piston for high rpm

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Straight8
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piston for high rpm

Post by Straight8 » Sun Oct 22, 2017 2:06 pm

What qualities would you look for in a max effort 4.6 bore piston looking at 8800-9000rpm.small inch pulling class with 3.6 stroke with long rods.

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Re: piston for high rpm

Post by MTENGINES » Sun Oct 22, 2017 3:47 pm

Straight8 wrote:
Sun Oct 22, 2017 2:06 pm
What qualities would you look for in a max effort 4.6 bore piston looking at 8800-9000rpm.small inch pulling class with 3.6 stroke with long rods.
pin bore shape and size. how flat the ring grooves have been machined. amount of gas ports vertical and horizontal, skirt shape. What the need for long rods? using a std deck height block would be a good start. i'd still want a shorter deck height.

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Re: piston for high rpm

Post by Mark O'Neal » Sun Oct 22, 2017 3:50 pm

That is not near enough information to answer your question.

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Re: piston for high rpm

Post by engineguyBill » Sun Oct 22, 2017 3:57 pm

Big bore, short stroke, long rod combination is great for high RPM power output. Any of the major piston suppliers can supply sturdy, light weight pistons for this combo. Follow the piston manufacturer's recommendations on the pins, my preference for pistons is CP-CARRILLO. 1.2mm, 1.2mm, 3.0mm ring package will work fine for this engine, along with stainless steel, gas nitrided top ring; cast iron Napier second ring and low tension oil ring assembly; vertical gas ports are the best choice, as well.
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Re: piston for high rpm

Post by Straight8 » Sun Oct 22, 2017 4:15 pm

Mark O'Neal wrote:
Sun Oct 22, 2017 3:50 pm
That is not near enough information to answer your question.
Elaborate on what you need to know and I'll try and fill in the blanks.

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Re: piston for high rpm

Post by Straight8 » Sun Oct 22, 2017 4:18 pm

MTENGINES wrote:
Sun Oct 22, 2017 3:47 pm
Straight8 wrote:
Sun Oct 22, 2017 2:06 pm
What qualities would you look for in a max effort 4.6 bore piston looking at 8800-9000rpm.small inch pulling class with 3.6 stroke with long rods.
pin bore shape and size. how flat the ring grooves have been machined. amount of gas ports vertical and horizontal, skirt shape. What the need for long rods? using a std deck height block would be a good start. i'd still want a shorter deck height.
10.3 deck with short 3.6 stroke kinda puts me in that situation.

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Re: piston for high rpm

Post by MTENGINES » Sun Oct 22, 2017 6:11 pm

engineguyBill wrote:
Sun Oct 22, 2017 3:57 pm
Big bore, short stroke, long rod combination is great for high RPM power output. Any of the major piston suppliers can supply sturdy, light weight pistons for this combo. Follow the piston manufacturer's recommendations on the pins, my preference for pistons is CP-CARRILLO. 1.2mm, 1.2mm, 3.0mm ring package will work fine for this engine, along with stainless steel, gas nitrided top ring; cast iron Napier second ring and low tension oil ring assembly; vertical gas ports are the best choice, as well.

Why such huge rings? If they are custom pistons, why not go .8 or.7mm

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Re: piston for high rpm

Post by piston guy » Mon Oct 23, 2017 3:55 pm

I'm guessing this is a BBFord. A 7.100 will give a 1.400 C/H. The short stroke makes weight a little less "critical" due to the lesser inertia from the short stroke / long rod. If you are going to use a longer rod , piston stability "could " come into play.

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Re: piston for high rpm

Post by engineguyBill » Mon Oct 23, 2017 6:38 pm

MTENGINES wrote:
Sun Oct 22, 2017 6:11 pm
engineguyBill wrote:
Sun Oct 22, 2017 3:57 pm
Big bore, short stroke, long rod combination is great for high RPM power output. Any of the major piston suppliers can supply sturdy, light weight pistons for this combo. Follow the piston manufacturer's recommendations on the pins, my preference for pistons is CP-CARRILLO. 1.2mm, 1.2mm, 3.0mm ring package will work fine for this engine, along with stainless steel, gas nitrided top ring; cast iron Napier second ring and low tension oil ring assembly; vertical gas ports are the best choice, as well.

Why such huge rings? If they are custom pistons, why not go .8 or.7mm
1.2mm, 1.2mm. 3.0mm ring package will work very well for your application; possibly 1.0mm, 1.0mm, 2.0mm too, but you won't realize much if any gain in going to the very thin ring widths such as 0.7mm or 0.8mm. (ten years ago I would have recommended 0.043", 0.043", 3.0mm ring package, but just about everyone has gone to metric widths these days . . . . . .)
Bill

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Re: piston for high rpm

Post by Straight8 » Mon Oct 23, 2017 7:46 pm

piston guy wrote:
Mon Oct 23, 2017 3:55 pm
I'm guessing this is a BBFord. A 7.100 will give a 1.400 C/H. The short stroke makes weight a little less "critical" due to the lesser inertia from the short stroke / long rod. If you are going to use a longer rod , piston stability "could " come into play.
You're right it's a BBF. The rods I have are 7.250 olivers but I'm not opposed to going another direction but really don't care for aluminum. These have a .927 pin also and thats another concern. It's nothing special,tfs A460 heads ,Motorsport block,dry sump, etc...tfs new style intake with 1450 QF. Crank is a factory steel 429 with 2.2 rods.

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Re: piston for high rpm

Post by piston guy » Tue Oct 24, 2017 11:29 am

The 927 pin is small for sure , not my first choice. I would use a 2.950 length and .180 ( or thicker) wall pin. A light weight pin in this situation WILL fail , guaranteed. Plus the pin flex will cost you HP. The 1.250 c/h will reduce piston weight , yet still provide enough space for adequate ring land spacing , especially with thin rings.

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Re: piston for high rpm

Post by Straight8 » Tue Oct 24, 2017 8:04 pm

Thanks for the input,I'll keep all this in mind when I decide who to go with. :D

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Re: piston for high rpm

Post by Mark O'Neal » Wed Oct 25, 2017 3:10 am

Is there any way to come up with a 10.000 aftermarket block?

It's a lot of RPM, but it's a puller. Running components that are too light will hurt, it would seem to me. You want to store all the energy you can to help you at the end of the pull.

There is nothing wrong with the rods you have, they'll move a lot of weight off the piston and move it toward the crankshaft.

Dome, dish, or flat?

I'll only complain about the pin when I know how much compression you're running. What wall pins have you been running?

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Re: piston for high rpm

Post by Straight8 » Wed Oct 25, 2017 9:32 am

Mark O'Neal wrote:
Wed Oct 25, 2017 3:10 am
Is there any way to come up with a 10.000 aftermarket block?

It's a lot of RPM, but it's a puller. Running components that are too light will hurt, it would seem to me. You want to store all the energy you can to help you at the end of the pull.

There is nothing wrong with the rods you have, they'll move a lot of weight off the piston and move it toward the crankshaft.

Dome, dish, or flat?

I'll only complain about the pin when I know how much compression you're running. What wall pins have you been running?
Would a block .300 shorter deck really be a big plus? I know that would lighten the rod a little but I've been involved with the BBC crowd where the tall deck has ran successfully with short deck stuff. Personally I haven't had an engine operated at this kind of rpm,8000 or so with bigger cid and never ran a small .927 pin. I would " think" that pin in a little thicker wall would be ok even for high rpm NA deal,but that's why I'm asking. :D it's gona need all the dome I can get with that short stroke for hopefully 14.1 or more.

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Re: piston for high rpm

Post by stealth » Wed Oct 25, 2017 4:43 pm

Straight8 wrote:
Sun Oct 22, 2017 2:06 pm
What qualities would you look for in a max effort 4.6 bore piston looking at 8800-9000rpm.small inch pulling class with 3.6 stroke with long rods.
Look at NASCAR pistons & rods listed on eBay for inspiration...ro7, sb2.2., etc

They run 9000 rpm for hours....pretty sure the have a handle on design criteria to accomplish your request.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man.

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