Clarifying 04-05 3500 vs 06 3500

[Will'sFiero]

I don't see this distinction made very much when searching for info on the 3500.

For 04-05 the 3500 (LX9) had a 94 mm bore, 84 mm stroke and did not, AFAIK, have VVT. Did this engine have the large crank pins and forged crank?
I'd call that a Gen III engine. Is that the general concensus?

For '06 the 3500 (LZ4/LZE) uses the same 99mm block with offset bores as the 3900 and has a 76 mm stroke instead of 84 and has large crank pins, forged crank and VVT. This is a Gen IV engine, yes?

[Superdave]

I thought we had decided that the LX9 was a gen 3.5 (coincidence?)... no it didn't have VVT.

quote from GM:

The 3500 V-6 is a derivation of the proven 3400 V-6 engine, which is itself a very close relative of the 3100 V-6. The 3500 V-6 engine is built at GM’s advanced Ramos Arizpe, Mexico plant.
The 3500 V-6 was launched in the 2004 Chevrolet Malibu, and includes a host of improvements incorporated into the older members of the 60-degree powertrain family, namely the 3.4L. Compared to the similar 3400 V-6, the bore was increased from 92 mm to 94 mm to achieve the 0.10L increase in displacement for the 3500 V-6.
To accommodate the new applications, a large-pin crankshaft is added, and it is stiffer than the original crank. The
stiffness added by this type of crank improves the stiffness of the engine, resulting in a quieter and smoother engine. This crank is used in all 3500s except those powering the Buick Terraza, which uses a steel crank instead of cast iron.
The 3500 LX9 utilizes new front and rear crankshaft seals made from polytetrafluoroethylene (PTFE). The improved sealing will help further improve long-term durability of the LX9. PTFE, discovered by Roy Plunkett at DuPont in 1938, is well known for its versatility. The compound is found in TEFLON®, GORE-TEX® and a myriad of other products. PTFE's excellent sealing capabilities, as well as its ability to withstand thermal cycles, makes it a superior material for gaskets.

[SappySE107]

(EDITED FOR CONTENT) If gen 1 is all iron head regardless of changes, why should the non vvt 3500 be 3.5 or 3 like the 3100 and 3400 when its more closely related the VVT engine setup.

I thought 04-06 was lX9, then in 07 it was all the VVT engines.

[Guest]

(EDITED FOR CONTENT) If gen 1 is all iron head regardless of changes, why should the non vvt 3500 be 3.5 or 3 like the 3100 and 3400 when its more closely related the VVT engine setup.

I thought 04-06 was lX9, then in 07 it was all the VVT engines.

(EDITED FOR CONTENT)

I haven't heard of a distict generation distintinction for the 3500 or larger engines.

Myself, I call the 3500 (non-vvt) a genIII engine, because other than the larger rod journals on the pins, it's extremly close to the 3400 and 3100, save a few other changes, like the cylinder 5/6 oil squirter, different upper intake, and lack of power steering pump that has an extra bolt hole added to the front cover, for an idler pulley and crank trigger being a 56x. Other changes, are more of an improvement over the existing design than a complete change, like the larger intake runners, on both the LIM and head, other changes seem to be more for ease of assembly at the plant or possibly for maintenace reasons.

The VVT engines, well I haven't looked at them closly enough, but they are quite different than the existing genIII engines, and wouldn't hesitate to refer to them as a genIV they are still pushrod based, so to put them into a seperate catagory like the 3.4 DOHC doesn't seem to make sense. I'm still waiting to see what GM refers to these engines as, before I make any generation specific refernce to them, for now, 3X00 VVT will sufice.

[Superdave]

woot! '660 g33k fight!

(kidding guys)

Personally i feel that there are enough changes between the 3400 and 3500 to warrant a full gen +1.


1. Reconfigured crank (larger rod journals, different material, different reluctor wheel.
2. Different rods, 5.9" VS 5.7", powdered-forged instead of forged steel.
3. Oil squirters
4. Reconfigured heads (raised and reshaped ports, lightened valves, revised rockers)
5. Different exhaust manifolds.
6. Different fuel rail/Injectors
7. Electronic 65mm TB
8. Revised LIM and Plenum
9. Revised timing cover and water pump

Now if you look at the upgrade from the gen2 3.1 to the Gen3 3100 what do you have?

1. same crank
2. Similar rods
3. higher SCR (8.9:1 VS 9.5:1)
4. reconfigured heads, LIM and plenum
5. Different fuel rail and injectors
6. different exhaust manifolds
7. Different cam/valvetrain



So i'm thinking there are about the same if not more differences from the 3400 to the 3500 than there is from the 3.1 to the 3100.


'06 was a crossover year, iirc both the VVT3500 and the LX9 were offered. 06 was the last year for the LX9 officially.

[SappySE107]

(EDITED FOR CONTENT)

So if I put a 94 3100 on a stand and an 04 3500 on the stand in front of you, you are going to tell me they are the same generation? Since I can bolt 3500 heads to a gen 1 3.4, they must ALL be gen 1 right? That means only the new VVT pushrods are gen 2.

Back to reality.

The rockers were used on the 3400 in 03, and the exhaust manifolds were in 05. Im not aware of any 3400 heads getting the 3500 valves though. Not sure if the 3500 springs are stiff cause russ hasn't speced it for me yet. Returnless fuel rail is new for the 3500, as is the crank and rods and everything else that has been said. Add the oil pan pattern was changed as well.

[sil]

i feel the 3.5 is a gen 4

[Guest]

(EDITED FOR CONTENT)

So if I put a 94 3100 on a stand and an 04 3500 on the stand in front of you, you are going to tell me they are the same generation? Since I can bolt 3500 heads to a gen 1 3.4, they must ALL be gen 1 right? That means only the new VVT pushrods are gen 2.

Back to reality.

The rockers were used on the 3400 in 03, and the exhaust manifolds were in 05. Im not aware of any 3400 heads getting the 3500 valves though. Not sure if the 3500 springs are stiff cause russ hasn't speced it for me yet. Returnless fuel rail is new for the 3500, as is the crank and rods and everything else that has been said. Add the oil pan pattern was changed as well.

(EDITED FOR CONTENT)

Dave: You bring up some valid points for a full generation move up, again, I'm waiting to hear what GM themselves are refering to the 3500 as, in generation. For now I just refer to as a "3500" or "non-VVT 3500". I personally see it as I already said as a genIII, a lot of that has to do with the direct swapability of the parts. I.E the fuel system layout, is so close you can swap the fuel rails, genII to genIII you could not, you can swap just the UIMs, genII to genIII you could not. To refer to the 3500 as a genIV would mean that the 3400 and possibly the large port 3100 should be refered to as a genIV, then making the 3500 a genV. *shrug* Exhaust ports and placement are virtually identical between 3400 and 3500, though the exhaust manifolds are different, again between genII and III, the exhaust changed drastically, very similar here.
The redesigned crank and con rod I do not see as being enough to change generation desgination, if that were the case, the SBC would be into the 9th or 10th generation. The 2.8 received a larger main journal in 1985 and is still a genI, so that negats that as a generation change IMO.
I don't see manufacturing processes as a reason to go up in generation, that happens all the time for many items that we all use.
Again, Im just waiting until GM indicates what they refer to it as, and then I'll go by that, regardless if I agree with it or not.

[Will'sFiero]

I think I'll go with the LX9 being gen III. One can bolt LX9 cylinder heads on a 3400 and have a useable engine. The same is not true of the LZ4 heads because the chamber centers have moved. I think that in and of itself constitutes the difference in generations.

I don't think rod length or journal size impact engine generations. After all, the 400, considered by everyone to be a gen I SBC had larger mains and shorter rods than all the other gen I small blocks. The L99 4.3 litre V8 was a gen II Chevy, but had 5.940 rods instead of 5.700.

Despite having the same bore, 2.8's and 3.1's use different pistons... that doesn't make them different generations.

Thanks for the thought and input. It's nice to hear that the LX9 got the larger journals and longer rods. I'll have to look for one (or two) out of a Terraza.

[95SleeperAcheiva]

I thought the 3400 '03-'04 had a forged crank? So whats the differances on the 3500? Mainly, whats the differances on a '06 3500 from a malibu to a '06 3500 in a G6 pontiac? Now according to Chevy and Pontiac the Pontiac got like 50 more horse. And if it a major differance, does this mean I need to find my pontiac motor for its benefit and the buick motor for the forged crank than?

[SappySE107]

No 3400 came with a forged crank.

The pontiac didn't get 50 horse more. The VVT 3500 is just over 20 more hp if you are comparing that. The LX9 came with iron or steel cranks. My engine is from an 05 malibu and has the forged crank. Most of them do from what I can tell regardless of early GM documents stating on the buick version would have it.

[Will'sFiero]

How do you tell the forged crank from the cast crank?

[Superdave]

How do you tell the forged crank from the cast crank?

well.. IF it's forged... the way to tell them apart is on the end of the crank snout, it'll have the number 7484 on it..

[Joseph Upson]

I don't see this distinction made very much when searching for info on the 3500.

For 04-05 the 3500 (LX9) had a 94 mm bore, 84 mm stroke and did not, AFAIK, have VVT. Did this engine have the large crank pins and forged crank?
I'd call that a Gen III engine. Is that the general concensus?

For '06 the 3500 (LZ4/LZE) uses the same 99mm block with offset bores as the 3900 and has a 76 mm stroke instead of 84 and has large crank pins, forged crank and VVT. This is a Gen IV engine, yes?

The first design 3500 goes from 04-06 Will'sFiero, with the all of them being made VVT based on the 3900 block for 07. They may have introduced the VVT 3500 in one possibly two cars in 06; Impala and Monte Carlo. I can no longer find the info I thought I encountered supporting that.