Which combo?

[bbcharger71]

All right guys. I have talked myself into a pickle. I am about to get my car back for the body shop in a couple of months to start putting it together. I currently have a 400 "with all the goodies" on it. My car is an auto car, so was just going to but a 727 in it and be done with it. Well, as you all know, gas is continuing to rise and I want to be able to afford to take this car out every once and a while and not spend $100+ in gas in two days. I want to drop a modern Manual trans in it, but I am not sure of all of the options and how hard each option would be "surgically". My father-in-law owns a salvage yard, so I can get my hands on about anything. Also, I have been debating on going ahead now and just dropping in a 5.7 hemi. What are your thoughts? I love the car and I want to be able to drive it without burning a hole in my wallet.

 

[67 coronet]

by the time you spend the money on the conversion,you could have driven a long way on gas.even getting parts for free you will still spend a couple grand in add ons,not to mention the time and labor.

 

[IQ52]

Rather than the poll, I think more people will want to know if your wife has an unmarried sister so they can marry a wrecking yard.

Just considering the mileage, I like the sound of the 5.7 and the 6 speed.

 

[bbcharger71]

Ha ha. She actually does. I forgot to add in that I do not have a trans yet. To buy a new 727 or rebuild one to handle the power, I will have spent the same amount of money to have a Challenger 6 speed. The Challenger 6 speed retails used for about 1200. But I have family hook up.

 

[67 coronet]

Ha ha. She actually does. I forgot to add in that I do not have a trans yet. To buy a new 727 or rebuild one to handle the power, I will have spent the same amount of money to have a Challenger 6 speed. The Challenger 6 speed retails used for about 1200. But I have family hook up.

with that info,go with the challenger 6 speed and the 400!:headbang:

 

[bbcharger71]

with that info,go with the challenger 6 speed and the 400!:headbang:

would I get decent mileage with that combo? I want to be able to drive this car long distances (like 200+ mile trips). I live in Knoxville and my family lives in Middle Tennessee. The 400 will have a 750cfm if I go that route. I'm not too worried about the gearing right now. I have plenty of options with my 8 3/4.

 

[67 coronet]

would I get decent mileage with that combo? I want to be able to drive this car long distances (like 200+ mile trips). I live in Knoxville and my family lives in Middle Tennessee. The 400 will have a 750cfm if I go that route. I'm not too worried about the gearing right now. I have plenty of options with my 8 3/4.

find out what your final drive ratio is on the challenger 6 speed.i think 6th is like overdrive,but not sure.you rear gearing will make a huge difference on your millage.try to shoot for about 1600 rpm at 75 mph in sixth and your mileage should be ok.will never be as good as fuel injection,but you should still be able to reach 17mpg or so depending on how hot your motor is.

 

[IQ52]

You know, I seem to remember a conversation with my son who owns a 2011 5.7 6speed Challenger and I "think" 5 an 6 are both overdrive gears. Someone who knows for sure will chime in.

 

[Larry523]

The Challenger uses the Tremec 6-speed manual, so yes, 5th and 6th are both overdrives. Tremec makes two variants of the T56/TR6060 with different gearing. One has a 2.66:1 1st gear, with 0.8:1 5th and 0.62:1 6th. The other has a 2.97:1 1st, a 0.74:1 5th, and a 0.5:1 6th. I'm not sure which one is standard in the Challenger, but I'm guessing the second one with the deeper overdrives. It can bolt right up the to 5.7/6.1 Hemi's, and can be adapted to a wide variety of other engines, including the Mopar 400. From everything I've read, it will require a fair amount of surgery on your drive tunnel to fit, as well as modifying the torsion bar crossmember, but it's definitely doable if you have the skills and patience. Good luck with whichever route you go!

 

[Supershafts]

DO NOT even consider a tci....

A&A or MSPerformance . . .

 

[67 coronet]

The Challenger uses the Tremec 6-speed manual, so yes, 5th and 6th are both overdrives. Tremec makes two variants of the T56/TR6060 with different gearing. One has a 2.66:1 1st gear, with 0.8:1 5th and 0.62:1 6th. The other has a 2.97:1 1st, a 0.74:1 5th, and a 0.5:1 6th. I'm not sure which one is standard in the Challenger, but I'm guessing the second one with the deeper overdrives. It can bolt right up the to 5.7/6.1 Hemi's, and can be adapted to a wide variety of other engines, including the Mopar 400. From everything I've read, it will require a fair amount of surgery on your drive tunnel to fit, as well as modifying the torsion bar crossmember, but it's definitely doable if you have the skills and patience. Good luck with whichever route you go!

i think larry523 is correct.we just had a challenger in the shop and i peeked at that trans.that is one big piece,will take a lot of floor mods to go in.have you looked at bolt up overdrives for the 727?

 

[rj1971plym]

4 speed?

Sorry, I would have to have a 400 B engine with an A833 4 speed.

 

[Meep-Meep]

Before you decide on the tranny it's important to know how your engine is set up. What cam are you running?

I'll agree with 67 Coronet. The cost associated with the conversion will buy a lot of gas. Your motor is already built and waiting to go in. Why not add EFI to the 400 and perhaps a cam that has a broad power band to take advantage of the 6 spd tranny? Much easier and cheaper I think.

 

[Ron 73]

The manual shift cars are more fun, and would be a good choice with the 400 but myself personally i believe the 400 with a 727 would be an excellent choice... Im not a engine builder and have had both and i always felt the 727 was the best ones with gas mileage.. And with the right set up, they to can be a lot of fun to play with. There is a lot to do and buy to do a conversion to a manual.. Remember, when your done, your the one who needs to be satisfied with your car, im not trying to discourage just throwing in my 2 cents

 

[robinsonwr]

I love the retro idea with 400 married to a new 5 or six speed manual. The idea of putting fuel injection on the 400 would be great also. Suggestion use the EZ EFI on the 400. It is a self learning system that will help your gas mileage and married to an overdrive, awesome!

 

[rolling_Thunder]

I made an EFI system I put on my old 512" stroker... was a good way of adding mileage. Behind it was bolted my Tremec 5-speed trans...

I ended up going with a 6.1L with the 5-speed... currently building a Viper spec T56

 

[Jim Bob The Dancing Bear]

I want to row gears and am leaning towards a Passon 5 speed. but if you have the junk yard, get a 46rh. You will have 4th gear, the strength of a 727 and a lock up torque converter.

You still need the adapter from small to big block bell, rebuild, drive shaft (cut down the one you have if you have one?). Would be about the same cost as a built 727 outright or comparable.

To do the T56 you have to cut out the torsion bar cross member center section and replace along with other floor pan work. You may want to do more looking to see if that is what you have. I believe the Viper transmission TR6060 has the .5 6th. The modern TR6060 does not have a Speedo gear. You will have to get an electric Speedo or an electric to manual (if they exist) adapter.

 

[HT413]

If this is all about gas mileage and nothing more:

Gas mileage with 400/727:
2400 miles per year / 12 mpg = 200 gallons of fuel per year

Gas mileage with 5.7 / 6 speed:
2400 miles per year / 20 mpg = 120 gallons of fuel per year

This leaves 80 gallons per year saved.

At $3.00 per gallon, you save $240 per year.
At $4.00 per gallon, you save $320 per year.

Years until this pays off:

Total job costs $3k, it'll be 8-10 years before it pays off.
Total job costs $5k, it'll be closer to 15 to 20 years.

These are just ballpark numbers, but you get the idea. In my opinion, the payback isn't worth it.