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Are the Keith Black 2.2 pistons still a good choice?
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Author:  MazdaRX8/6 [ Fri Jun 12, 2026 1:23 pm ]
Post subject:  Are the Keith Black 2.2 pistons still a good choice?
I am building a street slant with Molnar 7.005 long rods. Are the Keith Black KB239 pistons still a good choice? They have wrist pin retainers for the full floating pin. My heads are 60cc, so this setup should give me 9.88:1. I'm using a bigger than stock Oregon regrind. It is port injected with a knock sensor. I don't mind using premium fuel.
Author:  Greg Ondayko [ Sat Jun 13, 2026 6:26 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Are those pistons cast or forged?

Do they have valve reliefs? (you likely will not need them) Is this an N/A engine or boosted / sprayed with nitrous?
Author:  MazdaRX8/6 [ Sat Jun 13, 2026 6:49 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
NA. No nitrous. Cast aluminum. Hypereutectic This my Mazda RX-8 that I have been working on for 4 years. Just a fun project. No racing. Just local parking lot car shows. Dutra Duals, Gill Welding port injection intake, Gill Welding exhaust, Haltech ECU, LS coils. Just something for me to inker with. I have a local engine builder building the engine. Boring to 3.445" 87.5 mm. Money is not a consideration. The KB239 plus the 7.005 rod gives me a zero deck. The modern pustons are lighter to rev a bit higher and have thinner rings for less friction.

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Author:  Charrlie_S [ Sat Jun 13, 2026 6:58 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Quote:
I am building a street slant with Molnar 7.005 long rods. Are the Keith Black KB239 pistons still a good choice? They have wrist pin retainers for the full floating pin. My heads are 60cc, so this setup should give me 9.88:1. I'm using a bigger than stock Oregon regrind. It is port injected with a knock sensor. I don't mind using premium fuel.
Why not use the Wiseco "forged" pistons Price is about the same when you consider the Wiseco pistons come with the rings, and the KB pistons do not come with rings. Granted with the KB's you will have two spare pistons.
https://www.campbellenterprises.com/sla ... istons.php
Author:  Rick Covalt [ Sat Jun 13, 2026 8:49 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Yes to what Charlie said. Forged pistons cover you for anything in the future too. Especially if money is not an issue.
Author:  Greg Ondayko [ Sat Jun 13, 2026 10:12 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Agree with Charrlie and Rick.
Author:  MazdaRX8/6 [ Sat Jun 13, 2026 7:17 pm ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
How bad do the forged pistons rattle when they are cold?
Author:  Charrlie_S [ Sun Jun 14, 2026 4:58 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
My opinion. If the engine is bored/honed to match each piston with the proper clearance, you might hear a slight rattle for a minute or two. But most time, with the exhaust noise and/or radio, you will not even hear it.
Author:  MazdaRX8/6 [ Sun Jun 14, 2026 5:28 pm ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Guys, thanks for the input. I'm going to go with the Keith Black pistons. I'm never going to boost or use nitrous. I want the car to be as quiet as possible. Everything I have been able to read says that cast is fine and Keith Black is a step up. My car will have a knock sensor, so I'm not worried about detonation. The car weighs 3,000 pounds. I don't think it will ever detonate.
Author:  Dart270 [ Mon Jun 15, 2026 1:48 pm ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Should work great. You can make plenty of power with cast pistons.

Lou
Author:  MazdaRX8/6 [ Tue Jun 16, 2026 8:13 pm ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Now if I could just get the machine shop to move.....
Author:  MazdaRX8/6 [ Tue Jun 23, 2026 5:24 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
I know the Mohlner rods and modern pistons are lighter than factory. Is there any noticeable increase in RPM because of that?
Author:  Dart270 [ Tue Jun 23, 2026 6:41 am ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Nope.
Author:  slantzilla [ Tue Jun 23, 2026 2:55 pm ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
Quote:
I know the Mohlner rods and modern pistons are lighter than factory. Is there any noticeable increase in RPM because of that?
The biggest thing I saw from the 2.2 piston/long rod was the motor loved nitrous.

Running N/A you won't see much difference.

The stock rod/cast piston motor in my Valiant would rev to 7000, but stopped making power around 6200ish so I shifted at 6300.

My long rod motor will also rev to 7000, but gets shifted at 6500 because it has a bigger header on it.

:mrgreen:
Author:  MazdaRX8/6 [ Mon Jul 13, 2026 5:37 pm ]
Post subject:  Re: Are the Keith Black 2.2 pistons still a good choice?
I guess I will find out what long rods plus KB pistons do. In a few months.
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