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| Custom low compression CP pistons https://slantsix.org/forum/viewtopic.php?t=45566 |
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| Author: | pinkiedog64 [ Sat Jul 09, 2011 8:31 pm ] |
| Post subject: | Custom low compression CP pistons |
Hello all, I have not been around here in a while but am getting back into working on the slant. Here's the deal: moderately built NA 225 ('64 block .030 over, surfaced, ported head, head milled .100", big valves, 340 springs, ARP rod bolts, balanced rods and cast pistons, double roller chain, .465 lift 280 deg cam, Clifford ceramic coated headers, Offenhauser 4 bbl intake, Edelbrock 500, 4" 4 hole carb spacer, HV oil pump, Accel HEI module, Magnecor wires, MSD blaster coil, Mopar electronic dizzy) in my '64 D100. Bought a '68 383 B block to turbocharge and put in the truck. Am headed to Dallas next weekend to pick up a '60 Valiant. Going to pull the fresh 225 out of the truck, turbocharge, and install in the Valiant. I have a quite a bit of work and money invested in the current 225 head and would like to use it on the turbo Valiant, the only problem is that it has been milled .100" for higher compression on the original build. Question: Would it be better/less expensive to order custom low compression (8-8.5:1) pistons from CP or to build up another head with less shaved off for lower compression? I would imagine CP could make up a set that had the wrist pin set higher on the piston without too much trouble. Any advice is appreciated. Thanks, Stephan |
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| Author: | 805moparkid [ Sat Jul 09, 2011 8:45 pm ] |
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well depending on how much porting was done to the head it could be fine... if you have alot of hours or money into some else porting it then figure out another way but if its just a couple hundred bucks go for it... |
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| Author: | ceej [ Sat Jul 09, 2011 9:22 pm ] |
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A core head and a couple Benjamins. Your there. Pistons, not likely. Gonna want forged. How much boost? What did your compression come out at? With hi-test, and moderate boost, 9 or 10 to 1 is do-able. Your tune has to be right on the money though. CJ |
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| Author: | Joshie225 [ Sat Jul 09, 2011 10:03 pm ] |
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I would keep this head and run a thick copper head gasket. |
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| Author: | pinkiedog64 [ Sun Jul 10, 2011 8:22 pm ] |
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CR by calculation with a measured chamber volume of 45cc (milled .100") with a .183" deck height comes out to be 9.17:1. I would like to run as high as 20 psi gage. I know that's quite a lot and will require thorough prep work on the short block to be able to hold up. CP's slant six pistons are forged and should be good for turbo use but the ones listed on the website (http://www.campbellenterprises.com/slan ... istons.php) already have CR in the 10-10.5:1 range and that is calculated at a 54cc chamber so putting those pistons in an engine with a 45cc chamber would yield a higher CR. I will do the numbers tomorrow on what compression height pistons I would need for no more than 9:1 with the 7.005 center:center K1 rods. While I might regret it later, I am not afraid or shying away from the idea of using race gas in the motor. |
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| Author: | Joshie225 [ Sun Jul 10, 2011 8:39 pm ] |
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Is this a street car? If so I wouldn't run race gas unless you never take it out of town and you have space to store a 55 gallon drum of fuel. With that much boost I think you're going to want an o-ringed copper gasket anyway and it's not hard to get a thick copper gasket to drop the compression ratio. Do you already have pistons? |
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| Author: | pinkiedog64 [ Sun Jul 10, 2011 8:59 pm ] |
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It will mostly be a non-street car (with ability to store a 55 gallon drum). Yes, I am planning on having the block and head grooved for o-rings. I do not have the pistons yet, which is why I am trying to figure out exactly what I want/need before I purchase them. Unless the numbers I do tomorrow happen to magical, I'm guessing they will have to be custom compression height. |
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| Author: | Shaker223 [ Mon Jul 11, 2011 7:07 am ] |
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Go with the copper head gasket (Hussy). They can make just about any thickness you need. There was a group buy a while back. |
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| Author: | Rug_Trucker [ Mon Jul 11, 2011 5:08 pm ] |
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Instead of race gas why not E-85??? Cheaper, at the pump, and IIRC 14:1-15:1 N/A? It is high octane, low BTU's. |
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| Author: | 805moparkid [ Mon Jul 11, 2011 9:20 pm ] |
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Quote: Instead of race gas why not E-85??? Cheaper, at the pump, and IIRC 14:1-15:1 N/A? It is high octane, low BTU's.
most people wont because if its inconsistency... some times its alot of ethanol and sometimes not...
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| Author: | pinkiedog64 [ Mon Jul 11, 2011 9:28 pm ] |
| Post subject: | |
I am definitely thinking about setting up the system for E85 or methanol, or if nothing else running methanol injection. Plenty to think about and research. I ran the numbers and to get a CR of 9:1 with the K1 7.005" long rods, piston volume of 6cc (that's what the Wiseco forged pistons have for a piston volume), 4.125" stroke, and .050" (semi arbitrary) thick head gasket I need a piston compression height of 1.484" which is not terribly shorter than the Wiseco forged piston's compression height of 1.625". I will call them in the next day or two to see how much they will charge for a set of forged pistons with a 6cc volume and a compression height of 1.484". Hopefully the damage will not be too bad... |
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| Author: | Rug_Trucker [ Tue Jul 12, 2011 5:35 am ] |
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Quote: Quote: Instead of race gas why not E-85??? Cheaper, at the pump, and IIRC 14:1-15:1 N/A? It is high octane, low BTU's.
most people wont because if its inconsistency... some times its alot of ethanol and sometimes not...You watch the moonshine go in first, then the gas. Little windows on the hook ups going into the tank. BP has injectors that adjust the blend as you load. One company here might load straight ethanol. That is Mapco. That is only at one loading terminal. I can ask. |
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