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240search
11-01-2002, 08:45 AM
I have owned and maintained a 91 240sx manual for 2 years. I always thought it was fairly fast. recently I bought a another 91 240sx for my wife which is a auto. both cars are in great condition, no engine,tranny flaws whatsoever.  since purchasing the auto 240sx, it seems it has better pick up then my manual 240sx, which disappoints me. and my manual 240sx has no problems what soever. it is so smooth, but this auto picks up much faster. no mods in both cars, only intakes.

If you think about it, both cars are estimated at 155hp. manual has 5 speed. auto has 4 speed, Do you think it only takes 4 gears to reach to 155hp and it takes 5 gears to reach that. does that explain why the auto feels faster. I know many of you may disagree, but after driving a manual 240sx, have you tried a automatic 240sx?
its sad, but it has better pick up for some reason

240search
11-01-2002, 08:49 AM
just another note, auto has a overdrive, which is like a 5th gear, but when the overdrive is on at 1st gear, it is much smoother then when its off. is this a reason the auto is faster. please i need help on this. im beginning to like my wifes automatic 240sx, only because it picks up so easily.

AKADriver
11-01-2002, 09:39 AM
'better pick up' doesn't mean a damned thing.  Actually it does point out one thing that automatics do...  the torque converter performs a bit of torque multiplication (like gears do) as it spins up.  The result is that from a standing start, first gear will effectively feel 'lower' than it really is, causing the car to scoot off the line.

Do metered 0-60, 1/4 mile runs and the automatic will be consistently slower.

Engine output is independent of gearing.  That 155hp figure was obtained by Nissan with the engine attached to a dynamometer by itself with no transmission.

Having fewer gear ratios is typically what makes automatics slower.  Increased power lost to the transmission itself to maintain fluid pressure is a factor, but less of one.  Notice that when the automatic shifts at full throttle, the revs drop farther then they do in your manual.  The 'spacing' between the gears is wider.  As you've noticed, the auto's 4th is like the manual's 5th - 4 gears in the same space as 5.  This means you spend more time outside the torque band.

Compared to most small cars, the 240SX is less affected by this, since the torque band is quite wide.  But, it still makes a difference.

Personally, I drive manual transmissions because they're more fun.

Jeff240sx
11-01-2002, 10:20 AM
Yea.  I ran a 17.7ish in a 1/4 mile with my auto.  It is about 2 seconds slower than a manual.  Also, that "5th" gear you feel the car shift into is just the torque convertor locking up, which only drops the revs by a couple hundred rpm.
Also... the shifts in the automatic drop the car out of the torque peak, unlike a manual.  It even drops me out of the boost range.  
The automatic will lose to a manual off the line due to the launch, and every rolling start you will lose.  Trust me, I raced Rampid360 a couple times.  He was stock, and I had an intake and cold air extension.
So, in conclusion... your butt dyno needs to be recalibrated.
-Jeff

240 2NR
11-01-2002, 10:56 AM
I've noticed the same in my girlfriend's auto altima.  Just tooling around town her car feels faster and smoother from a standing start.  But it also has a taller first gear and doensn't have to slip a clutch.  So the initial start in my manual is slower due to trying to have a smooth takeoff, and with the same shift point (in rpm) her car is moving faster.  However, when overtaking or driving for speed, my 240 is a lot faster.

sykikchimp
11-01-2002, 11:00 AM
it's also possible his car is low on power..

I mean my car is running smooth as silk, only a slight idle problem, but in the gas she runs good..  had her dynoed..  only put down 122whp  with I/E..  so If my engine was as healthy as it should be a could have an additional 20hp waiting on me somewhere..  if one engine of his is running stronger than the other..  this could also make up the difference..

I would make my wife race me to see for sure..  lol

misnomer
11-01-2002, 11:20 AM
Sykikchimp is right, it is likely a tuning or maintanance issue with your car. Also keep in mind that it is impossible to get exactly identical performance out of every car produced. It is quite possible that her car with it's automagic transmission is quicker than yours, but that's an exception and not the rule.