3.9L LZ9 87 IROC-Z28 - GT4088 turbo

[Mars]

Ok, got the engine in, it replaces my 3500 (which still runs fine, I just wanted more power) ran a best of 11.13, hoping this motor will run a little quicker.

Basically an internally stock LZ9 :

60# Mini Siemens injectors
Proform elec. waterpump
TCE timing cover / thermostat outlet
TCE external crank trigger
WOT Tech Street Strip Turbo Cam with pushrods
PAC springs
TCE SBC cam bearing spacers
Durabond SBC cam bearings
75mm GM Truck TB
LZ4 intake manifold (ported)

Pass side mount, was real easy to make, easier than the old 3500 mount it replaced on account of it all being on one plane whereas the 3500 mount had 3 different angles.



Other side is my 3500 mount, so nothing new there, bolts right up...



All kinds of room for my turbo, there's PLENTY of room under the alt. for a 4" downpipe, should I ever require one... 3.5" will do for now :



New Kirkey racing seat, i got the 16" wide Pro Drag with a velour cover. It's very comfy and has all provisions for 5 pt harness, the hole for the submarine strap, ect.

I ordered a bolt in Racecraft mounting braket for it, should be in soon.




And finally I have to re-do some of the charge piping cause I want to run a little bit of 3" before i hit the 75mm LS1 throttle body. Started off by making this 2.5" to 3" cone and will incorporate that somplace into the charge pipes when I get that all figured out.



I ordered a V8 model radiator as my rad hose connections don't work soo well with this 3900. The inlet/outlets on a V8 rad are opposite the V6, left right bottom upper are all criss-crossed so that'll work and be cleaner looking.

Got rid of the power steering :



More to come...

[caffeine]

What rad did you go with? I got an aluminum Champion rad a while ago off eBay for my car and it fits with minor mods to the rubber bushings which hold the rad in place and I also had to oval out two of the upper fan shroud holes. Never had an issue with it so far.

They're priced very reasonably as well .

[Mars]

I just got a NAPA replacement. Should be in tomorrow 140$. Figured it would be enough... I'm going to get a small slim-fan for it, done.

[ericjon262]

In for timeslip!

[young gun]

In for timeslip!

Same. Too bad it won't be until next spring

[Z26-T]

That is awesome..

Random question. Why are you using a LZ4 intake instead of the LZ9 or LX9 one?

[Mars]

That is awesome..

Random question. Why are you using a LZ4 intake instead of the LZ9 or LX9 one?

LX9 won't fit, not even close, the ports on this LZ4 are HUGE comapred to a 3500, plus it uses 8 bolts instead of 6... also, the LZ9 one has a variable intake runner and that was just one more thing do deal with, could likely hook it up to a window switch or something, it would likely take soo much dyno time to figure out that it's not worth it for me. If I want more power, I'll press a button on my EBC.

[young gun]

If I want more power, I'll press a button on my EBC.

Jealous.

[Z26-T]

Ah ok, gotcha. So the LZ4 only has VVT, but the LZ9 has a variable intake runner and VVT. Good to know for future reference .

[Mars]

You got her Pontiac. haha

[Mars]

Alright, made a mount for the turbo. Still need to run the exhaust to it and it is *TIGHT*. There is a plumbing nightmare under that thing, but it will work out and the 3.5" downpipe clears everything. It's super tight. Don't have anything welded yet, but it's getting close. The driver's side will be a breaze after figuring the pass side mess out.



As you can see the turbo is mounted alot lower in the engine compartment compared to my old setup so that the dp can go under the alt.






Alt. clearance is tight.




I'm quite proud of how it turned out.

I bought some 4" radius bends and they aren't even close so I busted out the pie cut bends for the pass. side.... lol It's honestly the only way I can make this work. I ended up with about a 1.50" radius. It was either that tight bend, or running an extra 18"-20" of pipe that would be like a total of 270* of bends to get where I needed to go.



I'm hoping I can stick both wategates right between the alt. and the throttle body for easy spring changes if I ever feel the need. There is a ton of room there now.

big ass 31X12X4 intercooler is in the mail. (i'll only have to do this mod once, this cooler will work for the future L33 build)

[Maple Leaf]

Looking good, I'm glad GM finally made a 60 degree V6 with some displacement.

Did you ever dyno your last setup? I'm very curious what kind of power this will be making compared to your 3500.

Good luck with the project! Should sound wicked!

[caffeine]

I'm planning on dynoing my setup when its done. It should make similar power since its pretty much the same setup with a slightly smaller turbo

[Mars]

Nope never dynoed the car with the 3500 in there. The 3500 will likely make MORE power with a smaller turbo, as I think the 4088 was too much for it.

I hope that my 3.9 runs the same times as my 3.5 with 3 psi less. I have 5 psi springs in my gates right now, with the old 3.5 I had 8 psi ones and at that boost level I think I was running around 11.65-11.85.

I am looking online at all the 3900 head gasket issues... Kind of scared now. lol. I think I'll pickup a spare motor next time I'm at the j/y and do cometic MLS gaskets, headstuds and gap the pistons for boost then when I have issues with my motor, I'll just pop that one in there.

I got a bit of work done today. Installed the new intercooler it's an Ebay special CXracing 31X12X4 unit. These seem to get good reviews online,so I decided to get one. My old IC had both inlets on the same side and it was alot of extra piping and very tight bends to get it all to work. The piping for this one will be alot cleaner and less cramped.





Hopefully the cooler intake charge will offset the shear weight of this heavy mofo. haha.

[MidnightriderZ24]

Nope never dynoed the car with the 3500 in there. The 3500 will likely make MORE power with a smaller turbo, as I think the 4088 was too much for it.

I hope that my 3.9 runs the same times as my 3.5 with 3 psi less. I have 5 psi springs in my gates right now, with the old 3.5 I had 8 psi ones and at that boost level I think I was running around 11.65-11.85.

I am looking online at all the 3900 head gasket issues... Kind of scared now. lol. I think I'll pickup a spare motor next time I'm at the j/y and do cometic MLS gaskets, headstuds and gap the pistons for boost then when I have issues with my motor, I'll just pop that one in there.

I got a bit of work done today. Installed the new intercooler it's an Ebay special CXracing 31X12X4 unit. These seem to get good reviews online,so I decided to get one. My old IC had both inlets on the same side and it was alot of extra piping and very tight bends to get it all to work. The piping for this one will be alot cleaner and less cramped.





Hopefully the cooler intake charge will offset the shear weight of this heavy mofo. haha.

you wouldnt believe how many 3500/3900 gen 4 head gaskets i have done for oil leaks and oil consuption. New HD gaskets are black sealant, old style is blue. headstuds and black gaskets i wouldnt worry about much mars