454 HP ratings
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Racer
Joined: Sep 2004
Posts: 495
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From: Spokane Washington
454 HP ratings
I have noticed that from 1970 to 1975 the 454 specification are very similar. they all have the same bore, stroke, mains, rods, and valves dimentions. The cranks from 70-72 are forged steel and from 73-74 the are nodular (what is that). The heads vary a little with (73-74 having 113 cc heads), (72 113 cc's), (71 118 cc for the 425 hp, and 113 for the 71 365 hp motor), Since most of the specs are similar does that mean the HP diferances are primarily due to cams.
thanks
thanks
Senior Member since 1492
Joined: Aug 2000
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From: Just because I'm paranoid doesn't mean people aren't out to get me...
St. Jude Donor '09
Originally Posted by Neo Fender
HP ratings changed from Gross to Net during that time too.
Decreasing compression too.
Burning Brakes
Joined: Apr 2003
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From: Central KY
Originally Posted by cal camara
I took my info from "chevrolet by the numbers" 1970-75 by alan colvin
cal
cal
Melting Slicks
Joined: Feb 2000
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From: Vancouver BC, Canada
Originally Posted by cal camara
I have noticed that from 1970 to 1975 the 454 specification are very similar. they all have the same bore, stroke, mains, rods, and valves dimentions. The cranks from 70-72 are forged steel and from 73-74 the are nodular (what is that). The heads vary a little with (73-74 having 113 cc heads), (72 113 cc's), (71 118 cc for the 425 hp, and 113 for the 71 365 hp motor), Since most of the specs are similar does that mean the HP diferances are primarily due to cams.
thanks
thanks
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
Chevrolet reported gross HP numbers in '71. The LS6 had 425 Hp gross in '71. The bis performance drop between these years was due to the drop in compression.
1972 brought net power ratings. 1973 brought exhaust gas recirculation (I believe) and recalibrated ignition timings that ferther choked the engines.
1974 would be the end of the line for the big block.
1975 brought a 100 cid cut in engine size and catalitic converters.
The bark times.
BigBlockk
Later.....
1972 brought net power ratings. 1973 brought exhaust gas recirculation (I believe) and recalibrated ignition timings that ferther choked the engines.
1974 would be the end of the line for the big block.
1975 brought a 100 cid cut in engine size and catalitic converters.
The bark times.
BigBlockk
Later.....
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Instructor
Joined: Nov 2001
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From: St. Paul MN
71 engines were rated both gross and net. The LS5 was 365 gross hp and 275 net. This shows just how inflated the old gross numbers were...
Race Director
Joined: Nov 2002
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From: Taylor Michigan
A couple of other 454`s available were the LS6 in a Vette rated at 425HP and in a 70 Chevelle at 450HP because of a compression differential from 70-71 and the very potent and rare top of the line 454 LS7 which was only a over the counter service package engine that basically replaced the 427 L88 and ZR1`s of similar 550+HP but at a little less potential RPM`s due to the longer stroke. But still one hell of an engine. 
Last edited by Ironcross; Dec 17, 2004 at 01:25 AM.
