Installshield 2
Gothenburg Superiority
Sorry in advance for the long post (before the TL;DR ensues haha)
A very long time ago, i did a lot of NA work on my P5. An engineering elective in college gave me access to equipment to custom make long rods and associated pistons for an FS engine. for a brief while, i was running a 13:1 compression FS with 8mm (iirc) longer rods that could easily rev to 8000+ rpm (making nearly 200bhp on a free-standing brake dyno)...but all with a borrowed $4000 motec ecu that was never intended to be permanently wired in my car...and like most things...i never got around to finally finishing the project, and its been on the stock engine other than all the bolt-ons ever since...This was a tricky dance with a high strung light-weight internal race engine...but stuck with a factory oil system, as well as limited access to a full dyno and a decent cam shop to nail that down (we ground one off customs that 'worked', but never put the time in to the math to figure out exactly what i needed)...to say this thing was 'peaky', was an understatement...as in it was either an animal, or barely driveable...under 50 degrees...wouldn't start...under 5,000 rpm, barely moved...above that, its hard to explain how much fun it was.
Now considering this was more of a school thing, i was rushed...and didn't get to ever do exactly what i wanted, as i couldn't go and purchase some other things to really do it right. I now have some more time to work on this stuff, a little more money to throw around...and better access to some harder to find parts...
So i'm now toying around the idea of a new naturally aspirated engine build (using some parts from the engine i already built)...The idea starts with a 1.8L crank from the FP...this brings the assembly much closer to square, gives me something like 7mm more 'room' to start with on rod length before i even start playing around with compression ratios. But, after digging for weeks, i simply can't find any of the crank specs i need. so thats where i need some help.
Does anyone have any info on it? Bad news off the start is that almost every retailer lists 1.8L flywheels and clutches separately from the 2.0L. This could be simply that the 1.8L has a shorter deck height, therefor a smaller rear 'face'...and that the F series gearbox has a smaller bell housing...and thats the only difference, but i've never confirmed any of that. This wouldn't be an issue though, as this would use the 2.0L block and G series gearbox. I more need to know if the crank end will mount a 2.0L flywheel (and therefor a 2.0L clutch) properly..as there are almost no proper clutch options for a 1.8L other than factory replacements.
The rest is bearing sizes. I get mixed results from multiple parts stores. I know that FS and FP connecting rods and pistons are said to be interchangeable...the FPs are actually shorter, so no use to any of us, but you can get a slight compression bump right off the bat by running FP pistons in the FS (to 9.4 iirc)...so this leads me to believe the crank arm end diameters are the same (as well as big and small ends of the connecting rods)...but its the main bearings i'm after...
so if anyone knows the bolt pattern size for the flywheel...as well as the bearing size...and associated cradle dimensions (if they are in fact different) it would be much appreciated. I know these cars are old, its more of a nostalgia thing for me any more...but i still see posts from guys that have been around as long as i have, and if this goes right we could see one of the first street driven 9,000 rpm FS's to date...
A very long time ago, i did a lot of NA work on my P5. An engineering elective in college gave me access to equipment to custom make long rods and associated pistons for an FS engine. for a brief while, i was running a 13:1 compression FS with 8mm (iirc) longer rods that could easily rev to 8000+ rpm (making nearly 200bhp on a free-standing brake dyno)...but all with a borrowed $4000 motec ecu that was never intended to be permanently wired in my car...and like most things...i never got around to finally finishing the project, and its been on the stock engine other than all the bolt-ons ever since...This was a tricky dance with a high strung light-weight internal race engine...but stuck with a factory oil system, as well as limited access to a full dyno and a decent cam shop to nail that down (we ground one off customs that 'worked', but never put the time in to the math to figure out exactly what i needed)...to say this thing was 'peaky', was an understatement...as in it was either an animal, or barely driveable...under 50 degrees...wouldn't start...under 5,000 rpm, barely moved...above that, its hard to explain how much fun it was.
Now considering this was more of a school thing, i was rushed...and didn't get to ever do exactly what i wanted, as i couldn't go and purchase some other things to really do it right. I now have some more time to work on this stuff, a little more money to throw around...and better access to some harder to find parts...
So i'm now toying around the idea of a new naturally aspirated engine build (using some parts from the engine i already built)...The idea starts with a 1.8L crank from the FP...this brings the assembly much closer to square, gives me something like 7mm more 'room' to start with on rod length before i even start playing around with compression ratios. But, after digging for weeks, i simply can't find any of the crank specs i need. so thats where i need some help.
Does anyone have any info on it? Bad news off the start is that almost every retailer lists 1.8L flywheels and clutches separately from the 2.0L. This could be simply that the 1.8L has a shorter deck height, therefor a smaller rear 'face'...and that the F series gearbox has a smaller bell housing...and thats the only difference, but i've never confirmed any of that. This wouldn't be an issue though, as this would use the 2.0L block and G series gearbox. I more need to know if the crank end will mount a 2.0L flywheel (and therefor a 2.0L clutch) properly..as there are almost no proper clutch options for a 1.8L other than factory replacements.
The rest is bearing sizes. I get mixed results from multiple parts stores. I know that FS and FP connecting rods and pistons are said to be interchangeable...the FPs are actually shorter, so no use to any of us, but you can get a slight compression bump right off the bat by running FP pistons in the FS (to 9.4 iirc)...so this leads me to believe the crank arm end diameters are the same (as well as big and small ends of the connecting rods)...but its the main bearings i'm after...
so if anyone knows the bolt pattern size for the flywheel...as well as the bearing size...and associated cradle dimensions (if they are in fact different) it would be much appreciated. I know these cars are old, its more of a nostalgia thing for me any more...but i still see posts from guys that have been around as long as i have, and if this goes right we could see one of the first street driven 9,000 rpm FS's to date...
