Another forged engine rebuild

[mituc]

The mods list is in my signature, but the relevant parts are:
- SP63 Custom 88mm pistons, at that time I think they were machined Wisecos, the piston rings they came with were from Wiseco (part# 8800XX);
- Manley piston rods;
- GTX3071R turbo;
- Clevite H Bearings (rod & main);
- ARP L19 head studs from SP63 with custom larger nuts;
- CoolingMist WMI kit;

Everything else was factory: EGR, balance shaft, PCV system, all left in place for emissions and smog tests.

So when I bought the pistons one of the things the machining resolved was that they were clearing the oil squirters.
On Sep. 8 in the last 10kms of a longer road trip (250 miles/400kms) the engine started to sound like a diesel. Everything else was absolutely fine, the engine was pulling properly, there was no knock registered, and so on.
I started the car next morning, limped another 5 miles to the dealer driving at around 1500rpm mostly and left the car there because it was clear something was wrong.

They had 4 other engines already in process of being rebuilt (from the first batches of the SkyActiv 2.2D) so they could open my engine only yesterday.

This is what they found:
- oil squirters on cyls 2 and 3 were broken;
- one of them was floating in the oil sump;
- the other one got between the crankshaft and the balance shaft which resulted in balance shaft gears and the crank gear loosing several teeth;
- some of that steel powder got carried by the piston rods and scratched some bearings (the crankshaft is untouched, so it needs 0+ size bearings like new from the factory).

Therefore I need the following:
- new piston rings - but because these custom pistons were supposed to clear the oil squirters I'm wondering how they managed to hit them. They were indeed close but were not touching them, and I think they started touching them only after I raised the rev limit from 7000 to 7150rpm and did a few pulls. Should I get different pistons as well? Which ones? I need 88mm with 22.5mm wrist pin (the rods are good so I would not change them);

- I'm debating if I should do a balance shaft delete for $35 or get a new crank plus new BS for probably $2500 in total. This car is used both for long family cruises and for hooning on track so I still need it to be relatively quiet inside, and I kind of affected its quietness with the Cobb 3" catback. I already purchased a SouthBend Stage3 Endurance clutch kit so the single-mass FW may also induce a bit more noise, but I'm not sure and I have no idea how bad is it going to be or if the exhaust noise will cover the FW noise and the deleted BS noise or if these will just add to the existing.
One other option would be to replace the crankshaft with a good one and do a BSD delete, and when my wallet will recover I can add the balance shaft if I don't like the car with the deleted BS without having to tear the whole engine apart.

- For rod bearings I will go with the King bearings, and I'm not sure if for the main bearings I should go back to more expensive OEM or get another set of Clevite H. What's the best choice here?

- I'm going to replace the valve springs with Crower 65lb. The target is a 7500rpm rev limit and whatever the GTX3071 can push up there. I will to a VCTS delete as well so that should help with the intake flow a little bit;

What else?


Later edit:
Ok, so I just purchased an used BS from ebay and I will get a new crank.

Are the MS3 and MS6 BS identical? I thought they are, but it's just the ebay listing which made me wonder because their vehicle compatibility list is not complete.

[Mazdazilla6]

Definitely check squirter clearance before sealing up the engine. Throw some clay on them and roll it over a few times. Check and see how deep the pistons press into the clay.

Also, you should consider looking into using the crank out of the 2.3 Ecoboost. It can be had for much cheaper than our crank brand new.

[mituc]

Originally Posted by Mazdazilla6 Also, you should consider looking into using the crank out of the 2.3 Ecoboost. It can be had for much cheaper than our crank brand new.

I didn't pay for the crank just yet, but I'm not sure about the crank specs, clearances, and everything. I could easily get the 2.3EcoBoost-ex-2.3DISI-fTw crank otherwise. But you know how it is, all it takes is a groove somewhere or some journal 0.5mm wider and it's all gone.

[Mazdazilla6]

Oh yea it doesn't take much but it does look very promising.

[mituc]

Originally Posted by Mazdazilla6 Oh yea it doesn't take much but it does look very promising.

I didn't take any chances and paid for an OEM crank.

[Tomas]

The GTX3071 is too small to be trying to increase your redline to more than 7K unless you are running less than 26 psi.

You bought a used balance shaft but a new crank. Not sure your take no chances ideology makes a lot of sense. At any rate. You need to ensure your gear lash for the balance shaft you bought is set correctly. You can't just slap that thing on there. There are shims on the mounting feet of the balance shaft assembly. These come in different sizes and need to be the correct size for the gear lash to be set correctly. Manual goes into all this.

[mituc]

Originally Posted by Tomas The GTX3071 is too small to be trying to increase your redline to more than 7K unless you are running less than 26 psi.

I see... I was running like 30PSI with a 7150rpm red line. Ofc with meth, a CM10 nozzle which I think is the size of a DO12.
The turbo is still good and the car was pulling quite good with this tune.
I'll do a VCTS delete as well during this rebuild so I should get the same amount of air with a tad less boost (the tune is load based).

Originally Posted by Tomas You bought a used balance shaft but a new crank. Not sure your take no chances ideology makes a lot of sense. At any rate. You need to ensure your gear lash for the balance shaft you bought is set correctly. You can't just slap that thing on there. There are shims on the mounting feet of the balance shaft assembly. These come in different sizes and need to be the correct size for the gear lash to be set correctly. Manual goes into all this.

I just needed a balance shaft in there and a new one was just too much over the 4k in parts I already spent. If it's not going to be perfect I'll spend those $1300 on a new BS later, it's easier to replace just the balance shaft than crank+BS.
I'm rebuilding the engine to a mazda dealer so they will first go with a 50 shim (0.5"/1.22mm thick), measure it, and then order the right shim. This is the standard procedure when a BS and a crank that never been together before are paired. They will do this by the book.

[mituc]

Ok, so all 4 cylinders need to be bored +0.5mm, which leaves me with no piston option as I'm already at 88mm. I could go with 90mm pistons but I'm not sure this would be a good decision, probably the 90mm pistons would wiggle even more inside the cylinder and the only options are also 2618 alloy.
Therefore I decided to sleeve it and go with the 87.5mm SP63 4032 pistons.

I already paid for the 88mm wiseco piston rings to pair them with the existing custom SP63 wiseco pistons (totally my fault, I didn't wait for the machinist to reply with the measurements) but at this point I think the best and most reliable option is to pay $600 more for the more DD friendly pistons.

[mituc]

4032 pistons ordered, waiting to finally win.

[mituc]

So this is where the squirters touched the pistons. Piston #1 is at the machinist with the engine block, they said they may not be able to sleeve it. Squirters on #2 and #3 were blown off and one of them got between the crank and balance shaft.

I'm already at 88mm and they need to bore it 0.5mm more to bring the cylinders back in shape, which sucks. Probably the pistons wiggled a little bit in the cylinder when repeatedly touched the squirters which scored just a bit the cylinder walls as well. I'm already looking for another block, I may be able to get one from jimellis mazda because they have it a few hundred bucks cheaper than edgeautosport. I'll ask SP63 if they can source one even cheaper, since they are 1.8 miles away from the HQ of the freight forwarder I'm using to get parts from the US.

[sheston]

What pistons are these? Sorry, too lazy to go back to your old threads and see

I don't remember my Wiseco's being that beefy around the wrist pins

[mituc]

Originally Posted by sheston What pistons are these? Sorry, too lazy to go back to your old threads and see I don't remember my Wiseco's being that beefy around the wrist pins

It's the first generation of custom SP63 pistons which are based on some Wiseco pistons.
These are not the OTS Wiseco pistons because even after machining these are about the same weight as those (348 grams mine versus 355 grams the OTS). I know that because I also had a set of OTS wiseco in my hand and I weighted all of them.

This is my piston:

...and this is an OTS wiseco:

[mituc]

Ok, I just sourced a CX7 block which is supposed to have 0 wear. We will inspect and measure it prior to purchasing it.