[revah2]

I remember reading a while back on these forums about several people who had brought their 335is in for a software upgrade and claimed to have lost around 5-10whp.

Well, to make a long story short, ever since I got my 2nd 335i, (production date May 07), I always felt a very noticeable but slight and almost insignificant loss in power in comparison to the first 335i- (September 06 production date). To prove it i even did several runs with my Gtech pro in both cars, both 6MT, both cars launched at 3k rpms.

The September 335i managed 13.35 @105.58 mph, with a 0-60mph of 4.82s.
The May 07' 335i managed 13.52@104.8 mph, with 0-60mph of 4.92s
>These were my best runs after 10 runs in each car<

I know this is somewhat pure speculation, but considering the fact that the September 06 335i hasnt been brought in for service yet (avoiding that upgrade for as long as possible lol), I began to wonder if BMW was sending the newer 335is out of the factory with 5-10 less whp. So, is my september 335i quicker than my May 335i? Was there really a software "fix" that shaved off a few whp from our 335is?Was it the temperature/ humidity that made the difference?
Both cars were run on the same road at the same time of night. Ran the september car in January and the May car last night

[1clean335i]

I think its just the weather... You pretty much answered it yourself in your last sentence saying you ran the older car in january and the newer one last night.

In january it was much cooler at night than it is now at the end of august. The air in the winter is much denser which is most likely why the older car ran a little better. Im sure miami is still humid as hell right now cause it is here in the tampa bay area as of right now...

I wouldnt worry about it too much

[TheAcAvenger]

That was rumored for a while but never verified. I think shiv actually proved it to be false. What you're more likely experiencing is the dramatic the difference between running a car in the summer and running the car in the winter. Not to mention that you live in Miami, so i'd imagine its pretty hot there.

Wait til it cools off out there and do it again.

Edit: clean beat me to it

[Dr_Dirt]

I also have a Gtech and I often wonder how to be sure that your Gtech is properly calibrated?
How often do you need to calibrate this thing?

[wj4]

I think like a member mentioned...the weather is the culprit. It is still relatively hot right now, compared to 6+ months ago when it was cooler.

Turbo'd car performs noticeably better under cooler conditions. If you were to put a boost gauge in your car, you'd see it spike 1-2 PSI higher than normal on cool nights.

If you really want to put this to the test, have both cars dyno'd back to back and see if the difference is small or big. Gtech is well known not to be accurate.

[E90ice]

The weather plays an important factor everytime you run your car, but who knows? Maybe BMW realized that the 335s were running too much hp in comparison to the new M3 afterall .

[wj4]

Originally Posted by E90ice

The weather plays an important factor everytime you run your car, but who knows? Maybe BMW realized that the 335s were running too much hp in comparison to the new M3 afterall .

This is why they watered it down from the start.

There were words way even before the release of the 335 that the car can handle more power than what it comes stock with not to steal the candle from the upcoming of the M3.

[E90ice]

Originally Posted by wj4

I think like a member mentioned...the weather is the culprit. It is still relatively hot right now, compared to 6+ months ago when it was cooler.

Turbo'd car performs noticeably better under cooler conditions. If you were to put a boost gauge in your car, you'd see it spike 1-2 PSI higher than normal on cool nights.
If you really want to put this to the test, have both cars dyno'd back to back and see if the difference is small or big. Gtech is well known not to be accurate.

Thats were I get kinda confused, because, yes, you do feel like your car is running slightly slower on hotter days, but I did 2 different track days with totally different temps and I got pretty much the same times:

90 F 13.1 @ 106
74 F 13.0 @ 107

I'm confused

[wj4]

^20 degree is quite a difference I will say. Maybe you had a bad day one day and couldn't shift the gears and launch correctly?

I don't even bother redlining my car if the weather is more than 70 degrees myself, soo slow

[revah2]

Originally Posted by Dr_Dirt

I also have a Gtech and I often wonder how to be sure that your Gtech is properly calibrated?
How often do you need to calibrate this thing?

Not sure there is a way to calibrate it minus putting in the appropriate weight of your car, redline, and all that other stuff it asks you before you use it for the first time.
Didn't think weather could have such a heavy impact on turbo engines. .2 seconds off the quarter mile is no laughing matter

[revah2]

One other thing about the gtech is it needs to be put in a place where it doesn't move. The slightest movement of the gtech while recording completely effs up thereadings. What I like to do is put it in that slot in the passenger seat, fits perfectly.

[pauly1]

I'm not the slightest bit surprised to see a variation of .2 sec in your times, and I wouldn't worry about it.

There are 4 big variables involved here

1. (Weather) As others have pointed out, Weather plays a substantial factor in your times. Comparing a crisp bone dry January night to a thick humid summer day is truly night and day.

2. (The G-Tech Pro) These have been know to be questionable in the past

3. (6 Speed Manual) Launching the car isn't always the same, and your 60' times really determine your quarter and 0-60.

4. (YOU) For as hard as you try, you might not be hitting your gears as hard every time through the gate.

Add all that up and you can easily account for the time difference. Not to mention that fact that 5 to 10 hp will not shave more than a tenth to begin with, if that.

[Lee Rambler]

Originally Posted by E90ice

Thats were I get kinda confused, because, yes, you do feel like your car is running slightly slower on hotter days, but I did 2 different track days with totally different temps and I got pretty much the same times:

90 F 13.1 @ 106
74 F 13.0 @ 107

I'm confused

1 mph is not a negligible difference in trap... that's roughly 10hp

[hool97]

Originally Posted by Lee Rambler

1 mph is not a negligible difference in trap... that's roughly 10hp

I agree and so is a tenth.

[Lee Rambler]

a tenth can be traction though... but you can't fool mph

[gloster]

What about natural variation between 335i's? I bet if you took any two of them, you are going to see some variation. Maybe not 10hp, but they're not going to be identical.

[Lee Rambler]

I would believe 10hp variance between cars - at the extremes, ie lowest ones being 10hp lower than the highest ones

[SGP335i]

Originally Posted by 1clean335i

I think its just the weather... You pretty much answered it yourself in your last sentence saying you ran the older car in january and the newer one last night.

In january it was much cooler at night than it is now at the end of august. The air in the winter is much denser which is most likely why the older car ran a little better. Im sure miami is still humid as hell right now cause it is here in the tampa bay area as of right now...

I wouldnt worry about it too much

+1 all cars are slightly different as well

[AlpineM6GC]

i can believe that. Remember the car and driver test(or some magazine) where one earlier production 335 made more HP than the newer 335 on the dyno? I believe they said that the eariler one made 1 or 2 psi more then the other. I can't confirm it was the updated software that caused this but it would make sense. Esp. since the 335 is underrated and the m3 is on its way.
Danny

[hotrod182]

The variables are caused by:
Temperature, Humidity, etc.
Break in mileage....car should be faster after about 5000 miles or so..
Car differences..
And simple launch differences...and autos are definitely more consistant.

Also, make sure when you press start on the Gtech, your car is COMPLETELY still, not rocking on the springs still. So usually come to a stop, count about 3 seconds or more before hitting the start button.

[revah2]

Thanks for the input but I'm still
Some saying that it's very well possible that they are being released from the factory a bit slower than the earlier production models
As much as I'd like to believe its the temp/humidity its hard to>.<
In Florida, the difference in temperatures in the middle of january compared to temperatures at the end of August is very minimal.
Sure, there is a difference, but at night i wouldn't say more than 10 degrees or so.
Thanks for the tips on the Gtech, I'll try it out tonight.
For the record i raced my buddies M3 last night
We're both stock.
On a 40 roll i had half a car on him up until 110. (His front end at my rear tire
On a 20 roll i almost an entire car on him approaching 110
The only M3s I tend to loose to on a roll are the ones with SMG Perfect, quick shifts>.< But from a dig its a different story. I'm not even sure how you would launch an SMG from a dig
Anyhow I'm straying off topic, point being here is if I'm beating M3s I guess i have nothing to complain about

[1clean335i]

if you take your car to the track in january, and again at this time of year you will see what i am talking about.. sure the temperature difference might not be too much, but the humidity changes alot between the seasons... i've experienced this personally with my lexus which is also boosted.

you should take your other 335i and run your buddy with the m3 again and see how it compares. im sure the difference will be minimal to none.