Porsche Decision to use a slant 4
03-19-2010, 04:52 PM
#31
Drifting
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944 block is completely different than any 928(even if "cut in half"). Only the components bolted to it are similar. The 944 block is fitted with an oilpan, bell housing and motormounts that allow it to be packaged in the 944. Take all that away and the motor stands up straight. The term "slant" is slang of which was applied to domestic inline motors of decades past and has no technical relevance.
03-19-2010, 04:58 PM
#32
Drifting
Thread Starter
Read and learn.
IE. a straight 8 is an engine that has the pistons orientend straight up.
a V8 (i shouldnt even have to explain this)
Im not sure what the geometry has to do with an engines performance but it could result in less even cylinder wall wear.
03-19-2010, 05:12 PM
#34
i would imagine that you have to offset the oiling system so the higher side of the slant gets enough lubrication.
but otherwise, i doubt it's much diff than a traditional vertical straight 4.
now....what if porsche decided to put in a 2.5L boxer 4 in...heh
but otherwise, i doubt it's much diff than a traditional vertical straight 4.
now....what if porsche decided to put in a 2.5L boxer 4 in...heh
03-19-2010, 05:19 PM
#35
Race Car
Straight means inline. The flat or vee more precicely refers to the crank angle of stroke. It could be like ^, <, >, and still be a vee.
The different configurations have advantages and disadvantages in packaging obviously, but the orientation of the crank journals change and thus give them a different firing order. As a result and more importantly they have different internal harmonics and thats where the problems happen. A straight six is a perfectly(naturally)balanced motor, same for a straight 8. A V6 is probably the most unnaturally balanced motor and lots of people have played with different angles and crank firing to get them right,... and balance shafts. You have to consider why an I-5 works and a V-5 does not. Also think why a radial aircraft engine works with all the cylinders in the same plane (no pun intended) - they only have one crank journal and a common connecting rod for all the cylinders(and the crank is the cam).
"Slant" is more of a slang term. Nobody is "wrong" in this thread, just different perceptions.
The different configurations have advantages and disadvantages in packaging obviously, but the orientation of the crank journals change and thus give them a different firing order. As a result and more importantly they have different internal harmonics and thats where the problems happen. A straight six is a perfectly(naturally)balanced motor, same for a straight 8. A V6 is probably the most unnaturally balanced motor and lots of people have played with different angles and crank firing to get them right,... and balance shafts. You have to consider why an I-5 works and a V-5 does not. Also think why a radial aircraft engine works with all the cylinders in the same plane (no pun intended) - they only have one crank journal and a common connecting rod for all the cylinders(and the crank is the cam).
"Slant" is more of a slang term. Nobody is "wrong" in this thread, just different perceptions.
03-19-2010, 05:24 PM
#36
Race Car
flat (boxer) motors take this to an extreme and the reason 911s, Ferraris and BMW motorcycles all puff smoke at start up - the oil puddles in the "bottom" or one side of the barrels. Otherwise no real differance in oiling.
03-19-2010, 05:35 PM
#37
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Straight means inline. The flat or vee more precicely refers to the crank angle of stroke. It could be like ^, <, >, and still be a vee.
The different configurations have advantages and disadvantages in packaging obviously, but the orientation of the crank journals change and thus give them a different firing order. As a result and more importantly they have different internal harmonics and thats where the problems happen. A straight six is a perfectly(naturally)balanced motor, same for a straight 8. A V6 is probably the most unnaturally balanced motor and lots of people have played with different angles and crank firing to get them right,... and balance shafts. You have to consider why an I-5 works and a V-5 does not. Also think why a radial aircraft engine works with all the cylinders in the same plane (no pun intended) - they only have one crank journal and a common connecting rod for all the cylinders(and the crank is the cam).
"Slant" is more of a slang term. Nobody is "wrong" in this thread, just different perceptions.
The different configurations have advantages and disadvantages in packaging obviously, but the orientation of the crank journals change and thus give them a different firing order. As a result and more importantly they have different internal harmonics and thats where the problems happen. A straight six is a perfectly(naturally)balanced motor, same for a straight 8. A V6 is probably the most unnaturally balanced motor and lots of people have played with different angles and crank firing to get them right,... and balance shafts. You have to consider why an I-5 works and a V-5 does not. Also think why a radial aircraft engine works with all the cylinders in the same plane (no pun intended) - they only have one crank journal and a common connecting rod for all the cylinders(and the crank is the cam).
"Slant" is more of a slang term. Nobody is "wrong" in this thread, just different perceptions.
Yah, I think with a "straight 8" the "straight" refers to the relation of the pistons to each other from above-- not the same as the use of the term "slant." You could have a "slant-straight 8" too.
WTF is a VR6? It's sort of a V, but if you look at it from above it's actually a Z6!
03-19-2010, 05:49 PM
#39
straight/inline means that all the cylinders are in a straight line.
slant means the piston motion is not vertical in relation to the ground.
V configuration is alternative to straight/inline.
if u wanna make up engine configurations, u could have a slant V engine.....although I dunno why u'd want to hehe.
slant means the piston motion is not vertical in relation to the ground.
V configuration is alternative to straight/inline.
if u wanna make up engine configurations, u could have a slant V engine.....although I dunno why u'd want to hehe.
03-19-2010, 05:57 PM
#41
Rainman
Rennlist Member
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if you want something weird, VW made a VR5 for a while. 3 on one side and 2 on another.
03-19-2010, 05:58 PM
#42
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straight/inline means that all the cylinders are in a straight line.
slant means the piston motion is not vertical in relation to the ground.
V configuration is alternative to straight/inline.
if u wanna make up engine configurations, u could have a slant V engine.....although I dunno why u'd want to hehe.
slant means the piston motion is not vertical in relation to the ground.
V configuration is alternative to straight/inline.
if u wanna make up engine configurations, u could have a slant V engine.....although I dunno why u'd want to hehe.
03-19-2010, 06:15 PM
#45
Race Car
It helps to look at at the crank. The typical V8 crank has 4 rod journals where two opposing cylinders share a journal. The I4(944) has 4 journals - 1 and 4 go up and down together, 2 and 3 do the same but 180 degrees apart - basically a two cylinder with 4 pistons. A flat 4 has 4 rod pins that are 90 degrees apart - no two pistons are at TDC at the same time. V6 - 3 rod journals, I6 - 6 rod journals, on and on. This definitly translates to different characteristics in torque and power delivery. Imagine one of those straight 8 supercharged Deusenburgs - they claim like 185 HP, but you know that thing was powerful enough to twist axles in half...and smooooooooth.