Porsche Decision to use a slant 4
03-17-2010, 12:54 PM
#1
Drifting
Thread Starter
Porsche Decision to use a slant 4
Ive been wondering the past couple days why porsche decided to use a slant 4 instead of straight 4 for the ending design.
Can anyone provide any reasoning? Reduced vibrations or is it jus the fact that they halfed the V8 in the 928 engine
Can anyone provide any reasoning? Reduced vibrations or is it jus the fact that they halfed the V8 in the 928 engine
03-17-2010, 01:23 PM
#6
Rennlist Member
The 944 motor is half of the 928 block. Apparently because all the engineering work was done already the company decided to use the 928 block design. The balance shafts are the Mitsubishi patented design and Porsche paid a royalty on each engine.
03-17-2010, 01:31 PM
#7
Former Vendor
The original 2.0L slant four was unquestionably chosen for two reasons: cheap to adapt (coming out of the Audi - VW - Porsche parts bin); and needed to fit within the low profile front end of the original narrow body 924.
As for the 944, it would be purely speculation as to why they chose to retain a slant four configuration, but it's highly likely, as others have pointed out, that it was due to similar engineering cost considerations: adapt existing technology from the 928 parts bin, and a winning configuration in the sleek, low profile 924S/944 chassis.
As for the 944, it would be purely speculation as to why they chose to retain a slant four configuration, but it's highly likely, as others have pointed out, that it was due to similar engineering cost considerations: adapt existing technology from the 928 parts bin, and a winning configuration in the sleek, low profile 924S/944 chassis.
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03-17-2010, 01:33 PM
#8
Race Director
Hood clearnace.
The 924 had angled 4. Its angle was 40 degrees. This was needed to clear the low hood profile. When they switch to the 2.5L motor it was actually a bit shorter so it sits at a 30 degree angle. Interstingly this maybe the same agle on the V as the 928 motor. Is that a 60 deg V? Not sure.
Any way no vertical engine would fit under the hood.
Porsche did consider a V6 during 944 development, but found they could get to the desired smoothness and hp levels with a 4 cyl version of the 928 motor with the balance shafts. So they chose to do that.
Back in 82 when the 944 came out it was a big hit. Smooth running, Good power, and excellent fuel milage. Fuel mileage was a big deal back then. Only when car got to the 968 stage did the idea of only 4 cylinders become a liablity in the market place. Even so in 1992 the 240 hp 968 four was the most powerfull 4 nomally aspirated cylinder around at the time. And consider the E36 M3 was rate at 240 hp in the USA using a 6 (3.0 to 3.2L) you can see the hp output was comparable even if you had to drive a "little four banger".
Seems like what really hurt the 968 was the 70's era body panel gaps. The gaps were huge compared to the mid 90's standard and given the cost of body tooling it just was never profitable to change all the tooling for tigther panel gaps. Much easier to just create a new car. Considering the sales sucess of the boxster can you really argue it was not a good move for Porsche? Even if we can say a 95 968 is faster than a 97 boxster, the boxster sold where as the 968 did not.
The 924 had angled 4. Its angle was 40 degrees. This was needed to clear the low hood profile. When they switch to the 2.5L motor it was actually a bit shorter so it sits at a 30 degree angle. Interstingly this maybe the same agle on the V as the 928 motor. Is that a 60 deg V? Not sure.
Any way no vertical engine would fit under the hood.
Porsche did consider a V6 during 944 development, but found they could get to the desired smoothness and hp levels with a 4 cyl version of the 928 motor with the balance shafts. So they chose to do that.
Back in 82 when the 944 came out it was a big hit. Smooth running, Good power, and excellent fuel milage. Fuel mileage was a big deal back then. Only when car got to the 968 stage did the idea of only 4 cylinders become a liablity in the market place. Even so in 1992 the 240 hp 968 four was the most powerfull 4 nomally aspirated cylinder around at the time. And consider the E36 M3 was rate at 240 hp in the USA using a 6 (3.0 to 3.2L) you can see the hp output was comparable even if you had to drive a "little four banger".
Seems like what really hurt the 968 was the 70's era body panel gaps. The gaps were huge compared to the mid 90's standard and given the cost of body tooling it just was never profitable to change all the tooling for tigther panel gaps. Much easier to just create a new car. Considering the sales sucess of the boxster can you really argue it was not a good move for Porsche? Even if we can say a 95 968 is faster than a 97 boxster, the boxster sold where as the 968 did not.
03-17-2010, 01:47 PM
#10
Rennlist Member
03-17-2010, 02:10 PM
#11
Race Car
I don't see a distinction between a Inline four and a slant four. The 944 motor is an I4 period and has no comparison to it's V8 cousin in architecture - just componentry. BMW layed their four and six cylinders on their sides from the start and still do today. A four cylinder is a remarkable engine and has inherent qualities that make them superb motors in sports cars. Small, light, free revving motors that can make serious power and fit in a narrow/low chassis. I much prefer a I4 in a sport sedan like the E30('90,'91) and the Mercedes C230 Kompressor and is a much easier car to drive in fury. You just have to keep the revs up, and live with the buzzyness of a four. It was a hard sell in luxury cars as market perception that a six is more than a four prevailed. V6s have replaced most four cylinders and a V6 can be a real pig - a compramised motor at best. There are a few good V6s
03-17-2010, 02:27 PM
#12
there really isn't much difference other than the oil pan and pickup and motor mounts is slanted.
of course it woulda been really interesting if porsche used a flat 4 or a v4 hehe
of course it woulda been really interesting if porsche used a flat 4 or a v4 hehe
03-17-2010, 02:42 PM
#13
Race Director
One major reason for using this engine was that it required less development than brand new design v8 or lopping two cylinders off the 928 V8. That engine was probalby too wide for the frame rails given that v8 is too wide.
So they chose to do just one side and use balance shafts to achieve the smoothness.
03-17-2010, 03:43 PM
#14
Drifting
Thread Starter
Thanks for the answers. I had forgotten that porsche was in a tight situation with money so it makes sence that they use the 928 halfed to get the 2.5.