7.4 MPI question

[Jyruiz]

What is the horsepower of the 7.4 MPI? And if there are other versions with different horsepower, can you please let me know.

[doesitfloat?]

454 MAg: 385 HP
454: 330 HP

[CBadDad]

It all depends if you're telling your friends, selling the boat or applying for insurance.
Which one would you like?

[Outnumbered]

454 MAg: 385 HP
454: 330 HP
Nope, the 7.4 MPI is acually only 310HP. It's a pretty weak motor as far as BB's go; for whatever reason it was tuned way down. The non-MPI 454 actually has better cam and compression and makes more HP, thus the 330HP 454. The Mag MPI is the best of the bunch with 385 as stated above. The reason I know this is that I got the 454MPI in my boat and I was surprised to see the HP was so low. It still has good torque and runs pretty good for a family boat.

[Outnumbered]

From trailer boats:
...The 7.4L MPI has a slight edge with 310 hp at the prop vs. 300 hp at the prop for the 350 Mag MPI...
The 7.4L is the least powerful in MerCruiser's two-engine 454-cid sterndrive class. The other is the 385hp 454 Mag MPI. Both engines are equipped with multi-point electronic fuel injection. A major difference between the two engines is the compression ratio, which is 8.0:1 for the 7.4L MPI and 8.6:1 for the 454 Mag MPI.

[Outnumbered]

The article...
http://www.stingrayboats.com/products/reviews/tb2_99.html

[doesitfloat?]

Nope, the 7.4 MPI is acually only 310HP. It's a pretty weak motor as far as BB's go; for whatever reason it was tuned way down. The non-MPI 454 actually has better cam and compression and makes more HP, thus the 330HP 454. The Mag MPI is the best of the bunch with 385 as stated above. The reason I know this is that I got the 454MPI in my boat and I was surprised to see the HP was so low. It still has good torque and runs pretty good for a family boat.
You're right. I forgot about that 310 hp slug. I had one 2 boats ago and rebuilt it to gain about 50 ponies...not a huge improvement but a lot better than 310!

[Jyruiz]

So is this the 454 Mag MPI?
http://www.***boat.net/forums/attachment.php?attachmentid=15149&stc=1

[Outnumbered]

Ya, I'm pretty sure that's it. I guess they do not put "MPI" on the cover like they do on the one in my boat. What year is the motor? Here are some specs I found that should be correct:
454 Magnum MPI
MerCruiser's 454 MAG MPI cranks out a potent 385 propshaft horsepower. Technicians enhance the performance of the stock 454 GM block by using high flow cylinder heads with enlarged intake ports that improve air flow throughout the engine. Hardened exhaust valve seat inserts are more tolerant of low lead fuels, improving reliability and engine life. For maximum reliability and strength in high demand situations, we use a forged steel crankshaft, connecting rods, and forged alloy pistons. A technologically advanced roller cam design improves low-end torque, offers higher levels of performance, and aids fuel economy. This, in addition to MerCruiser's exclusive Cross-Ram fuel injection system, results in added torque, improved acceleration, and increase top-end speed. Everything you expect from MerCruiser.
Features:
An advanced roller cam design provides a lower friction coefficient, added torque, improved fuel economy, and greater horsepower for improved acceleration and top speed. Bravo One Performance drive available The new MEFI 3 ECM features advanced electronics for more precise fuel and spark control along with better top-end throttle response. Powerful 65-amp/917 watt alternator easily compensates for extra power required by EFI systems and fully charges batteries for dependable starting and powering of additional electrical accessories. EDP coated cast iron exhaust elbows for excellent corrosion resistance. Steel cone clutch provides smooth, quiet shifting operation. Lab finished Mercury Racing Mirage-Plus and Bravo 1 propellers available. Water-cooled and insulated fuel system helps keep fuel temperatures down.
454 MAG MPI Specifications
Propshaft Horsepower: 385 (287 kw)
Displacement (Liter/CID): 7.4/454
Cylinders: V-8
Bore (in/mm): 4.25/108
Stroke (in/mm): 4.00/102
Compression Ratio: 8.6:1
Fuel Requirements: 87 Posted Octane (R+M)/2
Full Throttle RPM Range: 4600-5000
Ignition Type: Digital
Alternator: 65/917
Length (in/cm): 39/991
Width (in/cm): 32/813
Height (in/cm): 22/559
Weight (lbs/kg): 1177/534 (Weight with Bravo One Drive)
Warranty: 1-year limited, 3-year limited corrosion

[Jyruiz]

Ya, I'm pretty sure that's it. I guess they do not put "MPI" on the cover like they do on the one in my boat. What year is the motor? Here are some specs I found that should be correct:
It is in a 94 28' Conquest deck boat.

[Outnumbered]

It is in a 94 28' Conquest deck boat.
Is it a re-power?

[Outnumbered]

I found this. Its the oldest EFI/MPI 454 data I could find. Its from 1995:
Motor Specs
Manufacturer: Mercruiser
Model: "454 EFI/ MP MAGNUM BRAVO-1; 454 MAGNUM EFI/ MP BRAVO-I"
Year: 1995
Horsepower: 385.0
Cylinders: 8
Type: 4 stroke
Gear Ratio: 1.50:1
Min WOT RPM: 4600
Max WOT RPM: 5000
Spline Count: 15
Drive Type: Sterndrive
******* Note *******
Double check values In Red as they have not been verified on this model.

[Jyruiz]

I found this. Its the oldest EFI/MPI 454 data I could find. Its from 1995:
Motor Specs
Manufacturer: Mercruiser
Model: "454 EFI/ MP MAGNUM BRAVO-1; 454 MAGNUM EFI/ MP BRAVO-I"
Year: 1995
Horsepower: 385.0
Cylinders: 8
Type: 4 stroke
Gear Ratio: 1.50:1
Min WOT RPM: 4600
Max WOT RPM: 5000
Spline Count: 15
Drive Type: Sterndrive
******* Note *******
Double check values In Red as they have not been verified on this model.
Thanks for all your help.