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Volvo 1800s Part III: Vintage Racing Exhaust System Fabrication

This sport exhaust system was designed and constructed last month while preparing the 1967 Volvo 1800s to run at the recent VSCCA Mt Equinox Hillclimb. It will also be used for racing at tracks that require mufflers, and for driving to and returning from competition events. The overall length of the system was recommended by Volvo Competition Services (VCS) in the 1960s to help in extracting the exhaust from the engine and to produce more power in the higher r.p.m. range.

The system is made up of a post-1968 B20 2-litre 2.0-inch two-into-one front exhaust pipe which replaces the original 1.750-inch B18 1.8-litre piece; the larger front pipes also fit the ’67 B18B manifold. It is followed by an original appearing two-inch straight through sport muffler without baffles; it also has an offset center for added ground clearance. All of this is followed by a 2.o inch mandrel bent 45-degree elbow and a straight length of 2.0-inch pipe that ends on the right-hand side behind the door and is visible in the lead image.

This system is quite LOUD if you accelerate quickly, climb a hill, or above 3500 r.p.m. while driving it on the road. A removable baffle for the end of the side pipe will be constructed to quite down the system soon for road use.

  • The straight through muffler, mandrel bent elbow, rear pipe, and light weight stainless steel band clamps. Please excuse the mud spray under the car, as our workshop is located on one of the many gravel and dirt secondary roads here in Vermont.

VCS four-two-one tubular exhaust headers would add another four-to-five h.p., although at this point are not needed because this added power would be produced past at the 6500 plus redline necessary due the original single valve springs. The new B18B engine was up-graded to 115 h.p. in 1967 by the use of a higher 10:1 compression ratio, slightly richer British SU carburetor needles, and the changes require the use of higher 93 octane fuel.

  •                Volvo Competition Service B18 1.8 litre tuned tubular four-two-one exhaust header
  •                and some other performance parts. Cars imported to the US from Sweden were not
  •                supplied with optional accessories or parts which were either installed at the port
  •                of entry or by Volvo dealerships. All of these items were also available thru dealer
  •                parts departments.

No modification or holes needed to be drilled by designing the rear pipe hanger beforehand; removal of one of the four plastic plugs located in the right-hand side rear floor ended up being a good location for a custom built spring loaded rear exhaust pipe mount. A short 1.0 by .250 inch mild steel tab with a hole drilled and tapped into it for a 5/16 inch SAE fine thread was welded to the front side of the rear pipe.

Three 1.0 inch cupped cylinder block water jacket core plugs were converted into spring cups by drilling  .687 inch (11/16″) holes in the center for clearance for the stud necessary due to exhaust system vibration. Two short medium-strength springs (heat has not affected the temper of the springs) are located inside of the cups both above and below the floor. In this application, a threaded stud tightened by a lock nut below the tab on the pipe was used. On the upper side of the floor at the top side of the second two cup and spring assembly, a nut and check nut is used for adjusting the spring pressure.

  • The rest of the VP sport exhaust system that will be set up with an under axle pipe for quick installation and removal in the near future.

This system adds about five plus HP due to the addition of the shorter and larger pipes, muffler, and length, and also eliminates about fifty pounds of weight due to not using the rear pipes, rear muffler, clamps, and hangers. The system has been used for over 1000 miles including 33 miles of competition at the Mt Equinox Hillclimb and has worked out very well so far. The increase in power due to the changes is noticeable.

  • Volvo 1800s parts book drawing (center) of the original 1961 to ’65 single pipe front pipe exhaust system. Two into one front pipe no. 2, 1966 t0 ’68 with sharper than production curves (upper-left.) And early single port cast iron exhaust manifold, with the same free flowing shape as the later and better breathing 1966 to ’68 four into two manifold (botton-right.) 

The rear section of the system behind the muffler will be welded together soon and a short section of straight pipe will also be made up to take the place of the muffler at tracks that allow open exhaust systems.  In addition, the rest of the sport exhaust system (above) will be modified by the use of a single under axle pipe that can easily be added or remove within 15 minutes when desired for regular road use on longer trips.

All parts used in this series are via VP Autoparts.

5 responses to “Volvo 1800s Part III: Vintage Racing Exhaust System Fabrication

  1. It only seems noticeable due to the extra sound, always good for a ‘noted’ 5hp increase….hahaha. Nice job there, very well thought out. BTW, how did you do at the hillclimb. I couldn’t find any results.

    • No, its not the sound, it defiantly does rev up quicker, and pulls a little harder and that can be felt by the seat of the pants method. Need to use a stop watch over a set distance with both systems to find out what the difference is, or a 12 year old could probably calculate it with an iPhone.

      • Of course it has to be Levi’s, preferably 501’s to get an accurate reading! BTW, red was never my favorite vehicle color until I got m first Ducati….then I fell in love and also ended up with a very red Isuzu Big Horn (Trooper in the US). So, i do love that nice paint job you have.

  2. Your Competition Services exhaust header is a thing of beauty.

    As to exhaust volume and increased power; When I would open the exhaust cutout on my ’14 Ford or on my ’14 Metz I could hear the “Sound of Power”.

    Have fun and be safe in the twisties.

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