Real Fiero Tech

It was cheap, and at first I thought it was a 3900, but turns out it was a 3.5. So I figured I'd play with it, see what it could do.

135k miles junkyard
Sbe
Comp cam 218/236 and around 560/590 lift
Pac1218
Arp head studs.

That's it. I am reusing one of the 3.5 heads which I swapped the springs onto from my blown 3.9. The head from the blown 3.9 had some ptv contact, and I didn't trust it without machine work, which I am too lazy to have done right now. I cleaned it, and slapped it on. The other head from the blown 3.9 appeared good so I am reusing it.

I got this back in February I think and I have been taking my sweet time to reinstall. I am still waiting on a new tob as the old one was making some noise, so it can't go in until then.

You must love retightening that belt.

Curious about how the LZ4 responds vs the LZ9. Will the longer rod assembly take more boost, even if it doesn't make as much power?

I predict it will make very similar numbers but at a higher RPM required if all other variables remain constant to the previous setup. I think with a stock cam it would make less overall as it won't be able to use the higher RPMs as effectively, but with the upgraded cam it should be able to get there IMO. Slightly slower spool and less torque down low.

Any updates on this?

Nah. It's ready to go in, just haven't done it yet.

After procrastinating for 2 months I finally got it back in.

Progress is slow. It's hot. Very little motivation since I won't be driving it for several more months. But I did get the turbo mounted up today.

Looks good

People who accomplish things are not consistently great, but rather are great at being consistent.

Shaun, why don't you install AC in the car?

Will, that's a great quote.

Fired it up today. I had Howard over keeping an eye on any potential fluid leaks. Seems to be ok. I might have a small leak at an injector. What I will have to do to verify is to pull the upper intake off to see if anything is leaking.

I had pulled the injectors to clean my rails just in case the e85 gummed anything up but it actually looked good and it was all clean. Maybe I didn't get the injector correctly seated. I also noticed one o ring has a small tear. So that could be an issue.

No vid or pics. It looks just like a 3900 but smaller.

Fuel trims need some work. I pulled 50% to get it to idle. And it still wanted to stall.

Injectors are not leaking. But I seam to have a rear main seal leak, or the rear cam plate has a small leak. I had to remove the cam seal to install the new cam bearings with spacers, so I am leaning that way, however this engines oil pan was covered in oil and dirt when I picked it up so who knows.

I inspected things, but I wasn't that thorough.

She runs good though. Sounds healthy with the cam in it.

Because the leak appears to be coming from the rear of the engine, I'm gonna have to pull it again. I don't want to contaminate the clutch or pressure plate assembly. Since that has to happen, I'll prob just install the 3900 engine again with the forged rotating assembly of Pauter rods and JE pistons with the cam, and shoot for 700hp.

Kind of a bummer but that's the way it goes. In the meantime I'll be doing a full docu on what it takes to install one of these LZ engines as I'll be doing a swap for Howard.

https://youtu.be/8bcptB_V-B4?si=83NUar0_0SFbHku5

It still leaks oil and it's def coming from the bell housing area so it's gonna have to come back out.

But I think I'll try to put a couple miles on it first and do some pulls and see how it feels on 14 lbs. Maybe a Dyno just to see where it sits powerwise? Lmk what you think.

If the oil leak contaminates your clutch, you'll be that much more frustrated and pissed off at it... and still have to pull the engine.

The Dark Side of Will wrote: ↑Thu Oct 19, 2023 10:12 am If the oil leak contaminates your clutch, you'll be that much more frustrated and pissed off at it... and still have to pull the engine.

I said the same thing to Howard actually.

Maiden voyage with the 3.5 today. She runs good. Sounds healthy. No boost today. I just wanted to see where the fuel trims were going to be vs the 3.9 on a stock cam. A decent amount was pulled on this new tuneup. I don't have exact percentages to share at this time however.

We'll see what happens.

Bummer about the rear main seal, one of the few seals I always replace on a used motor for any car since it is requires pulling the engine or trans (or both) to replace. Worth the <$20 and 10 min to replace. Especially when motors get pressure washed by the pullers and sometimes it is very hard to tell if it is leaking. Are you going to swap any parts from the LZ4 to the LZ9? Or will it remain a functional motor? Might be nice to keep on the shelf as a backup.

I am building a whole new lz9 with the Pauter rods so nothing from this lz4 will transfer over. I'll keep it as a backup for sure or for r&d.

I pulled a datalog of a stock lz9 with the lnj stock cam, vs the 3.5 with the aftermarket cam. you can see the boost curves at the same rpm here. much less boost on the 3.5 clearly my turbo is oversized for the engine at lower rpm. the 3.5 needs more rpm to make up the difference which is to be expected.

about 8 psi difference at the same rpm which is about 125 lb ft less tq. Its quite noticeable. Trust me. the 3.5 def requires a much smaller turbo pending on power goals of course.

stock 3.9 with lnj cam.

3.5 with 218/236 comp cam.