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compression for a twin turbo 427ci 6 bolt LSX build

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Old 12-05-2016, 10:39 AM
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Default E Content of E-85

OK, a fair request.
He stated that his requirement was 12:1 and the heads where not yet received, just ordered.
I too would use a flat top piston of possible AND fit "piston oil jets" from the block main area.

The "range" of compression choices IS affected by "local" E-85, the "E" content.

That is the main reason for a direction to try and find E-95 a more regulated fuel.

I agree, it is a "bit" of stretch.

Lance
Old 12-06-2016, 06:11 PM
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Heads came in. Goodness these things are sexy in person.
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Old 12-06-2016, 11:19 PM
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Thanks for the explanation, Lance. I agree that a more regulated/consistent fuel would be greatly beneficial to an effort such as this. And if he was using E95 for this, I would say 12:1 compression would probably be optimal, which sounds insane when considering twin turbos. Either way, definitely going to need a custom cam to keep the dynamic compression in check.

RonStoppable, those heads do look nice. This thing is going to be a freaking beast. I hope you have an adjustable suspension and the full compliment of traction goodies, because upwards of 1000+rwhp is going to roast those 275's right off the rims.
Old 12-17-2016, 11:06 AM
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Feels good to get everything mocked up!
Old 12-17-2016, 12:20 PM
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Bad *** man! Cant wait to see it running.
Old 12-17-2016, 01:28 PM
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Hell yeah.
Old 12-17-2016, 02:11 PM
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12:1 is insane.. IMO unnecessary but not my car. I see where you decided on 10.8. Much better choice. My buddy's Vette (9.5:1 427 LSX block twin precision 66/67's made 1097 on 9lbs with only 15* on E98) hell the motor can probably hold 40lbs.. a lot of power being thrown around these days.

Last edited by oscs; 12-17-2016 at 02:17 PM.
Old 12-17-2016, 02:15 PM
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Originally Posted by alocker
One thing to consider, no matter how good it performs down low it's gonna feel like a pig compared to when it's in boost. Just the nature of a turbo car. I say the happy medium would be 11-1 which should be pretty snappy out of boost. I wouldn't give up that safety net for the small gains above that.
"Pig" "nature of turbo car" it's a 427 not a 4.8l junk yard motor.
Old 12-17-2016, 05:56 PM
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I'm around 9.7-1 on a 427 Dart ls next single turbo. Thing makes 650hp na not a slug at all.
Old 12-18-2016, 05:20 AM
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Originally Posted by oscs
"Pig" "nature of turbo car" it's a 427 not a 4.8l junk yard motor.
I always laugh when people say about being a turd or pig etc low down.

What ******* drugs are these people on !! These arent 2.0 4cyl engines or smaller lol
Old 12-18-2016, 01:20 PM
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Originally Posted by stevieturbo
I always laugh when people say about being a turd or pig etc low down.

What ******* drugs are these people on !! These arent 2.0 4cyl engines or smaller lol
You can't do anything but laugh.
Old 12-18-2016, 02:13 PM
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I didn't mean to upset you guys. My point was zero PSI feels like a pig versus 20 PSI on pretty much anything.
Old 12-18-2016, 02:20 PM
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Originally Posted by Ron_Stoppable
Feels good to get everything mocked up!
That is a sick looking setup! Are those Ebay headers with the CX racing 90's on them? If so they worked really well with my twin 66 setup in the Camaro.
Old 12-18-2016, 02:33 PM
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eBay manifolds FTW
Old 12-20-2016, 11:32 AM
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Originally Posted by hellbents10
fuel type and camshaft should be considered when picking a static compression ratio.

thank you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Old 12-24-2016, 03:51 PM
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So I got two cams specd out.. what do you guys think as far as the specs go?
240/243. .608"/.612" 114 LSA
Or
243/249. .610"/612". 114 LSA

also any recommendations for lifters? Wasn't sure if I should go with Johnson Linkbar lifters or not
Old 12-24-2016, 06:54 PM
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Jesel .937 tie bars
Old 01-14-2017, 10:08 PM
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Should've just made a build thread lol
a few pics of my cable drive fuel setup, all from AEI. I also have a badass nice tubular core support, Griffin radiator already has the fittings welded up for the Remote electric waterpump. Truck will also be getting 4-linked aswell haha after a lot of thinking
powdercoated the Upper HOLLEY plenum aswell 😎











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