[brycey2010]

I find my 335 feels faster some days than others, same outside temp, same tank of gas, why would that be? i have noticed this on other cars before, my 335, jb3 map5.
Rich

[bimmerlex]

I thought I am the only one who feels it sometimes

[brycey2010]

thanks, keep it garaged, wheels get dirty quick though, anyway, the difference i feel in power one day to the next can be allot, im sure there is no problem with the car, it felt this way before the jb3 was installed, i have felt the same thing with my motorcycle, and on my vw gti back in the 80's.....

[GaryS]

Barometer and humidity affect it too. Your car will usually feel slower on cloudy or humid days.

[edo]

Maybe it's just your butt, which is less sensitive somedays?

Many factors influence performace, that's why it is normal, imo.

[triggz]

It's all about the weather and how heatsoaked your car gets. If you run it hard it will feel slower after awhile.

[BrianMN]

Originally Posted by brycey2010

I find my 335 feels faster some days than others, same outside temp, same tank of gas, why would that be? i have noticed this on other cars before, my 335, jb3 map5.
Rich

My car DID feel different some days. ....until I got a Procede.

[Bimmer This]

Mine is pretty fast.....when it's like 50 degrees outside.

[Calvin@Vishnu]

With the jb3, you are running what is essentially a boot controller that doubles the factory boost level. And then relies completely on the stock knock controls system to keep the engine from detonating. When you always run at (or beyond) the knock threshold, any engine will be super sensitive to operating conditions (octane, ambient temp, etc,.). It's understanding for any engine, with any tune, to be effected by conditions. But probably not as dramatic as the swings you see with your set up.

[STONEY_M5]

what about the more power with gradual pedal engagement as oppose to pedal to the metal and it feelslike its slower????

sorry lol.

[brycey2010]

[QUOTE=edo;8010264]Maybe it's just your butt, which is less sensitive somedays?

LOL.....

[brycey2010]

Well im glad im not the only one who notices this, the weather here in florida does not vary that much this time of year, at least not enough in my opinion to make any significant impact on performance, just one of those things i guess!!

[brycey2010]

Originally Posted by Calvin@Vishnu

With the jb3, you are running what is essentially a boot controller that doubles the factory boost level. And then relies completely on the stock knock controls system to keep the engine from detonating. When you always run at (or beyond) the knock threshold, any engine will be super sensitive to operating conditions (octane, ambient temp, etc,.). It's understanding for any engine, with any tune, to be effected by conditions. But probably not as dramatic as the swings you see with your set up.

so what setup would you suggest, and why? to get more consistent performance?

[Doug007]

Originally Posted by Calvin@Vishnu

With the jb3, you are running what is essentially a boot controller that doubles the factory boost level. And then relies completely on the stock knock controls system to keep the engine from detonating. When you always run at (or beyond) the knock threshold, any engine will be super sensitive to operating conditions (octane, ambient temp, etc,.). It's understanding for any engine, with any tune, to be effected by conditions. But probably not as dramatic as the swings you see with your set up.

Do you really think he is at (or beyond) his knock threshold on map 5? This kind of stuff is what really turns people off from Vishnu.

These engines, whether stock or tuned, will change performance depending on conditions (ambient temp, humidity, barometric pressure, octane).

The PROcede may very well change more with autotuning, although I think this is a great feature to "downtune" when conditions do not support the power and "tune up" when they do.

I've had this feeling in lots of cars. I think it's a combo of butt dyno calibration and real changes due to conditions (some of which we don't observe well like small changes in humidity or barometric pressure). I do LOVE those cool dry days when the car just seems to be in a mood to party!

Datalogging, dyno runs, or 1/4 mile are the only way to really observe any real differences.

[JhnR]

this war jb3 vs procede = WIN FOR GIAC

[MTV]

It's all in your head dude

[TMR]

With meth and proceed my car feels the same everyday.

[Calvin@Vishnu]

Originally Posted by Doug007

Do you really think he is at (or beyond) his knock threshold on map 5? This kind of stuff is what really turns people off from Vishnu.

Don't mean to turn you off but it's true. Any Procede users can test this by simple running a map5 equivalent boost set up and set ignition correction to 0. On hotter days, the aggression level (which is a weighed and averaged knock count) will go very high. And the higher it goes, the more the DME over-reacts to knock which is what makes the car feel sluggish. But adding proactive ignition retard will not only keep aggression level within the desired range BUT also result in more average ignition advance. Add in some reactive boost reduction if required ignition correction creeps up beyond a given threshold, and you have an engine that is running optimally for the given conditions (temp, baro and octane). As opposed to an engine that i running too much boost with a too high of a timing setpoint. The latter will feel very inconsistent which is what the OP (and others) have experienced first hand. Both set ups will produce less power in worse conditions. But the latter will have a bigger delta.

These engines, whether stock or tuned, will change performance depending on conditions (ambient temp, humidity, barometric pressure, octane).

Yes, but the factory DME responds in the opposite direction and increases boost when ambient temp is high/baro is low. So a pigggback boost controller will have to compensate for these compensations and then apply its own. The factory tune does it so the engine will make close to the same power regardless of conditions. And CAN do it safety because, at just 5-9psi of boost, it operates much further way from the knock threshold.

The PROcede may very well change more with autotuning, although I think this is a great feature to "downtune" when conditions do not support the power and "tune up" when they do.

I've had this feeling in lots of cars. I think it's a combo of butt dyno calibration and real changes due to conditions (some of which we don't observe well like small changes in humidity or barometric pressure).

Datalogging, dyno runs, or 1/4 mile are the only way to really observe any real differences.

The fact that reacting to serious knock results in lower power than preventing the serious knock in the first place is called "knock hysteresis" and it's a fundamental point of concern when tuning an engine. Again, no one is arguing that our engines make less power when operating conditions take a turn for the worse. That is a fact. What I am stating is that you an minimize this power loss by monitoring the effects of the tune and actively adjust boost/timing/fuel to make the best of what Mother Nature throws your way.

[mithiral67]

I notice it too. So many things can effect a cars performance on a given day (even though you think they are the same), that unless you feel like something is off, just keep on motoring.

[SpmnE9zero]

climate is a big factor in performance for most any car, but especially in cars that are turbo'd

[Mike@N54Tuning.com]

Some day to day variation is normal stock and tuned. Lot's of factors contribute that you may not notice such as heat soak, humidity, barometric pressure, oil and water temp, etc. And of course the JB3 has its own set of calculations going on that vary on the above as well.

With the upcoming G4 board the JB3 (finally!) will be reading timing advance (octane), EGT, water temp, oil temp, etc, in addition to IAT and be continuously optimizing the car for the current conditions.

Mike

[Doug007]

Originally Posted by Calvin@Vishnu

Don't mean to turn you off but it's true. Any Procede users can test this by simple running a map5 equivalent boost set up and set ignition correction to 0. On hotter days, the aggression level (which is a weighed and averaged knock count) will go very high. And the higher it goes, the more the DME over-reacts to knock which is what makes the car feel sluggish. But adding proactive ignition retard will not only keep aggression level within the desired range BUT also result in more average ignition advance. Add in some reactive boost reduction if required ignition correction creeps up beyond a given threshold, and you have an engine that is running optimally for the given conditions (temp, baro and octane). As opposed to an engine that i running too much boost with a too high of a timing setpoint. The latter will feel very inconsistent which is what the OP (and others) have experienced first hand. Both set ups will produce less power in worse conditions. But the latter will have a bigger delta.

I agree that IF the car starts knocking, the DME will start pulling timing to save the engine and will really affect performance negatively. Keep in mind he is in FL so probably runs 93 everyday. I don't know what other mods he has (meth?) that would raise the knock threshold even higher.

Originally Posted by Calvin@Vishnu

Yes, but the factory DME responds in the opposite direction and increases boost when ambient temp is high/baro is low. So a pigggback boost controller will have to compensate for these compensations and then apply its own. The factory tune does it so the engine will make close to the same power regardless of conditions. And CAN do it safety because, at just 5-9psi of boost, it operates much further way from the knock threshold.

The factory DME targeting a torque level certainly levels out performance with varying conditions, but performance will still change in cold dry vs. hot humid conditions. When tuned to higher boost levels (any tune) you will feel more variation because the tunes are targeting a boost and this target does not move to maintain a constant power because you are much closer to the knock threshold as you said.

Originally Posted by Calvin@Vishnu

The fact that reacting to serious knock results in lower power than preventing the serious knock in the first place is called "knock hysteresis" and it's a fundamental point of concern when tuning an engine. Again, no one is arguing that our engines make less power when operating conditions take a turn for the worse. That is a fact. What I am stating is that you an minimize this power loss by monitoring the effects of the tune and actively adjust boost/timing/fuel to make the best of what Mother Nature throws your way.

Ugh.

Again, if this thread was about losing performance when hot on a JB3/map 5 with some datalogs showing knock I might agree with you. But it's not. I understand the point on knock hysteresis (i.e., one knock event will cause the car to retard timing across the board and timing will only gradually be advanced), but there's nothing to say his car was knocking here...

He just said the car feels different some days. I have felt this in everycar i've owned. I've felt it stock and felt it tuned.