Repower advice
08-01-2014, 08:08 AM
#21
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iTrader: (4)
No inner cooler needed with the larger blower running low boost, it will not make heat. For extra protect get some 120 degree stats and tune your mixture to them. Again if target is 700 hp you will have no problem with the stock rectangular port heads.
That is the beauty of the larger blower. To get the same amount of CFM (air) with a smaller blower you will have to spin the hell out of the 250 and run a higher psi, this makes heat both compressing the air and the letter blower working so hard. Large blower at 3.5 lbs will be ice cold
Add some 02 bungs to your risers on the 1-7 bank of both engines, then get a hand held meter to help you tune after completion.
You can also upgrade your stock drives to xr internals and sell what parts you have left over. I am thinking a 10k lb boat with that power will rip a stock bravo apart as soon as you hit the sticks :/ but I dunno. You can also do the xz upgrades and have longer gear life. I had good luck with xz on my 36 Baja OL with blown 500s, never an issue.
08-01-2014, 09:50 AM
#23
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Compressed air means more air in the combustion chamber, effectively making the engine a larger displacement. Boost is the replacement for displacement, and the next wave of engineering is all about boost in small packages (see Ford eco boost)
No way I would give up the pull and sound of my blowers for bigger ci. N/A, its just not the same.
You have people on here telling him to drop his 454 blocks in favor of 502 ci? There are guys on here (mild thunder) making 800+ HP on 468 ci.
He is trying to make 700 hp, not 1000. 700 blower HP is easy and inexpensive on the 454 platform he has.
Now.....back to those bravo one drives
No way I would give up the pull and sound of my blowers for bigger ci. N/A, its just not the same.
You have people on here telling him to drop his 454 blocks in favor of 502 ci? There are guys on here (mild thunder) making 800+ HP on 468 ci.
He is trying to make 700 hp, not 1000. 700 blower HP is easy and inexpensive on the 454 platform he has.
Now.....back to those bravo one drives
08-01-2014, 12:31 PM
#26
If he goes with bigger cubes and the huge torque that they develop he can forget about Ever having a bravo drive last. I have had several big cube boats with bravos and that is why I do not have them anymore... Even a strong NA 540 in a 42 staggered will destroy bravo drives especially in big water .... Ask anyone that has owned a 42 with big power with bravo drives and they will enlighten you. After replacing them time and again they either got rid of the boat or went to a different drive. Bravo is a great drive to it's threshold which in my opinion is about 600HP. Once you cross that they will not hold up. Yes some do get away with it in light boats, but very few and changing gears all the time...
If you are going to build big power the first thing to do is the drives. Most everyone does it backwards by doing the engines first including myself until you have had enough drive trouble. A lot of time it will cause lost interest in the boat....
If you are going to build big power the first thing to do is the drives. Most everyone does it backwards by doing the engines first including myself until you have had enough drive trouble. A lot of time it will cause lost interest in the boat....
Last edited by Meshikinquah; 08-01-2014 at 04:52 PM.
08-01-2014, 01:21 PM
#29
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Compressed air means more air in the combustion chamber, effectively making the engine a larger displacement. Boost is the replacement for displacement, and the next wave of engineering is all about boost in small packages (see Ford eco boost)
No way I would give up the pull and sound of my blowers for bigger ci. N/A, its just not the same.
You have people on here telling him to drop his 454 blocks in favor of 502 ci? There are guys on here (mild thunder) making 800+ HP on 468 ci.
He is trying to make 700 hp, not 1000. 700 blower HP is easy and inexpensive on the 454 platform he has.
Now.....back to those bravo one drives
No way I would give up the pull and sound of my blowers for bigger ci. N/A, its just not the same.
You have people on here telling him to drop his 454 blocks in favor of 502 ci? There are guys on here (mild thunder) making 800+ HP on 468 ci.
He is trying to make 700 hp, not 1000. 700 blower HP is easy and inexpensive on the 454 platform he has.
Now.....back to those bravo one drives
This is the same conversation that I have with customers all the time. They want to build a 632 and put oval ports on it because "Cubic inches make power!".
Another thing to consider, fuel usage at idle, in no wake zones, and at cruise. The fewer cubic inches you have to feed at these times (90% of your boating time) leads to less money spent on gas at the pump. Make the best usage of the cubic inches you have by selecting heads with ports matched to your application (FI or NA), and efficient combustion chambers. A nice set of heads will cost about the same or less than a 502+ CI short block anyway.
This is what I'm doing with the LS twin turbo motors that I'm building. I am running turbos for the added performance benefits without the parasitic loss of blowers and a large bore motor. Consider how much HP it takes to spin a blower over the life of your motor, then relate that to gas you have to buy. Then consider if the HP that you are using to turn that windmill directly equates to a loss in potential speed. My little 370CI motors use 60% of the fuel at idle in gear that my old 525SC's used and less fuel at cruising RPM while making more torque and HP and top out at 900HP.
Efficiency will be the name of the game for the entry to mid level boater of the next generation.
EDIT: I'm not really trying to start a forced induction debate, just illistrating my point about using the cubic inches you have.
Last edited by Precision; 08-01-2014 at 01:32 PM.
08-01-2014, 04:04 PM
#30
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Higer rpm doesn't always mean more wear, if the internals are rated for it, I would rather spin at peak slightly unloaded then load it down to 5200 (which everyone thinks is the safe rpm). Full roller with his internals he will be safe at 5600 plus. I thought we were trying to save this guy money?
