DIY Forged Internals in the comfort of your garage without removing the engine; and how I almost blew my engine.

[Supraman40]

This is only for the brave (and if you're like me the desperate and dumb )

You don't have to remove the engine or subframe to install forged internals.

This all started with the oil cap breather I installed. It didn't cause the issue but it masked it.

The issue I had was a cracked valve cover that was allowing oil to enter the cylinders and slowly and gradually leaked oil onto the outside of the cylinder head. I assumed this oil residue was only due to the oil cap breather, so I ignored it. This was going on for maybe 6-8 months.

Near the end, I was getting misfires in cylinder 6 (it could have been and cylinder), I checked the spark plug and it was black and had lots of carbon. I replaced it and everything went back to normal.

I did this multiple times until the check engine wouldn't go away and the supra sounded like it was cammed or had an exhaust leak. After much research I found another symptom, exhaust being sucked back into the cylinder, confirmed by holding a plastic bag at the end of the exhaust and it was getting suck in. I used a bore scope camera down the spark plug hole and found what looked like a hole the the exhaust valve.

So here's a write up generally describing the process.

1. Preparation, about $500 in special tools.
• B58 Timing tool from Amazon
• B58 cam spring removal tool from Amazon (comes with 16 point socket for cam gears, if upgrading cams)
• Digital scale
• 24 inch torque wrench 50- 150 lbs
• 1/2 inch T55 socket (short version) with 6 in and 12 in extension for cylinder head.
• Bolt stretch gauge
• Plastigauge
• Vice
• Head gasket
• Turbo: oil/ coolant seals, nuts, and gasket, v-band clamp
• Intake manifold gaskets
- Valve Cover Gasket
• Feeler gauges
• Piston install tool (ring compression tool)
• 12 point sockets
• E torx and torx sockets
• Pass through bit driver (for oil pump sprocket)
• Connecting rod balancing tool (to check weight)
• BMW oil pan gasket making
- injector seals and special tool to install them
- Boregauge and micrometer (to verify piston to cylinder clearance)

2. Forge internals
• pistons and rods (I went with CP Carillo Pro-Xtreme with heavy duty wrist pin by 5150Autosport)
• Manley Connecting Rods by 5150
• ACL Bearings (I assumed they are better than King bearing because they're more expensive)
• Kelford cams and springs
• ARP head bolts
• ARP girdle bolts and oil pump bolts
• ARP oil pump sprocket bolt

3. Disassembly Top Side
• Disconnect the battery to ensure safety
• Drain engine oil and coolant completely
• Remove downpipe, intake, charge pipes
• Remove turbo assembly
• Remove intake manifold
• Remove ignition coils, HPFP, injectors, and spark plugs
• Remove the plastic linding near the windshield and the aluminum brace
• Remove the valve cover
• Remove timing chain tensioner and guide
• Rotate engine to top dead center position
• Lock cams in place with timing tool
• Remove the cam gears with 16 point socket
• Remove the cylinder head, following the correct bolt sequence
• Remove cams once the head is out

4. Disassembly Bottom Side (All these Torx bolts are fragile and will shred if you hit them at the wrong angle)
• Support the transmission and unbolt the circular engine mounts on one side, maybe both sides.
• Remove the steering assembly bolts and allow it to hang
• Jack the transmission the engine with go up to, this give you space required to remove the oil pan.
• Remove the oil pan, if you need more space jack the transmission higher
• Remove the oil pump sprocket bolt, you may have to hold the crank shaft with a special tool (IMPORTANT: ITS A REVERSE THREAD BOLT).
• Remove the 4 oil pump bolts
• Remove the girdle bolts
• Remove the connecting rod bolts and the caps
• From underneath, push the pistons out of the engine block through the top of the engine.

5. Cleaning and Inspect

6. Piston and Rod Assembly
• Weigh the entire rod, piston, rings, pins, bearings (The goal is less than 1.0 grams difference between each piston assembly)
- measure piston with digital caliper (piston manufacturer will specify where to measure)
- Measure bore with boregauge
- The difference in piston measurement and bore measurement is the clearance.
- Measure/verify ring fap in cylinder
• Install new piston rings, properly oriented per manufacturer spec (stagger ring gaps).
• Assemble rods and pistons
• Check bolt stretch with gauge with rod in a vice
• Drop pistons with caps removed into the cylinders using piston ring clamp install tool
• Install caps with plastigauge to verify clearance
• install bolts and caps

7. Reassemble in Reverse
• Use timing tool to set timing after head and cams are installed.

Helful videos: I couldn't find any videos of doing this job with the engine installed, so I had to piece together multiple videos to figure it out.

B58 Teardown videos



Weighing pistons and rods


Kern417 Cam Job 3 Part Series



Remving Oil Pan and Pump (don't remove subframe)


Papadakis Teardown and Build Guide

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[SmurfA90]

2. Forge internal
• pistons and rods ( I went with CP Carillo Pro-Xtreme with heavy duty wrist pin by 5150Autosport
• Manley Connecting Rods
• ACL Bearings (I assumed they are better than King bearing because they're more expensive)
• Kelford cams and speings
• ARP head bolts
• ARP gurdle bolts and oil pump bolts
• ARP oil pump sprocket bolt

Great write-up and thanks for sharing!
How long did the full build take you from start to finish?

I had a few questions if you don’t mind:

1. Did you go with the OEM head gasket?
2. What compression ratio did you choose for your pistons? My understanding is that the 6-port Supras run 10.2:1 compression, but I’ve seen a lot of suppliers mentioning 11.0:1.
3. Did you have to do any machining work to ensure the gasket surface was perfectly flat?
4. Where did you source your parts from? 5150 or another supplier?

 

[Supraman40]

I might have jumped the gun, but I am currently on the reinstall steps, i've installed the pistons and rods and will get to the oil pump and oil pan next.

I've been taking it very slow and ensuring I research everything before I go into the next step. I've put well over 25 hours of work into it over the course of a month. I've been learning as I go.

5150 website has the best price that I can find on the pistons and rods as a set and they offer a ton of variations.

I went with the OEM gasket, mainly because papadakis did, and I don't plan on going over 900hp.

For me, the head had damage in cylinder 6 so I had to get it machined, but there are tools you can buy to check the surface of the block.

The tuner, Pureboost, recommended against going down in compression.

 

[lucky phil]

Drop in piston kits, sigh. How do you set the piston to bore clearance?
Phil

 

[SupraTR]

Appreciate you documenting all of this and hope all is good once you fire it back up. What was your reason for not just pulling the engine? Seems like you're only a few steps away from being able to work on it on an engine stand.

I haven't pulled/built an engine since my 300zx TT so for all I know the additional steps for a Supra are a nightmare...just curious.

 

[razorlab]

My DSM roots commend this. My years of experience deplore this.

 

[Evolution]

That thing is going to shake like none other. I cant even imagine how much heavier the new pistons and rods are compared to the old ones.

 

[Supraman40]

That thing is going to shake like none other. I cant even imagine how much heavier the new pistons and rods are compared to the old ones.

It's about 80 grams more per piston/ rod assembly. I was able to get the new pistons exactly balanced though. I haven't heard anyone with a built 558 talk about shaking. But if the engine explodes, I'll be sure to let everyone know

 

[Supraman40]

Appreciate you documenting all of this and hope all is good once you fire it back up. What was your reason for not just pulling the engine? Seems like you're only a few steps away from being able to work on it on an engine stand.

I haven't pulled/built an engine since my 300zx TT so for all I know the additional steps for a Supra are a nightmare...just curious.

The main reason for not pulling the engine is the lack of space in the engine. Yes, probably just a few more steps and some more money for the lift.

 

[Evolution]

It's about 80 grams more per piston/ rod assembly. I was able to get the new pistons exactly balanced though. I haven't heard anyone with a built 558 talk about shaking. But if the engine explodes, I'll be sure to let everyone know

80 grams! That is huge. And you are right, no one with a built B58 says anything about the engine shaking cause they get the entire rotating assembly balanced as a unit, on a machine. I would take your loss at this point and just pull the engine all the way out and do things right. Otherwise, you will be doing all this work again.

 

[Supraman40]

80 grams! That is huge. And you are right, no one with a built B58 says anything about the engine shaking cause they get the entire rotating assembly balanced as a unit, on a machine. I would take your loss at this point and just pull the engine all the way out and do things right. Otherwise, you will be doing all this work again.

You're giving me some disappointing things to consider. Thank you .

 

[M340Manny]

I applaud you for the effort. I built my last N54 at home and it's still living, you got this.

 

[lucky phil]

You're giving me some disappointing things to consider. Thank you .

You don't need to worry about the piston and rod additional weight. An inline 6 has perfect primary and secondary balance. This means that the opposing pistons perfectly cancel each others imbalance out as a consequence of the engines design. As long as all the new pistons and rods are exactly the same weight you won't have any balance issues. The main problem is like any drop in piston kit you don't get to control the piston to bore clearance which is a fundamentally important and critical element in engine building.
Phil

 

[i3igpete]

You don't need to worry about the piston and rod additional weight. An inline 6 has perfect primary and secondary balance. This means that the opposing pistons perfectly cancel each others imbalance out as a consequence of the engines design.

I agree with Phil for once.

Front bank cancels the rear bank's whirl moment on the crank

Piston 1 at tdc cancels planar shaking forces from piston 2 and 3 just before and just after bdc.

The pistons can be made out of lead and it will cancel out.

 

[razorlab]

If you haven't done drop in pistons with ball honing lubed by your own spit, in a wet parking lot, at 2am, then have you really lived life yet?

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