Several guys have expressed interest in a thread about the 392 stroker Hemi that I'm building. I figured I'd go ahead and chronicle everything the best I can.

 

I'm still waiting for some parts to show up, but here's the basics of what I'm doing.

 

The stock Dodge 5.7 Hemi has a bore of 3.917", and a stroke of 3.58", for a total displacement of 345 cubic inches...or 5.7 liters. I am having a little fun with this one, so I'm boring it .010" just to clean up the bore. I'll be using Mahle forged pistons specifically designed for the crankshaft and rods that I'm using. Speaking of crankshafts, that's where all of the fun will come from on this particular engine. Several manufacturers make a crankshaft for both the 5.7 Hemi as well as the 6.1 liter Hemi (they share the same stroke) with a stroke of 4.05". Why 4.05"...? That's kind of an arbitrary number, isn't it? Well, with a 5.7L block, bored .010" over, and a 4.05" stroke, the engine displaces exactly 392 cubic inches, and the same crank in a 6.1L block (also bored .010" over), yields a displacement of exactly 426 cubic inches... Both of these numbers are throwbacks to the Hemis of old...the old elephant engines.

 

Up top, I'm keeping the 5.7 heads, but I'm installing the larger stainless valves from the 6.1L's. Replacing the intake seats is something you'll want to do on ANY Hemi engine that you build because they are notorious for dropping them even when mildly overheated. There is not much of a press-fit from the factory, and they drop right out when they get hot enough. So, since I was having the seat replaced anyway, I had larger seats installed in both the intake and exhausts to accommodate the larger 6.1L valves. The OEM 5.7L valves measure 2.0" inches on the intake side, and 1.55" on the exhaust. The OEM 6.1L valves are 2.08" on the intake, and 1.6" on the exhaust. Plus, the 6.1L valves are much lighter due to the hollow stem on the intake valve, and the exhaust stems are sodium filled for better heat transfer away from the combustion chamber. I am using PSI LS1511 valve springs with Comp Cams spring locators to keep them in place at the bottom. These were both made for the GM LS engines, but work great in the Hemi after machining the top of the valve guide down to .510". Valve spring installed height is set at 1.8". These springs have exactly 135 lbs of pressure on the seat at 1.8" installed height. Perfect...

 

As far as the camshaft goes, the stock 5.7L cam is VERY small...! In the last Hemi I built (in my wife's Durango), I used a 6.1L SRT8 camshaft, which is quite a bit "larger", and runs very nice. On this build, I'm taking things a step further and had a camshaft ground with 221 degrees of duration (at .050") on the intake, and 227 degrees on the exhaust side. Lift is .575" on the intake, and .585" on the exhaust, and the lobe centers (LSA) are pretty wide at 115 degrees. This will help it play nice with the computer at idle.

 

So, that's what I'm building...a 392 cubic inch "stroker" Gen III Hemi engine with ported big-valve heads and a custom ground camshaft for an '04 Durango that I bought.

 

Pictures to come...

Nice ride...

 

It sounds like you have some decisions to make. If you want a 5.7 based 392, I would not hesitate to recommend the parts that I used. The one big decision you'll have to make, though, is whether or not you're going to run a supercharger because that will drastically affect the compression ratio you spec out for your build. With the pistons that I used, and the chamber size in the heads, my compression ratio is about 10.8:1. This would be quite high for a supercharged application. I would shoot for closer to 8.5:1 - 9.0:1 if I were going to supercharge mine. The lower the compression, the more boost you can run.

 

I don't believe the '07 Hemis used VVT, so camshaft specs should be easy. If you want that idle chop, you're going to want something in the high 220's or low 230's on both sides (duration at .050") on tighter lobe centers. This will maximize valve overlap, which gives that idle lope. But, it also drastically complicates tuning. Early 5.7 Hemi heads are happy in the .550"-.580" lift range, plus then you can get valve springs that work well and are affordable. I am using PSI LS1511 springs (which are a GM LS valve spring) on mine. My lift is .575"/.585". The other thing about camshafts is that a grind that is spec'd out for a supercharger is going to look quite a bit different than one spec'd for a naturally aspirated engine. I'm a big believer in custom ground camshafts. Get exactly what you want, not an off-the-shelf compromise...

 

As far as headers go, I haven't tried any yet, but there are a couple of Ram 1500 P/U long tube header sets that look like they may fit. It's a tight squeeze on a Durango/Aspen, especially on the driver's side, but I think the Dynatech headers may work. I'm basically a header snob, and only recommend stainless steel long tube headers. In my opinion, shorty headers are not worth the hassle. You still have to reconfigure the front part of your exhaust system to get them to connect to the rest of the exhaust system, and most offer little gain over the stock manifolds. Stainless looks good, last longer, and won't rust like mild steel headers will.

Man this is BADA**!! 

Thank you fellas! I'll be sure to post a few more custom pics! I've done a lot of custom work including custom interior and I eve baked the headlights and installed some halo Oracle leds and HID conversion kit! So Dynamic as far as horsepower and torque go with what you're running and your setup in general what am I looking at? And how can I tell about the VVT? I am clueless? I would like 600 hp out of the block, cam, and heads without N/A for the time being as it'll be another year or so before I can afford the supercharger or should I just go for some top pistons and go cheaper with NoS?!

Yours is an '07. You don't have VVT. You likely DO have MDS (Multiple Displacement System), though. Larger cam grinds don't usually play nice with MDS. It's easier to eliminate it.

 

600 hp is a pretty tall order for any naturally aspirated, streetable setup. With my setup, I'd be happy if I hit the 500 hp mark, but high 400's is realistic. Big hp numbers don't come easy.

How do I go about eliminating MDS to play nice with a large Cam? I've read about 100hp cam upgrades on these 3rd gens, and curious because from factory just a large cam can get a stock 5.7 to almost 450hp? But with bored and stroked 392 with port and polished heads and full catback  how it can't make at least 600hp? But then again I'm not a mechanic! Lmao

MDS plugs in the block. Tuning...

 

Haha... If only things worked that way! It would be a heck of a camshaft to get a stock 5.7 Durango to 450 hp! But, if it did, it would be in some pretty ideal conditions. But, assuming that you did find that magic camshaft that brought you to 450 in an otherwise stock 5.7 with a Durango intake and exhaust (which I highly doubt), the extra displacement of the 6.4L (392) certainly isn't bringing another 150 horsepower to the table; more like 35-40, with an ideal intake and exhaust situation. Same with head porting; just a few more hp is all...

 

Believe me, I'm in the process of building one, so I'd love nothing more than for you to be right! LOL But, I think you're about 100 hp or more on the optomistic side.

Dynamic you're breaking my heart here! Lol, I was being optimistic and it got shot down. Ha, so let's say I build the healthy block like I've mentioned with the 392 stroker build and get the MDS out of the way and tuned, cammed, and the proper headwork. And I'm able to retrieve the almost 500hp just from that build alone. To get that extra 200 hp I'm looking for would you consider the supercharger? Turbocharged? Or pro charger? I was looking into the 671, and to me it looks like those are the $2k to $3k range much better than then newer super chargers, however, it looks like the 671 are on built for carbureted engines? Otherwise if there was a way to get a 671 to work with my build and the EFI I'd be happy with one of those for the price! Just not sure which to go with. Again on a budget so I know it's harder to get that hp! Could I just get a 572 crate long block and it'll go right in or a crap ton of mods for a bigblock? Would love to go with that instead. Lol

Here's what I did custom to the headlights! They're RGB oracle lighting, will be doing the fog lamps as well soon

 

Edited July 9, 20168 yr by Chad

Hello, hope everyones weekend was great! Unfortunetely today is my monday and I am here at work! So I have had a change in plans after reading a bunch today on what to do with my Hemi build. And I have also increased my budget by another $1000 or so. So with this new idea in mind I am stuck on how to build the 5.7 for use with either a procharger or a supercharger. Don't know alot about either one except the way they work but for my application on the rebuild being a 392 Stroker and all how I should build the lower half and what to do about my cam situation. So what do you think? Continue with the forged stroker 392, and just port polish heads, upgrade throttle body and fuel injectors and keep a mild cam for tuning? I just need a good starting point. The price between procharger and superchargers are roughly about the same I am just wondering which is a little easier to install and the power outcome differences matched with what I am wanting to do to the rebuild. Thanks again!

 

Chad,  

 

I would suggest you start your own thread in this section for your build and questions so we can keep things in both topic on track.

 

Thanks

 

Nick

Sorry fellas, I'll create a new thread! I've never really spoke on forums before so didn't know the rules! Thanks again

you're fine, I just want to make sure you get the answers you need as guys may not always check dynamic's thread to answer a question of yours.

Much appreciated Me78569!!!!

Well, it has been a busy summer. Lots of family trips, a lot of transmissions built, a lot of music played, a lot of outings on the boat, etc...

 

Progress on the Hemi has been slow, but I have managed to get it just about finished. The custom thickness head gaskets arrived from Cometic, the new head bolts came in, the heads final assembled with the stainless 6.1L valves and PSI LS1511 valve springs, and now the heads are torqued on permanently. The bottom end is all together, and its new oil pan installed (the original pan was destroyed by an angry connecting rod). I'm just waiting on rocker shaft collars from Stanke Motorsports (top shelf stuff for Hemis...), and then I can assemble the rocker shafts and final assemble the valve train. I was afraid that I would have to use expensive custom-length pushrods with all of the block decking and head shaving that went on, plus the smaller base circle of the custom-ground camshaft. But, after mocking everything up and measuring pushrod lengths, I found that stock length 6.1L pushrods work perfectly, and give about .060"-.065" of lifter preload...perfect! Manley makes a nice set with those lengths, so that's what I will be using. It's the same set that I used on my other Hemi...

 

Here are a few pics...

 

A shot of the bottom end before the oil pan went on. On the Hemi engine, the oil pan gasket incorporates the windage tray to help control...well, windage. Because of the much longer stroke of this setup, I used an OEM 6.4L pan gasket (mucho $$$, by the way...). The 6.4L gasket has some extra reliefs in it to accommodate the longer stroke of the factory 6.4L crankshaft. This made it easier to clearance everything so that there were no interference issues. I only had to tweak a couple of spots. No big deal...

 

Here's a pic of the GM LS engine lower spring locators I used to stabilize the bottom of the valve springs. Valve spring breakage is a known issue with the Hemi engines and engine builders tend to agree that aside from poor quality OEM springs, the lack of good locators on the bottom of the spring is to blame. This is my solution... Aside from the extremely high quality springs from PSI, I machined the top of the guide down .018" so that I could use these Comp Cams locators. There is also a .015" shim under each locator to bring the valve spring installed height to exactly 1.800".

 

And here are a couple of pics with the heads final installed, as well as the timing cover, balancer/crank pulley and water pump.

 

Cheers...!

 

Looks too wide to fit!

Haha... Yeah, it's a pretty wide engine, and it's pretty tight getting it in and out of there, but it DOES fit...

Got the engine installed and running. It fired right up...perfect oil pressure, no leaks, cooling system bled right out, valve train silenced itself after a couple of minutes to pump the lifters; no mechanical issues to speak of. Everything as expected.

 

I do have some tuning issues to deal with, though. The factory programming isn't working real well with the larger 6.4L fuel injectors, and the considerably larger camshaft. Nothing a little time with HP Tuners and a pair of wideband O2 sensors won't fix. Even with the poor fuel and timing maps, running quite rich at the bottom, and extremely lean up top, this thing has some muscle...! Traction control and AWD might come in handy should I somehow, by some strange happenstance, find myself at a drag strip someday. 

 

Up next: tuning and exhaust system...

Video request...

I knew that was coming... LOL

 

Soon...!

Well, I finally got Project Hemi on the road. It's got about 300 miles on it now, and I'm zeroing in on the final tuning of the engine. It definitely runs good, that's for sure.

 

I spent some time yesterday getting the rear ride height where I wanted it. I ended up lowering it exactly one inch. I may go another 1/2" or so, but it definitely looks better now than it did. The wheels and tires I put on it are a little larger in diameter, and whole lot wider than the stock size, so they fill out the wheel openings better.

 

Here are some pics...

 

 

 

 

Edited September 25, 20168 yr by Dynamic
Bad pictures