My '75 Monza 5.3/Turbo Build Thread *Dyno Video*

[CableDroid]

Hey guys, I picked up this car from the original owners family back in February of this year. It's a rare factory 350/5.7 car (only 3xxx built), all the other V8 Monza were powered by the 262 or 305. Unfortunately the original engine had long been ditched in favor of a '72 LT1. So because the car isn't original anymore anyway, perfect candidate for a LSx swap.

After towing the car home (car was in a rural town, a hour away) I immediately starting ordering parts for it, mostly stuff to convert the lame and rare 4x4" lug pattern to typical GM 5x4.75" pattern. The front non-vented front rotors, calipers, and spindles were ditched in favor of new S10 2" drop spindles, vented-slotted/crossdrilled rotors, calipers, and stainless braided brake lines. I also bought some aftermarket S10 axles for the rear and had a buddy weld up and redrill the new lug pattern on the rear drums. Then of course I had to buy new rims (15x4" & 15x8") and tires (205/75/15 & 235/60/15") for the new setup.....


A few weeks ago I pulled and sold the LT1 to a buddy of mine and had the original TH350 rebuilt with the usual upgrades. I also ordered a 10" billet converter from a local outfit (PTP). I plan on cleaning up the engine bay a little, including a coat or two of flat black to replace the battleship gray.

I already had a spare 2004 5.3 with a LS6 cam in the corner of my garage that used to be in my K5 with a Roush TVS1900 Supercharger. I went ahead and pulled the heads and took them to the machine shop for a valve job and valve spring swap (BTR .660" Kit).

While I was there, they asked me if I wanted to install a set of 2.00" intake valves and some stainless 1.57" exhaust valves that they had ordered for another customer, but they flaked out. Since it was only going to cost another $150 total, I figured why not. They also shaved .003" off the heads to make sure everything was nice and flat. I also went old school and painted the short block classic Chevy Hugger orange. Then I ordered a set of LS9 head gaskets and some head studs, after everything got here, I slapped on the heads.

Now I just gotta find sometime to modify the factory V8 frame perches to accept a different and more common motor mount, probably from late '60's Chevy SBC truck. Then I can install the engine and transmission and start mocking up the turbo hotside.

[spyderracing]

Sounds like what I'm getting ready to do lol awsome

[corvettejim1968]

sounds awesome. i just bought a 1975 Towne Coupe with the rare California 5.7L 350 V8 option only 3,699 built and the previous owner spent $150 to have research done on that piticular car and found less than 50 are known to exsist.

[CableDroid]

Finally some pics....

[CableDroid]

More...

[CableDroid]

Finally got the swap done and tuned.

https://youtu.be/08nKHw6zWm0

[zeke]

Sounds wicked! Numbers?

[CableDroid]

Only 400 to the wheels on this pull at 7 psi. Was out of methanol and the tuner was out too, so intake air temperatures were a bit high (230). The next day I had methanol mixed up and ready and set the boost controller for 12 psi.... 550 to the wheels. I am good with that.

[zeke]

That should do!

I'd like to see a pic of the finished engine bay.

[Monza Harry]

Where are you going to buy Traction for that? That will be fun if you can live with those numbers. 550 ought to be enough to cause all kinds of Mayhem!! Now we need track and or burnout Video. We are a needy bunch aren't we Harry SWEET!

[Kenova]

It really is amazing how much power those little engines can generate.
Are you willing to share details like cam and turbo selection?
Your pictures show two different intake manifolds, which one did you use?

Ken

[CableDroid]

Due to the site's ridiculous file size limitations, it's not allowing me to post any pictures. I am not interested in setting up a third party Web page for the sole purpose of linking pictures to this site, especially when no other msg board I frequent has such issues. I will gladly email pics if you PM me your email address.

Right now I am running a set of used Mickey Thompson 26x10.5x15 ET Streets (DOT legal). Even at 20 psi they hook way better than regular 235/60/15 I had on there. I railed a brand new Hellcat on a private road on Thursday. Not trying to brag, but it wasn't even a close race.

It's a regular stock LS1 intake manifold and throttle body, stock fuel rails, flow matched Siemens Deka 80# injectors. I think most of the combo is in my sig, but the cam is just a LS6 cam and the turbo is a Chinese copy of a Garrett T72.

Thanks guys!!

[zeke]

A few resized pics for Cabledroid.

[Monzsta]

Looks great! What oil pan is that? F-body? And what fuel are you using? These cars fly with way less horsepower than other vehicles. That Hellcat, while powerful, is still a battleship at 4,439 lbs. My car weighed 3,000 even, with me in it and an iron block, T56 and 9". Someday someone's going to ditch the blower and put two proper turbos to that Hellcat and do some wrecking.

[CableDroid]

Looks great! What oil pan is that? F-body? And what fuel are you using? These cars fly with way less horsepower than other vehicles. That Hellcat, while powerful, is still a battleship at 4,439 lbs. My car weighed 3,000 even, with me in it and an iron block, T56 and 9". Someday someone's going to ditch the blower and put two proper turbos to that Hellcat and do some wrecking.

The oil pan is the H3 5.3.....aka GM Muscle Car Oil Pan Kit. I drilled a hole for the turbo oil drain in the front, just behind the balancer. I am running E85 in the factory fuel tank and a stand alone methanol/water injection setup on a progressive controller. My car weighs 2900 with the roll bar installed.