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4.8L build to 366 c.i.

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Old 04-25-2008, 04:22 PM
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The guys at tsp told me the 383 on a 4.8l couldnt be done.. This is what they said..
"Thanks for your inquiry. You will not be able to use your 4.8L block for this rotating assy. It uses a 3.905" bore, and your block would have to be bored well over .100"! This would not be good for your setup considering that you're looking to run two power-adders. You may consider a 370 cid iron-block short-block for your truck. This will be a very strong setup, and with an upgrade to an ARP 2000 rod bolt and using the Diamond Racing dished piston set it will make for a very strong setup. You can see the forged 370 cid short-blocks on our website at the link below:

It had a link there.. think they are tryin to get me to buy one of their set ups? or they tellin the truth.. And should i go with a 370 set up?
Old 04-25-2008, 04:30 PM
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tsp is full of ****.
you can bore out the 4.8 to 3.905 with a 4" crank so you can have your 383.
Old 04-25-2008, 05:23 PM
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Old 04-25-2008, 05:49 PM
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asholes.. just tryin to get me to buy on of their 370s.. Well ill let u know how the build is going.. i found an assembly for the block.. now some heads.. i was thinkin ported 6.0l heads
Old 04-28-2008, 01:13 PM
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Does the 4.8l and the 5.3l share the same piston? If your going to boost it big time, you could bore the 4.8l block out to 5.7l bore, but some LS1 forged pistons (stock bore) and run the 4.8l crank and rods (with ARP Rod bolts). I think that would give you a RPM happy shortblock that may still return some decent mileage.

I have thought about building that combo but at 10:1 compression and then boost it 15-16 lbs. It would need a ton of Meth under boost to control detonation but the 10:1 would make it efficient without boost. The 10:1 would keep the torque up without boost. I have read that the Turbo Buick guys build a lot of high Compression shortblock and run crazy boost numbers. It would be cool to have a truck with 500-550 RWHP and still return 18-20 MPG.

Rick
Old 04-28-2008, 02:54 PM
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Originally Posted by Rick_Vor
Does the 4.8l and the 5.3l share the same piston? If your going to boost it big time, you could bore the 4.8l block out to 5.7l bore, but some LS1 forged pistons (stock bore) and run the 4.8l crank and rods (with ARP Rod bolts). I think that would give you a RPM happy shortblock that may still return some decent mileage.

I have thought about building that combo but at 10:1 compression and then boost it 15-16 lbs. It would need a ton of Meth under boost to control detonation but the 10:1 would make it efficient without boost. The 10:1 would keep the torque up without boost. I have read that the Turbo Buick guys build a lot of high Compression shortblock and run crazy boost numbers. It would be cool to have a truck with 500-550 RWHP and still return 18-20 MPG.

Rick
I believe the compression height of the 5.3 and 4.8 piston are different since the crank and rod lengths are different.
Old 06-12-2008, 02:45 PM
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anyone have any updates? I have a 4.8L on my floor that needs something done to it now that my 6.0 is blown to pieces!!!
Old 06-12-2008, 06:00 PM
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The 4.8L piston is a flat top with around a 1.331" compression height.

The 5.3L piston is dished with the same compression height.
Old 06-28-2008, 09:10 PM
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compression height the same, weights are different. rod length makes up the difference of the stroke. go ahead and bore it out and stroke it to 383. with moderate boost and juice, the motor will be the least of your worries. have fun with it no matter what you decide
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