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Old Nov 30, 2009 | 11:43 PM
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Fast 95 Z28's Avatar
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Default Need help with engine build

First off i've been doing a lot of research. So far I have decided to go with a FAST 90/90, a tsp228r cam on a 112 asa, and some PRC Stage 2.5 LS6 heads milled down to give me a 11:1 compression ratio. Stock cubes. It will be run through a M6. My goals with the car are 425rwhp and to still get decent gas mileage while cruising, because this is my daily driver. And hopefully be somewhere in the 11's. My questions with this build are the following. 1. What size header should I run, 1 7/8''s or 1 3/4"s? 2. What size pushrod will I have to run with a milled down LS6 head? 3. Will I have to flycut the pistons with the 2.02/1.57 valves? 4. Will I be safe running a 11:1 compression ratio on a street car on 91 octane? The reason I want the higher compression is because it will help with torque as well as gas mileage.

Any help is appreciated!
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Old Dec 1, 2009 | 09:18 AM
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From: FredVegas, Va
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Its 112 LSA, not asa...for future reference.

On a stock cube LS1 the 1-3/4" headers are fine.

Whoever you get the heads from should be able to tell you the PR length you need although buying a length checker and checking yourself would be ideal.

From what I remember, the lift on the newer 228R cam is pretty stout (over .600) and it may not clear depending on your cc size and headgasket thickness your going to use.

You can probably squeek by on 91 octane but the timing is going to have to stay lower than normal being that you should really have 93 and with the shitty gas/ethanol blend these days.

Hope this helps
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Old Dec 1, 2009 | 02:32 PM
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Originally Posted by TooLateVTEC
Its 112 LSA, not asa...for future reference.

On a stock cube LS1 the 1-3/4" headers are fine.

Whoever you get the heads from should be able to tell you the PR length you need although buying a length checker and checking yourself would be ideal.

From what I remember, the lift on the newer 228R cam is pretty stout (over .600) and it may not clear depending on your cc size and headgasket thickness your going to use.

You can probably squeek by on 91 octane but the timing is going to have to stay lower than normal being that you should really have 93 and with the shitty gas/ethanol blend these days.

Hope this helps
I'm planning on buying the heads from texas speed. The specs on the cam are 228/228 .588/.588 112 LSA and I would run 93 octane if California had it. All I have access to is 91 octane. And will the 2.02/1.57 valves clear the stock LS1 bore?
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Old Dec 1, 2009 | 03:04 PM
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From: FredVegas, Va
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AFAIK they will, b/c my heads have 2.00 intake valve in it and clear fine.

TSP should be able to tell you what length PR's you need b/c theyll know how much is coming off the head and how thick the gasket is, etc.
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Old Dec 1, 2009 | 03:35 PM
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Originally Posted by Fast 95 Z28
I'm planning on buying the heads from texas speed. The specs on the cam are 228/228 .588/.588 112 LSA and I would run 93 octane if California had it. All I have access to is 91 octane. And will the 2.02/1.57 valves clear the stock LS1 bore?
TSP can give you better info than somebody guessing your clearance for you. TSP can also sink your valves deeper into the heads your planning on buying from them giving you addditional clearance. How much? You'll have to call them or maybe Jason or Jon will respond.
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Old Dec 2, 2009 | 11:40 PM
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bump bump
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Old Dec 3, 2009 | 09:57 AM
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From: Turnin' Wrenches Infractions: 005
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Questionable about valve clearance, measure. Unsure for any reason about pushrod length, measure. To run elevens you will likely need a good rear end, sticky tires, driveshaft, and rear suspension.
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