1984 GMC K2500 Sierra Classic

[MattStrike]

Interesting on the pistons. I know of a few LG3/LN3 turbo builds, I've also seen a few Holden L27 builds, makes me think they can handle the boost.

I managed to find a junkyard steering column for the EPSA motor, so one step closer on the steering.

Turbo bracket #1 is done, ready to mount the turbo and build the header. Turbos are going to have to sit below the oil level in the pan, so I'll need to run a scavenge pump as well. I'm on the lookout for a serpentine belt driven pump that wont cost an arm and a leg, otherwise I'll end up with an electric pump.

[MattStrike]

It would appear that since I bought the electric pump for the Bonneville, China has figured out that there is a niche market for them, so now the market is flooded with "Electric Scavenge Gear Pump 12 volt Turbo Oil Evacuation New 12v BEST DEAL" pumps for $70 that can lift 15ft (5ft self prime) and of course it's a racing part so don't expect it to be quiet...

So good luck finding a helical cut brass spur gear unit that was actually designed to pump aerated oil.

[MattStrike]

I started working on the first header tonight. Trying to keep it simple, cheap, so the primaries are a little larger than they really need to be, and they are not quite equal length. Total cost for materials is $40 each.

[Wes]

in the interest of symmetry, has the thought of adding a second twin turbo L27 to the bed ever crossed your mind?

[MattStrike]

My wife is telling me no.

[crash93ssei]

Tell her she can have three more cats

[Wes]

My wife is telling me no.

Once she steps into the garage...

[BonnieBoy08]

Tell her she can have three more cats

Lmao!! I'm not sure who gets the better deal there. Maybe 3 fixxed cats.

[MattStrike]

Managed to get the other turbo rebuilt over the weekend, still scouting for a place that can check/re-balance it. I've got one, maybe two potential prospects there. Hoping to start making headway on this project again.

Edit: Found a local rebuilder that can balance it!

[haro1225]

I may or may not need the info for this rebuilder to pass along to Travis. His turbo is possibly broken.

[MattStrike]

This place is going to balance the turbo rotating assembly for free

[BonnieBoy08]

Nothing wrong with that! Good score

[Wes]

This place is going to balance the turbo rotating assembly for free

What's the catch? Did they like the project that much? lol

[MattStrike]

Randomly decided to post up the adapter plate dimensions.

GM Corporate Metric & Northstar to Chevy adapter plate:


Blue dimensions on the inside are the corporate metric pattern, purple dimension is the Northstar hole (which I have not verified is correct against actual parts), and red dimensions on the outside are the Chevy pattern.

Dowel pins for Chevy trans: McMaster P/N 91259A792 - Shoulder bolt that threads into the adapter. Holes are sized to be tapped, except countersink/bore and 3800 dowel holes.

[1oldman]

Matt, you belong and should work n GM product development. - BC

[MattStrike]

I've spent too much time not working on this project, so it's time to make up for it!


Started work on the header downpipe and wastegate setup. I've had most of the parts, but had to wait on fixing the drill press and a few other small things. I had to make an adapter to mount the vice on my lathe, build a welding table for the TIG welder, etc..

Dowpipe started:


Adding a hole for the wastegate using the lathe:




And what this is going to look like, welding is going on now, literally the last 1/2" is all that's left before I ran out of gas:

[MattStrike]

Got some stuff done again!

First header is done, installed:


And making the second one:






2nd one done, also with the hand-made dead-soft copper manifold gaskets:


Hot side all setup:







Then working on some plumbing. First up, home made oil distribution block:


And the current status:




Turbos have blankets, and the starter motor is getting a heat reflective wrap as well.

Things I'm going to be working on in the coming days:

81" belt routing, going to have to make it work with a standard belt
Oil pressure sensors need to be adjusted to clearance the piping off the compressor
Finishing the water lines
Finishing the oil lines/cooler/remote filter
Wire harness. Going to try to tuck and simplify it without going overboard. I'll be converting this to the OBD-2 pcm, so need to pull a pcm and harness. Can't find the '97 PCM and harness from the LeSabre build, not sure if I threw it out or what.

[MattStrike]

I'm having some fun, trying to locate a Saginaw 525 steering box with a 16:1 'quick steer' ratio. Mostly because the information isn't easily found online. I'd have to find a shop that rebuilds them and talk to the expert.

I can't use the existing power steering gear, a 14:1 Saginaw 800, to convert to EPS. It's just not going to handle the high-input torque long term because the input shaft isn't really meant to function without power assist. There is basically a stop inside that prevents the input from rotating too far (in the event that you suddenly lose power assist), but it's not going to hold up to full-time use.

The Saginaw 525 was used in the late '70's K20/K30 chevy truck with a 1:24 ratio. I know that the quick steer 16:1 was used in some applications but I'm not sure where to find one that isn't a $400 rebuilt unit though. The side benefit to changing to the 525 is the input shaft is different, and has more aftermarket adapters available. I'd have to get the pitman arm with the box though, or find an aftermarket one. Then hopefully I don't lose any turning radius, but there is some wiggle room there because the EPS can compensate for a longer pitman arm.

Does anybody know what cars would have had the 525 16:1? As far as I can tell it was used all the way up into the '90's, but having a hard time finding applications for the 16:1 ratio.

[MattStrike]

Progress:


This weekend is going to be focused on getting that steering gear, I found a rebuilder that's open on the weekend so going to stop in for a visit. Then it's on to the wiring and putting some of the body put back on.

[Zeik75]

Whats the blue on the header wrap for? just color or what, I would think that paint would burn off eventually.