NA only light wieght pistons for a Coyote?

[twistedneck]

I am looking for a set of pistons specific for NA, 12.5:1, 2618 alloy.. everything I see on the shelf including the Mahle pistons has a big ring stack, a lot of extra thickness at the top ring land, and a tall skirt.

If I am going to build for NA, I want something that takes advantage of it and is light as hell and looks like a Cup car piston - flat, short, and good for NA - horrible for FI. thinking weight on the order of 300g for a bare piston.

Anyone know if Manley or one of the typical vendors has these for a Coyote engine?

Here is an example of Nascar type piston, with the super light weight thin wall and low friction design you see on a cup NA only engine.. i'll be keeping my one piston jet to help these stay cool. wish I had more.

http://cdn1.bigcommerce.com/server2...mages/156/014__97781.1291841753.1280.1280.JPG

http://galleryplus.ebayimg.com/ws/web/370573627740_1_0_1/1000x1000.jpg

http://www.k20a.org/uploadnew/formulaone/Piston_Minardi_1.jpg

http://www.auto123.com/en/multimedi...mula-1-engine?bid=116952&binding=3#pg=p_8_n_a

Goal is lower inertia and less friction, quicker acceleration.

 

[Dizzyscure1]

op:

 

[pufferfish]

Cup pistons mean cup rebuild schedule. There's a hell of a lot of dynamic forces in high rpm NA too!

That said, take a look at K1. They came out with a Swiss cheesed skirt piston a few years ago. Maybe they have an offering for coyotes?

 

[pufferfish]

Sorry, it's wiseco pistons that teamed up with k1 cranks and rods to make the 351 stroker coyote.

 

[twistedneck]

I will email Wiseco / k1. I know the world challenge guys are force to use a spec. Engine so they don't benefit from a wicked light piston. But we sure could! Stock gt I use is already lighter than boss by over 40g, I think more. Combine w stock light rods and I've got a taste of the light weight less than 1kgf rotating assembly.

The Capricorn pistons are works of art also, with asymmetric skirts and box bridge short pin design.

Was hoping Manley or Diamond, one of the big Mustang producers had something. The circle track guys have not started using coyotes yet or we would have a selection of these to choose from.

Anyone know if we can add a second oil jet to the piston underside? I'm also looking to add a jet to the finger follower and spring area. But that's a pipe dream.

 

[pufferfish]

I weighed the gt rod/piston ring compared to the boss equivilant and it was 39 grams more on each boss assembly, so that's 321 more grams swinging around...not an insignificant number. If you can get the forged strength with gt weight, it would be great for winding the engine up!

As for piston cooling jets, I would go the opposite route (none). That's extra windage, which reduces the free-revving nature you are looking for. There's a reason the boss engines go without them.

 

[twistedneck]

I weighed the gt rod/piston ring compared to the boss equivilant and it was 39 grams more on each boss assembly, so that's 321 more grams swinging around...not an insignificant number. If you can get the forged strength with gt weight, it would be great for winding the engine up!

As for piston cooling jets, I would go the opposite route (none). That's extra windage, which reduces the free-revving nature you are looking for. There's a reason the boss engines go without them.

Agree on everything except the jets.. I love them. NASCAR uses at least 4 per cylinder.. F1, up to 18 per cylinder. They are necessary w those thin wall pistons. Next argument is , those engies use a dry sump w compartmentalized crank case
. And they do, but the jet windage us only from actual jet on piston losses, and pressure drop on the jet.. W a thick piston we don't need jets but these insane paper thin pistons need.

 

[pufferfish]

Good points...just comes back to the fact that your reference engines get torn down after every race. That in your plan?

 

[twistedneck]

Good points...just comes back to the fact that your reference engines get torn down after every race. That in your plan?

No, once per season is my rebuild plan for preventive maintenance and inspection. Current cup engines can handle up to 3000 miles w just an inspection between races to catch any big fails. If I keep the ring types and thickness within reason, get the ring lands coated w something, use e85 to keep temps down, pcv system, and don't run at the edge of knock it should last at least 10,000 street miles between inspections.

If I sustain 8000+ rpm for a longer time like at a Texas mile thing or extensive road racing then probably would bore scope the chambers and inspect the springs.

What are you referring to specifically ? Maybe I can get a less race work around for that.