273 Supercharged...ITS HAPPENING PEOPLE!!

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Bakerlite said:
Yep, the 727 is overkill for your application. The Paxton is going to eat HP and so is a 727.
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How much more power does the 727 use over the 904?
You state the Paxton will eat power. How much HP is required to turn the unit?

The answer is a lot less than most people guess. But if you in fact have numbers, I'd like to know.

ProStocker273 said:
I would stick with 904. 727 robs to much power but stoked to see the build
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Same question as above. ^^^^
 
rumblefish360 said:
How much more power does the 727 use over the 904?
You state the Paxton will eat power. How much HP is required to turn the unit?

The answer is a lot less than most people guess. But if you in fact have numbers, I'd like to know.



Same question as above. ^^^^
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If someone has figured this out that would be really good info. I know that all things the same a 46RE robs about 11% more than a 727. That was behind a built 408ci in a Dakota. Beings the internals are all smaller in the 904 I would think it would be least that but would love to know. I seriously considered building the 904 and I still might sometime. But for the future of this car I wanted to go with a mild built 727 so that if I go with a bigger motor later it's there. I have to get my driveshaft cut and I wanted to only do it once.
 
Originally Posted by Bakerlite
Yep, the 727 is overkill for your application. The Paxton is going to eat HP and so is a 727.


Originally Posted by rumblefish360
How much more power does the 727 use over the 904?
You state the Paxton will eat power. How much HP is required to turn the unit?

The answer is a lot less than most people guess. But if you in fact have numbers, I'd like to know.


Originally Posted by ProStocker273
I would stick with 904. 727 robs to much power but stoked to see the build

Originally Posted by rumblefish360
Same question as above. ^^^^

Excellent Questions rumblefish360,
And x2!!!
I also would like to see some ' real #'s', or data/math to prove same...
Things are gettin real here !!!

Cudo's Mr chrissock great thread!!!
 
rumblefish360 said:
How much more power does the 727 use over the 904?
You state the Paxton will eat power. How much HP is required to turn the unit?

The answer is a lot less than most people guess. But if you in fact have numbers, I'd like to know.



Same question as above. ^^^^
Click to expand...

Sure, it takes no power to run a belt driven blower and a 727 will have exactly the same loads and internal friction and rotating mass as a 904. ...sure, whatever...
I'd be thinking that on a tiny little torqueless engine like this, with only 5 psi of boost, that every little thing would help, cutting down the weight of the trans, cost as well as the decreased internal drag and rotating mass would be a plus, but obviously, you think that's not the case and fitting the extra "lump" would be the way to go...

The last time I changed out a 727 to a 904, the car picked up almost .4 in the ET. From memory that worked out to about 8 percent.
 
I have read in the past that the 904 has allowed an extra 10th plus. At the lower levels of the engines there behind, the mathematical equation doesn't seem to work out the same on every note able case, but there close to each other.

Working with what he has and keeping costs down. And I do believe that changing to a 904 will allow more power to the wheels but then there is the governing favtor(s) of costs, how deep is his pocket, his build, his way, as much as allowable it can go.

Thanks for sharing what you know. A truly helpful mention.
 
Chrissock, I think I'm on your page? Do what you can with what you got and skip the extra costs associated with getting a newly well built trans, drive prop shortening, etc....
Even though there is power to be found in a different trans and maybe even a rear, the list goes on and on about what could be done. Of course, the Internet spending your money and the actual reality are two vastly different pockets.

Build on brother! Build on!
 
rumblefish360 said:
Chrissock, I think I'm on your page? Do what you can with what you got and skip the extra costs associated with getting a newly well built trans, drive prop shortening, etc....
Even though there is power to be found in a different trans and maybe even a rear, the list goes on and on about what could be done. Of course, the Internet spending your money and the actual reality are two vastly different pockets.

Build on brother! Build on!
Click to expand...

Thanks!! I do need to clarify though. I have a 904 that came with my 273 that is a working trans supposedly. There was so many question marks though that I didnt want to just stick it in the car even when I wasn't going supercharged. After the supercharger happened i was either going to need to build one or the other. The cost was higher for the 904 simply because we needed to go further than a stock rebuild. So it made sense to just do a 727. Frankly I don't care if it eats more HP. This is a street car not a race car. So if i give up a few pony's it aint going to hurt my feeling.

Also the Car is a slant six with a 7 1/4 rear which i am changing to an 8 3/4 so either way the driveshaft that I have needed to be cut.
 
I believe there's only a 21 HP drive train loss between the 904 (24HP) and 727 (45HP) not a big deal for a street car, interesting plan.
 
The early 273 crank used a smaller register for the torque convertor. Better factor that in, or check it to know what you have. Otherwise I'd say go 727, especially for the street and cost difference.
 
64DartGTinAZ said:
Have a look at this thread and see Bill Dedman's post where he talks about what he learned from a guy who has a lot of Torqueflite experience - 273's tend to wind high, so, that bit about 'above 6000 RPM' may be relevant to your build:

http://www.forabodiesonly.com/mopar/archive/index.php/t-50518.html

Also, this thread is interesting:

http://www.forabodiesonly.com/mopar/archive/index.php/t-288545.html
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These threads hold a lot of cool information. Long reads but good info. Being a full on full interior street car my trans choice was all about cost up front. The 904 was going to be more money even though I had the core. So I went 727. I still have the 904 and I'm not selling it. So maybe I will slowly build it myself after all is said and done. But for now I have a lot going on at work, 3 kids and I am staring at a huge build just to get this thing running and driving. So adding a trans build is not in the cards.
 
66fs said:
The early 273 crank used a smaller register for the torque convertor. Better factor that in, or check it to know what you have. Otherwise I'd say go 727, especially for the street and cost difference.
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Not sure I follow. It's a 68' engine. Here is a pic of the casting number. From what I gather it's a cast version.
 

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I've spent most of the morning looking at head gaskets for this thing. I'm going to put ARP studs in it but I really don't need a thin gasket. Just want something that's going to hold the extra cylinder pressure. Also most gaskets say they will work for 318 to 360 but I'm assuming that's only because the bore hole is larger than my little 4" hole. Any thoughts on a good gasket before I pull the trigger?
 
chrissock said:
This helps a ton!! I will look at the pics closer when I get to a computer but is the bottom pully two groovs or three? I know later motors had three grooves on the crank pully for smog pump right?
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the set up I posted has a three groove crank pulley
two belts run over the crank pulley, the A/C compressor and the alternator (though for some reason the blue engine I posted is only running one)
the third belt runs over the crank pulley, water pump and powersteering pump

there is no idler pulley on this set up, though I think the earlier A/C set ups were different and did include one?
 
chrissock said:
Hahaha well there is not much to post pics of YET. But stay tuned. My goal is to have this thing running by Christmas. And I most of the pieces just got ordered. I will though.
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All right i'll let it slide lol. Snap some shots when the setup starts to look like something. I like seeing people go off the beaten path and try something different.
 
chrissock said:
Not sure I follow. It's a 68' engine. Here is a pic of the casting number. From what I gather it's a cast version.
Click to expand...

The hole in the back of the crankshaft, that the torque convertor hub fits into, is smaller on the early 273 forged cranks. You should be fine if you are running a 68 crank. It is easier to check now than when you are trying to mate the transmission up and can't figure why it won't go together. Or worse force it together.
 
This is a cool thread. you dont see many blowers anymore,especially paxtons...
 
chrissock said:
]I've spent most of the morning looking at head gaskets for this thing. I'm going to put ARP studs in it but I really don't need a thin gasket. Just want something that's going to hold the extra cylinder pressure. Also most gaskets say they will work for 318 to 360 but I'm assuming that's only because the bore hole is larger than my little 4" hole. Any thoughts on a good gasket before I pull the trigger?
Click to expand...

Was this an original 2bbl engine???, I read the heads have been reworked, & 4BBL
mani,... or did I miss something? thx !!

P.s, still a great thread !!!
...as to 727/904/Novi HORSEPOWER USE
No one answered, so I will try to seek out info & start another thread.

P.s.s,
Thanks for the grace
 
66fs said:
The hole in the back of the crankshaft, that the torque convertor hub fits into, is smaller on the early 273 forged cranks. You should be fine if you are running a 68 crank. It is easier to check now than when you are trying to mate the transmission up and can't figure why it won't go together. Or worse force it together.
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Wow....that's a good tidbit. Thanks man!
 
Ramcharger360 said:
I believe there's only a 21 HP drive train loss between the 904 (24HP) and 727 (45HP) not a big deal for a street car, interesting plan.
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Do you mean that it takes 21HP to drive the 904 & 45HP to drive the 727?
 
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