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Piston help #681024 04/26/10 07:15 PM 04/26/10 07:15 PM
Joined: Oct 2007 Posts: 846 Illinois moparmattkos OP mopar addict
moparmattkos OP mopar addict Joined: Oct 2007 Posts: 846 Illinois	Ok guys I am looking for some 400 big block pistons. I am searchin for stock stroke , dish ,forged with the .990 size pin. Any ideas? I scored a great deal on a stock stroke eagle crank and a set of 6.385 eagle h beam rods and i want to stick some pistons together for a low compression turbo motor. I need like 8.5 or 9 to 1 with 75cc heads. www.sikosracing.net Heads up Drag racing

Re: Piston help [Re: moparmattkos] #681025 04/26/10 07:58 PM 04/26/10 07:58 PM
Joined: Oct 2007 Posts: 846 Illinois moparmattkos OP mopar addict
moparmattkos OP mopar addict Joined: Oct 2007 Posts: 846 Illinois	I found these pistons and the add says stock stroke 400 but it also says 3.75 stroke.??? It also doesnt mention rod length??? http://www.hughesengines.com/Index/produ...mp;partid=23785 www.sikosracing.net Heads up Drag racing

Re: Piston help [Re: moparmattkos] #681026 04/26/10 08:37 PM 04/26/10 08:37 PM
Joined: May 2008 Posts: 5,399 Aurora, Colorado 451Mopar master
451Mopar master Joined: May 2008 Posts: 5,399 Aurora, Colorado	Check the compression distance. The Diamond piston you linked to has a 1.32" CD, This would be for the 3.75" stroke 6.768" rod engine. FWIW, those pistons in a stock stroke / rod 400 with would have the piston sitting 0.612" below the deck, and with 84 cc heads new a whole 4.24:1 compression ratio. Depending on the head volume you are using, stock flat top 400 pistons are already a low compression design. The stock replacement flat tops have a compression height of 1.812" and the piston sits 0.120" below the deck at TDC. with 84 cc heads and 0.040" head gasket the compression ratio is 7.75:1. For the stock stroke/rod combination there is not much of a selection of off the shelf pistons. For what you are doing, you will likely need to order custom pistons.

Re: Piston help [Re: 451Mopar] #681027 04/27/10 08:37 AM 04/27/10 08:37 AM
Joined: Mar 2008 Posts: 5,746 Ontario, Canada Dodgem master
Dodgem master Joined: Mar 2008 Posts: 5,746 Ontario, Canada	You best bet would be to go to diamond pistons and have a custom piston made they are real reasonable about the same price as their good forged shelf pistons http://www.diamondracing.net/

Re: Piston help [Re: 451Mopar] #681028 04/27/10 05:55 PM 04/27/10 05:55 PM
Joined: Oct 2007 Posts: 846 Illinois moparmattkos OP mopar addict
moparmattkos OP mopar addict Joined: Oct 2007 Posts: 846 Illinois	Quote: Check the compression distance. The Diamond piston you linked to has a 1.32" CD, This would be for the 3.75" stroke 6.768" rod engine. FWIW, those pistons in a stock stroke / rod 400 with would have the piston sitting 0.612" below the deck, and with 84 cc heads new a whole 4.24:1 compression ratio. Depending on the head volume you are using, stock flat top 400 pistons are already a low compression design. The stock replacement flat tops have a compression height of 1.812" and the piston sits 0.120" below the deck at TDC. with 84 cc heads and 0.040" head gasket the compression ratio is 7.75:1. For the stock stroke/rod combination there is not much of a selection of off the shelf pistons. For what you are doing, you will likely need to order custom pistons. I have 72cc indy big ez's full cnc heads and i need low compression forged pistons for a turbo appication. I would ideally like to have 8.5 to 1 www.sikosracing.net Heads up Drag racing

Re: Piston help [Re: moparmattkos] #681029 04/27/10 06:06 PM 04/27/10 06:06 PM
Joined: May 2008 Posts: 1,238 North Cackilacky S sdaurity pro stock
sdaurity pro stock S Joined: May 2008 Posts: 1,238 North Cackilacky	Quote: Quote: Check the compression distance. The Diamond piston you linked to has a 1.32" CD, This would be for the 3.75" stroke 6.768" rod engine. FWIW, those pistons in a stock stroke / rod 400 with would have the piston sitting 0.612" below the deck, and with 84 cc heads new a whole 4.24:1 compression ratio. Depending on the head volume you are using, stock flat top 400 pistons are already a low compression design. The stock replacement flat tops have a compression height of 1.812" and the piston sits 0.120" below the deck at TDC. with 84 cc heads and 0.040" head gasket the compression ratio is 7.75:1. For the stock stroke/rod combination there is not much of a selection of off the shelf pistons. For what you are doing, you will likely need to order custom pistons. I have 72cc indy big ez's full cnc heads and i need low compression forged pistons for a turbo appication. I would ideally like to have 8.5 to 1 The pistons would prob have to be custom but do you realize how much those pistons would weigh and how tall of a compression height they would be, and then put them boat anchor pistons under a nice set of big ez's not a good idea in my opinion. I would sell your rods and find you some 440 length rods with a .990 pin and use the pistons you posted up top. One day I will have something cool here.

Re: Piston help [Re: sdaurity] #681030 04/27/10 06:09 PM 04/27/10 06:09 PM
Joined: Oct 2007 Posts: 846 Illinois moparmattkos OP mopar addict
moparmattkos OP mopar addict Joined: Oct 2007 Posts: 846 Illinois	The pistons up top are 10.5 to 1 at 72cc i need 8 to 8.5 to 1 compression. www.sikosracing.net Heads up Drag racing

Re: Piston help [Re: moparmattkos] #681031 04/28/10 08:08 AM 04/28/10 08:08 AM
Joined: May 2008 Posts: 1,238 North Cackilacky S sdaurity pro stock
sdaurity pro stock S Joined: May 2008 Posts: 1,238 North Cackilacky	well you need to call your favorite piston company and place a custom order. One day I will have something cool here.

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