Horsepower loss

[Stangman]

Curious they say a C-6 drains 60-70 horsepower and a C-4 about 40 horsepower. Does a manual tranny cost any horsepower. Wondering if a car would be faster with a stick compared to an automatic if traction was the same for both.

[plovett]

Curious they say a C-6 drains 60-70 horsepower and a C-4 about 40 horsepower. Does a manual tranny cost any horsepower. Wondering if a car would be faster with a stick compared to an automatic if traction was the same for both.

A manual trans costs some power, but much less.  My opinion is that a fully setup track car, with scienced-out suspension will definitely be faster with a manual.  On the the street, on un-prepped street surfaces, on street tires, with a street suspension, the auto will be faster.  It just applies the power more smoothly.

So traction the same:  Is it great or poor traction?  That is the big difference.  Poor traction favors the automatic and great traction favors the manual.  .....in general.....

JMO,

paulie

[plovett]

I swing both ways.  Hey, it IS 2019.    As I get older and slower I tend to want a manual again.   When I was younger and just trying to go as fast as possible in a real street car, I liked the automatic.  It is all about hooking up in real street situations when you get over 550 hp. 

JMO,

paulie

[plovett]

Okay, low hp street cars are pretty much always faster with manuals because they don't have traction issues.  Say a 210 hp 1985 Mustang GT.  Always faster with a manual.  Start making real power and the auto gains the advantage, on the street. 

I can almost, but not quite hook up on the street with cheater slicks.  There is dust and pebbles and grease.  But with a stick I would be much slower in terms of ET at least, on the street. 

JMO,

paulie

[plovett]

street or track???  Makes all the difference.  shutting up now. 

paulie

[mike7570]

NHRA separates stock and super stock by stick and auto, just check the index's for each and you'll have your answer.

[plovett]

But that is racing on a track.  The street is a whole different place.

JMO,

paulie

[jayb]

The numbers I've heard for drag in an automatic trans are more like 55-60 HP for the C-6, and 20-25 for the C-4.  Powerglide is about 20 HP also.  Manuals aren't much better than that.  From my own experience, pulling out the C-6 and installing the C-4, it felt like the emergency brake had been released.  Stock C-6s do take a whole bunch of power to run.

[plovett]

The numbers I've heard for drag in an automatic trans are more like 55-60 HP for the C-6, and 20-25 for the C-4.  Powerglide is about 20 HP also.  Manuals aren't much better than that.  From my own experience, pulling out the C-6 and installing the C-4, it felt like the emergency brake had been released.  Stock C-6s do take a whole bunch of power to run.

I think the standard gain from C6 to C4 is about 0.15 seconds.  Very significant, IMO.

JMO,

paulie

[cjshaker]

And the standard gain from auto to manual is .05-.1 

Like Mike mentioned, NHRA manual trans class indexes are always equal or lower, meaning faster.  I'm not saying autos are slow, just given the same parameters, a manual frees up enough horsepower to show a difference.

[plovett]

And the standard gain from auto to manual is .05-.1 

Like Mike mentioned, NHRA manual trans class indexes are always equal or lower, meaning faster.  I'm not saying autos are slow, just given the same parameters, a manual frees up enough horsepower to show a difference.

Are you not listening?  There is a huge difference between going fast in a track car and a real street car.   The manual trans car will always have more potential, but as you have found it is harder to get to the ground.

JMO,

paulie

[jayb]

Like Mike mentioned, NHRA manual trans class indexes are always equal or lower, meaning faster.  I'm not saying autos are slow, just given the same parameters, a manual frees up enough horsepower to show a difference.

As far as I can tell that is not true, usually the manual indexes are 0.05 seconds faster, but some are the same, such as L stock and M stock.  Also, the class records are all over the place.  Here are some current record comparisons from the Stock Eliminator classes, from the NHRA web site:

A/S: 10.45;    A/SA:  9.65
B/S:  10.04;   B/SA:  10.05
C/S:  10.85;   C/SA:  10.90
D/S:  11.0;    D/SA:  9.99
E/S:  11.15,   E/SA:  10.44

I think a manual transmission's main advantage is due to the additional gear that is usually found in our older cars, allowing you to keep the engine closer to the peak powerband on the track.  Automatics have the advantage in shift time and torque multiplication via the torque converter.  The parasitic loss between a good race prepped manual and automatic is pretty insignificant, IMO.  Even a race prepped C-6 won't take much more power to run than a manual, although a stock C-6 is a real power hog.  I love driving a stick car on the street, but I'll take an automatic at the track every time.

https://www.nhra.com/stats/class_indexes

https://www.nhra.com/stats/14-mile-records-stock-eliminator

[mike7570]

^^^can't really compare records because NHRA retires them periodically. The number that shows a stick car higher is a new minimum. Also records are only set during official attempts. You'll see a r in a circle on windshield. So cars can run quicker and not set a record. Using the index’s would be more accurate.
Rory should have some input on stick vs auto.

[jayb]

The problem with hanging your hat on the indexes is that everyone runs so far underneath them, that they are practically meaningless.  They are also arbitrary; for example, most of the indexes for manual cars are exactly 0.05 seconds faster than for the stick cars.  Real life doesn't work like that.  Back to the original point, I think if the manual trans has an advantage, its due to the extra gear, not power loss in the automatic.

[cjshaker]

Are you not listening?  There is a huge difference between going fast in a track car and a real street car.   The manual trans car will always have more potential, but as you have found it is harder to get to the ground.

JMO,

paulie

Uhh, Paulie, perhaps you should read Joe's initial question...."if traction was the same for both". So to answer your question, no, I'm not listening to your opinion, I'm looking at facts.

I'm not trying to be biased,  just looking at the facts, nothing else. Indexes are the best comparative to look at, and I don't think you can find one instance where an automatic is quicker than a manual. And I don't think you'll find an instance where a manual draws more power than an automatic. More available power means more power to the wheels. Getting it to hook is another matter; one that class Eliminator racers generally don't have a problem with.

I agree that autos have an advantage over manuals in some ways, as Jay noted, but in the end, manual indexes are usually quicker, and never slower. And once you get out of Eliminator classes, air shifting and clutchless manuals negates any advantage that an auto has in shifting.

If it were strictly a 'more gears' thing, then why aren't there 5-10 speed automatics dominating the racing scene? They've been around for some time now.