PBS Engines
Introduction
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PBS Chassis
Sales Flier (to be added) |
| In 1962, PBS Engineering got involved in sports car racing with the SCCA. That first attempt was in the H-Modified
class, which at that time had a 750cc displacement limit. They produced various engines over many years, as well as PBS Chassis to complement their engines.
PBS had some experience with the Abarth twin cam engines, but it was difficult to get parts for these engines in the United States. These engines were too complicated, too
expensive, too hard to work on, and were not very reliable.
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SOHC engine
DOHC engine
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Fiat 600D Improved
So, PBS made the decision to make their own engine. This involved the design of a new cylinder head to bolt onto the Fiat 600D block. The PBS head was an 8-port hemi with a
valve angle of 36 degrees per side. The valves were operated by push rods with the intake push rod crossing over from the exhaust side. PBS opted to do this because BMW had been
somewhat successful with this system.
PBS tested this engine in 1963, and ran into several problems. The 600D cam system was too small and the weight of the valve train was too heavy which severely limited the RPM
of the engine. However, it did run well other than that.
PBS reworked the patterns to adapt a cam tray to the head with two overhead camshafts, a single row timing chain and bucket type cam followers. This engine was very successful
and remained in production for five years. The last twin cam was delivered in 1969. PBS still services these engines for vintage racers.
One of the problems PBS had with the 600D block was that, when it was bored from 62mm to 65mm to raise the displacement to 850cc, the cylinder walls became too thin. Some of the
blocks had to be discarded.
PBS-8-P 850cc
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When Fiat came to the US in 1967 with the 850 series cars, PBS thought that this would cure the 600D block problem because the cylinder bore of the 850
block was 65mm to start. Unfortunately, the 850 engine was not a solution. Fiat had changed the bore spacing and it did not match PBS' twin cam cylinder head or piston
configurations. Something had to be changed.
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PBS Fiat 850cc engine
which made about
90 bhp at 8500 RPM
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| At that time, there were other types of racing in the US that used 850cc size engines. Those included three-quarter midget cars that were run on dirt
ovals, and 850cc hydroplane boat racing. In both cases, those applications required what were called single gear service. No gear changes and no clutch could be used.
For those applications, and sports car racing, PBS designed a new push rod type cylinder head using the Fiat 850 style wedge combustion chamber, but with a high angle four port
intake. The stock distributor was used. This PBS-8-P head was design and first saw service in 1968. |
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| The cost of this 8-Port push rod engine was lower and it was very easy to maintain. It produced as much horsepower as the Twin Cam over a
wider range. This engine was very successful in the United States and overseas. It set many records and won many championships in various racing classes. It was popular in 1000cc
form and in that size was used mostly in hill climb cars.
The only PBS head currently in production is the PBS-8-P push rod head. It is currently used in SCCA HP racing, and in 1000cc hill climbs in Europe.
SOHC 850cc
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In 1974, PBS produced yet another cylinder head for the 850 block. This time it was a SOHC hemi, cross flow head with rockers and a 55 degree valve angle.
It produced more horsepower again, but over a small range of high RPM. It was only used in Sports Racer service. these were light weight cars with close ratio transmissions. This
engine was only sold by PBS and was used exclusively in the United States.
16 Valve 1300cc
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SOHC engine as used
in a PBS MK-4 DSR
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| This engine was design in the latter part of 1968 and was run in the PBS Mk-4 CSR. driven by Bob Swenson. A second car was driven by Randy McDaniel, both
winning many races.
The engine in the color photos on the right was purchased from Randy to go back into an Mk-4 CSR that runs vintage races.
The engine is shown on the PBS engine dyno. Chief mechanic Fred is shown getting ready to pull power on it. |
This DOHC 4 valve head
was used on the
Fiat X1/9 block and
run in the CSR class
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