Choosing the best 5.7 engine and Transmission

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Travis Mitchell

Travis Mitchell

Active Member
Joined
Feb 8, 2018
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Location
Birmingham, AL, USA
Hey guys, I have been reading through all of the gen 3 hemi posts I can but need some help making a few choices... I got my 74 Scamp gutted and I've been collecting parts to start getting it back together. Was a 318 727 car. My goal is to build a fun daily driver. Will likely only see some highway miles, and more just around town and road course only a couple times a year.
My last DD was a 2009 Challenger R/T. Pretty fun car, but my goal is to build something much lighter with a little more power.
I am looking for guidance on which Engine and Transmission to run.
I am planning to pick up a junkyard 5.7 (or hopefully a complete car I can pull everything from) and doing at least a cam swap. Want to be in the ball park of 425 hp & tq.

For the engine, what year and model car/truck should I be looking for? Have I understood correctly that the earlier ones are easier to work with, but are more prone to issues. Then the 09+ have more to deal with electronically but the eagle heads are a big improvement.

Then I am wondering what transmission to go with. Seems like if i am using hotwire already, then using a nag1 or 5454rfe would be the way to go if I am willing to tackle the tunnel and cross member. I have read mixed reviews on which one of these would be better for what i am trying to do.
I am assuming that if I just keep it simple and just run a 727/904 I will be wishing I did the extra work for either one of the newer transmissions.
Not totally opposed to the a518/a500 but if i am going to do an overdrive swap, I'd like to use the shifter and slap stick from the donor car.

Thanks in advance for all the help and input!
 
Just a quick question before I give an opinion, any plans to further mod the engine? Other than a cam swap?
 
Other than just repairing any major wear, probably not. It seems like that should be about all I need to hit my power goals. But feel free to give your input on that as well!
 
For the money, I would try to find a decent running, lower mile 5.7 Eagle(09 and newer) truck engine. The trucks were rated 395 hp. Intakes are better than car. Swap in the SRT 6.4 cam. Manual or auto. I've used the MDS/ auto cam without using the actual MDS. Either one is 220 bucks from Mopar. The auto cams used to be 70 bucks. They took a price hike for some reason. I've done this myself. It works very well. Don't have any dyno numbers, but, the "butt dyno" says hell yeah. With this cam, cold air, headers, and a tuner(Diablo), you should easy be at 425. The trans deal is a tricky one. The 545 is cheaper to do, but, can't handle a lot of power like the Nag. Not only that, but all the additional parts needed for the Nag. Read about that directly on Hotwireauto.com. Helps if you do have a donor car for that. The 518 will still require surgery, too.
 
Do the math, the new hemis are cool and all but expensive...

You already have the trans if you stick with older iron, and will save a ton of money by doing so.
You could keep your 318 and stroke it, or just check out rusty's hot rod bliss thread.
RustyRatRod's Guide To Hot Rod Bliss

or,

Magnumswap.com - Your source for Dodge Magnum and Mopar engine swap tech.

or,

have you considered something like this?

Mopar 360 engine and radiator for sale

or,

have you considered talking to @Johnny Mac from blueprint engines?
 
Thanks for the response! The engine build you are describing is right what i was thinking.
I've read a bunch on the nag and it seems like a lot, but doable.
I guess my goal has been to just buy a complete car. Just seems like it would be easier to pull everything from one car...

I've been leaning towards a 09+ ram, durango, or jeep with the 545, rather than try to track down truck motor, then track down nag1/electronics/shifter, then deal with the install of the nag.
 
Ottmundr said:
Do the math, the new hemis are cool and all but expensive...

You already have the trans if you stick with older iron, and will save a ton of money by doing so.
You could keep your 318 and stroke it, or just check out rusty's hot rod bliss thread.
RustyRatRod's Guide To Hot Rod Bliss

or,

Magnumswap.com - Your source for Dodge Magnum and Mopar engine swap tech.

or,

have you considered something like this?

Mopar 360 engine and radiator for sale

or,

have you considered talking to @Johnny Mac from blueprint engines?
Click to expand...


Thanks for the feedback! I've actually gone back and forth on all of those options but ultimately have settled on the hemi. I also have a 440 and BB 727 in the garage. The builds I looked at for both the 318 and 440, or even a magnum just added up pretty quick to get reliable power. I've been seeing a ton of 5.7 engine and trans pulled out of wrecked cars for under 2,000. Even less at pull-a-part. For the cost the engine/trans plus the hotwire wiring and some engine parts listed above, it seems like I can get super reliable power pretty reasonably priced. Certainly open to ideas and I'll keep researching all options, but I'm pretty set on the idea of selling what I have and building a mild 5.7 with an OD trans. Just seems like the perfect combo for what I am wanting.
 
Travis Mitchell said:
Thanks for the feedback! I've actually gone back and forth on all of those options but ultimately have settled on the hemi. I also have a 440 and BB 727 in the garage. The builds I looked at for both the 318 and 440, or even a magnum just added up pretty quick to get reliable power. I've been seeing a ton of 5.7 engine and trans pulled out of wrecked cars for under 2,000. Even less at pull-a-part. For the cost the engine/trans plus the hotwire wiring and some engine parts listed above, it seems like I can get super reliable power pretty reasonably priced. Certainly open to ideas and I'll keep researching all options, but I'm pretty set on the idea of selling what I have and building a mild 5.7 with an OD trans. Just seems like the perfect combo for what I am wanting.
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Why settle for the 5.7 when you can get a 6.4? I absolutely love my '16 392 Charger. 4,400 lbs and it's _still_ quick.
 
If a person is patient, does research, and, waits(patience, again!) the right deal will come along. I haven't done the tally yet on my son's car, I can GUARENTEE I don't 6500 into it. That's including the price of the car. 73 Scamp 5.7 Swap That was rebuilding the 5.7 myself. These engines don't take much to freshen up. You're ahead of the game with a lower mile pull out. They can go for under a couple grand around here. Just saw one on Minneapolis c-list for 1600, 46,000 miles. Out of a truck.
 
Oh trust me I would love a 392! We are unfortunately talking way different budgets at that point...
Sounds like I may need to do a little more research on the Nag1 and 545 to be sure. But like you said I'll be patiently looking for deals. What deal comes up may help me make a better decision between the transmissions since neither sounds like a bad option.
 
Why not an 8HP70? Looks like Hotwire has figured it out. That would make a seriously cool cruiser (IMO).

No idea how costs would add up, but everything I have heard says they put the earlier 5 speed autos to shame.

I filed away the info because I want to do a 5.7/8HP70 swap someday. With the 8.4 Uconnect and all the stuff to turn on the Performance Pages, too. :thumbsup:
 
DionR said:
Why not an 8HP70? Looks like Hotwire has figured it out. That would make a seriously cool cruiser (IMO).

No idea how costs would add up, but everything I have heard says they put the earlier 5 speed autos to shame.

I filed away the info because I want to do a 5.7/8HP70 swap someday. With the 8.4 Uconnect and all the stuff to turn on the Performance Pages, too. :thumbsup:
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I honestly haven’t researched that much. I have no doubt Hotwire got it figured out already though! I’ll look into it more so if a deal comes up I can jump on it.
 
I've seen 5.7 long blocks for $1000.00 or less. my brother's neighbor had one from an '07 Charger with around 70k miles, with trans, he said he could probably score the whole thing for $1000.00, but no computer or wiring harness. One thing I have heard is the front accessory drive from a truck or SUV is preferable as the alternator and a/c compressor are mounted up higher, and will be less likely to cause interference with the k-member. Same goes for exhaust manifolds, go with the one from a truck or Jeep.
 
missing linc said:
I've seen 5.7 long blocks for $1000.00 or less. my brother's neighbor had one from an '07 Charger with around 70k miles, with trans, he said he could probably score the whole thing for $1000.00, but no computer or wiring harness. One thing I have heard is the front accessory drive from a truck or SUV is preferable as the alternator and a/c compressor are mounted up higher, and will be less likely to cause interference with the k-member. Same goes for exhaust manifolds, go with the one from a truck or Jeep.
Click to expand...
Yeah seems likely there a lot of good deals on them. I’ve seen that as well. I’m going to try for a truck motor unless it’s a screaming deal on a car motor.
 
I agree with the 09 and up unless the heads have been rebuilt as the earlier engines have valve seats that liked to drop. If buying used I would recommend at least a cam and lifter swap depending on the mileage of the engine. I have seen the lifters fail as early as 60k miles. I would do the MDS delete at the same time. If using a A518 trans (or similar) you need to have some kind of throttle linkage to the transmission for throttle pressure. There are a few ways to accomplish this. Also the factory ECM must be run with an electronic DBW throttle body (as far as I know anyway). You could go with Holley injection as they have nice setup for the Gen III Hemi's but they wont control the VVT so if going this route you will need to lock out the VVT but you can run either a regular mechanical throttle body or an electronic DBW one. Also food for thought is the 09 and earlier ones don't have VVT so you don't need to worry there. Also with no VVT there are many more cam choices. I wouldn't be too worried about the head flow unless you are really going aggressive as the early heads already flow 270 cfm stock and can be improved quite easily. The 09+ eagle heads flow 330 cfm out of the box....Oh and Holley has no transmission support Mopar transmission control as of yet but it is coming as there is a drop down in the software but no options there to choose so if you are wanting to run anything more modern than the A518/A500 the factory controller is the way to go right now (I know there are some stand alone transmission controllers in the works). Megasquirt is an option too, it controls VVT but not electronic DBW throttle bodies as far as I know yet.

That's all I can think of right now. I'm working on my own Gen III Hemi swap so I'm in the middle of this right now too. I was going to run a rebuilt 05/06 5.7 based stroker with Holley injection but I got a very good deal on an '18 5.7 hemi with 10k miles on it. I will probably go with the factory controller and tune it with HP software.

Garth
 
I know it’s been a while but thought I’d update y’all on the input you gave me. finally came across a deal. I was able to scoop up a 2015 5.7 with the 8hp70 out of a wrecked charger with only 80k miles. Found it local and traded it for an old stand up jet ski I built. My ski was probably worth about 2500. So the way I see it I got a low mile engine and trans for 2500 bucks.
Seems like Hotwire has the harness I need. Just need to get the rest of the chassis work done then I’ll freshen up the motor!
 
Travis Mitchell said:
I honestly haven’t researched that much. I have no doubt Hotwire got it figured out already though! I’ll look into it more so if a deal comes up I can jump on it.
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A guy 30 miles from me has a low milage one for $600. I don't know if that's a good deal or not
 
How are you guys getting these big gearboxes into an A body?

And of course by that I mean "photos" LOL
 
I have a 2 pin 518 rebuilt if you are interested. Pretty easy solution.
 
The more engine you have, and
the broader it's powerband;
the less torque multiplication and the fewer the gears it needs to have.
I have had as many as 8 behind my HO367LA, and as few as 4. It really only needs 3, but they don't make 2+1s. I need two gears to hustle to 60/65mph; and then an overdrive, to cruise with.
So instead, I have a Commando 4-speed mt, with a GVod. Fourth gear is mostly along for a free ride. Even third I could do without . But I like 65=2240rpm.
In a lightweight car, I would do a 3 or 4 auto with a loc-up, and a higher stall; so that the TC acts like a two-speed. Add the loc-up, and the 3-od trans will act like a 5-speed.
Say you had an A999 with ratios of 2.74-1.54-1.00.
And a hi-stall TC with a hydraulic multiplier of 1.6/1
and a rear gear of 2.94s.
Yur looking at a starter gear of
14.50, then~ 10.47-5.88-3.23-2.94 in loc-up.....65=2370rpm with 27s
splits of; .72-.56-.55-.91
Most of the time, you will be driving it 1-2-3L, so your splits will actually look like;
.72-.56-.50 into 3L. As you can see, this combo wants a wide powerband, so you'll need an appropriate cam.
Or
Say you had an A998 with 904 ratios of 2.45-1.45-1.00
And same Hi-stall,2.94 gears.
You might be looking at
~11.52-8.06-5.11-3.23-2.94 in loc-up ....65 still=2370rpm...
splits of .65 -.63-.63-.91.... Needs a different cam than above; and ba-BAM!
And BTW, this trans fits in the A-bodies, like it was designed to go in there,lol. And is cheap to buy,build and rebuild; millions of them are out there.

jus saying.
 
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Travis Mitchell said:
Oh trust me I would love a 392! We are unfortunately talking way different budgets at that point...
Sounds like I may need to do a little more research on the Nag1 and 545 to be sure. But like you said I'll be patiently looking for deals. What deal comes up may help me make a better decision between the transmissions since neither sounds like a bad option.
Click to expand...

There are a couple sellers who regularly sell 6.4 truck engines and parts. Short blocks and bare blocks. Even saw a couple remanned short blocks cheap. I am both cheap and broke but scraped up enough to make a bid on one and they had free shipping. Now I am just taking it slow and bidding or buying parts to assemble it.

Mike
 
CichliDart said:
There are a couple sellers who regularly sell 6.4 truck engines and parts. Short blocks and bare blocks. Even saw a couple remanned short blocks cheap. I am both cheap and broke but scraped up enough to make a bid on one and they had free shipping. Now I am just taking it slow and bidding or buying parts to assemble it.

Mike
Click to expand...

Sounds like youre talking about Ebay?
 
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