355 Earliest 355 engines have the lightest pistons. Fact or Fiction???

It’s time to straighten this out .

Early engines (pre 38150) allegedly have the lightest pistons according to Fchat history. Do they? If so, what is the weight?


Bradan documented an engine build on a 97 Berlinetta (5.2) here:

https://www.ferrarichat.com/forum/threads/bradan-f355-berlinetta-bare-metal-paint-job-upholstery-mechanical-service.569058/

They measured a few things:

Piston - 292 g
Pin - 83 g

Piston + Pin = 375 grams


If curious, they also measured a titanium rod, which appears to have an “F” designation on the side. 401 g.




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Here’s where it gets interesting. Jetfxr, who owned an early 2.7 car claims the original motor came with OE (Mahle) pistons “18 grams” lighter than new replacement OE Mahle pistons he ordered to rebuild his engine.

https://www.ferrarichat.com/forum/threads/355-pistons.162479/

If new pistons are 292 g, this would indicate his early pistons were 274 g, for a total Piston+Pin (274 + 83) of 357 grams.


Ricambi’s site states New OE pistons + pins are 380+ grams.

https://www.ricambiamerica.com/355pset-high-performance-f355-piston-set.html

Assuming 380 grams, this implies piston weight of 297g if ordering a new OE piston today.

297 - 18 = 279 g (possible weight of Jetfxr’s early engine piston).



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The developer of alternative after-market pistons sold by Ricambi initially claimed early OE piston/pin weight was 359g. He later changed it to “375g” saying he made a mistake.

https://www.ferrarichat.com/forum/threads/replacement-355-pistons.171280/#post-137153727


Did he realize his mistake after weighing his own alternative pistons/pins and realizing they were 376 grams? *376g is 1g heavier than the piston/pin Bradan weighed from a 5.2 engine.


Either way. I’m curious to know the actual weight of early 355 pistons so we can put this theory to rest once and for all .

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Slightly off topic… here’s the chart for titanium rod weights from WSM.



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You would think in 30 years we’d see enough early 355’s with blown up bottom ends … someone surely would have measured out it’s pistons by now .

Anyone care to measure out an early piston weight or there just not enough early blown engines to take samples from?

 

Here’s my theory:

The F355 was the first road-going Ferrari equipped with titanium rods. Mid 90’s era, Ti rods were reserved for race cars/race teams where engine builds were frequent and perhaps long-term durability of Ti rods are less of a concern. For Ferrari to make a decision to put them in road-going cars, one can say they were venturing into uncharted territory and understandably concerned with long-term durability.

The WSM shows there were 7 stages of weight increases in the rods. I’m going to speculate they were made slightly stronger at each stage with a slight weight penalty each time. So it’s not like there were early “bad” rods and subsequently one new updated stronger ti rod. Sure, you will probably get the last version if ordering a new one today, but there’s no denying there was evidence of progression in the changes. Changes made perhaps to minimize risks. There might have been a design change as well, but I’d like to see one side by side.

If my motor did pop due to a bad rod, I would certainly put in the most updated rod. However, I’d like to keep the light-weight pistons if they are still good and in fact lighter weight. This thread is about pistons.

 

Plus, if we can confirm the early engines did in fact have the lightest pistons and rods, it was most likely making the most power of all the 355 engine iterations… even if slightly less durable. This would help collaborate old stories of owners feeling an extra kick driving an early 355 and it wasn’t all in their imaginations.

Fwiw, I searched Fchat threads to find if any owners reported a busted Ti Rod when they were going thru a rebuild and could not find any. In the same token, there aren’t a whole lot of super early 355’s in the U.S.


@Buckets has an early 355 and will probably end up rebuilding a cyclinder (for other reasons). Hopefully, he’ll measure out pistons and rods and inspect the health of the Ti rod as well. He’s got 50k mi on the engine.

 

Personally, durability of the pistons and rods in the early engine is the least of my concerns. More concerned about reports of water seeping in with weak bronze guides as a second, which are not too difficult to replace and a known and resolvable issue with 355’s in general.

 

Fair point.

I guess we’ll have to wait and see if Bucket’s early engine marked “A” by the factory was merely a coincidence .



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There are 7 weight groups. 15% chance of receiving rods from the lightest group…

 

Depends on how much they weigh .

 

Here’s another early engine block marked “A.” That’s 2 for 2.



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Carrillos are a nice durable option. They’re just not titanium. Pankl, the manufacturer of our 355 Ti rods owns Carrillo fwiw.



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What I’m trying to find out is if pistons from early cars are lighter than current OE replacements and if so, by how much?

 

@Targatime

That’s 3 for 3.

 

It should be noted PaulK has an early engine. Sept 94 car build date.


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