terms any change in performance.

Driving around a circuit will measure so many more variables about a car and driver than altered engine performance.

The Digi-Tec tune does not advertise improvements around Eastern Creek or Wakefield. It advertises an increase in peak horsepower.

Yes, the digi-tec tune advertises an improvement in power delivery to a level roughly between a 125i and a 135i. In straight-line testing, we have already seen that yes, the power has increased to roughly that level.

As I said before, it all depends on what Drawn05's definition of "real world performance" is. If all he cares about is straight-line performance, then the drags would be the logical next step for him. By doing this he will get confirmation of what he already knows, but at least it will make you happy.

However if he wants to find out how the increased power increases the car's overall performance as, well, a car (that turns and stuff) then the track would be the logical next step. Do you think he'd be happy if the increased power upset the chassis balance and showed no ultimate laptime improvement over stock?

Horses for courses. There are people who buy cameras and only take pictures of test charts and brick walls, and never go shoot real subjects. There are people who buy high-spec computers then only run benchmarks and never play any actual games. Likewise with cars, there are some people who are happy to just be faster than anyone else off the line, whilst there are others whose race continues past the main straight, around the circuit a few times and to the finish line.

[chylld]

Originally Posted by MrBlonde

Edit: On second read of your comment I wondered if we aren't mixing topics here. I'm not commenting on the relative merit of drag racing a street BMW 1 series vs circuit racing a street BMW 1 series. I'm just talking about the best way to evaluate what you got for your money with a tune.

We are mixing topics slightly, but there is no right or wrong here. It will differ wildly from person to person.

If we are strictly trying to verify digi-tec's kW claims, then the ONLY way to do that would be on a dyno, immediately before the tune and immediately after, as you pointed out yonks ago. Failing that, a dyno against a stock car (and I'll happily lend my car for that purpose if he wants.)

If it's not a strict kW chase however, then it's all up to the owner and whatever metric he chooses.

[Jeef Beef]

Disregarding laptimes, all I really want to know (and I'm sure other forum members do too) is whether Digitech is truthful about their claims. The numbers do show an improvement, but they don't look that impressive.

[chylld]

Originally Posted by Jeef Beef

Disregarding laptimes, all I really want to know (and I'm sure other forum members do too) is whether Digitech is truthful about their claims. The numbers do show an improvement, but they don't look that impressive.

They claim (according to the dyno graph in post #1) an improvement from 171.7kW to 208.4kW, i.e. an improvement of 21%.

The excel number-crunching (power-to-weight vs acceleration force) I've done suggests that the tune is providing slightly less than advertised, after you factor in the performance intake and exhaust.

Only a dyno day will answer this question obviously...

[1q2w3e4r]

Originally Posted by chylld

Yes, the digi-tec tune advertises an improvement in power delivery to a level roughly between a 125i and a 135i. In straight-line testing, we have already seen that yes, the power has increased to roughly that level.

As I said before, it all depends on what Drawn05's definition of "real world performance" is. If all he cares about is straight-line performance, then the drags would be the logical next step for him. By doing this he will get confirmation of what he already knows, but at least it will make you happy.

However if he wants to find out how the increased power increases the car's overall performance as, well, a car (that turns and stuff) then the track would be the logical next step. Do you think he'd be happy if the increased power upset the chassis balance and showed no ultimate laptime improvement over stock?

Horses for courses. There are people who buy cameras and only take pictures of test charts and brick walls, and never go shoot real subjects. There are people who buy high-spec computers then only run benchmarks and never play any actual games. Likewise with cars, there are some people who are happy to just be faster than anyone else off the line, whilst there are others whose race continues past the main straight, around the circuit a few times and to the finish line.

Yes, because lapping ECR and Wakefield is indicative of real world use and performance How is it going to "increase the car's overall performance" if currently the power has been upped in the car. It's not going to change the handling or braking dynamics of the car or "upset the chassis balance" (your kidding right with an extra 20 kw?) Its simply going to impact the straight line speed hence the comment to take it to a drag strip to measure the improvement. Dropping in aftermarket suspension would result in a bigger drop as far as lap times go.

This isn't a drag race/vs track argument the best way to measure real world power improvements is at the drag strip with trap speed or the dyno as you mentioned, it'll tell you what the real world improvements are as far as power will much more than going to a race track with corners (I've heard they exist) but the strip is much more fun than standing around a dyno machine.

[chylld]

Originally Posted by 1q2w3e4r

Yes, because lapping ECR and Wakefield is indicative of real world use and performance How is it going to "increase the car's overall performance" if currently the power has been upped in the car. It's not going to change the handling or braking dynamics of the car or "upset the chassis balance" (your kidding right with an extra 20 kw?) Its simply going to impact the straight line speed hence the comment to take it to a drag strip to measure the improvement. Dropping in aftermarket suspension would result in a bigger drop as far as lap times go.

This isn't a drag race/vs track argument the best way to measure real world power improvements is at the drag strip with trap speed or the dyno as you mentioned, it'll tell you what the real world improvements are as far as power will much more than going to a race track with corners (I've heard they exist)

As far as I know, the real world contains both turns and straights Using the term 3 times in your post whilst advocating straight line performance is just slightly ironic.

But yes you're right, this isn't a drag race vs track argument. This is just about 2 things:

1) Whether digitec's claims are accurate. We will test this by putting both my car and Drawn05's car on a dyno, and see if we get the same 21% difference or more (due to intake and exhaust)

2) Whether Drawn05 is happy with his tune. This depends on how he judges his car's performance in the situation that matters to him. Obviously I favour the track as a proving ground and you favour the strip, but those are our decisions for ourselves and not for him.

[1q2w3e4r]

Originally Posted by chylld

As far as I know, the real world contains both turns and straights Using the term 3 times in your post whilst advocating straight line performance is just slightly ironic.

But yes you're right, this isn't a drag race vs track argument. This is just about 2 things:

1) Whether digitec's claims are accurate. We will test this by putting both my car and Drawn05's car on a dyno, and see if we get the same 21% difference or more (due to intake and exhaust)

2) Whether Drawn05 is happy with his tune. This depends on how he judges his car's performance in the situation that matters to him. Obviously I favour the track as a proving ground and you favour the strip, but those are our decisions for ourselves and not for him.

Not really, I don't agree with point 2. I think its a validation point to measure performance improvements via power increases at the strip compared with the track. Dynos are great, however there are a lot of variables that go into one of those as well, how tight the vehicle's strapped down, tyre pressure, ramp rate, shootout mode and the like. Before and after trap speeds don't lie, especially when its your car and your driving and you want to go as quick as possible. I guess I'm just trying to articulate there is no ulterior motive when your out there doing it. The car runs what it runs as opposed to on the dyno. However when its on an independent dyno it doesn't matter so much.

Though whenever I want to know if the Y power increase from X baseline has made a difference in the power of my car. I use the strip. I'm pretty sure I've run around the odd corner or two in my time for some fun as well!

[chylld]

Originally Posted by 1q2w3e4r

Though whenever I want to know if the Y power increase from X baseline has made a difference in the power of my car. I use the strip. I'm pretty sure I've run around the odd corner or two in my time for some fun as well!

Respect

In that case we should skip the dyno then - even a before/after one as MrBlonde suggested would be meaningless because the straps might have loosened or whatever. (edit: unless the car was tuned ON the dyno, which of course we know it wasn't)

I agree that if power was the only thing you were looking to measure, you eliminate corners from the test. My reasoning for bringing the track argument to the table was: if his car proves faster than a stock 125i at the strip, but not faster at all on the track, would he feel happy with his tune?

[Drawn05]

Originally Posted by Jeef Beef

Disregarding laptimes, all I really want to know (and I'm sure other forum members do too) is whether Digitech is truthful about their claims. The numbers do show an improvement, but they don't look that impressive.

I think it gives as much of an improvement as it can. BMW (and other car mags) state that the manual 130i does 1-100 in 6.1, which I have bettered with this tune.

I think the biggest issue now is the torque converter. The 130/330 auto uses R171TTD whilst mine uses R145TTD (same as 128i). I assume that having a lower spec'd torque converter isnt going to help the performance.

[MrBlonde]

Car mags are great. Here's how a 130 does at WSID.

[Drawn05]

Got the 313s installed yesterday and it drives like a dream, wish I had done this sooner.



Still feels that the torque converter isnt locking properly. That will be the next thing I look at, if i can replace it for the 130i one at a reasonable price.

[EgoPaintedGrey]

Does anyone know if 125 6mt and 130 6mt have the same transmissions?

[Drawn05]

No, the 125 has GS6-17BG while the 130 has GS6-37BZ.

[flinchy]

Theyre getting 170kw out of the160kw 128i... I'm guessing engine dyno? So the 125i actually makes 11kw more than the factory says? Then this tune puts it even 13kw over stock 130i.. Heck i'd be happy with close to 210kw at the crank lol

[flinchy]

Double

[koastal]

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.

I tell you it is very simple and a lot of fun.

My 18 year old daughter did it the other nite. She had fun and no one died or pointed and laughed