[achien]

Originally Posted by GraphiteBrawler

Wow, having Step, I've never experienced this, but it sounds like a pain in the ass, any way to fix it for you 6mt guys?

Step (AT) is also having this problem (no car w/ AC is immune to this), you just don't "feel" it as much as the drivetrain is not hard-coupled to the engine (the torque-converter in the AT cushions the impact).

To avoid this, I try to not to use the AC unless it feels hot enough to become "necessary". I usually turn the entire system off, including the fan.

P.S. That's probably why some Lotus buyers are paying $3,000 to have the standard AC removed.

[GeorgiaTech335coupe]

This is a blessing in disguise, the engine sounds awesome at high revs. Listen to it purr through each gear then shift!

[danimal]

Originally Posted by ward

FDC's right

with AC the way it is now, you have a certain amount of engine power that is required to turn the AC compressor

if you had an electric AC compressor, you'd need electricity, which is made by the alternator, which is spun by the motor. So if you needed electric AC the alternator would draw more energy from the motor

turning mechanical energy into electrical energy is not a %100 efficent process, so if you had an electrical AC compressor your engine would have to work harder than if you had a standard mechanical AC compressor

Makes sense, but could you please reconcile what you're saying with the following?

Electric A/C
There are real advantages in an electrically driven air-conditioning compressor. First and foremost, it relieves the engine of a major parasitic drag. Second, as the unit doesn't need any belt drive, it offers packaging advantages underhood. Third, its size and operation are enhanced by being independent of engine speed.

By contrast, an engine-driven a/c compressor has to be sized for worst-case conditions, namely providing maximum cooling at engine idle. A similar situation exists for power-assisted steering, though its power requirement is considerably less than a/c's. In fact, we have electric steering-assist on many 12-volt cars. Alas, electric a/c requires a hybrid's high voltage.

Source: Road & Track

[dmboone25]

Originally Posted by itsbrokeagain

i have noticed that as well...below 3000 rpm the engine drops like a rock and I have to quick shift or blip the gas to keep it from lurching.

Yeah, I have noticed this too. Price we pay to keep cool...

[mesier1111]

Originally Posted by wj4

I, too, notice that. But I notice it with other cars as well. I believe when the a/c is on, it's using a lot of juice from the surge compressor that's why.

Most A/C units grab anywhere from 20-25 horses from an engine.....that is a lot of HP. Why I hate using A/C/, though I do. Cruising on the highway with the AC I will get 30mpg, turn the AC off and I literally see the instant mpg monitor shoot from 30 to 33. Sick.

[mesier1111]

Originally Posted by Walked U

I got the cdv delete. Now it shifts like a hot knife through butter. Even with the AC on

Could you mkae a video of hot knife through butter for us? you are the vid man so no reason to keep it to cars.........

[mesier1111]

Its amazing to me how many people drive with their climate control in auto mode and don't realize/care that turns the A/C on if th etemp is over 40 degrees. Its amazing how many of my friends who own Zs and other performance oriented cars and like to drive fast do this......they are robbing so much power and killing their gas mileage.

[Atombyte]

Originally Posted by ward

FDC's right

with AC the way it is now, you have a certain amount of engine power that is required to turn the AC compressor

if you had an electric AC compressor, you'd need electricity, which is made by the alternator, which is spun by the motor. So if you needed electric AC the alternator would draw more energy from the motor

turning mechanical energy into electrical energy is not a %100 efficent process, so if you had an electrical AC compressor your engine would have to work harder than if you had a standard mechanical AC compressor

Actually, the drag the alternator puts on an engine does not vary by power output. It produces electricity based on how fast it is turned, but does not have a clutch to engage/disengage like the A/C compressor and doesn't have hydraulic drag like a power steering unit. The downside to using up too much power on accessories is the alternator may not be able to keep the battery charged.

An electric A/C unit would allow for cooling without the HP loss of a belt-driven unit. However, the power demands for it would be a bit high for a regular 12-volt system presently available in non-hybrid vehicles.

[Pangearox]

i have the best solution to your problem.

shift at a higher rpm....hahaha you bought a bmw, USE IT!!!!!

[itsbrokeagain]

Originally Posted by dmboone25

Yeah, I have noticed this too. Price we pay to keep cool...

I broke down and finally used mine for a good bit today. 95 degrees sitting in traffic trying to get over the George Washington Bridge to the Cross Bronx Expwy trying to get home from the meet. I drove with the windows down and the sunroof open on the way to NJ in the morning...beautiful weather and I needed to get a tan.

By late afternoon, it was sweltering and somewhat humid. Made it halfway back sitting in stop and go traffic, sweating my ass off and I said F this, closed the sunroof AND the shade, and up the windows went.

The downside? I burned $20 in gas to go....40 miles. Lousy freakin 1st gear traffic.

[srs148]

yup, same here with my E93. I noticed the same thing with my 1986 E30 325es as well as my 1989 E30 325i (both manual transmissions).... that is, if you don't shift fast enough or at a high enough RPM, you get a bit of a lurch with the AC on... oh well, i still love my car

[urbanite]

Damn. I knew I should have bought an AT. It sounds so much better.

So which is better overall ... MT or AT ???

[DCJAX]

Originally Posted by Pangearox

i have the best solution to your problem.

shift at a higher rpm....hahaha you bought a bmw, USE IT!!!!!

That's what I was thinking. I'm happy to lose a couple HP in order to avoid swamp ass.

[ALPINE6SPD]

Originally Posted by urbanite

Damn. I knew I should have bought an AT. It sounds so much better.

So which is better overall ... MT or AT ???

I hope your joking If not

[Sea2Ski]

Originally Posted by urbanite

....

So which is better overall ... MT or AT ???

NO!!!!!!!!!!!!!!!!!!!

Don't go doing that!

[achien]

Originally Posted by urbanite

Damn. I knew I should have bought an AT. It sounds so much better.

So which is better overall ... MT or AT ???

Here we go again, do you want this thread to be "Closed" too?

[urbanite]

Originally Posted by Sea2Ski

NO!!!!!!!!!!!!!!!!!!!

Don't go doing that!

It's a joke, it's a joke!

[STE92VE]

Originally Posted by mesier1111

Its amazing to me how many people drive with their climate control in auto mode and don't realize/care that turns the A/C on if th etemp is over 40 degrees.

I never touch the climate control and leave it on auto mode. Been driving this way since I took delivery. The car performs well at all shift points. I'm as sensitive about performance as the next guy and really don't have an issue with it. Maybe my N51 is a wonder engine!

[oldaccount]

i HATE driving with the AC on. I rarely ever do. Unless im really paying attention, and i remember that I have the AC on, a regular upshift feels like a rev-match downshift, without the rev matching part lol.

I can live without a modified CDV without using AC, the shifts feel fine to me, but if we have any more 100+ degree days that absolutely require AC, i may have to get one.

[homerunball]

Since the AC system is looped around the crank, when it is under load it upsets the balance between the crankshaft and the flywheel thereby producing the side effect of having a lightened flywheel. Anyone who has lightened their flywheel knows that the engine may climb up the rpm band a lot faster but it also comes back down with a vengence. Auto makers have balanced it in such a way that a normal driver can shift the gears comfortably and the engine speed will slow down at a rate that would automatically rev match to the next higher gear.

The climate control system is one of the most energy sucking features on any car, besides driving, and most cannot run on electricity alone; you would need many batteries to power that, hence you see it on EV's or hybrids. In the forseeable future, there may be systems implemented to reduce the AC load when accelerating but it will not likely switch to full electric any time soon.

[oldaccount]

Originally Posted by homerunball

Auto makers have balanced it in such a way that a normal driver can shift the gears comfortably and the engine speed will slow down at a rate that would automatically rev match to the next higher gear.

man, that kinda makes me feel bad....i must be worse than a "normal" driver:laughaboe

[homerunball]

Originally Posted by Suareezay

man, that kinda makes me feel bad....i must be worse than a "normal" driver:laughaboe

I meant it was balanced for no AC load.

I'm sure you are a fine driver with no shift issues when the AC is off. I have to change my shifting behavior when the AC is on in any car.