Twins with Twins, Anyone?

kidturbo

Piston Tester
Jul 21, 2010
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Day 2 at UCC, and my engine is still together.. Which makes me feel like a big winner...

Most respect for all these competitors. And special shout out to the FirePunk crew who's been graciously loaning me their forklift to unload and reload this engine every day. I've Been trying hard to convert them from the dark side. But after laying down a 7.88, I can see it's gonna require a lot more rum than I brought with me...

Nice to meet all the members who've stopped by to say hello. Tomorrow I'm packing up and heading home about 900lbs lighter. Next time you see this engine, it will be spinning and grinning.
 

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kidturbo

Piston Tester
Jul 21, 2010
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Wrapping up the Borg Warner marine transmission pattern to dyno driveshaft adapter on engine # 2 this week.

Bearing hub assembly is done. Just waiting for our 4130 shaft with EDM splines being cut by a shop in Michigan. Then that piece gets keyed, pressed, and welded into a 1" thick 10" dia chunk of 4150 that contains the 8 bolt pattern for Danville's dyno driveshaft. Last is balance that rotating assembly, and press everything into double roller carrier bearings.

Expensive little adapter project, which I hope to justify someday...
 

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kidturbo

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Jul 21, 2010
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Anyone have first hand experience hardening 4130 Normalized?

Had the splines cut, then double keyed this output shaft of the dyno adapter assembly. Think it should be hardened before this piece gets pressed into the 4150 driveshaft hub.

Youtube has a few examples, but I prefer comments with real world experience.
 

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2004LB7

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Dec 15, 2010
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Norcal
Is there any reason you choose 4130 vs a more robust option such as 4340?

I don't have any first hand experience with it but the treatment seams to be very close to plan carbon steels which I've done.

Do you have any idea what RC hardness you are looking for?
 

kidturbo

Piston Tester
Jul 21, 2010
2,539
1,377
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Somewhere On The Ohio
www.marinemods.us
Is there any reason you choose 4130 vs a more robust option such as 4340?

I don't have any first hand experience with it but the treatment seams to be very close to plan carbon steels which I've done.

Do you have any idea what RC hardness you are looking for?

Piece of 4130 is best I could come up with on short notice. No real idea on hardness. Since I don't expect it to take any hard hits on the dyno, goal is just harden those splines.