Noahs944

Can forged 951 rods & pistons be lightened?

924srr27l

Why?

Noahs944

Because I am considering internal components change at some point & will probably replace cast pistons & rods with forged. Brief research shows oem forge pistons with rods are around 300 grams heavier per cylinder. So obviously the aftermarket ones spin up faster & less rotating mass will probably help protect against wear/damage. But is it worth the extra expense? I don't know... if it's easy to trim say 100 grams off the rods and some off the pistons, then I'd think stock is better value.

marc abrams

Noah, I don't mean any disrespect to you. But you do seem to go to great lengths to gain performance from these cars. I wish that I had your budget to spend on cars. Anyhow if performance of a bottle fed car with great handling and road grip is what you are after, perhaps a late model Corvette is something you may want to consider. No bottle to refill, would eat any 944, and has a tush warmer build into the seat.
Just saying.

V2Rocket

Noah...
You'd save more meaningful weight by getting a lighter flywheel, or getting the crank "knife edged".

But if you really wanted lighter rods you'd be further ahead getting a set of Molnar H-beam rods for the 944 for about $600/set which are probably 30% lighter than the OEM Porsche forged rods, and stronger/brand new.

944 pistons are fairly light for how big they are so not sure I'd mess with anything there.

Van

That's a subjective, and personal, question. Only you can answer that.

It's certainly not good "bang for the buck" - but if you have deep pockets and your goal is to extract every percent of performance, than why wouldn't it be worth it? Although most people would be hard-pressed to justify a $10k engine in a $5k 944...

Jay Wellwood

^ this

Or pony up for Carrillo Rods.

Jeff951NJ

Walt, you can lighten the Pistons and Rod or get new ones but what you really want to achieve is having you whole rotating assembly balanced perfectly. It's not as easy as just buying lighter Pistons or Rods and slapping the motor together. If you want to get the most out of your investment make sure to send you whole Assembly to be balanced. (Crank, Pistons, rods & flywheel) PM me if you want more detailed information.

V2Rocket

Inline 4 doesn't require the crank to be matched against the piston/rods.
Would be a good idea to get the piston/rod assemblies balanced against each other though.

Jeff951NJ

When you are racing with 20+ other cars who have the "same" motor you have there are a lot of things you "don't" need to do. However if you want to have the best possible motor you can get these are the things you have to look into. For a street car way over kill I agree. For a race car that's biult you the highest standard these are the things that set them apart. Thats why there are cheap rebuilds and then NA motors that are way north of $10K.

Noahs944

Thank you for the comments gentlemen.

Marc, the reason I have my car budget is because I'm obsessive & don't have kids.
I like Corvettes, always have... in my opinion they look & sound better than a GTR or many other cars at the Autocross. LOVE THEM. But, I also really enjoy the 944 a lot. Part of my joy for these cars comes from the people within its community.

V2, I am looking at the Molnar rods.

... I am very surprise there isn't more response on modifying the oem rods. Geez...

Jeff, PM'D

tempest411

I wonder if a lightweight connecting rod could aid the longevity of stock-type rod bearings in a street driven application? My suspicion is that it wouldn't, since the force of rotation is nothing compared to the power pulses coming from the pistons. It's unfortunate than in all the time these cars have been around that no manufacturer has stepped up to make a better bearing.

V2Rocket

^^do a search for the michaelmount123 rod mod...he has a better bearing that he modifies the 944 rods to fit for a very good price.

tempest411

Yes, I'm familiar with the mod and have a set myself. A little fly in the ointment was created when I discovered I had to have my crank turned .25mm under and could not find the Clevite bearing in an under-size. In fact in the process of looking I was told by multiple vendors that this Clevite bearing is being discontinued in any size, so I had to go with an ACL bearing set. It would still be best if there was a drop-in bearing that would hold up to the sort of abuse they see in these engines.

Voith

You can get the weight of stock forged rods down by about 10% by only rounding outer surface on top and bottom and shave off sharp edges.