Power Loss on track?

TennTex · 09-25-2007, 09:05 PM

I've searched the track and NA engine forums and haven't seen anyone reporting a drop in power on 330i's.

I attended a Drivers Edge HPDE at Motorsport Ranch (MSR) outside Ft. Worth a couple weeks ago with my 330i Sport w/ Auto transmission. This is my 3rd event, and I decided to turn off all traction control, so I could really feel the car working.

On Sat. I drove with the auto in DS "Drive Sport" mode as usual. MSR has some significant elevation changes, and my instructor suggested driving in Manual mode to keep the powerband up. I confirmed on Sat. night that Manual mode will hold a given gear and not downshift until around 1K rpm.

On Sun. I used Manual mode and let the engine do the upshifts at 7K automatically, and then manually downshift when needed in slow corners. (Normally from 3rd to 2nd.) In my last 2 afternoon sessions, with the air temp around 90F, I noticed what felt like a drop in power. No indicators or anything on the display. I was too busy to look down at the gauges a lot, but I do recall that it was hovering around 5K and not ramping to 7K like I thought it should. That said, later in the lap, the car accepted the manual downshift to 2nd, and definitely revved back to 7K and shifted.

Unfortunately, my instructor had to leave a bit early, and while I was glad to have been signed-off to solo, I had hoped to get his opinion on the feel on my last run.

So, I'm stuck wondering if my car simply got hot and the Vanos dialed back the power, or was it my brain "slowing down" as my confidence went up.

I'm curious if any others have confirmed a power loss on track...

ScheerSpeed · 09-25-2007, 10:09 PM

hotter air=less air density=less fuel needed=less power made

ScheerSpeed · 09-25-2007, 10:10 PM

there is a BIG difference in the jetting (fuel-air ratio) depending on if its 80 degreess to 90. those 10 degrees can make a hell of a difference.

TennTex · 09-25-2007, 10:46 PM

Thanks. I remain suspicious of heat. BUT, the drop in power seemed more sudden, at about 10~15 min. into the session. If I just had a few hp less than on a cold day, I wouldn't have been able to tell the difference.

ScheerSpeed · 09-26-2007, 02:55 PM

Quote:

Originally Posted by TennTex

Thanks. I remain suspicious of heat. BUT, the drop in power seemed more sudden, at about 10~15 min. into the session. If I just had a few hp less than on a cold day, I wouldn't have been able to tell the difference.

when driving a car on a race track, you notice every bit of power gained of lost. not only do you lose some HP, your throttle response also suffers from heat. and although your engine temp actually remains the same, after running a car for a long while the engine will start to become "tired". why this is id ont know, but for instance towards the end of a Formula Renault race, you could feel the engin becoming weaker and weaker...

TennTex · 09-26-2007, 08:25 PM

Thanks ScheerSpeed. I assume it was just a general loss in power, as you say maybe it was "tired" after running hard for 8 sessions over 2 days. The car drove fine home, and I hope I didn't damage anything. I was mainly curious if anyone else had ever felt this in their E90.

09-25-2007, 09:05 PM	#1
TennTex New Member 0 Rep 6 Posts Drives: 330i Sport pkg, Monaco Blue Join Date: Jul 2007 Location: Tyler, TX iTrader: (1)	Power Loss on track? - 330i I've searched the track and NA engine forums and haven't seen anyone reporting a drop in power on 330i's. I attended a Drivers Edge HPDE at Motorsport Ranch (MSR) outside Ft. Worth a couple weeks ago with my 330i Sport w/ Auto transmission. This is my 3rd event, and I decided to turn off all traction control, so I could really feel the car working. On Sat. I drove with the auto in DS "Drive Sport" mode as usual. MSR has some significant elevation changes, and my instructor suggested driving in Manual mode to keep the powerband up. I confirmed on Sat. night that Manual mode will hold a given gear and not downshift until around 1K rpm. On Sun. I used Manual mode and let the engine do the upshifts at 7K automatically, and then manually downshift when needed in slow corners. (Normally from 3rd to 2nd.) In my last 2 afternoon sessions, with the air temp around 90F, I noticed what felt like a drop in power. No indicators or anything on the display. I was too busy to look down at the gauges a lot, but I do recall that it was hovering around 5K and not ramping to 7K like I thought it should. That said, later in the lap, the car accepted the manual downshift to 2nd, and definitely revved back to 7K and shifted. Unfortunately, my instructor had to leave a bit early, and while I was glad to have been signed-off to solo, I had hoped to get his opinion on the feel on my last run. So, I'm stuck wondering if my car simply got hot and the Vanos dialed back the power, or was it my brain "slowing down" as my confidence went up. I'm curious if any others have confirmed a power loss on track...
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09-25-2007, 10:09 PM	#2
ScheerSpeed Major General 414 Rep 5,768 Posts Drives: '13 F30 Estoril M-Sport 335i Join Date: Sep 2006 Location: Miami, FL iTrader: (14)	hotter air=less air density=less fuel needed=less power made
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09-25-2007, 10:10 PM	#3
ScheerSpeed Major General 414 Rep 5,768 Posts Drives: '13 F30 Estoril M-Sport 335i Join Date: Sep 2006 Location: Miami, FL iTrader: (14)	there is a BIG difference in the jetting (fuel-air ratio) depending on if its 80 degreess to 90. those 10 degrees can make a hell of a difference.
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09-25-2007, 10:46 PM	#4
TennTex New Member 0 Rep 6 Posts Drives: 330i Sport pkg, Monaco Blue Join Date: Jul 2007 Location: Tyler, TX iTrader: (1)	Thanks. I remain suspicious of heat. BUT, the drop in power seemed more sudden, at about 10~15 min. into the session. If I just had a few hp less than on a cold day, I wouldn't have been able to tell the difference.
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09-26-2007, 08:25 PM	#6
TennTex New Member 0 Rep 6 Posts Drives: 330i Sport pkg, Monaco Blue Join Date: Jul 2007 Location: Tyler, TX iTrader: (1)	Thanks ScheerSpeed. I assume it was just a general loss in power, as you say maybe it was "tired" after running hard for 8 sessions over 2 days. The car drove fine home, and I hope I didn't damage anything. I was mainly curious if anyone else had ever felt this in their E90.
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