454 to 427
Le Mans Master
Joined: Dec 2003
Posts: 5,727
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From: Fremont CA
You will lose some parts breaking toque but, the 427 will REV faster and I personally prefer a 427 to a 454 motor, so did several Chevy Corvette engineers. The Book Corvette Stingray by Tom Falconer has a chapter on the developemnt and cancellation of the LS-7 and the Chevy engine guy said the cylinder bore wear and cooling problems were some very difficult problems they were working on for the 70 model year LS-7 motor, he actually said the L-88 was a better motor.
Melting Slicks
Joined: Oct 2008
Posts: 2,154
Likes: 69
From: Regina Sk Canada
I have had both, and loved the torque of the 454 better. The 454 and 427 have the same bore, just different stroke. They use the same block, different crank. 4" stroke on the 454 and 3.76" stroke on the 396 and 427. The 396 uses a smaller bore block.
Race Director
Joined: Jan 2000
Posts: 13,018
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From: Corsicana, Tx
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496's rev to 7500 rpm too!!
I love 427's and have never been scared to jump on a 454 with one.....but if the crank is going to be changed it just makes sense to go the other way. More cubes, lighter pistons etc etc.
JIM
I love 427's and have never been scared to jump on a 454 with one.....but if the crank is going to be changed it just makes sense to go the other way. More cubes, lighter pistons etc etc.
JIM
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
Why gain the weight of a BBC when all that you really have are the cubes of a big SBC?
The L88's might have made more HP/Cubic Inch, but I doubt that would've been the scenario if the 454's were internally balanced.
If I were you I'd do one 3 things, I'd build a 427/434(SBC), keep it a 454, or build a 496. IMHO a building a 427 BBC is not very smart unless NCRS is your thing.
The L88's might have made more HP/Cubic Inch, but I doubt that would've been the scenario if the 454's were internally balanced.
If I were you I'd do one 3 things, I'd build a 427/434(SBC), keep it a 454, or build a 496. IMHO a building a 427 BBC is not very smart unless NCRS is your thing.
Burning Brakes
Joined: Mar 2006
Posts: 793
Likes: 1
From: Houston Texas
I've had 2 real LS-6 Chevelles and the term "stump puller" is an understatement. The low end torque difference is very noticeable. I speak in comparison to the 427/435's (L-71's) I've had/have.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
It all depends on what you are trying to accomplish with the engine rebuild. If you are not looking for big power and you do want better fuel ecomony [that's really an oxymoron with a BB], destroking it might make sense (assuming you have to replace the crank anyway).
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Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Same engine, two different animals,,,if your going anywhere the crank would determine what essentials you could use..If its a hydraulic cam engine and you want to keep it that way just chrome it up and slam the hood.... 
Melting Slicks
Joined: Jun 2001
Posts: 3,281
Likes: 6
From: NC USA
IMO, why destroke it unless you're feeling nostalgic...
With todays roller cams, aluminum heads, and the fact that the motor looks identical from the outside, I say build it as BIG as you want or can stand!
With todays roller cams, aluminum heads, and the fact that the motor looks identical from the outside, I say build it as BIG as you want or can stand!
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
Parts needed for 496 conversion: stroker crank, rods and pistons.
Oh yeah, can't forget the 427 badge for the fender.
NOBODY can tell how much engine you have under those valve covers.
"Build it as big and bad as you can or you'll get tired of getting your A$$ handed to you by those that do."
Old Fart Somewhere in My Past
Oh yeah, can't forget the 427 badge for the fender.
NOBODY can tell how much engine you have under those valve covers.
"Build it as big and bad as you can or you'll get tired of getting your A$$ handed to you by those that do."
Old Fart Somewhere in My Past
Tech Contributor
Joined: Jun 2004
Posts: 20,910
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
I did, and have no regrets. I bought a used 454 and a used 427 crank, and rebuilt the motor as a 30 over 427. (It's my expendable track motor, while the original engine sits safely in storage.) I already had the balanced flywheel and damper, and didn't feel like buying new ones.
I've got enough horsepower with the 427 to break stuff if I feel the need, and a 496 won't get around a corner any faster than a 427 will (these are sports cars, after all).
I've got enough horsepower with the 427 to break stuff if I feel the need, and a 496 won't get around a corner any faster than a 427 will (these are sports cars, after all).
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Joined: Jan 2000
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From: Corsicana, Tx
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Team Owner
Joined: Apr 2002
Posts: 62,198
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From: All humans are vermin in the eyes of Guru VA
Cruise-In IV Veteran
Cruise-In V Veteran
It is my belief that for every bore diameter, there is a corresponding RPM range to go along with every available stroke. This being dictated by the biggest valve you can cram in the motor without shrouding. (according to some people, about 53% of bore diameter for intake valve diameter). So for a given bore and stroke, it is possible to determine the appropriate RPM band. Do I know the math no.
Whenever I get done with my 355 my next motor is going to be a Hyd Roller 632
Whenever I get done with my 355 my next motor is going to be a Hyd Roller 632
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
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632's are fun...but even if it's a hyd roller....think BIG on the other parts! They really like airflow!!
JIM
JIM
Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
Do you want low end torque, or do you want high rev's and horsepower? Is your engine gonna live at 5000 RPM or higher? do you want just cruising and passing power or low ET?
there is no replacement for displacement.. just get you the biggest displacement you can and cam/port/carb/gear it for the power band you want... there are trade offs on everything..
there is no replacement for displacement.. just get you the biggest displacement you can and cam/port/carb/gear it for the power band you want... there are trade offs on everything..
Thread Starter
Intermediate
Joined: Aug 2009
Posts: 28
Likes: 0
well ok so tell me what you guys think? 454 block line bored and set for bottom end splay bolt set. 496 scat rotating assembly w/flat pistons. I'm looking @ a set of AFR headsw/ a 500 solid roller cam set up. I'm wanting to be able to run pump gas and be streetable. Ive got a demon carb, and an edelbrock, so well see wich one it likes more.any thanks for the imput I was wonderng why i never seen a 454 to a 427 now i know