butteboy

first actual forum question gents please help

the boat 96 baja 208 islander 61 gps 1.36 bravo drive 20p 4 blade with 310 454 carb gen v flat tappet engine

from what i can find online it has cast pistons at 8.0 to 1 and a whimpy cam but a steel gm crank 4 bolt block and the smaller gm forged rods

i already have a 1.36 x upper laying in the shop for it and got 12x16 tabs laying next to that all for the boat now my question to you fellows is should i put a 177 blower on it with about 4-5 lbs or try and find a 502 or something take out engine for it looking to spend least amount of money and keep turn key reliable and dock idle friendly so big cams and heads not really an option asking the local engine guys they seem very confidant it will hold 4 lbs especially if i do better springs in heads fact or fiction?

2tonchevy

hands down teh best way to go :

1)sell the 454 in your boat for a good price.

2)take the cash, add it to the money that you woulda spent on the blower, blower carb, fuel system upgrades, etc.... and find a good 502 (efi, magnum, custom....whatever) there are some good deals on engines around these days...be patient and buy from a reputable source.

3) install it and buy the right prop. your at 70mph pretty easily

alot more dependability, longevity and room to improve later if you desire...for about the same money that you woulda spent upgrading a motor that wont live very long under harsh conditions created by supercharging. it MAY cost a tad more initially ( i repeat MAY)....but it will end up being cheaper and more reliable in the end....i promise.

JMO.....

pqjack

i find it strange ,having a 1:36 on such a small engine....jmo

1BIGJIM

iTrader: (1)

I don't see any mention of exhaust. If you do not have a good exhaust you can throw all the money you want at it and will not get the performance gains you are looking for.

Every performance marine builds requires a good exhaust system.

chewymalone

Judging from the thread title, you are looking for 100HP and 10MPH. Those two numbers typically don't go together.On a flat bottom boat, I'd expect to maybe pick up 5 MPH with a 100HP increase.

dbkski

iTrader: (1)

Put a blower on your 7.4L. You'll be just fine.

butteboy

there's a buddy of mine running same lake with a 496 ho in a hammer and its similar boat style and size who is seeing 73-75 on gps and thats got roughly 130 more horse than mine only thing is he has a big 3 blade so its slow out of the hole and i romp on him to about 50 ish then he starts trimming drive and blows past me

and about the drive ratio it seems to be a popular numer on local baja here i am not to sure if they just got ordered that way or what thats all i know

A.O. Razor

When you are currently running 61, you should easily be in the 70-72 mph range with a 502. Many boats with that power, heavier and slower than yours, run 68-70 with the 502. The 502MPI is a better choice than boosting the 454. Less headaces and likely money saved down the road. I'd also say that resale is better too when time comes, the Merc 502MPI is a popular motor. BTW, if your motor is a non mag from '96 you have either the 7,4L 300 4B carb or the 7,4LX EFI 330. In '97 there was the 7,4L 300 4B carb, the 7,4LX 300 EFI and the 7,4LX MPI 330. The mags in '96 and '97 were the 454MAG 350 4B carb or the 454MAG MPI 385. The 7,4L MPI 310 showed up in '98,
To my knowledge and memory, all the non-mag 454's had cast internals all the way around, not ideal for boost. A 502 with a Baja labbed 23" M+ will make that thing really cool. Consider hydraulic steering

butteboy

i was in correct on hp rating sorry AO it is a 300 310 makes me feel better and speeking to multiple people ie local guys other oso members and this web page http://www.perfprotech.com/store/art...fications.aspx general conclusion on gen 5 block is 4 bolt main steel crank etc kinda middle ground for boost safe according to my engine guy he said real lazy timing and premo fuel should last he said the 525sc that he took down looked "overbuilt"

A.O. Razor

HHRRRUUH?????? Not really imo. Build for its intended use. The key word in high performance boating is "overbuild". Not trying to bash your motor guy at all, I don't know him. But that's a first for me.