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More power from 57 V8

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baytro23

Regular Contributor
"What are some ways to get mor

"What are some ways to get more low end power without sacrificing economy? 1994 5.7 alpha1 thunderbolt IV with 4 barrel on a 23' Trophy walk around running a 17" pitch aluminum prop. Aluminum intake? Port and polish heads? It starts and runs fine up to rated rpm's, looking for more power out of the hole. Perma-trim added to cavitation plate? I've got trim tabs but hate having to lower them all the time when starting off.
THANKS"
 
Your intake is aluminum but an

Your intake is aluminum but anything you can do to make it breathe better is good. Add some cup to your prop or go to stainless- aluminum props flatten out a bit on hard hole shots but stainless is stiffer. Porting and polishing can't hurt but I would want to find out how well they and the intake manifold flow before doing anything. The boat's weight and hull design will have a lot to do with any speed and handling but it's never going to snap your head back on a hard start.

Economy and hole shot don't go well together.
 
"That's a big boat for a s

"That's a big boat for a small block and my guess is it's quite heavy. It will be difficult to get good hole shot without the torque of a big block 400+ hp Bravo drive. This of course won't do anything good for economy. You can't have it both ways. You could consider a blower, but the result will still be a thristy beast."
 
"...if you just installed a bl

"...if you just installed a blower you would melt that power plant. If you want performance, write off economy. The general order of operation for adding performance to a Chevy v8 - stacked least expensive to most expensive... not specific to products:

1) Reduce restriction in intake exhaust configuration. (intake, carb, free flow exhaust, more aggressive fuel and timing curves)

2) Number 1 plus more aggressive cam and head work

3) Numbers 1 and 2 plus lower end engine work such as bore work, forged pistons altering comp ratio...

just thoughts

hays"
 
true ...given the same level

true ...given the same level of efficiency. A nice multi point fuel injection system might give this gent a little more power and economy.
 
"Not to be argumentative, but

"Not to be argumentative, but I'm not yet convinced that two SIMILAR engines (carb and EFI) are that different in actual results. The MPFI engines have superior manifolding that acounts for much of the gains.

Jeff"
 
"This venue is always fun to d

"This venue is always fun to discuss theory. And you can always argue with me, Jeff!! I'm a car guy, but the theoretics of carb vs EFI would hold true i suppose... maybe…

As i understand it, more efficient spray patterns/fuel atomization from port fuel injectors and the precise application of fuel from pulse width modulated port fuel injection - coupled with sophisticated closed loop fuel and ignition controls gets you 1)much more precise acceleration enrichment and decel enleanment, 2)allows for a more stoic mixture at steady state cruise speed/load conditions (vs a slight rich condition that a carb would yield, and 3) limited economy robbing fuel condensation on the insides of the manifold and plenum vs a carbureted set up. The result is better fuel economy and more power, not to mention better cold starts and improved drivability.

All this assumes the EFI strategy is of the "speed density" or "mass flow" closed loop variety vs the less sophisticated "N Alpha" found on aftermarket kits and race cars (looks at TPS and RPM only). Not sure if boat EFI is as sophisticated or is even closed loop. Doubt it needs to be given the lack of emission controls, cats, and less frequent transient throttle/speed/load conditions. Rambling off my soap box now..."
 
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