6" Rod Pistons Heavier Than 5.7"?

[2Quickrides]

Here's a new one for me. Anyone seen this before? Is this common or just my #$%@ing luck?

Had new 5.7" rods and pistons for the new motor and had the opportunity to switch them to 6" rods and pistons for no cost so went for it. Figured at the very least it'd be less bobweight for balancing the crank.........yet when they showed up the 1.125" compression height pistons are 20 grams each HEAVIER than the 1.425" ones I had. Exact same piston. The ONLY difference is the 5.7" rod vs 6" rod setup. Wiseco Pro Tru Streets.

Everyone including every post on here and common logic dictates they should have been lighter. So add the weight of the now required oil support ring and the slightly heavier rods and the free upgrade has added 37 grams of bobweight. Needless to say I'm not impressed, especially if this ends up costing me more to balance the assembly.

[2Quickrides]

Hell, the longer rods were only 23 grams heavier each!

[BillK]

Heavier pin maybe ? Or maybe on the 5.7 rod version they cut more of the pin bosses for counterweight clearance. The oil ring rails probably dont add that much when you figure they have to cut the ring groove deeper to compensate. If I remember correctly the ring rails are usually around 9 grams.

Either way I would have never assumed anything about the weights. The catalog probably lists the weights too so you could have checked it ahead of time.

[ProPower engines]

Here's a new one for me. Anyone seen this before? Is this common or just my #$%@ing luck?

Had new 5.7" rods and pistons for the new motor and had the opportunity to switch them to 6" rods and pistons for no cost so went for it. Figured at the very least it'd be less bobweight for balancing the crank.........yet when they showed up the 1.125" compression height pistons are 20 grams each HEAVIER than the 1.425" ones I had. Exact same piston. The ONLY difference is the 5.7" rod vs 6" rod setup. Wiseco Pro Tru Streets.

Everyone including every post on here and common logic dictates they should have been lighter. So add the weight of the now required oil support ring and the slightly heavier rods and the free upgrade has added 37 grams of bobweight. Needless to say I'm not impressed, especially if this ends up costing me more to balance the assembly.

It will depend on what rods you choose.
Scat has some Q light rods in 6" that are the same weight +/- 5 grams between there 5;.7 00 or 6"
Pistons are always a crap shoot and unless you spec a target weight you will get the heavier slugs every time.
Cost is the other issue as if you are trying to match costs part for part for a swap like this the seller is not really forth coming with all the info you need and again you get the heavier stuff every time.
Pin lengths and thickness ring pak may change with less comp. height depending on piston type.

You can get lighter pins if they are a std. 2-1/2" length from a common 130 to 98 grams which is a ton and not loose strength from the lighter.

[2Quickrides]

Heavier pin maybe ? Or maybe on the 5.7 rod version they cut more of the pin bosses for counterweight clearance. The oil ring rails probably dont add that much when you figure they have to cut the ring groove deeper to compensate. If I remember correctly the ring rails are usually around 9 grams.
Either way I would have never assumed anything about the weights. The catalog probably lists the weights too so you could have checked it ahead of time.

Pins are identical, oil ring supports are 5g each. The weight difference is one bare piston to the other.
Wiseco quoted me 412 grams each. The 5.7's were all exactly 489, the 6's are 505-509. So not putting much faith in catalog weights.
Though Scat's weights for the Pro Series rods were within 5 grams for both the 5.7's and the 6's. Here's hoping the bobweight they quoted for the forged standard weight crank (5.7, internal balance) is also accurate as it's 28 grams over what the current bobweight will be. They claimed it's done with 1850.

Scat has some Q light rods in 6" that are the same weight +/- 5 grams between there 5;.7 00 or 6"
Pistons are always a crap shoot and unless you spec a target weight you will get the heavier slugs every time.
Cost is the other issue as if you are trying to match costs part for part for a swap like this the seller is not really forth coming with all the info you need and again you get the heavier stuff every time.
Pin lengths and thickness ring pak may change with less comp. height depending on piston type.
You can get lighter pins if they are a std. 2-1/2" length from a common 130 to 98 grams which is a ton and not loose strength from the lighter.

Both sets came from Summit as finding stock of what you want lately seems to be crap shoot. Especially up here.
I'm going to call Wiseco on Monday and see what they have to say about it.

[ProPower engines]

Heavier pin maybe ? Or maybe on the 5.7 rod version they cut more of the pin bosses for counterweight clearance. The oil ring rails probably dont add that much when you figure they have to cut the ring groove deeper to compensate. If I remember correctly the ring rails are usually around 9 grams.
Either way I would have never assumed anything about the weights. The catalog probably lists the weights too so you could have checked it ahead of time.

Pins are identical, oil ring supports are 5g each. The weight difference is one bare piston to the other.
Wiseco quoted me 412 grams each. The 5.7's were all exactly 489, the 6's are 505-509. So not putting much faith in catalog weights.
Though Scat's weights for the Pro Series rods were within 5 grams for both the 5.7's and the 6's. Here's hoping the bobweight they quoted for the forged standard weight crank (5.7, internal balance) is also accurate as it's 28 grams over what the current bobweight will be. They claimed it's done with 1850.
Both sets came from Summit as finding stock of what you want lately seems to be crap shoot. Especially up here.
I'm going to call Wiseco on Monday and see what they have to say about it.

When you say the rods differ by about 5 grams is that total weight or end to end weights.
I was referring to total weight not specifically either end.
Funny thing is 2" journal rods are heavier on the big end then the 2.100" journal size cause the hole is smaller.again you never mentioned if you were using a small or large journal crank.

You can call Trend Performance in Michigan as they are part of the RWB group that own's Wiseco.
They make wrist pins for all applications. They make the pins Wiseco as well as Diamond and JE/SRP.

***What is your current pin weight as supplied by Wiseco??? I had some recently I had to get different pins for to match a Mopar but for a previously balanced rotating assembly.*** They had no issue getting pins close enough that they could be made the same. Which I had them machine the pins to match my requirements. They came dead nuts bang on to the gram weight requested

Mahle Motorsports also have a selection of pins wrist pins.
But the other option is to change piston manufactures

[2Quickrides]

When you say the rods differ by about 5 grams is that total weight or end to end weights.
I was referring to total weight not specifically either end.
Funny thing is 2" journal rods are heavier on the big end then the 2.100" journal size cause the hole is smaller.again you never mentioned if you were using a small or large journal crank.
You can call Trend Performance in Michigan as they are part of the RWB group that own's Wiseco.
They make wrist pins for all applications. They make the pins Wiseco as well as Diamond and JE/SRP.
***What is your current pin weight as supplied by Wiseco??? I had some recently I had to get different pins for to match a Mopar but for a previously balanced rotating assembly.*** They had no issue getting pins close enough that they could be made the same. Which I had them machine the pins to match my requirements. They came dead nuts bang on to the gram weight requested
Mahle Motorsports also have a selection of pins wrist pins.
But the other option is to change piston manufactures

The Scat rods were within 5 grams of their catalog weight. I haven't scaled them for big/small end weights yet, but overall weights are to the gram identical.

Wiseco supplied wrist pins are also dead on, all 116 grams.

The crank is a Scat 4-400-3750-5700 4340 standard weight, 2.1 rod journal, 2.65 main. Anyone with experience with these know how accurate the listed balance weights are? I'll found out in the next few days anyway. Will see what it is currently balanced to and form a plan from there.

The pistons in question are the PTS510A3 (489) and the PTS525A3 (505-509).

[leahymtsps]

Funny thing is 2" journal rods are heavier on the big end then the 2.100" journal size cause the hole is smaller.again you never mentioned if you were using a small or large journal crank.



That's not really true about the better stuff now is it?

Tom

[rustbucket79]

The std weight Scat forged cranks take a pretty good bob weight so I think you’ll be ok.

My Scat ultra light 6” 400 forged crank was pretty disappointing, needing a slug per end to balance with Scat 6” H beams and Wiseco 10 cc dome pistons.

[BillK]

It sounds like you haven't balanced the crank yet so I am not sure what the big deal really is ??