4.8L build to 366 c.i.
Apr 25, 2008 | 04:22 PM
#61
TECH Enthusiast
Joined: Aug 2005
Posts: 526
Likes: 0
From: Chandler, Arizona
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?
"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?
Apr 28, 2008 | 01:13 PM
#65
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 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
Apr 28, 2008 | 02:54 PM
#66
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 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
Jun 28, 2008 | 09:10 PM
#69
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
Mar 22, 2025 | 07:21 PM
#70
Registered User
Joined: Mar 2025
Posts: 1
Likes: 0
Boat anchor
Why would the block be weaker compared to a 6.0L? In my mind, when I think about the bore centerline on the 6.0L compared to that of the 4.8L/5.3L, I think it has potential to be stronger if left at a relatively stock bore (3.780"). Last time I checked people couldn't bore the 6.0L much without having to worry about having thin cylinder wall thicknesses. I know the 6.0L is tried and true. My brother has one in his truck, and I have wanted to do the same since we did his swap. But since I thought up this build, it looks like it would work just as good as doing a built 6.0L lq4/lq9 (in stock displacement). I'm not looking to build some big cubic inch engine... But for the money, I think it would be worth the effort of trying something different, especially when I know it will work. I don't have any doubts that this engine will be any weaker then a 6.0L... and who knows, it might be something new people start building if it make nice numbers. Worst case scenario, I lose 500-1000 on the block work/pistons, and end up taking the crank/connectings rods and putting them into a lq4 block and buying a new set of pistons and would have a 408. I know these engines are strong, there is a guy running a stock 5.3L at 18psi making over 700 rwhp with a twin turbo setup. The kind of numbers he's making is what I'm looking for, but with a little more reliability from the engine.
