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different piston faces?
Dear All,
I'm having my early 944 porsche's engine done. When it comes to replace the pistons, I bought a set from eBay. The sizes are same. However I noticed that the "piston face" is different. I'm not sure what to call it but one of the "cuts" or "grooves" (the circular one) on the piston surface is larger than the ones on my original pistons. So, do you think I can use the new pistons or should I ditch them and buy a set whose cuts are the same as the originals? What difference do these cuts make? Cheers, porsche_lover |
RE: different piston faces?
There are multiple different piston types depending on the engine. You should find pistons that are the same as the originals.
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RE: different piston faces?
Thank you Doc, for your reply.
it seems that the sizes are the same. how can i find it's spare part number? i bought the "early 944's pistons" thru eBay. can you tell me what difference does the shapes on the piston crown(piston head?) make? i also have the manual and the catalogue for the spare parts but the only difference between the pistons seems to be the "tolerance group". the following is from the catalogue: 944 103 074 04 - piston 100,00 MM tolerance group 0 Model M44.01/03 944 103 074 14 - piston 100,00 MM tolerance group 0 Model M44.01/03 944 103 074 24 - piston 100,00 MM tolerance group 0 Model M44.01/03 so what would be the difference between these three pistons? and how should i know the part number of mine? any ideas? Cheers, porsche_lover |
RE: different piston faces?
ORIGINAL: porsche_lover Thank you Doc, for your reply. it seems that the sizes are the same. how can find it's spare part number? i bought the "early 944's pistons" thru eBay. can you tell me what difference does the shapes on the piston crown(piston head?) make? i also have the manual and the catalogue for the spare parts but the only difference between the pistons seems to be the "tolerance group". the following is from the catalogue: 944 103 074 04 - piston 100,00 MM tolerance group 0 Model M44.01/03 944 103 074 14 - piston 100,00 MM tolerance group 0 Model M44.01/03 944 103 074 24 - piston 100,00 MM tolerance group 0 Model M44.01/03 so what would be the difference between these three pistons? and how should i know the part number of mine? any ideas? Cheers, vakur |
RE: different piston faces?
Dear Doc,
Thank you for your reply. The part numbers that I listed are all from the original 944 catalogue. I can send you the catalogue in pdf format. There's this piston picture and the numbers are different. There are no pictures of the piston faces whatsoever. What would the different compressionscause? The car would go slower orwill it use more fuel for the same performance or something like that? It seems no one is capable of telling me the exact part number of my piston. But here's a photo: http://img84.imageshack.us/img84/2148/dsc08605by2.jpg Any more ideas? Thank you in advance? porsche_lover [IMG]local://upfiles/3651/CD84BA2C3B904406AC440575A43A1DEA.jpg[/IMG] |
RE: different piston faces?
the cuts are for allowing the valve to miss hitting the piston. It must have been for running more aggressive cams.....that might get you thinking?
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RE: different piston faces?
thank you pete917,
well the mechanic says that new piston that I bought, wouldn't hit the valve either. he tells me to use the new pistons. the only thing that will change -according to him- will be the octane of the gasoline?! if only I could know the spare part number. any ideas? porsche_lover |
RE: different piston faces?
Lol, no i think i am good on technical literature.
If you are running a turbo piston that has the oval dish in it, it will greatly drop your compression, which is going to make the NA car a real dog. You need to find something close to the originals. Your motor guy should be able to figure this out for you, if not, I wouldn't trust him building the motor. |
RE: different piston faces?
Thank you Doc,
But I didn't understand one thing: Do you mean that my pistons are for a turbo 944? I mean the piston in the picture (the piston with the eyebrows and the oval dish in it) is my original piston and my car is NOT turbo. What do you say? Cheers, porsche_lover |
RE: different piston faces?
Argh. No, I am saying if the pistons you go have big oval cutouts, those are turbo pistons that won't work.
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