what is so bad about gen ii engines?

[Canyonero]

Building the iron heads for N/A is really pointless if Gen III is an option. They will simply never match up performance wise.

The reasons I see for people using iron heads is typically to
- avoid having to do a hybrid swap
- keep the stock look
- avoid any wiring

When you think about it, the vast majority who use iron heads are using them because that's what their vehicles came with. If you have a front engine, RWD vehicle that came with an iron head engine, a Gen II swap is the same amount of work as a Gen III swap. So why would anyone bother?

You'll probably see more people sticking with the Gen IIs in the cars that they were available in.

Admittedly, I did not read past the first page. But I have a Gen-I build - not ultra high-performance or anything, but cam, rockers, bored intake, exhaust, soon to use a MegaSquirt ECU, etc. I have a FWD block in a RWD/4x4 application (Isuzu Troopers had that for some reason). I actually bought an LX9 to install in the Trooper years ago, but found I can't use a Gen-III/IV block because of clearance issues on the bottom end. 4x4s used a steel oil pan and the front axle for the IFS and the steering are just too close. I have a Gen-II engine that I wanted to use in another project because of the steel pan advantage (and I got the Gen-II parts car cheap and I don't want the good running engine to go to waste), again I'd have stick with Gen-I/II because of clearance issues in a RWD application and not being able to modify the Opel transverse-leaf front suspension to clear a Gen-III/IV pan. However I do have a Gen-III top end set that I may install.

[SwiftDrift]

that is crazy.. wow, just wow. i read a thread somewhere recently that said no one has done it, must have been an older thread i guess

[Superdave]

imagine... why not see it? http://60degreev6.com/forum/showthre...8-GT4088-turbo


do some forum searching, there are plenty of threads that discuss the differences between all the generations of engines. Lots of pictures and everything, plenty to show you why gen 4 heads won't work on early blocks.. etc... In the download section you can find the full GM spec sheets for all the bearing sizes, tolerances and fastener tightening specs for the 3100, 3400, 3500 and 3900.

[SwiftDrift]

i could have sworn i saw a pic of the 3500 non-vvt and the block was different than the 3400s. and back to the 3900, how different are the heads? i doubt they would work on any older motors, but i like knowing these things for certain. *side thought* imagine a thirdgen with a 3900

[ericjon262]

OH, Right! I remember reading that somewhere now.. Sorry to be so ignorant, LOL.

Yeah, well, I really want to keep the P4 ECM in it, for boost later when affordable.

Thank you for the info!

you need an external crank trigger to keep running the P4 EBL.

[IDCavalier]

OH, Right! I remember reading that somewhere now.. Sorry to be so ignorant, LOL.

Yeah, well, I really want to keep the P4 ECM in it, for boost later when affordable.

Thank you for the info!

[caffeine]

what is so bad about gen ii engines?

The ECM on a 3500 is very different from the 3400 PCM, and they also changed the crank trigger from 7x to 58x (like the 3900). However with an external crank trigger you can run one on your existing ECM.

The ignition coils are also newer like the 3900 style so you have to use an older coil pack with an external crank trigger.

[IDCavalier]

OK Thanks!

So, even though they are considered a gen III, they did adapt a DBW throttle and some other minor changes. Not enough to make serious changes though, for example, say the ECM?

I was hoping to perform a 3500 swap in my 1993 Cavalier and still retain my EBL P4 Flash ECM from Bob at Dynamic EFI.

Is that a realistic expectation do you think?

Like the OP, I was originally planning a 3x00 top swap, but looking at the information provided in this thread, it sounds to me like it is not much more costly to go with the whole shebang and just get a lot more power.

Wikipedia said that the 3500 LX9s put out damn near 200hp in stock trim. That seems to be fairly accurate and even a little conservative based on the numbers I read in many sig pics!

[caffeine]

For the 3900, bore spacing changed, coolant crossover was moved out of the intake manifold and into the timing cover, VVT cam/actuator was added and cam journals got larger. Exhaust flanges changed. Piston oil squirters on all 6 cylinders. Some were available with displacement on demand (could run on 3 cylinders)

The 3500 LX9 shares similar crank specs and same rods as the 3900. It's DBW throttle also has the same bolt pattern IIRC.

[SwiftDrift]

oh ok. well since the subject of gen 3 and gen 4 is being discussed, is the 3900s block completely different than the 60 degrees? i think it is but just want to be 100 percent sure. and you said the 3500 lx9 is a gen 3, so are the blocks the same? how different are they?

[caffeine]

Malibu 04-06, G6 05-06, Uplander and Montana 05-06, Rendevouz 05-07 IIRC.

[Superdave]

'04 and '05 for sure, some other cars had them too. I think there is a topic on all the sources.

[IDCavalier]

the 3500 LX9 is a gen 3 engine, just the last revision. the Gen 4 "high Value" 3500/3900 is where there was a redesign of the block and many other changes. Those are the LZ engines.

Thanks AGAIN Dave!

What years of Malibu/ Whatever have the 3500 before the change to Gen 4?

[caffeine]

what is so bad about gen ii engines?

Anything with the 3.5L DOHC engine. It comes in Oldsmobile intrigues and auroras from around 99-02.

[SwiftDrift]

what car and what engine would i have to look for for the tb?