LZ9 or LX9 in a 97 Silhouette

[Tijoe]

I am new to the forum and have been reading all of the postings on LA1 to LX9 or LZ9 swaps. I have a 99 Olds Silhouette with lower miles where I have the leaking intake manifold problem. Lots of water has been introduced into the engine oil and I am concerned about wear and damage to the bearings... I think that I will need to either rebuild or replace the engine.

I was wondering if It might be worth it to replace the LA1 motor with a later year LX9 or LZ9. What do you guys think the major challenges would be? Mounts, exhaust, sensors, electronics...

Thanks.

Joe

[Superdave]

the LX9 would be the easiest, you'll still need to get an external crankshaft trigger and swap a few things over from your LA1 but it'll bolt in and run. You'll pick up about 20 HP and some torque as well.

the LZ9 would require extra work being that it's a gen4 engine.


Welcome to 60v6!

[Tijoe]

Thanks. This is the type of input I am looking for. I assume that the engine mounts, tranny bolt pattern, Clutch plate, and basic installation is the same between the LA1 and LX9 engines.

I will read up on the LZ9s before asking questions on compatability issues with this engine. But I am captivated with this engine's horse power, even if it is just being installed in a minivan.

Joe

[RedBird]

is this a daily driver? if so it's probably not worth it, i'd just stick a stock 3400(with revised LIM gasket set) in it and drive it.

if you're specifically looking for more power, then LX9 is easiest..... i'd do it.... but then again i've always wanted to turbo a 60*v6 minivan so i'm biased..... :P

[Tijoe]

Right now it is a nice vehicle that is sitting around collecting dust. If it ran I would use it as a back up vehicle. I would take it on long distance trips 1000+ miles a pop, and/or hauling big items that wont fit in my Jaguar or Camaro.

This is the third time the intake manifold has failed! Even if I repair it again, I don't trust the engine for long distance drives. I will have to drop the engine in no matter what I decide. (96K miles)

I've been looking at repair costs for the 3.4L engine. Rebuilt long blocks cost $1,100 to $1,500. New long blocks are $2,000+. There is nothing that indicates to me that even with a rebuilt engine that the intake manifold will stay sealed, even with the new gasket sets. In my opinion, this generation (LA1) of engine sucks.

Ebay and other listings are selling low mileage late model LX9 engines starting at $400. I can purchase an LX9 with less than 12,000 miles for under $1,000. Low mileage LZ9s can be purchased for under $1,000.

I am thinking about buying a 2007 Impala 3.9L Police Interceptor engine and Trany with less than 15K miles. I think it has the same trany gear ratios of 3.29:1 but I am waiting to see if it has a 4T65E or 4T65E-HD Trany. I believe that it should be a direct drop in. I will probably have to change the ECM in the van to the 2007 Impala. If I know GM, this means that the harnesses will be basically the same between the 1999 and 2007, but the pin-outs on the connectors will have to be mapped out and moved and a few wires rerouted and added. I am worried that if I keep the 1999 ECM that I will run into problems with the Variable Cam Timing and the Variable intake manifold.

I have about 3 months to do this in and want to spend about $2K in parts, but no more than $3K total.

Joe

[IsaacHayes]

2007 probably is CAN interface and will need body control modules swapped over and a bunch of other crap. Plus the trans is the 65-E variety, I think your van only had a 4t60-e which means the PCM will be looking to control line pressure and possibly other sensors.

[WrathOfSocrus]

The vans have a 4T65-E. Not HD. The LZ9 will need the complete system (computer(s), fuel) to run at the stock HP. It can be made to 'run' on the computer you have but a lot of things will be custom and things like vvt will not be functional, so there would be a performance hit. An LX9 is much more 'plug and play' so to speak, and they can be had for well under $500 with under 50k miles in a lot of areas. If you are looking to do the swap in a reasonable amount of time and under your budget the LX9 is the way to go.

With a little work the LX9 can easily put out the same HP a stock LZ9 has. I'm not sure how the mounts on the LZ9 are but the LX9 doesn't need a lot of modification to work. The 3.9L engine would be cool and one of a kind in an Olds Silhouette but there is a hefty premium (mostly wiring) to be paid for that luxury. The same time and money spent on the LX9 would likely yield very similar results.

[Joseph Upson]

The 3900 only requires that you degree the stock cam in and lock the module into place by installing the appropriate size make shift spacers ahead and behind the module rotor so that the cam functions the way a non VVT cam does, otherwise it requires the same adaptation as the 3500 since with that motor you wouldn't have VVT anyway. I strongly advise against trying to incorporate the PCM for either of these motors into a daily driver that you are not serious about turning into a performer or true sports car for example.

The management system is complicated and picky and I see nothing positive about an electric throttlebody that affords the PCM the privilege of second guessing your throttle commands. There's no guarantee that certain safe modes can be deactivated to stop the PCM from making you drive in a civilized manner at all times.

Put on the throttlebody adaptor, crank trigger and necessary sensors and use your current transmission and PCM with some programming. That will greatly reduce your down time and swap difficulty.

With the cam degreed in you should get very good performance. You can also take the route I intend to and use primitive on off energizing of the VVT module to retard the cam at a certain rpm like 4-5000 for maximum output. If you lock the cam in the full retard position from the start gas mileage will be awful. I know that from experience with my 3900 Fiero swap. With the cam advanced and in the parked position the difference in fuel economy was drastically better.

Both engines are good upgrades, just make sure you go with what you want now so that you don't end up spending more money in the long run to do so.

Keep the initial swap simple, trust me on that. I did a 3900, twin turbo, 6 spd tranny swap all at once and it's still not done 2 yrs later although it's driveable. I have to find time to get away from school and go back home to work on it. Start with the engine and the necessities first and you can't go wrong. Also go with an engine that has the single stage intake if you decide on the 3900.

[IsaacHayes]

You can swap over the vvt 3500 upper on the 3900 as far as i know to rid the variable intake. The VVT of the 3900 from what I've gathered is mainly for emissions/etc and not so much for power.

[robertisaar]

The VVT of the 3900 from what I've gathered is mainly for emissions/etc and not so much for power.

you would be wrong. in full retard, that's where the 3900 makes the advertised 240/240 HP/TQ. full advance it makes an abysmal 150HP... TOTALLY changes the power curve.

[Joseph Upson]

You can swap over the vvt 3500 upper on the 3900 as far as i know to rid the variable intake. The VVT of the 3900 from what I've gathered is mainly for emissions/etc and not so much for power.

Some 3900s come with the single stage intake and the VVT is for power increase also otherwise it might be an inexplicable manufacturing waste given its cost compared to an EGR valve.

The extreme lobe separation of the VVT cam is what provides a good portion if not all of the EGR function, the VVT allows for a wider range of efficiency which automatically improves emissions. I posted an article in the tech section that shows the effects of a VVT cam advanced and retarded. I've already demonstrated its effect on fuel economy and power. With the cam fully retarded I could chirp the tires on the 1-2 shift but fuel economy was lousy. With the cam fully advanced fuel economy was great (night and day) but I could not chirp the tires on the 1-2 shift as easy as before.

The validity of my experience comes with an asterisk since my cam has been reground and does not perform exactly the same as the stock grind does under various positions.

The LS7 has cam in block VVT also and it sports the characteristic wide LSA of about 122 degrees.

[robertisaar]

The LS7 has cam in block VVT also and it sports the characteristic wide LSA of about 122 degrees.

when did that happen?

[Joseph Upson]

when did that happen?

Correction, L99 6.2L vette for 2010

[Gord Robinson]

LZ9 follow-up

Joseph, likely a dumb question but I have to ask - if you include the harness and ECM and PCM from the 3900 (with VVT) as part of the swap, wouldn't these controllers handle the VVT as if it was stock and then all you'd have to worry about was hooking up a drive-by-wire accelerator pedal?

Uh, that is also assuming you installed the 3900's transmission as well ...........

Seems a stock operating 3900 with VVT would be a nice power plant in this swap

[bszopi]

The 3900 PCM is also tied into the BCM, which would mean you'd have to include a whole lot more as well...