Gen 2 or Gen 3 Hemi?

[G-man]

Hi Guys,

Looking at Gen 2 or Gen 3 Hemi. Why would one want one over the other? What are the pros and cons to each?

People told me the Modern Hemi makes 700 HP out of a 426ci block while a 572ci Gen 2 block makes that. In other words, the Gen 3 is more efficient at making power, runs better on fuel, more reliable, and weighs 50% less, thus the car will be better from all aspects.

However, what do they sound like compare to older gen 2 hemis, and what benefits do the Gen 2's have that the modern one doesn't?

I mean, if we are talking 500-700 Horsepower... both engines make that power. Do the gen 2 hemis produce more (overall) like if we want to go 1000+ HP or what?

Just trying to understand why one over the other.

[Mike DC]

Weight:

The absurd weight figures for the gen-2 only happen if you combine the heaviest possible scenario.  Repro iron everything, full size heavy starter, even the intake & exhaust manifolds are iron, etc. 

Comparing a more realistic scenario of a repro iron block + everything else aluminum + lightweight starter + tube headers = more like low 600s.  (A lot of that weight is the 310-lb reproduction iron block which is reinforced everywhere.  I think the stock iron Hemi blocks were around 240 lbs.   A repro aluminum gen-2 block is like 135.)   

A gen-3 Hemi with an iron block won't be much less than 500 lbs.  With stripped accessories and an aluminum block you might get down as low as 400 lbs.



Power:

The modern motor is "more advanced" but it doesn't make the low/midrange torque of an old Hemi (or even an old 383/440).  It will win races and post fast times.  But it won't feel as powerful when you are just goofing around town at half throttle, occasionally goosing it to 4000 rpm.  It will require more RPM than a big stroked old g2 to hit a given amount of power. 

[Ghoste]

I would think the newer one is easier to maintain in one sense as well.  The Gen II Hemi was a race engine detuned for the street so it was running a bit off when you got it new (and it should be obvious the Race Hemi was highly tuned thoroughbred not easily suited for common driving) whereas the Gen III is a passenger car engine modified for more so even when it falls off it could still be a good performer. 
On the other hand, all that technology has its drawbacks too.  A failed sensor or coil pack and you're walking. 

[Mike DC]

 

The price of a 650-lb stroker Hemi could also probably build a 500-lb stroker wedge.  Take the extra money you would have spent for the Hemi and dump it into an aluminum wedge block.

[Ghoste]

Unless you're a sucker like me and you want an iron block 426 Gen II just because thats what you want dammit!

[RamZCharger]

Devil's advocate . . .

[G-man]

Hold Up... nothing is resolved yet!

Are you saying 650lbs = Gen 2, and 400lbs = Gen 3?


Lets give this scenario, we buy a 700 horsepower built Hemi from Ray Barton. Gen 2, 500+ ci, alloy block, heads, etc, so its as light as it will ever be.

Compare that to a 426ci 700HP (due to efficient) Gen 3 Hemi with Alloy block, heads etc.

Both = 700, weight will be different... how much?

Torque figures etc, how much different?

And honestly speaking, though both will suck, how much fuel different? Is the Ray Barton Hemi driven like a grandma still gonna get 5MPG while the fuel injected modern one may still see 15-20MPG, or will they both be stupid?

[Mike DC]

   
An all-aluminum gen-2 Hemi is more like 530 lbs, not 600-something.  The latter weight figure would be from using a 310-lb repro iron Hemi block. 

Mileage will be stupid either way but the smaller displacement motor would be better when you're not on the gas.  That's why the OEMs have gone to smaller-displacement higher-revving motors.  The power is there when you rev the motor up but it drops down to a lower figure when you let off.  (It also feels that much less powerful when you aren't in the high revs.) 
 

[hollywood1336]

You must have a pretty big budget my friend, the Gen III 426's don't make 700hp right out of the gate, and you can't just chip it to get that kind of hp either. A 700hp Indy hemi sells in the high teens. Money no object, no problem. I agree with a previous comment, you can make just as big hp with a 440 or 383 with half the money, then splurge elsewhere.
Check out the thread "amazing First Cruise Night". This guy said he had 300 grand in this build, I don't know how much in the motor. He said the motor made an estimated 650hp. I asked if he had the motor dynoed and he said it was an estimate. Big hp doesn't come easy or cheap, ask any experienced engine builder.
Despite all that I've said, that new 426 did look beautiful in that engine compartment.

[G-man]

I would be looking at about 40,000 for an engine.

So what is the charger better off with?

The Big Gen 2 is heavier, but stated more torque (lower in RPM's) the Gen 3 Hemi is making over 600 ftlbs of torque at 3,500 RPM. If the Gen 2 does it from 2000rpm onwards... I dont see how that means much except first gear. I mean, RPM's go up really quick anyway, and after that, it makes no difference.


So would the lighter Gen 3 still work out better over-all, or is there more difference than I am putting (meaning more than just a split second of 1000 rpms)

[Troy]

It depends on what *YOU* want. Ignore the power numbers for one second...

Old Hemi (stock):

• Has appeal even if it doesn't run. Just open the hood and wait for onlookers. That's one of the reasons I love it.
• Two giant carburetors that don't always work well on the street. That's one of the reasons I hate it.
• Massive torque at low RPM - lots of melted rubber and tricky in the curves.
• Fairly easy to install since they were an option. The sound when you open it up is (or even at idle) is intoxicating.
• Cost is usually a big deterrent.
• A/C is a pain to install - and probably not recommended at all.

Yes, you can fuel inject it - more cost and complication.

New Hemi (stock):

• Much more refined with (mostly) seamless power.
• Computer control: both a pro and a con because wiring one up into an old car can be complicated and very expensive.
• Not much appeal (visually) to most people who enjoy old cars.
• Sound is mostly bland - unless you come up with an amazing exhaust. No rumpity rump in stock form.
• Cost is generally expensive - mainly because of installation, labor, and sheer amount of "stuff" that comes with it.
• A/C is pretty much built in.

Yes, you can put carburetors on it but you lose a lot of the better things about the motor.

Once you go tearing into either to build something specific the costs skyrocket, the complication increases, and the longevity/livability becomes questionable. Both of these engines in stock form have more than enough power for the street. Once you go bigger the rest of the driveline has to be built to match and your option get severely limited. I've seen countless builds where the car basically becomes undrivable because the owner went too far purely for the sake of bragging rights. Chasing that last ounce of weight and last bit of horsepower/torque is best left to those with purpose built race cars and a love of spending more time tuning than driving.

RPM is a function of engine, transmission, rear axle gears, and tires. You can tweak the combination to keep the engine in the "sweet spot". Unfortunately, this gets tighter/smaller as you go up in power so the "usable range" affects what you can do with the car and how much of a pain it will be to drive.

So honestly, when I hear this I just think of a giant money and time sucking hole.

For reference: I have engine swaps in over half my cars. None have been as cheap or easy as planned. I have chickened out of most of my "street/strip" engine projects because the efficiency, drivability, and fuel requirements (race gas) weren't acceptable to me. I literally want to turn the key, drive the car around, and park it back in the garage. While driving I like to have enough power to have fun and possibly break a few speed limits. I don't stop light race or ever visit any kind of track.

Troy

[G-man]

Thanks Troy.

I wan't something reliable, just works (like a pro-touring car) and sounds good. I do not care about what you see in the hood because I don't go to car shows and when I am driving, my head is not inside the engine bay through the firewall to see what is there. The only time I need the hood up is when the car gets a service, that is about it.

So really, just want something that works (thats why I opt'd fuel injected) and good power 500-700HP. Just wondered am I better off getting that power from a Gen 2 or Gen 3. If you do fuel inject a gen 2, is that as reliable as a gen 3, or still not as the design is old trying to utilize a new function and therefor won't be as efficient?

[redmist]

Gen III Add Boost, Save money, weight, and time tuning old stuff.

[Mike DC]

Gen III Add Boost, Save money, weight, and time tuning old stuff.

Blowers, turbos, intercooler setups . . .  all that stuff adds dozens of pounds.  

A smaller motor's weight advantage can end up being pretty minor once supers/turbos get into the picture.

[Troy]

If you want "reliable" and "just works" then stay away from too many modifications. Stock is built the way it is because the manufacturer has to warranty it. Once you start bumping up the power levels you shorten the lifespan and, often, make it less reliable/more finicky. The new 392 Hemi is 485 hp and 475 ft/lbs and would be a bit better with a less restrictive exhaust. The old Hemi easily matches that and a few tweaks should get you over 500. The closer you get to 700 (especially with carbs) the less you're going to want to drive it all the time. My opinion of course.

Troy

[hatersaurusrex]

If you want "reliable" and "just works" then stay away from too many modifications. Stock is built the way it is because the manufacturer has to warranty it. Once you start bumping up the power levels you shorten the lifespan and, often, make it less reliable/more finicky. The new 392 Hemi is 485 hp and 475 ft/lbs and would be a bit better with a less restrictive exhaust. The old Hemi easily matches that and a few tweaks should get you over 500. The closer you get to 700 (especially with carbs) the less you're going to want to drive it all the time. My opinion of course.

Troy

I agree with everything Troy has said and will add one more thought that he touched on - the drivetrain.   If you get a newer Hemi, you can get it from a donor car WITH the tranny.   Assuming you're going automatic - then new trannies will have overdrive, which will let you gear your rearend lower (think 3.73 or 4.11) without having the motor screaming up to 4K RPM on the highway.   The shorter gearing also means you'll have much more fun from stoplight to stoplight and still be highway cruisable.  An older Hemi with 4.11's out back and a 727 with 1:1 top end will force you to trade off.   Then you wind up running 3.07 or 3.23 gears to give it highway manners, and those extra 150 horsepower you paid to get, you wont' even feel.

A gear vendors type overdrive could give you the best of both worlds in that case - but you're looking at 2 grand.

That said, I've personally chosen the old school 426 route and will be getting a nice beefy 727 and a GV overdrive behind it so I can gear my rearend nice and short for some pants-pissingly fun romps to 60

[Mike DC]

        
I don't think any OEM overdrive trans from a modern Hemi (or pre-Hemi smallblock) is going to clear the undercarriage of an old B-body Charger.  

You might make things sorta fit with some moderate hacking.  But that's going to involve compromising the drive angles & hanging the rear of the trans farther down than it should be.  Making it fit as well as the factory intended will mean a bunch of crossmember & tunnel reconstruction.  


There is also the option of a GM 4L60E conversion.  It fits the car pretty well & has some nice features but it's not the strongest trans for the job.  It costs a good $4k, maybe more if it's really beefed up.


I think the GV unit is closer to $3k than $2k when all is said & done.  

Not that it matters.  The price barrier of an overdrive setup shouldn't even factor into the conversation when we're talking about $30,000 motors.  Just the reduced wear & tear from the lowered RPM alone would make it a smart move.      

[ws23rt]

I agree with ^^

Wanting a 45 year old car to do what we are used to feeling these days is nothing more than a trade off between what it was and what we want. As soon as the drive system is up to desire other issues will soon follow. I say let's enjoy these old cars as they were and drive something else for another experience. I like my hemi coronet with a 3.54 rear gear.  The way it drives is as much a part of why I like it as the way it looks.

If one wants both than check out what stevearino is doing. My hat is off to him.

[Rolling_Thunder]

Hmmmmmm    well no offense but why are you concerned with weight so much? Planning on carving some canyons?  If so the charger isn't the most effective platform - but far from the worst.   Here's the thing....   

Gen II Hemi - inefficient, tempermental, poor gas mileage, ---  those are the stereotypes. But with an OD transmission, modern valvetrain, and EFI your second gen Hemi can make excellent power, get decent mileage, and wont give you as many maintenance issues like back when. The plus side is the "muscle car" look, heritage, and the whole "legend" persona.   $20,000 for a crate 700+HP Hemi.

Gen III Hemi - efficient, reliable, decent mileage --- With say my 6.1L you get EFI out of the gate, 425HP out of the box...   headers, tune, and some tinkering they make 470-525HP without having to open the engine up. The mileage is usually accomplished with the same OD transmission and EFI so don't think one engine makes gobs more mileage than the other....    the best part of the EFI is the tuning for light load / throttle - makes for better mileage than carbs usually.   

The cost is also very different. The Gen II Hemi is expensive...   everything about it....      Guys are talking alloy blocks...   great - look at the cost. Granted the new allow block for the 6.1L is $4300 itself so it is almost a wash. However, valvetrain on the Gen II is serious cost along with alloy heads....    Figure your Edelbrock aluminum head is $1350.00 each for an assembled cast aluminum head....     there's $2,700 just in heads. Now add expensive rocker shafts, rocker arms, etc, etc....      it adds up. Your Gen III has reliable and alloy heads already, flow very well, and come with your $5000 pull out engine. It gives you more money to play with CNC porting, stroker kit, forced induction....      That is why I went with the Gen III. I was interested in the pro-touring thing and I scored my 6.1L for $1000...    new forged crank, and some bearing I was into the engine less than $2000.

Some people mention less torque in the new engines...    true. They make less torque because they don't swing a long stroke....    but I run 3.91s and a T-56 so I get plenty off the line due to gearing....   I could run a 4.10 and not worry about RPMs on the highway as my 6th gear is .50. Do I really worry about the lack of torque?  not at all....      low end torque is violent - that's why we like it....      violence in my experience breaks things...   like U-joints, driveshafts, 3rd members, etc...     

I personally think the Gen III is an amazing engine with huge potential for its size...     downside is the size restrictions due to block architecture. The Gen II has its place and I enjoy building and driving them - but the Gen III cant be beat for what I am doing with my charger.

[Mike DC]

 
 
The gen-2's main power/torque advantage is that it goes so much bigger in displacement.  That probably affects it more than crank stroke or anything else.  We're talking another 100+ cubic inches.  

The gen-3 is sort of a gray area between a big or small block.  But it's arguably closer to a small block.

   

[SRT-440]

A GEN III 392 would give most GEN II's all they want powerwise regardless...

BUT, if u got that kind of money..Bochillion Performance has a crate Hellcat 6.2 for $16,000 (supercharger to oil pan)...buy a Holley Dominator computer, 8 spd trans (yes you'll have to cut ur floor board) and update your fuel system...all for less than $30K prolly...and none of us need to chit chat about how the HC motor stacks up to a Gen II. 

[Mike DC]

A GEN III 392 would give most GEN II's all they want powerwise regardless...

Depends on what you want all that power for.  To win races, or be fun to drive?

[Ponch ®]

New Hemi (stock):

• Much more refined with (mostly) seamless power.
• Computer control: both a pro and a con because wiring one up into an old car can be complicated and very expensive.

Im surprised you were the first one to bring it up. In my circles, I always know of someone selling a cheap 5.7 or 6.4 out of a wrecked LX something or other...and Im always tempted. Then I look into what is needed to get it to work on the old car and im like...nah.

So honestly, when I hear this I just think of a giant money and time sucking hole.

Troy

Us married guys are already used to such things anyway