What is the HP rating for a 1988 454 Mag motor?
03-21-2012, 05:08 PM
#12
Starting in 1988, The 330hp 454 was designated the 7.4L Bravo One package
The 365hp was designated the 454 Magnum.
It's a bit confusing when going back as 1987 the 454 Magnum was only 330hp, packaged with the Alpha One. '87 and earlier, what was called the 330 was mated with the TRS and to add further, the old 370 was basically what became the 365hp 454 Magnum. -Hope this helps.
The 365hp was designated the 454 Magnum.
It's a bit confusing when going back as 1987 the 454 Magnum was only 330hp, packaged with the Alpha One. '87 and earlier, what was called the 330 was mated with the TRS and to add further, the old 370 was basically what became the 365hp 454 Magnum. -Hope this helps.
03-21-2012, 08:37 PM
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03-21-2012, 09:35 PM
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Most Spyders came with twin small blocks but if you went single big block you would almost have to go with the biggest big block motor available at the time which would be the 454 mag and thats exactly what my motor says.
03-22-2012, 07:31 PM
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Does your engine say 7.4 litre or 454 mag? I know you could get either engine in 1988 but if it said mag then its the square port heads, forged internals and 360 hp (at the prop). Im pretty sure thats what I have anyways..Im turning a 23p prop at 4700 rpm on a 1.5 Bravo drive and the boat weighs in at over 5000 lbs wet--pretty hard to do that with 295 hp at the prop.
Most Spyders came with twin small blocks but if you went single big block you would almost have to go with the biggest big block motor available at the time which would be the 454 mag and thats exactly what my motor says.
Most Spyders came with twin small blocks but if you went single big block you would almost have to go with the biggest big block motor available at the time which would be the 454 mag and thats exactly what my motor says.
03-23-2012, 08:15 PM
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In 1986, outboard manufacturers started rating their outboard engines at the prop. So a 1985 115 merc was 115 hp at the flywheel...........1986, they changed the rating to 100 hp. Same engine, now just rated at the prop. Same goes for most all outboards of varying hp
In 1990 all sterndrive manufacturers started rating their engines at the prop.
1989 and prior was a 330 hp, rated at the flywheel....1990 and newer, the same engine (now called a 7.4 liter) was a 300 hp, rated at the prop.
As said before, this engine was an 8:1 comp ratio, small oval port heads with 119 cc chambers, and a cast crank, etc
The 454 Magnum, had a steel crank, strong rods with 7/16" bolts, forged pistons with 8.75:1 comp ratio and large rectangular port heads with ths same 119cc chambers. This engine usually had a hi-rise aluminum intake as well, so that can sometimes be a distinguishing identifier. This engine was rated at 365 at the flywheel and 350 at the prop.
Always wondered why the 30 hp loss on the 7.4 liter and only 15 hp loss on the magnum?
Early 502's (Mark IV and Gen V's) were rated at 425 at the flywheel and 390 at the prop. This number grew in the early 90's with the advent of EFI.
The EFI 502 went up to 415 at the prop and the 454 Mag went to 385 hp at the prop
Somewhere I have a spreadsheet of all the Merc stern drives and Mercury Racing (Formerly Mercury HiPerformance) which lists the displacement, HP ratings, years produced, etc. If I find it, I will post it
In 1990 all sterndrive manufacturers started rating their engines at the prop.
1989 and prior was a 330 hp, rated at the flywheel....1990 and newer, the same engine (now called a 7.4 liter) was a 300 hp, rated at the prop.
As said before, this engine was an 8:1 comp ratio, small oval port heads with 119 cc chambers, and a cast crank, etc
The 454 Magnum, had a steel crank, strong rods with 7/16" bolts, forged pistons with 8.75:1 comp ratio and large rectangular port heads with ths same 119cc chambers. This engine usually had a hi-rise aluminum intake as well, so that can sometimes be a distinguishing identifier. This engine was rated at 365 at the flywheel and 350 at the prop.
Always wondered why the 30 hp loss on the 7.4 liter and only 15 hp loss on the magnum?
Early 502's (Mark IV and Gen V's) were rated at 425 at the flywheel and 390 at the prop. This number grew in the early 90's with the advent of EFI.
The EFI 502 went up to 415 at the prop and the 454 Mag went to 385 hp at the prop
Somewhere I have a spreadsheet of all the Merc stern drives and Mercury Racing (Formerly Mercury HiPerformance) which lists the displacement, HP ratings, years produced, etc. If I find it, I will post it
03-23-2012, 10:38 PM
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In 1986, outboard manufacturers started rating their outboard engines at the prop. So a 1985 115 merc was 115 hp at the flywheel...........1986, they changed the rating to 100 hp. Same engine, now just rated at the prop. Same goes for most all outboards of varying hp
In 1990 all sterndrive manufacturers started rating their engines at the prop.
1989 and prior was a 330 hp, rated at the flywheel....1990 and newer, the same engine (now called a 7.4 liter) was a 300 hp, rated at the prop.
As said before, this engine was an 8:1 comp ratio, small oval port heads with 119 cc chambers, and a cast crank, etc
The 454 Magnum, had a steel crank, strong rods with 7/16" bolts, forged pistons with 8.75:1 comp ratio and large rectangular port heads with ths same 119cc chambers. This engine usually had a hi-rise aluminum intake as well, so that can sometimes be a distinguishing identifier. This engine was rated at 365 at the flywheel and 350 at the prop.
Always wondered why the 30 hp loss on the 7.4 liter and only 15 hp loss on the magnum?
Early 502's (Mark IV and Gen V's) were rated at 425 at the flywheel and 390 at the prop. This number grew in the early 90's with the advent of EFI.
The EFI 502 went up to 415 at the prop and the 454 Mag went to 385 hp at the prop
Somewhere I have a spreadsheet of all the Merc stern drives and Mercury Racing (Formerly Mercury HiPerformance) which lists the displacement, HP ratings, years produced, etc. If I find it, I will post it
In 1990 all sterndrive manufacturers started rating their engines at the prop.
1989 and prior was a 330 hp, rated at the flywheel....1990 and newer, the same engine (now called a 7.4 liter) was a 300 hp, rated at the prop.
As said before, this engine was an 8:1 comp ratio, small oval port heads with 119 cc chambers, and a cast crank, etc
The 454 Magnum, had a steel crank, strong rods with 7/16" bolts, forged pistons with 8.75:1 comp ratio and large rectangular port heads with ths same 119cc chambers. This engine usually had a hi-rise aluminum intake as well, so that can sometimes be a distinguishing identifier. This engine was rated at 365 at the flywheel and 350 at the prop.
Always wondered why the 30 hp loss on the 7.4 liter and only 15 hp loss on the magnum?
Early 502's (Mark IV and Gen V's) were rated at 425 at the flywheel and 390 at the prop. This number grew in the early 90's with the advent of EFI.
The EFI 502 went up to 415 at the prop and the 454 Mag went to 385 hp at the prop
Somewhere I have a spreadsheet of all the Merc stern drives and Mercury Racing (Formerly Mercury HiPerformance) which lists the displacement, HP ratings, years produced, etc. If I find it, I will post it
03-26-2012, 09:12 PM
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Does your engine say 7.4 litre or 454 mag? I know you could get either engine in 1988 but if it said mag then its the square port heads, forged internals and 360 hp (at the prop). Im pretty sure thats what I have anyways..Im turning a 23p prop at 4700 rpm on a 1.5 Bravo drive and the boat weighs in at over 5000 lbs wet--pretty hard to do that with 295 hp at the prop.
Most Spyders came with twin small blocks but if you went single big block you would almost have to go with the biggest big block motor available at the time which would be the 454 mag and thats exactly what my motor says.
Most Spyders came with twin small blocks but if you went single big block you would almost have to go with the biggest big block motor available at the time which would be the 454 mag and thats exactly what my motor says.
