YAC(ar)T : Automatic vs. Stick shift

[LAUST]

Originally posted by: CadetLee

Originally posted by: Zenmervolt

Originally posted by: Skoorb
In the _vast majority_ of cases the stick shift will win.

EDIT: Provided the driver is not a spaz and can drive a stick well as you said.

You're also assuming that the automatic uses a standard torque converter. A tweaked automatic will be consistantly faster. The only reason that a standard is generally faster is because in a typical stock, street setup the torque converter is a very lossy device.

ZV

Depends...there's also more loss through an auto tranny..if you're talking about little engines (like mine -- 1998 Corolla w/manual tranny), chances are the manual will win, assuming there's a good driver...autos lose more power through the tranny than manuals do.

On bigger engines & drag racing, some say autos are better..with a high stall torque converter & a fast tranny, an auto could have the advantage (instant shifting).

This is just from my limited knowledge..so wait for Roger to come around.

Why wait?... In cars for drag it is true, the faster shifting helps a bunch. As I stated above reciprocating mass slows em down abit but still results in a lower ET while the manual is capable of a faster MPH, it's very simple physics and it's proven on the track every weekend, just drop by a supergas event.

Also with boosted cars the shift is so fast it does not need to respool to get back into high boost.

Again, why go back and forth here when it's proven all the time, go pay $6 and watch a Test N' Tune some evening, go ask them "Why do you use that old 2 speed auto behind this big 500 cubic inch monster" Edit: yes that was NOT a typo I said TWO speed auto just go ask and make your life more simple and complete

 

[Zenmervolt]

Originally posted by: CadetLee

Originally posted by: Zenmervolt

Originally posted by: Skoorb
In the _vast majority_ of cases the stick shift will win.

EDIT: Provided the driver is not a spaz and can drive a stick well as you said.

You're also assuming that the automatic uses a standard torque converter. A tweaked automatic will be consistantly faster. The only reason that a standard is generally faster is because in a typical stock, street setup the torque converter is a very lossy device.

ZV

Depends...there's also more loss through an auto tranny..if you're talking about little engines (like mine -- 1998 Corolla w/manual tranny), chances are the manual will win, assuming there's a good driver...autos lose more power through the tranny than manuals do.

On bigger engines & drag racing, some say autos are better..with a high stall torque converter & a fast tranny, an auto could have the advantage (instant shifting).

This is just from my limited knowledge..so wait for Roger to come around.
Just for kicks, here's a video of a slow car (mine ) w/manual transmission...I was quite slow shifting to second, but second to third wasn't too horrible. link

Good point. Losses from a torque converter aren't linear with engine power, so the energy to drive a torque converter is far less consequentail with a more powerful engine.

It's also worth pointing out that turbocharged engines tend to do better with an automatic because an automatic allows the engine to stay at full throtte during shifts, which prevents the turbos from spooling down.

ZV

 

[jlee]

Originally posted by: Zenmervolt

Originally posted by: CadetLee

Originally posted by: Zenmervolt

Originally posted by: Skoorb
In the _vast majority_ of cases the stick shift will win.

EDIT: Provided the driver is not a spaz and can drive a stick well as you said.

You're also assuming that the automatic uses a standard torque converter. A tweaked automatic will be consistantly faster. The only reason that a standard is generally faster is because in a typical stock, street setup the torque converter is a very lossy device.

ZV

Depends...there's also more loss through an auto tranny..if you're talking about little engines (like mine -- 1998 Corolla w/manual tranny), chances are the manual will win, assuming there's a good driver...autos lose more power through the tranny than manuals do.

On bigger engines & drag racing, some say autos are better..with a high stall torque converter & a fast tranny, an auto could have the advantage (instant shifting).

This is just from my limited knowledge..so wait for Roger to come around.
Just for kicks, here's a video of a slow car (mine ) w/manual transmission...I was quite slow shifting to second, but second to third wasn't too horrible. link

Good point. Losses from a torque converter aren't linear with engine power, so the energy to drive a torque converter is far less consequentail with a more powerful engine.

It's also worth pointing out that turbocharged engines tend to do better with an automatic because an automatic allows the engine to stay at full throtte during shifts, which prevents the turbos from spooling down.

ZV

Another good point...but if you have a F/I engine with high redline (eg S2000..what, 9k?), you may be able to keep RPMs high enough to keep the turbo spooled..but I haven't had a chance to drive (or even ride in ) any f/i vehicle..

Solution to that? Supercharger..

 

[dxkj]

Originally posted by: ElFenix

Originally posted by: LAUST

P.S. Stopall that driver blabbin, that is a bunch of crap, another case of go to a track IN PERSON. Yes people mess up on their lights, but the clock on the 1/4 mile does not start until you break the beams. I don't care if you get a .508 (my personal best) or a 4.880 light, the clock doesn't start until the beams are broke. So quit that!!!! :| :| :|

its not quite crap... if you have someone who can't shift their stick right they're going to lose time shifting.

why are we discussing how well the person can shift ?

Given two same model car with Automatic transmission and Stick shift, given the driver drives the stick very well.

The assumption is the that the driver drives the stick very well, meaning fast shifting, good timing etc

 

[LAUST]

Originally posted by: CadetLee

Another good point...but if you have a F/I engine with high redline (eg S2000..what, 9k?), you may be able to keep RPMs high enough to keep the turbo spooled..but I haven't had a chance to drive (or even ride in ) any f/i vehicle..

Solution to that? Supercharger..

Eh whats so special about a supercharger?

 

[LAUST]

Originally posted by: dxkj

Originally posted by: ElFenix

Originally posted by: LAUST

P.S. Stopall that driver blabbin, that is a bunch of crap, another case of go to a track IN PERSON. Yes people mess up on their lights, but the clock on the 1/4 mile does not start until you break the beams. I don't care if you get a .508 (my personal best) or a 4.880 light, the clock doesn't start until the beams are broke. So quit that!!!! :| :| :|

its not quite crap... if you have someone who can't shift their stick right they're going to lose time shifting.

why are we discussing how well the person can shift ?

Given two same model car with Automatic transmission and Stick shift, given the driver drives the stick very well.

The assumption is the that the driver drives the stick very well, meaning fast shifting, good timing etc

Exactly, It's a variable that should not come up in this subject is what it is.. both drivers should be assumed to be seasoned drivers and this part of the equasion wiped from existance.

 

[Zenmervolt]

Originally posted by: LAUST

Originally posted by: CadetLee

Another good point...but if you have a F/I engine with high redline (eg S2000..what, 9k?), you may be able to keep RPMs high enough to keep the turbo spooled..but I haven't had a chance to drive (or even ride in ) any f/i vehicle..

Solution to that? Supercharger..

Eh whats so special about a supercharger?

I know that you know, but just in case someone else is wondering: A supercharger doesn't spool down between shifts like a turbo does.

ZV

 

[jlee]

Originally posted by: Zenmervolt

Originally posted by: LAUST

Originally posted by: CadetLee

Another good point...but if you have a F/I engine with high redline (eg S2000..what, 9k?), you may be able to keep RPMs high enough to keep the turbo spooled..but I haven't had a chance to drive (or even ride in ) any f/i vehicle..

Solution to that? Supercharger..

Eh whats so special about a supercharger?

I know that you know, but just in case someone else is wondering: A supercharger doesn't spool down between shifts like a turbo does.

ZV

Might as well explain for everyone else

A turbocharger relies on engine exhaust gas to power itself...so around 3000rpm (varies), there's enough exhaust pressure, and voila...forced induction.

A supercharger, on the other hand, runs off the engine itself..not the exhaust -- as such, you have instant power off the line.

I may be somewhat inaccurate somewhere -- if so, please feel free to correct me. =)

 

[LAUST]

Originally posted by: CadetLee

Originally posted by: Zenmervolt

Originally posted by: LAUST

Originally posted by: CadetLee

Another good point...but if you have a F/I engine with high redline (eg S2000..what, 9k?), you may be able to keep RPMs high enough to keep the turbo spooled..but I haven't had a chance to drive (or even ride in ) any f/i vehicle..

Solution to that? Supercharger..

Eh whats so special about a supercharger?

I know that you know, but just in case someone else is wondering: A supercharger doesn't spool down between shifts like a turbo does.

ZV

Might as well explain for everyone else

A turbocharger relies on engine exhaust gas to power itself...so around 3000rpm (varies), there's enough exhaust pressure, and voila...forced induction.

A supercharger, on the other hand, runs off the engine itself..not the exhaust -- as such, you have instant power off the line.

I may be somewhat inaccurate somewhere -- if so, please feel free to correct me. =)

yes it is better to explain here, we don't like assumptions

Those are the basics, centrifical superchargers do have to spool as they have a impeller desighn like a turbo. They are capable of much higher boost though then a Roots or Twinscrew but do have to spool where the other 2 don't. They do recover from a shift better then a turbo though because they are belt driven.

Being belt driven it's con is it requires engine power to power the compressor so it's better for V8 engines, but there are pro's and cons to all 4 (Turbo, Roots, Screw, Centrifical) for me the screw was the best due to it's far superior in low end grunt (towing), it's also very reliable and simple, it is also self contained lubrication.

All in all it's application need, there is no superior.

 

[Zenmervolt]

Originally posted by: CadetLee

Originally posted by: Zenmervolt

Originally posted by: LAUST

Originally posted by: CadetLee

Another good point...but if you have a F/I engine with high redline (eg S2000..what, 9k?), you may be able to keep RPMs high enough to keep the turbo spooled..but I haven't had a chance to drive (or even ride in ) any f/i vehicle..

Solution to that? Supercharger..

Eh whats so special about a supercharger?

I know that you know, but just in case someone else is wondering: A supercharger doesn't spool down between shifts like a turbo does.

ZV

Might as well explain for everyone else

A turbocharger relies on engine exhaust gas to power itself...so around 3000rpm (varies), there's enough exhaust pressure, and voila...forced induction.

A supercharger, on the other hand, runs off the engine itself..not the exhaust -- as such, you have instant power off the line.

I may be somewhat inaccurate somewhere -- if so, please feel free to correct me. =)

You're right to a degree, but it's not strictly RPM that produces the exaust gasses that drive a turbo. Between shifts when you take your foot off the gas, it closes the throttle, effectively shutting off the turbo. It takes a few instants for the turbo to come back up to speed after each shift.

ZV

 

[KokomoGST]

Well, you can fix the turbo spool down on a stick by speed shifting... I know some people that live by the mantra, "never lift to shift!" But I'm trying to keep my car in one piece while some of those guys have race trannies or don't care about breaking.

Ball bearing turbo technology now is such that for the some Garrett GTs, you can lift and shift and lose minimal time because the transient response is SOOO fast. But usually transient spool is of more concern to other types of motorsports rather than drag... that's why WRC cars have anti-lag systems.

With all that being said, a lot of pros use Powerglides or other race autos. The more power you make in the pros, the more likely you might see them move over to a custom heavy duty automatic tranny with a high stall. But then like some people said, most normal production autos aren't really comparable to customized trannies. If you can truly shift blazingly quickly in the manual, it'll take a VERY fast auto to keep up with just shifting. (BTW, Top fuel doesn't use autos)

Yet another factor in determining which car would win is also the gearing. Usually autos have less gears... and often are geared much taller than their manual counterparts. Depending on the way the engine is through the powerband, and the auto's gearing it could good for strip racing or bad.

 

[LiQiCE]

From this discussion it sounds like I could put a higher efficiency torque converter in my automatic car to gain back some of the power that is normally lost, is that true? What would I look for in a torque converter to gain back efficiency, a high stall torque converter?

I know in my car, an automatic tranny versus a manual there is about a 30hp loss to the wheels, so I'd be really interested if I could somehow make up for some of the difference by replacing the torque converter. With the current configuration, I'm losing about 23% of the hp at the crank ... I'd only be losing 11% (1/2 the loss) if I had a manual transmission.

 

[LAUST]

Originally posted by: LiQiCE
From this discussion it sounds like I could put a higher efficiency torque converter in my automatic car to gain back some of the power that is normally lost, is that true? What would I look for in a torque converter to gain back efficiency, a high stall torque converter?

I know in my car, an automatic tranny versus a manual there is about a 30hp loss to the wheels, so I'd be really interested if I could somehow make up for some of the difference by replacing the torque converter. With the current configuration, I'm losing about 23% of the hp at the crank ... I'd only be losing 11% (1/2 the loss) if I had a manual transmission.

You would have to have your car dyno'd and a TC builder could then build one for your car. But if you are talking a daily driver I would not do a stall converter, if you do don't go over 2400rpm

 

[Zenmervolt]

Originally posted by: LiQiCE
From this discussion it sounds like I could put a higher efficiency torque converter in my automatic car to gain back some of the power that is normally lost, is that true? What would I look for in a torque converter to gain back efficiency, a high stall torque converter?

I know in my car, an automatic tranny versus a manual there is about a 30hp loss to the wheels, so I'd be really interested if I could somehow make up for some of the difference by replacing the torque converter. With the current configuration, I'm losing about 23% of the hp at the crank ... I'd only be losing 11% (1/2 the loss) if I had a manual transmission.

Are you 100% sure that all your losses are in the transmission? It is not uncommon for manufacturers to slightly detune the engines of automatic transmission cars because they don't want to develop an automatic to handle the new engine. For example, the automatic transmissioned Mazda RX-8 is limited to fewer revs than the manual transmissioned RX-8 because the automatic can't handle the same revs as the manual transmission can. Because the engine in the automatic is limited to fewer revs, it can't develop the same amount of hosepower as the manual transmission engine.

A new torque converter may not be available for your transmission either, and if it is, you might be talking about a thousand dollars or so.

ZV

 

[LiQiCE]

Well, my car (Acura TL Type S) was developed as an automatic transmission, and then for 2003 they introduced a 6-speed manual transmission for the 2-door version of the car (Acura CL Type S). Dynos for both cars put the automatic versions of both the TL and CL Type S at about 200hp to the wheels (260 hp to the crank is what Acura states). The manual transmission version of the car puts down about 230hp to the wheels. Both the manual and automatic versions of the car redline at ~6800 rpms, so I'm assuming they make the same power. I don't know if the losses are 100% transmission related, but specification wise the cars are supposed to be identical other than the transmission.

LevelTen makes a high stall torque converter for my car, costs around $700, $500 if I mail them my own torque converter to be upgraded. (Although that would mean I would have no car for a few days). (http://www.levelten.com)

Supposedly they would set the high stall to around 3000 rpms, which sounds like it would be pretty bad as a daily driver.

Originally posted by: Zenmervolt
Are you 100% sure that all your losses are in the transmission? It is not uncommon for manufacturers to slightly detune the engines of automatic transmission cars because they don't want to develop an automatic to handle the new engine. For example, the automatic transmissioned Mazda RX-8 is limited to fewer revs than the manual transmissioned RX-8 because the automatic can't handle the same revs as the manual transmission can. Because the engine in the automatic is limited to fewer revs, it can't develop the same amount of hosepower as the manual transmission engine.

A new torque converter may not be available for your transmission either, and if it is, you might be talking about a thousand dollars or so.

ZV

 

[jlee]

I'm not too familiar with how the high stall TCs work..but wouldn't a 3000rpm TC chirp your tires on practically every start, or..?

 

[Zenmervolt]

Originally posted by: LiQiCE
Well, my car (Acura TL Type S) was developed as an automatic transmission, and then for 2003 they introduced a 6-speed manual transmission for the 2-door version of the car (Acura CL Type S). Dynos for both cars put the automatic versions of both the TL and CL Type S at about 200hp to the wheels (260 hp to the crank is what Acura states). The manual transmission version of the car puts down about 230hp to the wheels. Both the manual and automatic versions of the car redline at ~6800 rpms, so I'm assuming they make the same power. I don't know if the losses are 100% transmission related, but specification wise the cars are supposed to be identical other than the transmission.

LevelTen makes a high stall torque converter for my car, costs around $700, $500 if I mail them my own torque converter to be upgraded. (Although that would mean I would have no car for a few days). (http://www.levelten.com)

Supposedly they would set the high stall to around 3000 rpms, which sounds like it would be pretty bad as a daily driver.

Ah, in that case it's probably the same engine and not de-tuned. That kind of torque converter might be only appropriate for racing though.

ZV

 

[MC]

Wow, we have some very interesting and informative responds, keep 'em coming

 

[WinkOsmosis]

What is a stall convertor? Is that what controls at what rpm the torque convertor locks/starts to slip?

 

[Zenmervolt]

Originally posted by: WinkOsmosis
What is a stall convertor? Is that what controls at what rpm the torque convertor locks/starts to slip?

I think that all torque converters are "stall converters". What you're thinking of is a "high stall speed" torque converter, which has a higher RPM threshold for lockup.

More than you ever wanted to know about stall speed.

ZV

 

[LongCoolMother]

how can this be true? i heard race cars are automatic!!

 

[atom]

Originally posted by: CadetLee
I'm not too familiar with how the high stall TCs work..but wouldn't a 3000rpm TC chirp your tires on practically every start, or..?

Depends on the characteristics of the engine, but yeah, that would be pretty killer on an fbody.

I pity the foo and his daily driven car that has a 3000 RPM stall converter. How many tires would you go through in a year?

 

[Zenmervolt]

Originally posted by: LongCoolMother
how can this be true? i heard race cars are automatic!!

I think you're joking, but just to go through it all to the best of my understanding:

Top fuel dragsters: Proprietary air-pressure controlled "manual" that uses planetary gearsets instead of the typical input and output shafts.
Lower dragster classes: Some automatic, some manuals similar to Top Fuel.
Streetable drag cars: Automatics such as the famous TorqueFlite.
CART/IRL: Sequential non-computer controlled manual.
F1: Computer-controlled sequential "manual".
NASCAR and ALMS: Traditional manual (heavily beefed-up to handle the extra power).

ZV

 

[Zenmervolt]

Originally posted by: atom

Originally posted by: CadetLee
I'm not too familiar with how the high stall TCs work..but wouldn't a 3000rpm TC chirp your tires on practically every start, or..?

Depends on the characteristics of the engine, but yeah, that would be pretty killer on an fbody.

I pity the foo and his daily driven car that has a 3000 RPM stall converter. How many tires would you go through in a year?

Actually, if he's not power-braking on every take-off it shouldn't be too terribly bad. Remember that a Honda engine typically has peak torque at 4,000 RPM or above as opposed to the 2,000 RPM torque peak on a big V8.

ZV

 

[Walleye]

one question


in a quarter mile drag, assuming you built your car for quarter mile (lightened, supercharger (out the hood, we gotta have the looks. (this is for image, right? (image is for girls, right?)))), would you put in a triple plate clutch, and dump the clutch on every shift, with gas florred the whole time? isnt that the correct way to do it?

btw, i snapped my pressure plate 2 weeks ago