Perhaps the biggest "diference" is simply the most misleading one. Because the `87 was rated at a lower RPM than was the `86, there has been a recurring, quite misleading perception that the `87 V-6 produced 5 fewer horsepower than did the `86 V-6.
It didn't. Ratings games aside, horsepower production was the same with both engines.
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07:55 PM
pontiacman63383 Member
Posts: 819 From: warrenton, mo Registered: Jun 2007
During 87 they brought in the new engine block. It takes a single piece oil pan gasket. Some engines were actually internally balanced like the 88's. Most were externally balanced.
Actually, the block didn't get changed until the '88 year, though the parts of the block that the oil pan and timing cover fit on stayed the same so all covers and pans are fully interchangeable. The '88 block had some changes made to the casting to allow installation of a crank sensor in the version of the engine that went into cars with DIS ignition, but the hole for the actual sensor wasn't machined out in the Fiero version of the motor.
The cranks are functionally all the same from '85-87 and are externally balanced (requiring a counterweighted flywheel or flexplate), though the '87 crank had lead-in grooves added to the crank main bearing journals as a running change. The '88 crank went to internally balanced and kept the lead-in grooves.
Excuse me, but can you explain this? I have an 87 block sitting on my engine stand and I can assure you my 85 oil pan does not fit. The front end is completely different.
Arn
I spoke to GM and there were a large number of 88 style blocks produced in the latter part of the 87 run that were equipped with externally balanced parts. FYI
Actually, the block didn't get changed until the '88 year, though the parts of the block that the oil pan and timing cover fit on stayed the same so all covers and pans are fully interchangeable. The '88 block had some changes made to the casting to allow installation of a crank sensor in the version of the engine that went into cars with DIS ignition, but the hole for the actual sensor wasn't machined out in the Fiero version of the motor.
The cranks are functionally all the same from '85-87 and are externally balanced (requiring a counterweighted flywheel or flexplate), though the '87 crank had lead-in grooves added to the crank main bearing journals as a running change. The '88 crank went to internally balanced and kept the lead-in grooves.
JazzMan
Jazzman, does this mean the 87 crank was stronger than the 85-86 fiero cranks??
Thanks,
fierogt28
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06:41 PM
fierogt28 Member
Posts: 2937 From: New-Brunswick, Canada. Registered: Feb 2005
Realistically, I find that this topic of my disscusions just doesn't add up for me. It just seems that everyone has a different story about the fiero V6 engines on changes, improvements, design running changes, info. I'm not saying this in a bad way. I'm very interested on getting this technical info about the V6 crank, block, and different years for the engine that the fiero had.
I know that the 88 flywheel was internally balanced. The 85-86 blocks were the same. 87-88 blocks had a oil pan gasket improvement from a 2 piece gasket (85-86) to the rubber 1 piece for 87-88. I heard that the 88 fiero pistons were lighter. (to confirm, please)
I think the lighter pistons you are referring to are the dished pistons used with the aluminum heads. The piston used with the 88 with iron heads are the same, so far as my research goes. Check the 60degreev6 website above. It has the full history.
Jazzman, does this mean the 87 crank was stronger than the 85-86 fiero cranks??
Thanks,
fierogt28
No, they're the same strength. They were attempting to increase oil delivery to the rod bearings with the grooves to address the premature rod bearing failure problems.
Excuse me, but can you explain this? I have an 87 block sitting on my engine stand and I can assure you my 85 oil pan does not fit. The front end is completely different.
The blocks are the same, what changed was the timing cover and oil pan joint. You can swap the timing cover and oil pan as a set across all year blocks, and in fact they fit just nicely on the later 3.4 which was never offered in a Fiero.