HRM's 1200HP 4.8 LS
HRM's 1200HP 4.8 LS I've been watching HR put cheap ebay turbos on various engines lately, 5.3LS, some Ford V8 and a late hemi. Interesting reads with around 600HP but this month's dyno story was simply amazing.
The most amazing story I've read in HR, and I've been reading it since 1961.
A twin turbo 4.8 with minimal mods makes 1200HP, thats 4 HP per cubic inch.
The shortblock was stock except for increased ring gap on the reused STOCK rings and stock pistons. It did have a cam, ported heads, ARP head studs and a FAST intake and bigger throttle body.
They did use race gas, and very sharp tuning to prevent detonation, the killer of most turbo engines.
These are by far the most incredible numbers that I've even seen for a cast piston, pretty stock shortblock.
I'm wondering if using E85 would return around the same results?
E85 is alot easir to get and cheaper than leaded race gas.
I'd like to build a similar engine but toned down to say 6-700 HP level completely street friendly.
I'm thinking a duplicate of the short block, head studs etc but using the stock truck intake and throttle body and pocket ported heads.
After all the turbo buick guys have been building big HP for decades with V6s that have terrible heads in comparison to LS heads.
Any thoughts, comments are appreciated.
Jarhead
The most amazing story I've read in HR, and I've been reading it since 1961.
A twin turbo 4.8 with minimal mods makes 1200HP, thats 4 HP per cubic inch.
The shortblock was stock except for increased ring gap on the reused STOCK rings and stock pistons. It did have a cam, ported heads, ARP head studs and a FAST intake and bigger throttle body.
They did use race gas, and very sharp tuning to prevent detonation, the killer of most turbo engines.
These are by far the most incredible numbers that I've even seen for a cast piston, pretty stock shortblock.
I'm wondering if using E85 would return around the same results?
E85 is alot easir to get and cheaper than leaded race gas.
I'd like to build a similar engine but toned down to say 6-700 HP level completely street friendly.
I'm thinking a duplicate of the short block, head studs etc but using the stock truck intake and throttle body and pocket ported heads.
After all the turbo buick guys have been building big HP for decades with V6s that have terrible heads in comparison to LS heads.
Any thoughts, comments are appreciated.
Jarhead
Thanks I did read the other posts.
I was hoping to hear from some E85 users possibly running a turbo on a pretty much stock LS, like what I'm planning.
I had wanted a NA LY6 but a turboed 5.3 or 4.8 would out perform it and be more interesting.
My thinking is the 4.8s and 5.3s are super cheap and that small 3.78 bore makes for alot of head gasket between cyls keeping the motor alive under boost.
I'm wondering if the 4.8 with the shortest stroke and longest rod, and there fore the best rod/stroke ratio just might have partly responsible for that engine surviving such boost levels without bending the stock rods.
Another thought, I once read some reports that RollsRoyce did during WWII.
They were running very high boost levels on their 2000+ hp v12 Merlins.
They found that under high boost there was a relationship to bore size(piston area seeing pressure) and failure. Smaller bore engines would live longer underboost than large bores making the same power.
Jarhead
I was hoping to hear from some E85 users possibly running a turbo on a pretty much stock LS, like what I'm planning.
I had wanted a NA LY6 but a turboed 5.3 or 4.8 would out perform it and be more interesting.
My thinking is the 4.8s and 5.3s are super cheap and that small 3.78 bore makes for alot of head gasket between cyls keeping the motor alive under boost.
I'm wondering if the 4.8 with the shortest stroke and longest rod, and there fore the best rod/stroke ratio just might have partly responsible for that engine surviving such boost levels without bending the stock rods.
Another thought, I once read some reports that RollsRoyce did during WWII.
They were running very high boost levels on their 2000+ hp v12 Merlins.
They found that under high boost there was a relationship to bore size(piston area seeing pressure) and failure. Smaller bore engines would live longer underboost than large bores making the same power.
Jarhead
That is an awesome accomplishment. I however think that a guy would be better off doing at the bare minimum: a set of rods and more importantly a set of forged pistons. The ring lands on stock pistons won't hold for long.
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TECH Apprentice
Joined: Dec 2004
Posts: 358
Likes: 1
1200 hp is alot to ask of stock parts
I'm debating running either the stock 4.8 stroke, with forged rods and pistons
or a 4.0 stroker
I think the small bore size with a nice strong turbo piston is a great idea
less prone to detonation and improved cyl wall strength and head gasket sealing
I'm swapping out an ls6 alum block motor to boost a move with the stronger iron block and some studds
I'm debating running either the stock 4.8 stroke, with forged rods and pistons
or a 4.0 stroker
I think the small bore size with a nice strong turbo piston is a great idea
less prone to detonation and improved cyl wall strength and head gasket sealing
I'm swapping out an ls6 alum block motor to boost a move with the stronger iron block and some studds
TECH Fanatic
Joined: Mar 2011
Posts: 1,916
Likes: 8
From: Statesville, NC
These engines in a real world situation have been proven. Even though some don't believe it, Shawn Bryson has taken a stock head,piston,rod l33 to 4.8x at 150+mph in he 1/8. HP calculator puts that at 1400ish rwhp. Like said, ideal fuel (in his case M1), very precise tuning, lighter weight cars (think he is 2800ish). These engines have went way further that to magazine articles have taken them. But for the money and the risk most at least throw rods and pistons in there. I mean what a grand or so to having the risk of destroying a lot of other expensive components. Gm, Ford, Hemi, they all are coming out with very strong internals to be stock engines now days.
