Pre-09 5.7 Head Options

[Map63Vette]

As the title suggests, what all is even still out there nowadays? Back in the day I remember hearing about Thiteks and Inertia had heads to go with their cams, but lately I'm seeing very little offered for the earlier engines. I know the later heads are better out of the box, but I painted myself into a corner because I had no way of knowing what was coming back when I did my swap ~15 years ago.

I have an Indy ModMan intake for the early 5.7 ports and TTI headers as well. I'd really rather not have to redo everything on the top end if I ever did pull the trigger on some better heads, so I'd like to try to keep to original early 5.7 style ports and bolt patterns. I actually really like that my engine still looks kind of old school with the 4bbl throttle body setup, even if the injectors and rails are obvious if you look lower down.

I've been quite happy with the way my car is running now, but I always have that nagging in the back of my head saying "but could it be better?". It's basically my daily driver, so I'm not looking to compromise it away from that, but I figured some better flowing heads would be one of the "easiest" ways to get a little more punch out of it without redoing a lot of stuff. I've got an Inertia Motorsports SRT Max Plus camshaft in it now and I think I've got my tune to a pretty happy point. I'm not trying to set records or anything, so I'm not pushing it to the limit and trying to squeeze every last drop of horsepower out. Mostly just thinking of what kind of stuff I might be able to do if I wanted to get more without resorting to a whole new engine or forced induction.

 

[408 swinger]

I don't know for sure about what's actually "available". They respond well to basic modifications like any other head. The heads that are on my 426 are heavily modified early heads. They work well. Intake ports have been opened all the way up, lol. So that would not work in your case, for trying to keep your intake. I would think you'd benefit from a little larger inlet valve, basic port work, etc. It's gonna be a DIY thing for sure.

 

[408 swinger]

[hidden information]L HEMI CNC Ported Heads by Modern Muscle Performance
How far from Lawrence? Doesn't seem like a bad price.

 

[Map63Vette]

[hidden information]L HEMI CNC Ported Heads by Modern Muscle Performance
How far from Lawrence? Doesn't seem like a bad price.

Oh dang, that's not bad. Only about a 3 hour drive or so I believe. Never thought to look for used.

 

[Map63Vette]

I guess before I get too invested in the idea of actually swapping anything, might be good to ask if my setup would even see any benefit or not. I've tried looking at some online calculators, but I get pretty wildly varying results.

Short block is a stock 2006 5.7, so all stock pistons, crank, and rods. Intake is a large single plane with short runners, headers are long tube. Cam specs below:

Lift at valve: 0.549 / 0.536 (int/exh)
Duration at 0.050": 218/226
LSA: 110

I have the individual valve events as well if that makes any difference.

Some places say the heads flow more than the engine can even use without more displacement (ie. stroker kit), others say my cam is way more aggressive than what the heads can use. Conventional wisdom is max horsepower is 1.5-2.0 per cfm of head flow I think? I've always thought this combo should in theory be good for ~400 hp without really going for every last bit. I haven't had it on a dyno since I've redone my whole computer system, which should really probably be my first step I suppose. Also sounds like ported heads aren't a huge upgrade over stock, so not even sure I'd pick up much extra power without a rotating assembly swap to take advantage of them.

 

[408 swinger]

I would have to disagree, somewhat, with the heads flow more than the displacement can use. The Eagle head flows a bit more than the early. Both early and late share the same bore/stroke configuration. I wouldn't say your cam is too aggressive for an early head. I do know an early bottom with Eagles and a stock 6.1 cam is a runner. Those are 221/225 @ 50 on a 116 lsa.

 

[Map63Vette]

I didn't think about comparing the Eagles and the early ones, that makes some sense. I'm not sure how cam specs line up between the two in stock form, though I'm sure the VVT probably adds some of the difference in power between them. Whether it adds bottom end or top end would be an interesting question though.

I guess I'd have to figure out how much I'd be willing to spend for hp. I know NA is the most expensive way to make power, but I also know I don't feel like adding all the complexity of forced induction either right now (though I have always debated just tossing a blower on as my manifold is basically already set up for it). If ported heads are only worth ~20-50 hp, it feels like it might make more sense to put that money toward a stroker kit or something that may be more like 50-100 hp.

I had a chance to pick up some Eagle heads (or maybe they were 6.1, I can't remember) at a swap meet a few years back, but the compression ratio issues and port mismatches tempered my desire. A stock intake probably wouldn't be that expensive to pick up, and a cable drive throttle body wouldn't be that hard either. Guess one of these days I'd just have to add up the costs for different directions and see how they compare. In the long run I'm not sure how much power my chassis is really going to like anyway, so that's probably one of my upper limit points.

 

[408 swinger]

The 6.1 has an "open" chamber like the early 5.7, the ports are like Eagle. Big, square intake and D shaped exhaust. I agree with the HP vs money spent.

 

[dusterdoug]

There a few guys that run pretty good with a pre-eagle short block and eagle heads. Puts the CR north on 11:5. Only negative is that with the smaller chamber, it really limits cam choices. I have been told that the stock 6.1 cam specs is max.

 

[Map63Vette]

The cam I have was advertised as being about the biggest one you could fit with stock pistons. Since I'm trying to stick to pump gas (and the cheap stuff at that), I doubt I'd want to test my luck with too much compression. I could always tune it back a bit, but so far my car has been running great on plain old 87 octane.

 

[408 swinger]

The cam I have was advertised as being about the biggest one you could fit with stock pistons. Since I'm trying to stick to pump gas (and the cheap stuff at that), I doubt I'd want to test my luck with too much compression. I could always tune it back a bit, but so far my car has been running great on plain old 87 octane.

Hard to mess with that then.

 

[Map63Vette]

Now I'm going down the rabbit hole of stroker kits, lol. Found an old article where someone did a ~6.4 stroker kit on an early 5.7 and managed 500+ for torque and horsepower. Granted, they were using a Drag Pack manifold and a cam with ~10 degrees more duration than mine on both intake and exhaust, but I think torque is really what makes me happy. Driving my Viper around is fun because it doesn't take much throttle to give you that kick in the pants, and daily driving is going to see a lot more low rpm stuff where instant torque is more fun than top end power. Certainly a more involved refresh to make it work, but temping all the same.

I really need to get my car back on a dyno one of these days or to the track to see what it will do. Hopefully Heartland will open back up now that it looks like someone bought it to keep it alive. I don't relish the idea of driving to the other side of KC for a test and tune night when Heartland was practically in my backyard.

 

[408 swinger]

A customer just stopped by the shop to show me his finished product. We did a 5.7 based 392 for his 2012 Charger. Eagle and Mahle bottom end, 6.4 Big Gas Heads, and Texas Speed cam that I forget the specs on. It's lumpy. He just had preliminary tuning done so he can drive the car. Conservative, 455 to the tire. You can make great power with the 5.7/392.

 

[racerjoe]

As the title suggests, what all is even still out there nowadays? Back in the day I remember hearing about Thiteks and Inertia had heads to go with their cams, but lately I'm seeing very little offered for the earlier engines. I know the later heads are better out of the box, but I painted myself into a corner because I had no way of knowing what was coming back when I did my swap ~15 years ago.

I have an Indy ModMan intake for the early 5.7 ports and TTI headers as well. I'd really rather not have to redo everything on the top end if I ever did pull the trigger on some better heads, so I'd like to try to keep to original early 5.7 style ports and bolt patterns. I actually really like that my engine still looks kind of old school with the 4bbl throttle body setup, even if the injectors and rails are obvious if you look lower down.

I've been quite happy with the way my car is running now, but I always have that nagging in the back of my head saying "but could it be better?". It's basically my daily driver, so I'm not looking to compromise it away from that, but I figured some better flowing heads would be one of the "easiest" ways to get a little more punch out of it without redoing a lot of stuff. I've got an Inertia Motorsports SRT Max Plus camshaft in it now and I think I've got my tune to a pretty happy point. I'm not trying to set records or anything, so I'm not pushing it to the limit and trying to squeeze every last drop of horsepower out. Mostly just thinking of what kind of stuff I might be able to do if I wanted to get more without resorting to a whole new engine or forced induction.

I run an 06 5.7 as well. I hand ported the heads myself and run a Cam Motion Titan 2 cam.
Duration at .050": 225/235
114 Lobe Separation Angle
Lift : .594"/.577"
Based on the online HP calculator using 1/4 mile MPH and weight, it's making 443HP. This is a completely stock rotating assembly. This motor has really good midrange power and pulls easily to my self imposed rev limiter at 6800RPM. (I don't trust powdered rods for any more RPM)

I will be swapping 6.1 heads on to it soon along with a 6.1 intake manifold. The reason I went with the 6.1 heads is because they flow as good as the eagles, but I can use my existing rockers, valve covers, and probably pushrods (I have a set of Manley pushrods.) I can also use the aftermarket valve springs, and retainers I have on the 5.7 heads. The Cometic head gaskets I have will land me around 10.8:1 compression, which should be good for pump gas.
I'm not 100% sure of the valve spring compatibility with Eagle heads, but I do know the valve covers and rockers are Eagle specific. Cometic makes head gaskets that will bring the compression down to wherever you want it. FYI- go directly to Cometic's website. They are half the price there and have several options vs. going to MMX or any other Cometic distributor.
Your intake manifold will be your limiting factor unless you get the adapters to mount early intakes on the 6.1/Eagle. I'm not even sure those adapters are even available these days. I'd assume you could pick up an Eagle or 6.4 intake from a Junkyard. If you decide to go that route, the 6.4 is definitely a better intake, and you can setup the SRV using your ECM.

The 6.1 heads are harder to find and likely cost more than the Eagles. If you could find an Eagle at a pull a part yard, you can get all the parts for cheap and I think it would be worth the effort. I do think your cam is a little small though...

 

[Map63Vette]

The 6.1 heads are harder to find and likely cost more than the Eagles. If you could find an Eagle at a pull a part yard, you can get all the parts for cheap and I think it would be worth the effort. I do think your cam is a little small though...

I find it odd as well the more I read about other people's cam choices. The SRT Max cam was sold as "about the biggest cam you can fit with stock pistons", but it seems like there are plenty out there that are running more duration at least than what I have. I have a little tighter LSA though, which I'm not sure helps or hurts. Maybe it was a spring limitation as well. I know I'm running the stock 6.1 exhaust springs all around.

The 6.1 heads with intake adapters is an interesting idea. I actually don't think I would mind that as I have some extra height available to me, so if the intake had to go up a little bit I think I could make that work (though I'd have to double check my A/C compressor setup as I'm running the truck front cover. I'd still have to change the exhaust I think, though I'm not entirely sure how much the TTI setup differed between 5.7/6.1.

 

[Map63Vette]

So on a slightly different but related note, what are people's opinion of compression ratios with pump gas on these gen 3 Hemis? By published numbers my car is 9.6:1 and I've been running totally fine on 87 octane with my tune. I might be able to push it more, but I'm mostly just daily driving mine, so I'm not pushing it that hard and I've never noticed an issue, assuming my knock sensor settings are correct in my computer (a Megasquirt).

Looking at other head options out there and some will push things closer to 10.5:1, so I'm curious what others have been getting away with here. I know cam choice is going to affect that with dynamic compression ratio vs static, but that's a little harder to put my finger on. Some calculators use the IVC point as a hard stop, others add some buffer duration to it. One puts my engine at something like 8.5:1, the other more like 9. I'm wondering if maybe bumping to ~10:1 static would still be okay with less than premium fuel.

 

[408 swinger]

I ran pump 91 with that early bottom end with Eagle heads and 6.1 cam. I ran carburetor. With around 22 degrees, I didn't have any noticeable knock.

 

[Map63Vette]

I was looking through the literature and the Eagle engines are apparently 10.5:1 and the 6.4s are all the way up at 11:1, so maybe not as bad as I thought. I know my parent's truck with the Eagle seems to run okay on 87. Not sure what my dad puts in his 6.4 Challenger, though guessing it might get premium.

I'm in that same ballpark of low 20s for timing, never really tried any more than that. If I put it on a dyno I might play around and throw a couple degrees on back to back pulls to see if it made any difference, but everything I've heard and read is that these engines just don't need it.

 

[racerjoe]

It all depends on your dynamic compression ratio. With my cam, I should be able to go up to 10.8:1 and still run pump 93.

 

[408 swinger]

It all depends on your dynamic compression ratio. With my cam, I should be able to go up to 10.8:1 and still run pump 93.

Agreed. My 426 is 13:1, runs on 93.