how much HP can the stock 400 take?
Thread Starter
Joined: Dec 1999
Posts: 3,544
Likes: 19
From: WI,USA
Car: 89 FORMULA 350, 91 Z28 Convertible
Engine: ls1, LB9
Transmission: t56, Auto
Axle/Gears: S60/ 3.73
how much HP can the stock 400 take?
I know it is cast but, so are stock 87-92 350 ones right?
Supreme Member
iTrader: (1)
Joined: Aug 1999
Posts: 2,842
Likes: 6
From: Rowlett, TX
Car: 1988 GTA
Engine: 5.0 TPI
Transmission: T5
Axle/Gears: 9 Bolt, 3.45
Yes, the crank and rods on all 400s are cast. Its not really the power of a 400 that you must worry about, its the RPM. 400s are not good revving engines due to the long stroke. Even with forged rods and crank, I still would not recommend more than 5500 RPM. 400 connecting rods are weaker than 350 ones due to the larger crank journal size.
Thread Starter
Joined: Dec 1999
Posts: 3,544
Likes: 19
From: WI,USA
Car: 89 FORMULA 350, 91 Z28 Convertible
Engine: ls1, LB9
Transmission: t56, Auto
Axle/Gears: S60/ 3.73
well, I don't want more than 5000 rpm out of it so I should be fine right? I think 350 to 375 max hp is what I will be making these are real hp numbers not fast and furious numbers
Supreme Member
Joined: Sep 2001
Posts: 6,111
Likes: 53
From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
A friend of mine has a 700+ hp 400 small block.
It's in a 9 sec drag car.
He runs the factory cast crank to 7000+ rpm
Total reliability
He had the crank "Iced" (cryonic heat treat)
It's in a 9 sec drag car.
He runs the factory cast crank to 7000+ rpm
Total reliability
He had the crank "Iced" (cryonic heat treat)
Supreme Member
Joined: Apr 2000
Posts: 1,338
Likes: 0
From: Chander, Arizona USA
Car: 2006 Silverado 1500
Engine: 5.3L
Transmission: 4L60E
they'll handle about all you want to throw at them. the two bolt blocks are generally stronger though. may of my friends that run circle track turn them 7k plus for 15 minutes or more at a time. just use good rod bolts and main studs along with a good balance job and you'll be fine.
Junior Member
Joined: Dec 1999
Posts: 34
Likes: 0
From: Bangkok, Thailand
450-550 HP just don't wing the pee out of it 5500 Max use a rev limiter MSD 6A etc... After market parts billet crank, concreted block, racing pistons and splayed caps it will hold around 1200HP.
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