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How much faster is a 904 compared to a 727? #772062
08/12/10 10:17 AM
08/12/10 10:17 AM
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NJ
JCCuda Offline OP
mopar
JCCuda  Offline OP
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NJ
I'm sure the subject has been gone over before but I couldn't find anything. While the engine is out of my Duster I started thinking (that usually gets me in trouble and alway's cost money) maybe I should switch to a 904. The only thing I don't have is a converter. I'm hoping someone has done some back to back testing and has some real world conclusions that they could share. I've heard 1-2 tenths but don't know anyone that's actually tested.

Re: How much faster is a 904 compared to a 727? [Re: JCCuda] #772063
08/12/10 10:20 AM
08/12/10 10:20 AM
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Newark,Ohio
kissmyaspen Offline
pro stock
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Newark,Ohio
imo i would say its not worth it if your bracket racing, it will pick you up about a tenth if that. i dont think thats worth $800 bucks cuz thats what your gonna pay for a good convertor.


79 Dodge Aspen
12.265 at 109.75 MPH

67 Satellite NSS/E
11.83 @ 110

1968 Plymouth Road Runner 472 Hemi

3 time MOPAR NATIONALS CHAMP '03 FWD and '06 & '09 Street.
'07, '10, '12 Mopar Nats runner-up Street.
Re: How much faster is a 904 compared to a 727? [Re: kissmyaspen] #772064
08/12/10 10:27 AM
08/12/10 10:27 AM
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Wheels up, MO
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nhramark Offline
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Wheels up, MO


Depending on your power level, a 904 may not hold up as well as a 727. I'm only guessing based on the pic of your car, but there are likely a lot of things you could spend less $$ on and get more improvement.


[image]http://s1126.photobucket.com/user/nhramark1/library/Racing[/image] 9.100 @ 150 mph 5.780 @ 120 mph
Re: How much faster is a 904 compared to a 727? [Re: nhramark] #772065
08/12/10 11:10 AM
08/12/10 11:10 AM
Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda Offline
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las vegas
I switched back in 1993 or so...picked up .15 and 2 mph.

Been using same 904 since then, has been rebuilt twice, last time about 4 yrs ago went a broken ring gear took out the rear spraq.

Also been using the same trans with a tranzact transbrake since 1993. My 69 Barracuda has run low 11s to 10.70s thru those years.

Have second 904 in 71 Dart my daughter drives..it has been in use for 4 or 5 years now. Using tranzact brake in that one two.

So they work good for me.


Tony

70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
Re: How much faster is a 904 compared to a 727? [Re: 70AARcuda] #772066
08/12/10 11:50 AM
08/12/10 11:50 AM
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Kalispell Mt.
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HotRodDave Offline
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Kalispell Mt.
The less power you make the bigger the differance. Also if you go to low gear sets (a hole lot cheaper in a 904) that can help a tad also.

I am a 904 guy ( for most small blocks any how).


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: How much faster is a 904 compared to a 727? [Re: HotRodDave] #772067
08/12/10 12:21 PM
08/12/10 12:21 PM
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Fulton County, PA
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CMcAllister Offline
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Tenth and a half when I made the switch years ago. Need to keep up on the maintenance but I like the 904.


If the results don't match the theory, change the theory.
Re: How much faster is a 904 compared to a 727? [Re: CMcAllister] #772068
08/12/10 04:52 PM
08/12/10 04:52 PM
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Paul_Fancsali Offline
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You will gain at least .15 to .2, but at the expense of less reliability. I went threw 4 904s and 1 727 before I finally got a 727 trans that still got it for 19 years.The 904 is faster period

Re: How much faster is a 904 compared to a 727? [Re: Paul_Fancsali] #772069
08/12/10 05:42 PM
08/12/10 05:42 PM
Joined: Mar 2005
Posts: 3,445
N.Wilkesboro,NC
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DusterKrazy Offline
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N.Wilkesboro,NC
You will go faster with the 904. Years ago there used to be a problem with the converter necks cracking, I think they make them better now.

A 904 with the right stuff won't give you any problems for a long time

Re: How much faster is a 904 compared to a 727? [Re: JCCuda] #772070
08/12/10 05:56 PM
08/12/10 05:56 PM
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ggddemon Offline
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Just finished this exact issue. The 904 was .11 faster than the 727 and .08 faster than my glide that just went back in.Can't prove if it was all rotation issues or just convertor differences or just slight air quality .
But the average for my 410c.i. was a 1.31--1.32 60' with the glide and it dropped to a wheelstanding 1.27 many times with the 904.
The only reason I put the glide back, was I hated the creep from the transbrake and i took out 2 stock planetaries in the 904. Other than that was a great ride!!!!
Dave

Re: How much faster is a 904 compared to a 727? [Re: ggddemon] #772071
08/12/10 06:12 PM
08/12/10 06:12 PM
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Posts: 4,330
Lynchburg, VA
Leon441 Offline
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Lynchburg, VA
7.35 to 7.20 switching to 904 in freinds car. I don't know who charges $800 for changing the spline and neck on the converter. It cost me $150 in 1995 to change from 904 to 727 converter. The driveshaft must change though.

You will not creep with a tranzact VB. I had those issues with TA VB when trash got in VB. Run a stock filter helps too. Can't help you with the breaking stock planetaries problem. That's why I switched from 904 to 727. Then broke the planet in the 727. $500 truck planet fixed that.


Career best 8.02 @ 169 at 3050# and 10" tires small block power.
Re: How much faster is a 904 compared to a 727? [Re: Leon441] #772072
08/13/10 02:23 AM
08/13/10 02:23 AM
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Branson, Mo.
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joedust451 Offline
super gas
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Branson, Mo.
This is good to know, theres guys over on FABO claming .4-.5 tenths & a good 5 mph with the switch , I though that was a bit stetched .


75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU
Re: How much faster is a 904 compared to a 727? [Re: joedust451] #772073
08/13/10 09:05 AM
08/13/10 09:05 AM
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s.w.fl
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bonefish Offline
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changed from a 727 to a 904 in my 71 cuda 360 gaind 1 tenth and thats with the low gear set.

Re: How much faster is a 904 compared to a 727? [Re: JCCuda] #772074
08/13/10 09:45 AM
08/13/10 09:45 AM
Joined: Apr 2009
Posts: 447
NJ
JCCuda Offline OP
mopar
JCCuda  Offline OP
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NJ
Thank's for all the reponse's. I think i'll put the freshened 360 back in with the 727 and then make the change after I make few passes. I'll probably look at a PTC converter, either the 10" race ($425)or the 9.5 TF ($475). Anyone have any input on PTC converter's.

Re: How much faster is a 904 compared to a 727? [Re: JCCuda] #772075
08/13/10 11:16 AM
08/13/10 11:16 AM
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Carson City, NV
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babarracuda Offline
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Carson City, NV
PTC converters are great. I have one and it does exactly what the specs were promised.

Re: How much faster is a 904 compared to a 727? [Re: JCCuda] #772076
08/13/10 11:18 AM
08/13/10 11:18 AM
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United Socialist States of Ame...
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tboomer Offline
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I have a 9 1/2" PTC in my car...Works great!!


Need your rear end checked out? Contact Grizzly!!
Re: How much faster is a 904 compared to a 727? [Re: JCCuda] #772077
08/13/10 11:39 AM
08/13/10 11:39 AM
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On the south side of Nowhere
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S/ST 3040 Offline
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On the south side of Nowhere
Quote:

........either the 10" race ($425)or the 9.5 TF ($475).




If you are at all serious about ET, a good 8" converter
is worth the extra money.

Re: How much faster is a 904 compared to a 727? [Re: S/ST 3040] #772078
08/13/10 11:49 AM
08/13/10 11:49 AM
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Kalispell Mt.
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HotRodDave Offline
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The only time someone might gain .5 is if they had a weak slant six with a 727 then switched to a 904 with low gear sets. HP at the wheels would probably double


I am not causing global warming, I am just trying to hold off a impending Ice Age!



Re: How much faster is a 904 compared to a 727? [Re: HotRodDave] #772079
08/13/10 06:15 PM
08/13/10 06:15 PM
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Branson, Mo.
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joedust451 Offline
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Branson, Mo.
Quote:

The only time someone might gain .5 is if they had a weak slant six with a 727 then switched to a 904 with low gear sets. HP at the wheels would probably double




Don't qoute "me" on that 1/2 second gain, i'm just stateing what was said over on FABO when this was talked about, i thought it was alittle far fetched.


75 Duster, 451 10.87 @ 123.58 NA 97 Z28 6sp., 12.01 @ 115 on a 100 shot 71 Swinger. 360 magnum. 12.58 @ 105 78 cutlass, 469 BBC. 12.70 @ 108 on street tires. http://www.youtube.com/watch?v=Z2kqNmMfheU
Re: How much faster is a 904 compared to a 727? [Re: joedust451] #772080
08/13/10 06:29 PM
08/13/10 06:29 PM
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Gainesville,FL
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goldmember Offline
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Gainesville,FL
Quote:

Quote:

The only time someone might gain .5 is if they had a weak slant six with a 727 then switched to a 904 with low gear sets. HP at the wheels would probably double




Don't qoute "me" on that 1/2 second gain, i'm just stateing what was said over on FABO when this was talked about, i thought it was alittle far fetched.


The 904 is quicker,the problem is your also going to be changing the converter at the same which will cloud the test. I can see swapping a 727 with a crap converter to 904 with a good converter and picking up more than a .1 or .2.

Re: How much faster is a 904 compared to a 727? [Re: goldmember] #772081
08/13/10 09:52 PM
08/13/10 09:52 PM
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Benton, IL.
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DaveRS23 Offline
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I found out about PTC here on Moparts. I had struggled with converters off and on for years until I tried a PTC. Every PTC converter I have had has done exactly what they said it would. And I haven't broke one yet.

Great product at a reasonable price!


Master, again and still
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