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Re: How much power does a 727 consume? [Re: Sniper] #2850262
11/23/20 04:25 AM
11/23/20 04:25 AM
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Originally Posted by Sniper
Originally Posted by 3hundred
Originally Posted by volaredon
John Kunkel among others.


Check his response here:

JK Response linky

These numbers are from an article in Car Craft Magazine.

Powerglide_____18 hp
TH-350________36 hp
TH-400________44 hp
Ford_C-6______55-60 hp
Ford_C-4______28 hp
Ford_FMX______25 hp
Chrysler_A904__25 hp
Chrysler_727___45 hp


Car Craft isn't know to be overly scientific in it's procedures.

I can pretty much guarantee a 727 isn't sucking 45 HP out of a 100HP slant six.



I don't agree with those Clowns' numbers either, but it is something to go on. A percentage is what needs to be determined:

The generally accepted number for transmission AND differential power loss to the tires is 20% for a manual and 25 to 30% with an auto.

I did a bit of math based on their numbers and I come up with roughly 7% hp difference by dumping the 727 and switching to a 904.shruggy

I have switched from a 727 to an A833 and the 727-based 46RE to NV3500 with identical engines and the seat-of-the-pants difference was night and day. If anything happens to my 46RE it's getting replaced with a 904-based 44RE. twocents


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Re: How much power does a 727 consume? [Re: Grizzly] #2850338
11/23/20 11:02 AM
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Originally Posted by Grizzly
Originally Posted by Sniper
Originally Posted by 3hundred
Originally Posted by volaredon
John Kunkel among others.


Check his response here:

JK Response linky

These numbers are from an article in Car Craft Magazine.

Powerglide_____18 hp
TH-350________36 hp
TH-400________44 hp
Ford_C-6______55-60 hp
Ford_C-4______28 hp
Ford_FMX______25 hp
Chrysler_A904__25 hp
Chrysler_727___45 hp


Car Craft isn't know to be overly scientific in it's procedures.

I can pretty much guarantee a 727 isn't sucking 45 HP out of a 100HP slant six.



I don't agree with those Clowns' numbers either, but it is something to go on. A percentage is what needs to be determined:

The generally accepted number for transmission AND differential power loss to the tires is 20% for a manual and 25 to 30% with an auto.

I did a bit of math based on their numbers and I come up with roughly 7% hp difference by dumping the 727 and switching to a 904.shruggy

I have switched from a 727 to an A833 and the 727-based 46RE to NV3500 with identical engines and the seat-of-the-pants difference was night and day. If anything happens to my 46RE it's getting replaced with a 904-based 44RE. :

Where was the seat of the pants feeling different, low gear launch, cruising, where?



Re: How much power does a 727 consume? [Re: A727Tflite] #2850374
11/23/20 11:44 AM
11/23/20 11:44 AM
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Everywhere: from idle to redline.

You give it 10% throttle at 1500 rpm in a manual and the vehicle moves forward. Do the same thing in a 727 or 46RE and almost nothing happens. The lower the horsepower (318 for example) the more obvious the power loss is. That, and the real proof is seen at the fuel pumps.


Mo' Farts

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Re: How much power does a 727 consume? [Re: Grizzly] #2850397
11/23/20 12:06 PM
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Originally Posted by Grizzly
Everywhere: from idle to redline.

You give it 10% throttle at 1500 rpm in a manual and the vehicle moves forward. Do the same thing in a 727 or 46RE and almost nothing happens. The lower the horsepower (318 for example) the more obvious the power loss is. That, and the real proof is seen at the fuel pumps.


Understood - let me rephrase the question.

In high gear in any manual with 1 to 1 ratio, or 727 in high gear - the only real difference is the converter and loss from running the pump.
Yes a small weight difference in internal parts but that’s it.

The real test would be to take both the 833 and a 727 lockup and do an acceleration test between the two keeping the 727 locked up.
I doubt you would feel the difference.

All the chatter about differences between the two - depends on thru gear acceleration - the manual has a extra gear, lower first gear, etc., can’t compare the two this way.

I don’t have any records of parasitic loss on the autos, at Chrysler we had a test stand that measured that.
But some guys have gotten close here in their observations, by using on track performance. Assuming stall speed and converter efficiency remain close in their tests.

Re: How much power does a 727 consume? [Re: A727Tflite] #2850481
11/23/20 02:16 PM
11/23/20 02:16 PM
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Yes, and I had "when my 46re is locked up in 4th gear you get a sniff of how much power you are losing" typed up, but, I deleted it because the predicted responses would have misunderstood what I was talking about

I know you get it, wink but others have a pedal to the metal mentality and don't have the patience to drive an auto in top gear lockup without getting the big downshift to third or passing gear. twocents


Mo' Farts

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Re: How much power does a 727 consume? [Re: Grizzly] #2850650
11/23/20 06:52 PM
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Re: How much power does a 727 consume? [Re: A727Tflite] #2850654
11/23/20 07:03 PM
11/23/20 07:03 PM
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Isn’t there also the torque multiplication of a converter that comes into play? Lot of variables if you think about it!

Re: How much power does a 727 consume? [Re: 5thAve] #2850674
11/23/20 07:53 PM
11/23/20 07:53 PM
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Originally Posted by 5thAve


I've killed at least 2 904s more then just clutch wear and also end up going to 727. These were always behind 360s. I never had much problems with 318s.
For a slant 6 if you already have the parts to switch to a 904 that's the route I would go because you probably would notice a bit of a difference with it.


Ive had 904s die behind /6, 318 and 360's. All 3. common denominator.. 904. and I have never owned a race car.

truck already has the 727 in it, that's how it came when I got it. seems to be working fine. All I have done to it was a pan drop/fluid and filter swap, as the old pan gasket was leaking. Had not planned on pulling the 727. as long as it continues to work as is it aint coming out.
And no, I don't have a 904 sitting around collecting dust whether for /6 or V8.
I bring this up for a couple of reasons.... I can't be the only one that has ever wondered teh answer to my original Q, and a couple of certain guys on various forums seem to think there is something "wrong" with having a 727, that anyone would be crazy for wanting one, it "must" come out, it needs to be scrapped, you "have to" have a 904 "only" behind a slant 6 or small block, a 727 is a waste, etc......
When I build something I tend to the side of "overkill" which a 727 behind a slant certainly is. While I have had trouble over the years with both types of transmissions in various vehicles I have owned, by far more headaches and breakdowns from 904's than 727s...
In my experience a 904 does not seem worth the hassle and is more likely to burn up in any given vehicle. It has never seemed "worth it" to build up a 904/ when all I usually have had to do for better durability was a 6" shorter driveshaft, a fatter yoke, a different dipstick and tube, and bolt in the 727. no more effort to put in either trans over the other, since all these parts all have to be "handled" in the swap process anyway

Re: How much power does a 727 consume? [Re: volaredon] #2850681
11/23/20 08:12 PM
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A properly built 904/998/999 should not fail behind a small block street motor.

Does it have less clutch capacity than a 727, yes.
Does it handle more torque than a 727, no.

Don’t take this wrong, but given the engines you mention, sounds like there are issues with the build, cooler capacity, something.

In answer to your original question, I think you would be well served by building a good lockup 999 using the later 2.77 low gear planetary package.
Good mileage, good scoots off the line with plenty of durability for your application.




Last edited by Transman; 11/23/20 08:17 PM.
Re: How much power does a 727 consume? [Re: A727Tflite] #2850691
11/23/20 08:38 PM
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Has the ear tear off the sheet metal band in an a998 twice behind a 360. Finally got the earlier style forged band and that fixed that.

Re: How much power does a 727 consume? [Re: Sniper] #2850718
11/23/20 09:13 PM
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Originally Posted by Sniper
Has the ear tear off the sheet metal band in an a998 twice behind a 360. Finally got the earlier style forged band and that fixed that.



Seen flex bands rip the welds before in both small and large box trans. Not dependent on which engine it’s behind.
It’s all a matter of quality control at the band manufacturer.

Improper design developed for a certain purpose usually results in a design change later because of frequent failures.
We used flex bands for years and years with no issues in production. A bad design wouldn’t have lasted that long.

Re: How much power does a 727 consume? [Re: A727Tflite] #2850719
11/23/20 09:14 PM
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that may be it.... never "built" a 904/998, most were either stock and never having been into (no farther into than needed for fluid/filter swap) or rebuilt to "stock" specs. never really had to build up a 727 as I have rarely had anything very "Hi-Po".... a manifold and carb swap here and there..... back in the late 80s I had a 75 Cordoba. originally a 360, I swapped a 318 into it, and I kid you not, I had the trans out (and after the first few, apart, as well) about once a month. That was also my 1st exp with a shift kit, I put a "B&M" in it.. '80s "Super Shops special". and the particular trans that I had that shift kit in would bark 2nd gear without even trying, but I could never get it to "turn a tire" off the line, to save my life,.even with wet pavement. It was a peg leg 2.76, 8-1/4. I probably had 5-6 trannys for that car, the last year I had it, I'd pull one, put the other one in, rebuild the one I pulled... next month wash, rinse, repeat. Got sick n tired of it. the car "sounded mean," but was probably the worst turd I have ever owned.... I still like the looks of those cars though.


I was around 19 or 20 when I had that car. I junked it when I bought my Ramcharger, because I was tired of spending my paychecks on ATF for the Cordoba. .... now that Ramcharger, I had all sorts of "fun" with that thing in the local farm fields and over into Indiana's sand dunes near Lake Michigan and I never had to touch that trans.....

Re: How much power does a 727 consume? [Re: A727Tflite] #2850737
11/23/20 09:57 PM
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Originally Posted by Transman
Originally Posted by Sniper
Has the ear tear off the sheet metal band in an a998 twice behind a 360. Finally got the earlier style forged band and that fixed that.



Seen flex bands rip the welds before in both small and large box trans. Not dependent on which engine it’s behind.
It’s all a matter of quality control at the band manufacturer.

Improper design developed for a certain purpose usually results in a design change later because of frequent failures.
We used flex bands for years and years with no issues in production. A bad design wouldn’t have lasted that long.



they were factory bands. First time was shortly after I replaced the original 318 with a mild 360. Pulled the trans, found the issue, put another factory band out of a spare trans in. Same thing happened. So I pulled the forged band from a 68 trans and no more issues. Maybe I am just unlucky, but that 360 wasn't all that warm. Just a Performer intake, 600 cfm Performer carb and a 340 4bbl cam, it was originally a 2bbl.

Re: How much power does a 727 consume? [Re: slantzilla] #2850779
11/23/20 11:35 PM
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[quote=slantzilla]I run 904's in my junk. The only one I've wounded was a pump gear, and it cracked the snout on my PTC converter. 4000 on the chip on the brake could have something to do with it. laugh2 [quote][Linked Image]

Last edited by J_BODY; 11/23/20 11:36 PM.
Re: How much power does a 727 consume? [Re: Grizzly] #2852158
11/27/20 12:59 PM
11/27/20 12:59 PM
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I have three four speed cars with big blocks, I guess I have 135 free horse power.

Re: How much power does a 727 consume? [Re: Pacnorthcuda] #2852471
11/28/20 10:08 AM
11/28/20 10:08 AM
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If you're looking for efficiency you should be looking for something with a stick. Anyone who's driven the same gutless vehicle in an auto vs a stick will be able to tell you that!

Originally Posted by Pacnorthcuda
Isn’t there also the torque multiplication of a converter that comes into play? Lot of variables if you think about it!


I've heard that saying peddled my whole life and I still don't understand how a slipping converter is any different from slipping the clutch at launch on a stick.

Re: How much power does a 727 consume? [Re: DaytonaTurbo] #2852554
11/28/20 01:41 PM
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Originally Posted by DaytonaTurbo
Originally Posted by Pacnorthcuda
Isn’t there also the torque multiplication of a converter that comes into play? Lot of variables if you think about it!


I've heard that saying peddled my whole life and I still don't understand how a slipping converter is any different from slipping the clutch at launch on a stick.


Because a torque converter (when the output shaft is stationary e.g. at the moment of launch) multiplies the input shaft (engine) torque by an amount that varies with converter design, generally around 1.8 to 2 times. This multiplication quickly drops off as the rest of the driveline starts turning and reaches essentially 1:1 at high driveline speed.

Converter slip when operating above stall speed is a different animal. Then it's just wasted power.

The manual transmission's clutch transmits no torque to the output (transmission input shaft) when completely disengaged, and as the pedal comes up, passes more and more engine torque to the input shaft. But it never exceeds 1.0 (no multiplication) and that's when fully engaged with no slip.

Re: How much power does a 727 consume? [Re: DaytonaTurbo] #2852620
11/28/20 04:15 PM
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Originally Posted by DaytonaTurbo
If you're looking for efficiency you should be looking for something with a stick. Anyone who's driven the same gutless vehicle in an auto vs a stick will be able to tell you that!

Originally Posted by Pacnorthcuda
Isn’t there also the torque multiplication of a converter that comes into play? Lot of variables if you think about it!


I've heard that saying peddled my whole life and I still don't understand how a slipping converter is any different from slipping the clutch at launch on a stick.


I believe its because in a torque converter the input and output are fluid coupled together so it kinda acts like a gearbox - a gearbox is a torque multiplier. In a slipping clutch, you aren't coupled - just burning it off as heat.


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Re: How much power does a 727 consume? [Re: markz528] #2853417
11/30/20 03:48 PM
11/30/20 03:48 PM
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See I don't know if that's right though. When you slip a clutch you create a variable ratio between the crankshaft and the transmission input shaft. With any sort of gearbox an increase in ratio creates a corresponding increase in torque. Yes clutch slips does burn off some energy as heat but so does a torque converter or any hydraulic pump for that matter.

Re: How much power does a 727 consume? [Re: DaytonaTurbo] #2853473
11/30/20 05:41 PM
11/30/20 05:41 PM
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Originally Posted by DaytonaTurbo
See I don't know if that's right though. When you slip a clutch you create a variable ratio between the crankshaft and the transmission input shaft. With any sort of gearbox an increase in ratio creates a corresponding increase in torque. Yes clutch slips does burn off some energy as heat but so does a torque converter or any hydraulic pump for that matter.
In my opinion a properly adjusted "soft clutch" can have many benefits on a high horsepower manual shift car. It can help with traction and is easier on parts.

However it does not create any additional torque, any energy not passed to the rear wheels is turned into heat.

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