Gen 4 Heads on Gen 3

04BlackSRT10

Enthusiast
Joined
Jun 18, 2022
Posts
23
Reaction score
2
Location
USA
This post is directed towards Viper Specialty, as I know his company does this conversion, but anyone else can chime in also if they have info. What exactly is involved in putting Gen 4 heads on a Gen 3? I know they won't just bolt on, and have different exhaust ports. Is it worth it to do this aside from the superior looks of the Gen 4 top? What would be the approximate cost to have this done? I know you can run a Gen 5 manifold if you have Gen 4 heads, so that would likely be what I go with if I decide to do this.
 

MoparMap

VCA National President
VCA Officer
Joined
Jan 7, 2013
Posts
2,466
Reaction score
291
Location
Kansas
Mopar made a kit for this as well at one point. I believe the biggest changes were the intake setup as they had a sort of hybrid gen 3/4 unit with a cable throttle body since the gen 4 and 5 are both drive by wire. I know there is more to it than that, but that was the biggest "custom" piece that stands out to me. The rest I think were effectively off the shelf parts like the heads and exhaust manifolds. The part number was P5156137. Here is an old listing for one that details what all was in the kit: https://www.viperpartsrackamerica.c...r-v10-150-hp-performance-upgrade-kit-p5156137. Sounds like pretty much everything on the top end gets replaced (heads, intake, fuel rails, injectors, etc.). Sounds like ~150 hp gain, though I think you can get that with gen 3 heads with less work if you really wanted to. I know just a cam alone in my car (a Viper Specialty one actually) pumped it up to nearly 600 crank horsepower. There have been a few builds on here that have dyno'd 600+ at the tires with ported heads and a cam, so depends how patient you are and how much you feel like replacing.
 

Viper Specialty

Legacy/Supporting Vendor
Supporting Vendor
Joined
Feb 14, 2002
Posts
5,732
Reaction score
62
Location
Cape Coral, FL
This post is directed towards Viper Specialty, as I know his company does this conversion, but anyone else can chime in also if they have info. What exactly is involved in putting Gen 4 heads on a Gen 3? I know they won't just bolt on, and have different exhaust ports. Is it worth it to do this aside from the superior looks of the Gen 4 top? What would be the approximate cost to have this done? I know you can run a Gen 5 manifold if you have Gen 4 heads, so that would likely be what I go with if I decide to do this.
The short version, is a lot of machine work on the heads, modified manifold and mechanical throttle conversion. Generally I wont go into exact details, because information has more value than the components... and a LOT of people, vendors included, arent even aware of the specifics and are literally still building time-bombs seemingly unaware of their mistakes.

Yes, its absolutely worth doing. Looks are only a bonus.

Personally I am not a huge fan of the G5 manifold, but thats personal preference.

Cost I honestly cannot tell you... we haven't been building engines for a few years, and costs have gone sideways since. I hope to be back at it this winter, and a couple of these packages are exactly what I had wanted to build as I am sitting on a pair of partial kits up in NY right now that were being accumulated before I shelved engine work and moved to FL.
 
OP
OP
0

04BlackSRT10

Enthusiast
Joined
Jun 18, 2022
Posts
23
Reaction score
2
Location
USA
Personally I am not a huge fan of the G5 manifold, but thats personal preference.
I do think it's odd that they went away from metal for the intake manifold on the Gen 5. I've seen a video where a heavily modified Gen 5 literally blew a hole in his manifold from using NOS. I highly doubt that would have happened with the Gen 4 intake.
 

Goggles Pizano

Enthusiast
Joined
Nov 25, 2009
Posts
390
Reaction score
85
I do think it's odd that they went away from metal for the intake manifold on the Gen 5. I've seen a video where a heavily modified Gen 5 literally blew a hole in his manifold from using NOS. I highly doubt that would have happened with the Gen 4 intake.
Cost, easy of manufacturing and met the performance requirements. Why would I care about what mods you may do in the future and not meet the MSRP price point? No difference then them changing from forge pistons on the gen2s and carrying it on to gen3/4.

You want to modify then go ahead, just know what you are doing and if they blew the manifold apart then they do not know what they are doing. Look at the TT builds that are built by those that know. Gen4 intakes or custom intakes.
 

Viper Specialty

Legacy/Supporting Vendor
Supporting Vendor
Joined
Feb 14, 2002
Posts
5,732
Reaction score
62
Location
Cape Coral, FL
Cost, easy of manufacturing and met the performance requirements. Why would I care about what mods you may do in the future and not meet the MSRP price point? No difference then them changing from forge pistons on the gen2s and carrying it on to gen3/4.

You want to modify then go ahead, just know what you are doing and if they blew the manifold apart then they do not know what they are doing. Look at the TT builds that are built by those that know. Gen4 intakes or custom intakes.
There has been numerous G5 manifold failures on TT builds. In high-boost cars they revert back to G4 manifolds... I think you may have been implying the same.

Total cost-cutting measure.
 
Last edited:

Steve M

Enthusiast
Joined
Dec 29, 2011
Posts
1,082
Reaction score
208
Location
Dayton, OH
The composite intake makes a lot of sense for NA applications - lighter weight, less heat transfer, and from what I remember, slightly out performed ported Gen 4 units on the dyno.

Considering the majority of Gen 4/5 cars aren't running forced induction setups, it seems like a no-brainer to me.
 

ToothLess

Enthusiast
Joined
May 21, 2023
Posts
4
Reaction score
0
Location
Denton TX
I am also considering going this route with the G4 heads. I was not sure if it was worth the money and effort over some good Ported G3 Heads since I already have Headers on the car, and would have to swap if I did the conversion. I'm assuming yes otherwise people wouldn't do it.
 

MoparMap

VCA National President
VCA Officer
Joined
Jan 7, 2013
Posts
2,466
Reaction score
291
Location
Kansas
I am also considering going this route with the G4 heads. I was not sure if it was worth the money and effort over some good Ported G3 Heads since I already have Headers on the car, and would have to swap if I did the conversion. I'm assuming yes otherwise people wouldn't do it.
That's kind of where I am (assuming I ever wanted to really go all out on my car at least). I have the same problem on my G3 Hemi in my Dart. Any of the newer heads for it mean changing everything attached to them, which adds up pretty quickly. I've seen some pretty dang good results with well ported gen 3 heads on the Vipers though, so I think I'd probably still lean that way myself if I ever pulled the trigger, but just hard to have my car down that long since I drive it pretty often.
 

Viper Specialty

Legacy/Supporting Vendor
Supporting Vendor
Joined
Feb 14, 2002
Posts
5,732
Reaction score
62
Location
Cape Coral, FL
Short version: G4+ castings are as good out of the box as ported G3... but they do it better. All things being equal, you will require less cam and/or have better driveability at the same power in a G4 based car than a G3 based. The combination of head design changes, manifold changes and everything else together equate to an overall better package. You can get in the same ballpark with G3 porting, but G4 will always be better at the limits.
 

ToothLess

Enthusiast
Joined
May 21, 2023
Posts
4
Reaction score
0
Location
Denton TX
Thanks, Dan, that puts it into perspective for me, and it makes perfect sense. Better at the limits, and better overall driveability due to not needing to max everything out.
 

Members online

Forum statistics

Threads
153,345
Posts
1,683,129
Members
17,866
Latest member
biomedicatranslat
Top