Gen 3 vs 4 blocks and cranks

[MoparMap]

So I have some whacky questions for the day. I just blew a rod on my 04 at the track yesterday and am surveying the damage and looking at my options to get things fixed. I had a few different ideas I'm chasing down and figured I'd throw some wild longshot questions out there while I was at it.

The first one is will a gen 4 crank physically fit in a gen 3 engine? The ****** appears to be the same. I know the gen 4 uses a crank mounted tone wheel, but my 04 uses a flywheel crank trigger, so I would just ignore the crank one, assuming it doesn't cause interference issues in the block. Along those lines, is the oiling setup in the gen 4 crank any different than the gen 3? I have read about plugging some of the holes on the main journals to prioritize rod oiling, but I wasn't sure if this was unique to the earlier gens or something that is still present on the gen 4+ cranks. I toasted the 3/4 journal all over again on a rebuild with only 5000 miles on it and a fresh oil change right before the track. I run street tires on a course with limited high speed sweepers, so I really don't think a swinging pickup would have made any difference, though I could be wrong. Just trying to understand how the gen 4 oil system is different than a gen 3.

Second wacky question for the day. Will gen 3 parts bolt on to a gen 4 block? IE could I take a gen 4 short block and bolt all of my gen 3 stuff to it (heads, front cover, accessories, etc.)? How different are the blocks themselves? I know the bore is slightly different (0.5mm or so) and the gen 4 has the variable cam, but I wasn't sure if the block had anything to do with that. I thought it was more in the timing cover, but maybe not. I'm a little more interested in this particular idea as my block has a fair amount of damage from the rod letting go and I'm thinking I'm going to need a new one one way or the other. It might be salvageable, but at this point I think a short block is going to make more sense to get the car back on the road. I'm looking for gen 3 stuff to start with, but didn't know if a gen 4 short block might be another interesting option just to open up the amount of parts that might be out there to look for. Same issue with the crank trigger, but if I'm triggering off the flywheel it seems like I could just leave the gen 4 sensor in place as a plug and do nothing with it.

Anyone else out there done any frankenstein work like this? I know more people put gen 4 parts on a gen 3, but figured if that worked them maybe the opposite would as well. I'm looking for a short block regardless at this point, but until I get the whole engine out I'm not sure the full extent of the damage. Pretty sure I can salvage the top end at least. Hoping my cam and lifters are still okay, but won't know until I get them pulled out.

 

[wisetechscott]

I'm curious about these questions as well. I think it would be worth while to at least be able to figure out for the 05-06 Gen 3 that is also tone wheel crank sensor mounted. how much work needs to be done to be-able to use a gen4/5 crank seeing as the later model gen 3 cranks are impossible to find now.

 

[MoparMap]

Well, as it turns out you can use a later crank in the early gen 3s at least, or that's my plan so far. I talked to Prefix about it and they said they'd have to repin the flywheel ****** to correctly clock the flywheel for the early gen 3 sensor, but the crank itself should fit fine. That's what I'm doing on my car at least. Not sure about the later gen 3s though. I thought the tone wheel changed on them between gen 3 to gen 4, but I can't quite recall. I remember the gen 5 part number showed as superseding several others, and the late gen 3 cranks might have actually been on that list. So long story short, you can put about whatever crank you want in an early gen 3 at least with fairly minimal rework. Later I can't quite say.

As for blocks, I didn't get an answer on that one as it looks like mine could be saved. From what I've heard, the 05-06 gen 3 block is more or less a gen 4 block without the VVT setup and maybe a little less gusseting, though I'm unsure on that one. Seems sort of like the old gen 1.5 cars where it was a transition between the gen 3 and gen 4 and shared elements of each. Physically I'm sure the block would fit in my car, but I'm less sure if I could make my computer work with it and what you'd have to do about the VVT. Maybe you could just cap it off or maybe you put the VVT solenoid it and just leave it unplugged, but the cam sensor becomes a problem. I think you might be able to bolt a gen 3 timing cover to the gen 4 block, but guessing you can't just straight up run a gen 3 cam and timing gear in the gen 4 block.

 

[Viper Specialty]

Short version:

There are 3 versions of G3 blocks:
1. 2003 Only. Flywheel Pickup, No Knock Sensors, oddball oil cooler line adapter that screws onto the block.
2. 2004 Only. Flywheel Pickup, No Knock Sensors, Revision to eliminate adapter.
3. 2005-2006. 2004 Block with Knock Sensor Mounting Bosses & center crank sensor location boss grafted. Flywheel Pickup deleted.

All G4 blocks are the same.

G4 blocks are effectively 05/06 blocks with rather involved revisions. All of the hardware is changed to Metric, all of the VVT gallery changes made, and all of the bulkheads strengthened. Changes made on dowel pin sizes and such as well. General layout remains the same.

G3 Cam is nothing like G4, and in no way, shape or form will fit. Your timing cover will not bolt up. All of the hardware will differ.
Can it be done? Yes. But it would require a lot of one-off parts to make it proper... definitely more than simply locating a G3 block.

And yes, you can use a G4 crank in a G3 block pending the crank trigger modifications and the fact that again, flywheel hardware is different and dowel pin is missing... not to mention balancing is totally different.

Anyone looking to do this kind of stuff would be best served to call me, as this is the kind of oddness I get involved with constantly... I am not guessing.

 

[MoparMap]

What exactly do you mean about balancing being different between the cranks? I feel like I've read that before, but never quite understood exactly what it means. In my head balanced is balanced, but I know that a rotating assembly is just that, an assembly, so it's more than just each part being individually balanced. Is there a significant difference in rod/piston weight between gen 3 and 4/5? I would think the flywheels are probably fairly similar throughout all the gens, though I know the gen 4 went to a different clutch setup. Just curious if there's anything I should looking out for when putting the later crank in my car.

 

[Viper Specialty]

You answered your own question. G3/4/5 rotating assembly components all have different weights. You cannot bolt G3 parts to a G5 crank and expect it to be balanced. You NEED to have the crankshaft balanced by an engine machine shop or you may as well just flush the money down the drain. Balancing a crank is not like balancing a tire. Its a calculation, not a true zero balance.

External components are Zero Balance in an internally balanced engine, they are irrelevant to the calculation and balanced individually so they dont upset the actual crankshaft balancing.

 

[MoparMap]

Makes sense, I'll be sure to double check everything. Thanks for the heads up! Good to know the external parts shouldn't cause any issues at least.

 

[1slosnake]

Short version:

There are 3 versions of G3 blocks:
1. 2003 Only. Flywheel Pickup, No Knock Sensors, oddball oil cooler line adapter that screws onto the block.
2. 2004 Only. Flywheel Pickup, No Knock Sensors, Revision to eliminate adapter.
3. 2005-2006. 2004 Block with Knock Sensor Mounting Bosses & center crank sensor location boss grafted. Flywheel Pickup deleted.

All G4 blocks are the same.

G4 blocks are effectively 05/06 blocks with rather involved revisions. All of the hardware is changed to Metric, all of the VVT gallery changes made, and all of the bulkheads strengthened. Changes made on dowel pin sizes and such as well. General layout remains the same.

G3 Cam is nothing like G4, and in no way, shape or form will fit. Your timing cover will not bolt up. All of the hardware will differ.
Can it be done? Yes. But it would require a lot of one-off parts to make it proper... definitely more than simply locating a G3 block.

And yes, you can use a G4 crank in a G3 block pending the crank trigger modifications and the fact that again, flywheel hardware is different and dowel pin is missing... not to mention balancing is totally different.

Anyone looking to do this kind of stuff would be best served to call me, as this is the kind of oddness I get involved with constantly... I am not guessing.

Are there bosses for knock sensors in the G3 block?

Great Intel BTW!

 

[MoparMap]

Are there bosses for knock sensors in the G3 block?

Great Intel BTW!

Only 2005 and 2006, but I think you also have to have a computer to match that. Guessing you couldn't put a 2006 block in an earlier car and run it on a 2004 computer for instance. You'd have the crank sensor issue as well. Seems like the 05/06 was kind of like the old "gen 1.5" in that way. Almost closer to a gen 4 computer in a way, though gen 4 obviously had a lot more going on (DBW, VVT, etc.).

 

[Viper Specialty]

Are there bosses for knock sensors in the G3 block?

Great Intel BTW!

As I said,they are 3 versions of G3 blocks. One version has them, two versions do not.

These things can be mixed and matched if you know what you are doing. We can enable/disable knock sensors with hardware/software depending on configuration, etc. You can run a newer knock-block in a 2004 on a 2004 PCM and just "ignore" them being there, or "add them" if desired. If there is a wallet, there is a way.