INFORMATION page on Kenneth Nylén - alias "Grottis" (Sweden)
Web page by Anthony Hyde

Tragically Grottis passed away in a motorcycle accident in 2003. His company's former website was

Rolf Ohberg writes: "Grottis built the best GrA cyl-heads ever built ! He made all the heads for the Magnum Team, and later on for VMS (Volvo Motorsport) because they where the BEST.

Grottis heads were based on the 405 (special VMS spec 405 with smaller coolant passages). Later VMS heads are based on the 531 design. Grottis heads are stamped with his name and No. Apparently the modified 531 Grottis head had a 60 cc combustion chamber volume.

Volvo B21 Group A cylinder head modification
(Very careful English translation of former Grottis Head Service webpage by friends of Anthony) - VMS = Volvo Motor Sport

The Chief of VMS race division Bo Vikås rang on January 1986 and asked if I could port (modify) 40 cyl-heads for four Group A cars.

I had made a test cylinder head for them in summer of 1985 and it turned out my cyl-head gave 10% more power over the whole rpm range.

I accepted the job, and modified (so many) Volvo cyl-heads it was almost too much.

I finished in July, Volvo won, and people called the car the flying brick.

Year after (in) 1987, I modified *24 cyl-heads but this time I didn't have to do the combustion chamber, as they had them CNC machined, (which was good).

* (Reportably Porsche designed the combustion chambers)

Original Swedish text - Chefen for raceavdelningen Vikås ringde mig i Januari 1986 och frågade om jag kunde porta 40 st Volvo toppar till 4 st Volvo Gr A bilar.
Jag hade gjort en test topp till dom sommaren 1985 och det visade sig att min topp gav 10% mer effekt over hela registret.
Jag tackade ja, portade Volvotoppar så jag holl på att kvåvas.
Blev klar i Juli, Volvo vann och blev kallad den flygande tegelstenen.
Året efter 1987 portade jag 24 toppar då slapp jag porta forbrånningsrummet for dom var cnc fråsta, skont.

Click pics to enlarge

Hand crafted quality workmanship of Volvo 405 combustion chambers


The fun part is that he, the little alone guy, managed to beat Volvo´s own engineers and tuners at their home field. Grottis was THE MAN in Scandinavia when it came to heads, and almost every important race car or modified car had a Grottis head.

His heads have won:
Prostock: Swedish championships / Scandinavian championships / European championships
Superstock: European record
Roadracing / superbike: Swedish championships, German championship

He was nothing but a living legend during his life. One of the worlds greatest engine builders/headtuners and he deserves all credit he can get.
The nickname Grottis comes from the Swedish word grotta which translates to cave. The analogy if you look at a cylinder head intake/outlet the resemblance to a cave is obvious. A English nickname would be like "Cavie" or "Cave man" perhaps, although it´s pretty hard to find an equal translation.

Even his nickname had to do with cylinder heads, he was a true original...

Andreas Eriksson, Stockholm

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