Resurfacing a cyclinder head - GIF

[Altair]

Resurfacing a cyclinder head.




Previously:

Fly cutting a cylinder head - GIF
CNC machining a cylinder head - GIF
Engine cylinder honing tool - GIF
Engine cylinder honing tool - GIF
Making cylinder sleeves/liners for engines

[mr mikey]

How long did it take to weld and not have it warp and was it worth repairing, it must be a special head with a five valve configuration.

[Frank S]

How long did it take to weld and not have it warp and was it worth repairing, it must be a special head with a five valve configuration.

I imagine the head may have already been warped beyond being able to be cleaned up was the reason for welding.
As for being a special head yeah, you could say that the list of manufactures who produced engines with 5 valves per cylinder is small.
Here is a wiki of those. What's interesting is Peugeot did it in 1921. There is even 1 known engine built with 8 valves per cylinder
Peugeot had a triple overhead cam five-valve Grand Prix car in 1921.[14]

In April 1988 an Audi 200 Turbo Quattro powered by an experimental 2.2-liter turbocharged 25-valve straight-5 rated at 478 kW/650 PS@6,200 rpm (217.3 kW/liter) set two world speed records at Nardo, Italy: 326.403 km/h (202.8 mph) for 1,000 km (625 miles) and 324.509 km/h (201.6 mph) for 500 miles.[21][22]

Mitsubishi were the first to market a car engine with five valves per cylinder, with the 548 cc 3G81 engine in their Minica Dangan ZZ kei car in 1989.[23][24]

Yamaha designed the five-valve cylinder head for the 20-valve 4A-GE engines made by Toyota for use in some Toyota Corolla models in Japan. Yamaha also developed five-valve Formula One engines, the 1989 OX88 V8, 1991 OX99 V12, 1993 OX10 V10 and 1996 OX11 V10, but none of these were very successful. For their YZ250F and YZ450F motocross bikes, Yamaha developed five-valve engines.

Bugatti (EB 110), Ferrari (F355, 360 and F50), Volkswagen - Audi (Audi Quattro) - Skoda (Octavia vRS) and Toyota (4A-GE 20V) have all produced five-valve-engined vehicles.

https://en.wikipedia.org/wiki/Multi-...0with%20Yamaha.

[IntheGroove]

The Ferrari 360 Modena also had a five valve engine...

[mr mikey]

I see this head is made in Germany. Thanks for all the info.

[nova_robotics]

That looks suspiciously like the 5 valve head on a VW/Audi 1.8T motor. Might be a 2.0T motor, hard to say and I am certainly not an authority. My girlfriend has an Audi with the 1.8T 20 valve motor. Those motors are readily available. I wonder what the motivation was to do this work? I know it's a popular tuner motor. Is it possible that there was nothing wrong with this head and they were adding material to decrease the compression ratio so they could increase the boost pressure? It seems like a tremendous amount of work to repair something that you can find at every junkyard for $100.

[IntheGroove]

Most likely a welding exercise. Weld the surface, resurface it and see how well you did...

[nova_robotics]

I did a bit more research. It looks like somebody has spent a hell of a lot of time making a high horsepower race head. The stock heads have large coolant passage holes on the heads that line up with tiny little coolant passages on the block. Whoever has modified this head has filled in those coolant passages, then redrilled out only what's necessary to line up with the coolant passages on the block. I think they're trying to make a more closed deck head. Also the combustion chamber is way deeper than a stock 1.8T head. The video appears to have added 2-3 mm of additional height above the head gasket to that head. Have a look at the depth of the stock heads. The valves are almost flush with the mating surface for the head gasket.





There is a ton of work here that we're not seeing. Somebody spent many hours on this. Weld, machine, die grind around the outside of the head and in the combustion chambers, rinse repeat. That happened probably 3 or 4 times to get to the point we see in the video. There aren't even any inclusions in the surface after the fly cutter. One or two passes of weld is not going to produce a surface finish like that. We're looking at many hours of work here.

I also found 1.8T heads that have been CNC ported for crazy amounts of money. Like $5k for a head. I really don't understand why someone would spend that kind of money on a four cylinder engine, but then the Honda Civic tuner crowd exists so what do I know?

[mansworld]

How long did it take to weld and not have it warp and was it worth repairing, it must be a special head with a five valve configuration.

A few high-performance engines have 3 or 5 valves per cylinder. 3 valves (2 intake and one exhaust), 5 valves (3 intake and 2 exhaust).

[Frank S]

A few high-performance engines have 3 or 5 valves per cylinder. 3 valves (2 intake and one exhaust), 5 valves (3 intake and 2 exhaust).

I have a few engines that have 4 exhaust valves and no intake valves