The Mule rides again (sort of) - pics.

[pmbrunelle]

Every time you post pics of those breathing ports, I'm wondering if you managed to do it without cutting your hands on the sharp edges.

[The Dark Side of Will]

Nicking my hands in handling the major castings is why I spent time deburring them. Now that prototype machinist cut 0.007 off the bottom of the lower crank case, I'm close to needing to deburr that surface again. It's pretty easy to get scraped up inside a Northstar crank case. Leaving blood inside allows some of my power to flow into the engine.

[The Dark Side of Will]

Top rings are at Total Seal getting lateral gas ports cut into them.

Well.... I was kind of surprised they'd work with me on used rings. I guess we're both learning something.
They tried cutting the gas ports into the tops of my rings, and chipped the moly face coating.

We're still figuring out where things are going from here. I do need to get this resolved before I take the block to ProMar.

Most of me hopes we'll come up with something that drops in and lets me move forward with assembly and installation expeditiously.

A little piece of me thinks about the way that having a non-standard overbore has occasionally bitten me and wants new 12:1 hollow dome pistons (currently 11.5 solid dome) at a standard overbore...

The potential issue is that the very first set of gapless rings I tried didn't live up to my QC expectations (YEARS ago). That's not exactly TS's fault, as they had to start with a vendor's ring at that bore size and then make it gapless. The thickness variation across the set was >0.0015, IIRC. That meant that the grooves couldn't be cut for 0.001 side clearance. I had TS lap the rings via their Diamond Finish process, and that brought the thickness variation down to the level that CP was able to cut the grooves with 0.001 side clearance. This is very important for controlling ring flutter in order to make power at high RPM.

However, that also means that my rings and grooves are thinner/narrower than the standard 1.5mm rings, so either I need to have any new rings lapped or get new pistons, neither of which are cheap options.

[The Dark Side of Will]

Well... technology has advanced. My older rings are steel, but with plasma moly facing.
TS is going to replace them with stainless steel with a PVD coating (Don't know what the coating is... they just say it's PVD, but that's a deposition method, not a material).

Since they were taking a risk in trying to modify my rings, but still messed them up, we're going to meet in the middle on payment.

[The Dark Side of Will]

The race engine shop is done with my rotating assembly, but I wasn't able to pick it up last weekend.

[The Dark Side of Will]

I was at my rental property's garage looking for something else last night and found the 1-2 cluster gear that had been missing. Sweeeet. That saved me $2500 in having a custom input shaft made to match the output shaft I assembled with the modified first and second gears.
I also found in the same place three stock input shafts that I'd been missing. I have a bunch of disassembled transmissions, but no input shafts and no idea where they went. Lol... now I know!

[pmbrunelle]

Time to implement a scheme to record the coordinates of stored parts?

I'm starting to have trouble finding things myself.

[The Dark Side of Will]

I want to REDUCE my inventory, not make it easier to add more!

[The Dark Side of Will]

Was able to make it to the local race shop this morning.
We had discussed lathe turning the counterweights to balance them. He ended up grinding around the areas that the balancer told him needed to have weight removed. This actually accentuates the cam grinding that GM already did on the counterweight, so I don't think it has maximum reduction of MoI. Oh well.. It'll run great like that. I think I'll take measurements of what he did and do some nutty math to figure out about how much I'd have to turn off the counterweights on my other forged crank, then do turn them down and have him spin it, then compare the weights of the cranks. That'll make me a hit with the girls.

Also, the shop assistant had weighed the parts and calculated the bobweight. He had one number written down for the combo of Piston, Pin, Locks & Rings. I was immediately suspicious. We double checked and found that he'd just weighed everything with the steel pins in the pistons, instead of using the titanium pins. The shop owner was apologetic and said they'd make it right and I could pick it up the next weekend. I hold exactly zero blame for something we caught before it went live.

Proximal cause: Shop assistant didn't follow directions.
Root cause: My lazy ass didn't pull the steel pins out of the pistons before delivering pistons in a box and titanium pins in a box.

[pmbrunelle]

If your piston rings are at Total Seal, is the local race shop using an assumed mass for them?

[The Dark Side of Will]

Race Shop weighed the old ones before I sent them off to TS.

[The Dark Side of Will]

I should clarify that I only sent the top rings to TS.

[The Dark Side of Will]

I finally picked up the rotating assembly. WOOOOOOOOT!
I now have:
-Crankshaft (need to weigh it)
-Conrods & rod bearings
-CP Pistons & Titanium pins
-Napier 2nd rings & 3.0mm oil rings

Rod big end: 388.0
Rod Bearings: 72.0 (2 sets)
Rod small end: 158.6
Piston, Pin, Locks, Rings: 475.6
-Total bobweight was ~1485.2g/throw, which isn't bad. I could knock a little more out of the pistons with a hollow dome and/or X- or Box-forging, but there's not much easy weight reduction left there.

Now just need to:
-Get the new top rings in hand
-Hone the block
-Gap the new top rings
-Assemble the short block

Top end:
-Modify the '93-'99 heads to accept '00+ manifold
-Finish cleaning the heads up for Cerakote
-Modify '06+ right intake sprocket to fit '93-'99 right exhaust location
-Have the heads Cerakoted
-Have heads decked?
-Order fresh Cometic gaskets
-Order new timing chains
-Assemble to short block

Clutch:
-Order ARP 11mm flywheel bolts
-Order ARP or TI64 clutch bolts
-Order clutch
-Complete design/manufacture of throw out bearing holder
-Assemble clutch and transmission to assembled engine

Body:
-Replace right hinge box
-Install powertrain!

[pmbrunelle]

-Crankshaft (need to measure its mass moment of inertia)

Fixed that for you.

[The Dark Side of Will]

Would love to! Is there an easy way to do that?

drop the crank into a pair of ceramic RCBB's on V-blocks and wrap 5 feet of cord around one main journal with a 5# weight on the end of the cord. Hook up a sensor to read the reluctor, then let the weight fall, spinning up the crank. Measure the maximum speed attained and compare to the distance the weight drops before the string comes off.

Of course I don't have a before measurement, but I do have a virgin forged crank to use...

Also, if you start with two identical forgings and balance them for the same bobweight via different methods, the heavier crank will have the lower MoI.

[pmbrunelle]

Hang the crankshaft vertically with a string. Perhaps use an eyebolt threaded into the nose; said eyebolt could be made from a washer welded to a bolt.

You have created a torsional oscillator, with the inertia of the crankshaft and the stiffness of the string.

A period in the range of multiple seconds should be achievable, so you can time it with a stopwatch. With a good Q factor you can time multiple oscillations before they die out.

Redo the test with a known inertia added to the crankshaft (such as the flywheel, which you could calculate analytically).

You now have two equations; should be enough to solve for the two unknowns.

********************************************************************************

I actually oversaw this method to measure the inertia of some much smaller parts (in the 20 gram - 500 gram range), and the results were in good agreement with the inertia calculated by CAD, or manufacturer spec. Something like 5% difference or less; I don't remember exactly.

The string was tied to each end with simple knots.

I think the method would be applicable to a crankshaft.

[The Dark Side of Will]

We actually do have a torsion pendulum apparatus at work... maybe I should see if I can use it.

//

Even after I put the car together, I'm going to have to rebuild the wiring harness from scratch. I'm swapping to 58x engine management, so everything has to change anyway, and I'm extensively re-routing the harness, so everything has to change from that as well.

I have the harness that came off my first junkyard engine to work with. I'm not sure if I want to disassemble my current '93-'99 Northstar harness or sell it. Anyone have a Fiero engine bay harness I can buy? It doesn't matter which engine, as I only need the Fiero-specific circuits.

[The Dark Side of Will]

I placed the order for the Total Seal rings today. The upshot is that I'll still have lapped rings and 0.0015 side clearance and I'll gain gas ported rings.
However, because I previously ran the engine, the rings have seated in the grooves, which with gapless rings results in a ridge (should be microscopic, but 'tev) at the joint between the gapless rail and the parent ring.
TS didn't want to put new rings in used grooves, so I agreed to send the pistons to Rebco machine in Wichita to have the grooves widened slightly. TS will lap the new rings to 0.0580, while my current grooves are 0.0575. TS suggested 0.0595 grooves. I'm not sure if I'll have Rebco do 0.0590 or 0.0595, but I have that option. The groove touch up is surprisingly affordable... $10.50/groove.
I should have the TS rings next week. I'm thinking that I'll mic the new rings, then decide exactly what the groove width should be.

[The Dark Side of Will]

My dad and I did poorly thought through mods to the right hinge box years ago... Time to fix those.

Prior state. I got the left part removed this weekend... got most of the spotwelds cut on the right part, but there are 2-4 I can't get to without a drill extender.





Before I pulled the engine out, I also scribed the mark shown depicting where the surface of the cam cover actually falls. This corresponds to the top of the hole in between the studs on the original hinge box.

I'm installing the hinge box that FieroGuru removed from his car, so I'm putting a famous piece of hardware into my franken-rig.

[The Dark Side of Will]

I got the rest of the hinge box off over the weekend, but forgot to snap a pic.

My rings came in! Wooooot! SS, PVD, gapless, lapped, gas ported.



I measured their thickness and found that Total Seal has really upped their QC game over the years. These were lapped, but didn't look like it arriving in this packaging. However, they all mic'd in the 0.0578" to 0.0580" range, measuring 5 points per ring. 0.0002" over the whole set! That lets me talk to Rebco about how wide to make the grooves. SS, PVD, gapless, lapped, gas ported.

I also have the laser cut blanks for the Getrag throw out bearing holder for the PTT 7.25" dual disk clutch.