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Is this too much compression for 93 octane?

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Old Jan 24, 2007 | 04:56 PM
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Default Is this too much compression for 93 octane?

Dart 205's milled to 59CC,.040 Cometics,stock 346 shortblock = over 12.1CR?

Would u leave the heads alone and just run the 62CC with the .040 Cometics for 11.3CR?

Even with a small cam would the LSX intake help me?
Cam is 214-222-566-569 115+4...

Running threw shorties and HF cats (Thats why the big split)
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Old Jan 24, 2007 | 05:05 PM
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I think you definitely do not want to go 12:1 SCR and check your DCR - it's going to create more problems than you want with 93 octane.

I would say the LSX intake will be marginal but the head and port velocity/runner length guys will need to chime in.
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Old Jan 24, 2007 | 05:10 PM
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Originally Posted by JS
Dart 205's milled to 59CC,.040 Cometics,stock 346 shortblock = over 12.1CR?

Would u leave the heads alone and just run the 62CC with the .040 Cometics for 11.3CR?

Even with a small cam would the LSX intake help me?
Cam is 214-222-566-569 115+4...

Running threw shorties and HF cats (Thats why the big split)
I get 11.79:1 SCR for 59cc heads and .040 gaskets

I get 11.32:1 SCR for 62cc heads and .040 gaskets

And to the question of which one to use, it depends on the camshaft specs and what DCR you end up with.

Hammer
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Old Jan 24, 2007 | 05:13 PM
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I would check PTV on the .040 with 59cc heads, even with the small cam. If you dont have reliefs in the pistons PTV might be close.
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Old Jan 24, 2007 | 05:15 PM
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Yeah, what he said. I don't get 12.0:1. It's lower...closer to 11.7ish:1. Remember when calculating DCR that even XE-R lobes rarely get close to a 49 degree ramp rate. They're more like 50 or 51. This will make actual measured DCR lower than the "calculated" DCR.
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Old Jan 24, 2007 | 05:20 PM
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So IYO guys would u just stay with the 62CC and the .040 along with the LSX/90....or stick with the LS6/78TB or a ported LS2/90TB?
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Old Jan 24, 2007 | 08:41 PM
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I run 12:1 CR with no problems my DCR is around 8.8:1
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