Here's the other 1955 259 cid USA built V8 that was contemporary to the Stude 259. Both are the same Bore / stroke .
Also :
For Plymouth in 1955 the biggest news of the year was, of course, the “new”
V-8 engine. The engine was not really new and was supplied to Plymouth by Dodge
division until a new engine foundry could be completed to supply Plymouth with its
own engines. Plymouth’s first true V-8 would not appear until 1956, and then only
slightly changed from the Dodge version.
At first the Plymouth V-8 was offered in two displacements-a 241ci rated at
157hp with a bore and stroke of 3.44x3.25 in. and a 167hp, 260ci engine with a
larger bore of 3.563 in. Both engines featured a compression ratio of 7.6:1. Shortly
after introduction, a four barrel 177hp version of the 260 hit the streets. Maximim
torque was achieved at 2400 rpm on all engines, the 241 pumping out 217-ft and the
260 claiming 231lb-ft whether 2 or 4 Bbl equipped. Called the Hy-Fire V-8, it was
Plymouth’s first version of a Poly engine.
The Hy-Fire engine achieved some of a Hemi’s free-breathing characteristics
by placing intake and exhaust valves opposite each other in the combustion
chamber. This provided better breathing while not restricting valve size as was the
case in some other small block engine designs. The design not allowed adequate
“breathing” on the intake cycle but allowed the exhaust valve to open further into
the combustion chamber to exhaust spent gasses. Thus creating one of the famous
features of a Poly head.
Also :
For Plymouth in 1955 the biggest news of the year was, of course, the “new”
V-8 engine. The engine was not really new and was supplied to Plymouth by Dodge
division until a new engine foundry could be completed to supply Plymouth with its
own engines. Plymouth’s first true V-8 would not appear until 1956, and then only
slightly changed from the Dodge version.
At first the Plymouth V-8 was offered in two displacements-a 241ci rated at
157hp with a bore and stroke of 3.44x3.25 in. and a 167hp, 260ci engine with a
larger bore of 3.563 in. Both engines featured a compression ratio of 7.6:1. Shortly
after introduction, a four barrel 177hp version of the 260 hit the streets. Maximim
torque was achieved at 2400 rpm on all engines, the 241 pumping out 217-ft and the
260 claiming 231lb-ft whether 2 or 4 Bbl equipped. Called the Hy-Fire V-8, it was
Plymouth’s first version of a Poly engine.
The Hy-Fire engine achieved some of a Hemi’s free-breathing characteristics
by placing intake and exhaust valves opposite each other in the combustion
chamber. This provided better breathing while not restricting valve size as was the
case in some other small block engine designs. The design not allowed adequate
“breathing” on the intake cycle but allowed the exhaust valve to open further into
the combustion chamber to exhaust spent gasses. Thus creating one of the famous
features of a Poly head.
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