GM High Value LZ9 Swap? (Page 8/11)
Doober OCT 08, 10:36 PM
I'm never on here anymore, I just don't frequent forums near as much as I used to... but excited to find a thread in line with what I'm starting to consider

I have a complete Aztek ($0) that I've been slowly getting closer to finally getting to work on pulling the engine/harness/PCM (read: AZ climate is not conducive to manual work most of the year without a/c or swamp coolers). Lately I've been looking more into the LZ4/9 and after seeing what MARS did with his 3rd gen Camaro, I may just go with the LZ9.

https://www.thirdgen.org/fo...roc-z28-buildup.html

I may or may not plan on a turbo, but, like Chuck has said, info is real spotty. I did find a post with some LZ9 flow tests (Joseph posted here a while back)


Quick search showed a Motor Trend page with the flow vs cylinder number (HP = 0.25714 × CFM × No. of Cylinders), so in theory the 3900 heads are capable of close to 400hp at their peak, n/a (used 255cfm since the lowest from 3 cylinders was about 260cfm and I like to err on the safe side of estimating)... granted that would be a max-effort cam designed for n/a, but since turbo is the "in" thing nowadays, you can have the best of both worlds, so long as you build it properly and don't get hasty in your endeavors.

My 2.8 is still plugging along at a little over 197k, daily driving it about 40 miles a day, 6-7 days a week. Lowest oil pressure I've seen so far is a tick under 40psi, if the gauge is right, but it obviously feels a bit underpowered, even compared to most of today's commuter cars.

If I can seem to remember to, I'll try to keep tabs on this thread, since it seems Chuck's thoughts are similar to mine... I don't want to go through the extra fabrication labor involved with something like an LFX swap (not to mention the engine bay would be a bit more cramped than it already is), but I need something that will better keep up with the yahoos on the road today. For me it's either do this, or find something like a C5. I have a couple other vehicles available to drive if it comes to it, and wouldn't have the added car payment by doing the swap.

Motor on

82-T/A [At Work] OCT 09, 04:04 AM

quote
Originally posted by wftb:

I did a performance rebuild on the 2.8 that came with my 86 GT. I spent over 2000.00 on it, bored over balanced etc etc. It ate a cam lobe after about 800 KM. Later I learned that the only decent lifters are GM OEM, not the aftermarket lifters I put in. The GM lifters were 5 times the price.





This reads like my story as well.

Rebuilt my 2.8 into a 3.1 w/ crank and rods, and a .040 overbore. Went with an inexpensive (but recommended) cam and lifter kit. Wiped a lobe almost immediately. I set the valve lash pretty low so it wouldn't be aggressive to the cam during break-in. Babied the car, didn't make a difference.

I'm determined to stick with the 3.1 I've built because it's the original motor, and I'm past the point of making this car something it isn't. I just want to keep it as I remember it since it was my first car.

But, if I had no history with this car, and it was new to me... I would ABSOLUTELY be doing the 3.9 V6/60 w/ 6-Speed manual swap... all... day... long.
ChuckR OCT 10, 05:47 PM

quote
Originally posted by Doober:

I may or may not plan on a turbo, but, like Chuck has said, info is real spotty.

Quick search showed a Motor Trend page with the flow vs cylinder number (HP = 0.25714 × CFM × No. of Cylinders), so in theory the 3900 heads are capable of close to 400hp at their peak, n/a (used 255cfm since the lowest from 3 cylinders was about 260cfm and I like to err on the safe side of estimating)... granted that would be a max-effort cam designed for n/a, but since turbo is the "in" thing nowadays, you can have the best of both worlds, so long as you build it properly and don't get hasty in your endeavors.

My 2.8 is still plugging along at a little over 197k, daily driving it about 40 miles a day, 6-7 days a week. Lowest oil pressure I've seen so far is a tick under 40psi, if the gauge is right, but it obviously feels a bit underpowered, even compared to most of today's commuter cars.

If I can seem to remember to, I'll try to keep tabs on this thread, since it seems Chuck's thoughts are similar to mine... I don't want to go through the extra fabrication labor involved with something like an LFX swap (not to mention the engine bay would be a bit more cramped than it already is), but I need something that will better keep up with the yahoos on the road today. For me it's either do this, or find something like a C5. I have a couple other vehicles available to drive if it comes to it, and wouldn't have the added car payment by doing the swap.

Motor on



I will try to keep updating with more info and questions to try and get a lot of info all in one place. This thread has slowed down some since I started it since I am in a holding pattern on my project plans until I get some life out of the way.

There are a ton of these motors and transmissions in the yards now. Especially if you dont mind doing the LZ4 / LZE 3.5. This engine made it's way into fleet cars from 2006 to 2011. That is millions of motors out there and they are cheap since there is no demand for them. finding the 3.9 is a bit harder but not too bad . The Impala alone sold 1.37 Million in this time period. This is also not a ground breaking swap as I know of a few that have been done. Keep in mind if you want AC you will have some notching to do on the cradle. Also some thing to note - If you do want to do forced induction that will require an aftermarket ECU and most likely a cam swap due to loss of VVT. Or do what Joseph did and revert to an older ECU and still cam swap. Also if you use the 3.4 from the Aztec it has same trans as the 3500/3900 so that part of the swap will carry over. But I also understand not wanting to put that much effort into doing a swap then changing it out a few years later.


quote
Originally posted by 82-T/A [At Work]:
This reads like my story as well.

Rebuilt my 2.8 into a 3.1 w/ crank and rods, and a .040 overbore. Went with an inexpensive (but recommended) cam and lifter kit. Wiped a lobe almost immediately. I set the valve lash pretty low so it wouldn't be aggressive to the cam during break-in. Babied the car, didn't make a difference.

I'm determined to stick with the 3.1 I've built because it's the original motor, and I'm past the point of making this car something it isn't. I just want to keep it as I remember it since it was my first car.

But, if I had no history with this car, and it was new to me... I would ABSOLUTELY be doing the 3.9 V6/60 w/ 6-Speed manual swap... all... day... long.



Right on still having your first car, that is awesome!! You could always get your hands on another Fiero and do the F40/LZ9 swap

Though I am not trying to make my car something it isn't, I am trying to make it something I built And in the process make it something that it was supposed to be if it weren't for GM protecting the Corvette sales. the C4 was a cool car but it was not as good as it should have been, a Fiero with some performance should not be a threat to a flagship car if it was done properly.
ChuckR FEB 26, 09:38 PM
Just popping on here with another question / observation. Has anyone used a "Piggyback ECU" like the ECU Master DIGITAL ECU TUNER 3, 4 BAR for boost applications on these motors?

https://ecumasterusa.com/pr...ariant=8318137860157

I am not sure if this is something I should look into at a later date if I wanted to boost and not do a full stand alone ECU. If I understand it correctly these will intercept your incoming signals ( and be able to read boost since it has a 3 or 4 bar MAP with it) and then send correlating info to the stock ECU to trick it into operating the fuel and air according to what the boost needs. This raises a question of will it do this safely and is it worth it to add boost and keep your VVT and stock cam etc.
fieroguru FEB 27, 06:57 AM
Many of the later model GM ecm already have tables setup for fuel/spark control under boost, so an add on piggy back ecm probably isn't a requirement.

I am going to run the E40 ecm with boost and I know the E67 ecm has spark & fuel tables that will accommodate boost as well.
ChuckR FEB 27, 08:17 AM

quote
Originally posted by fieroguru:

Many of the later model GM ecm already have tables setup for fuel/spark control under boost, so an add on piggy back ecm probably isn't a requirement.

I am going to run the E40 ecm with boost and I know the E67 ecm has spark & fuel tables that will accommodate boost as well.



I asked Ryan this a few months ago on the LZ9 and here is his response.


quote
No 3900 was never turbo or supercharged in any factory application.

It is possible the factory 3900 ECM (even with DBW) could be custom tuned to work with a turbo. But these ECMs didn't use a wideband o2 sensor, and that would be preferred in any serious turbo build.

There are quite a few aftermarket ECUs on the market that use a wideband o2 input so they can accurately control air/fuel ratio at full throttle w/ boost. But I'm not sure if there are any that can control the 3900's VVT system - and that would be something I would want working if you kept the stock cam in the engine.



This is what made me look at possibly a piggy back situation. Since the piggy back ECU would be using a wideband and then tricking the factory ECM to use correct tables accordingly, this might be a solution to keep the VVT and have forced induction. But I can see a lot of issues on using a piggy back to do this... Just looking for input on this.
Will FEB 27, 11:41 AM
Most wide band controllers have narrow band simulator outputs which can be used to at least log the AFR along with other engine parameters.
wftb FEB 27, 11:45 AM
If the engine is supported by HP tuners you can add a wideband O2 sensor that gets wired in to the HP tuners hardware. Leave the stock O2 sensors hooked up to the original wiring. The wide band then is used as a tuning tool and not part of normal operation.

------------------
86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms

pmbrunelle FEB 27, 07:01 PM
I don't think that an aftermarket standalone ECU automatically implies losing the VVT.

Generally speaking, the MegaSquirt 3 ECU (I own this, so I am familiar with it) supports VVT. My work colleague has a Haltech, and he installed it on a DOHC Subaru with VVT (so that's four cam phasers, and four cam sensors).

I would not use a piggyback device... because why use two electronic boxes to control the engine when one box will suffice?

I leave it as an exercise to the reader to determine which aftermarket standalone ECUs are compatible with the High Value V6's particular implementation of VVT.

[This message has been edited by pmbrunelle (edited 02-27-2020).]

Will FEB 28, 09:51 AM
Most modern VVT actuators use a PWM signal to control the phasers. 50% DC = keep the cam where it is. I'm not sure if there's a standard for whether off is advance or retard (and vice versa).

BMW's early VANOS systems would hold timing with no input, then had separate solenoids for advance and retard, making the controls twice as complicated from an ECU I/O standpoint.