Piston?

[88bluestar]

Opinions on Speedmaster PCE305-1906 pistons.
Application is a hobby stock engine on a budget. E-85 fuel
9.8:1 compression/360 cid max....stock crank, eagle SIR rods, stock 350 block..425 hp/torque or less
2 bbl rochester -2701 edelbrock intake, Dart SS or 993/487 GM heads(no porting allowed)
-jones race cam/lifters- LT1 camaro exhaust manifolds.

[mag2555]

I don’t care for the multiple valve notches .

[Walter R. Malik]

I don’t care for the multiple valve notches .

Multiple valve notches are there so that same piston, (with slightly offset wrist pins), can be used on either side of a "V" type engine.

[Mark O'Neal]

Whoever designed those should be shot.

[Mark O'Neal]

I don’t care for the multiple valve notches .

Multiple valve notches are there so that same piston, (with slightly offset wrist pins), can be used on either side of a "V" type engine.

Offset is what, .060? Why do you need multiple reliefs, 3/8ths of an inch, apart for that?

The answer is that you do not.

[Walter R. Malik]

I don’t care for the multiple valve notches .

Multiple valve notches are there so that same piston, (with slightly offset wrist pins), can be used on either side of a "V" type engine.

Offset is what, .060? Why do you need multiple reliefs, 3/8ths of an inch, apart for that?

The answer is that you do not.

You do ... if you are trying to keep the pin offset to one side of the engine and still have the same Valve to Piston clearance.
Pin offset is probably what you could do without.
However, NVH from the O.E.M. manufactures say you also need that offset for quieter cold running.

[mag2555]

Since these pistons are Hypers and run with cast piston type clearances, they probably do not have any pin offset I would bet!

[Walter R. Malik]

Since these pistons are Hypers and run with cast piston type clearances, they probably do not have any pin offset I would bet!

With a centered pin having no offset, the two extra notches are certainly not required.
O.E.M. direct replacement pistons normally have a pin offset, whether Hyper or not; those are probably not direct replacements.

[ProPower engines]

Opinions on Speedmaster PCE305-1906 pistons.
Application is a hobby stock engine on a budget. E-85 fuel
9.8:1 compression/360 cid max....stock crank, eagle SIR rods, stock 350 block..425 hp/torque or less
2 bbl rochester -2701 edelbrock intake, Dart SS or 993/487 GM heads(no porting allowed)
-jones race cam/lifters- LT1 camaro exhaust manifolds.

I have seen them and they are not a quality piston by a long shot.
I would not even use them in a derby car. They are not accurately made and the material is questionable.
And the goofy VR thing that guy smoked too much for breakfast that day the design was conceived

[hoodeng]

Interesting piston! valve reliefs are all on the same side which suggests it has no pin offset [as has been pointed out ,reliefs are on opposite sides for universal installation] but has been made for two types of heads with different valve locations, but with the same piston architecture if such a thing exists????

I think this could explain things, the footnote of the picture says "Image is a representation of this item.Actual item may vary"
So, has anyone seen these things in the flesh?

The alloy is 4032, same as used in many Mahle forged pistons just to pick one manufacturer, nothing wrong with this material, there is a lot of it out there.

Cheers.

[frnkeore]

I believe that those double angle valve relief pockets, are so that they will fit 23° & 20° (sbc/sbf) valve angles and locations.

[Walter R. Malik]

I believe that those double angle valve relief pockets, are so that they will fit 23° & 20° (sbc/sbf) valve angles and locations.

That makes sense for a "spec class" of racing.

[88bluestar]

In the past I had used a Sealed Power 140CL piston which was 464 grams, but I guess it was discontinued. It held up fine with 7,000 rpms roughly for a full season(25 race nights) with pretty much similar rules. I honestly just want to be competitive but not break the bank.

[88bluestar]

Albeit I'm using a 5.7 rod so the 140 cl wont work in this case.

[Mark O'Neal]

Multiple valve notches are there so that same piston, (with slightly offset wrist pins), can be used on either side of a "V" type engine.

Offset is what, .060? Why do you need multiple reliefs, 3/8ths of an inch, apart for that?

The answer is that you do not.

You do ... if you are trying to keep the pin offset to one side of the engine and still have the same Valve to Piston clearance.
Pin offset is probably what you could do without.
However, NVH from the O.E.M. manufactures say you also need that offset for quieter cold running.

That is nonsense. the offset is only .060. You don't need to eat near that many ccs.

Dumb solution to a simple problem.