ICDEDPPL

iTrader: (1)

If youre looking for fuel economy may I interest you in a :

dereknkathy

post 17 i said Gil alum exhausts for 1100. i meant GLM alum exhausts. i was talking about a less expensive lighter exhaust.

Trash

Think of this problem in another light. Your boat, at a given weight will require X hp to travel at Y mph. Regardless of engine it still takes X amount of hp to move the boat at a given speed. Period. To make that amount of hp requires Z amount of fuel (lbs/hr, gal/min etc.) regardless of engine. One engine may make that hp with more to spare, others may be maxed out, but the hull still requires X hp for the given Y speed.

As others have alluded, weight and drag control your fuel consumption more than exhaust manifolds or headers.

Again it amounts to POWER required vs. POWER available.

In the end you are trying to measure with a micrometer and cutting with an axe. Don't buy headers to save fuel would be my recommendation.

SB

iTrader: (1)

Alluded ? LOL. I tried to wash his brain with it but it did not work.

Your post is dead nuts on.

A cheaper way to boat is leave friends at home. But, that's not always as much fun.

Another is to stop tubing/skiing/wakeboarding but your family may leave you and that's definately not fun.

NautiSouth

I agree that a hull at a particular weight will take X Hp to travel Y MPH, but I disagree that X Hp will always require Z amount of fuel. In fact, automotive manufacturers spend lots of time and money minimizing the amount of fuel it takes to produce a horsepower. The metric this is measured with is called Brake Specific Fuel Consumption (BSFC). Typical values of BSFC for gasoline engines at WOT are 0.3 (very good) to 0.6 (very bad) lb/Hp-hr. My suggestion is that by improving exhaust flow and tuning, it might be possible to improve BSFC's under part-throttle conditions, reducing fuel consumption. This of course assumes the boat is already at it's minimum of weight and drag.

And headers weigh less than cast manifolds, a potential win-win if you can swing the investment.

SB

iTrader: (1)

I'd take that $2500 and buy an SS drive.

I bet the less drag will trump the slightly lower BSFC's of headers on a small overlapped small block.

Wildman_grafix

Those colors are soooooo pretty just like a rainbow.

Trash

Adding headers will play a virtually insignificant role in the end when measuring fuel consumed. Again, measuring with a micrometer, cutting with an axe. Part throttle conditions are rarely hampered by stock exhaust. Headers are typically added for getting the 'big number' at WOT for that last bit of hp or speed. If you want to reduce fuel consumption lean it out by shortening the BPW if EFI or tweak the carb. Even then I doubt you will see any measurable results in your pocket book or at the gas station.

Many have chimed in on this, but in the end it sounds like you've convinced yourself. Put some headers on and test it. I'd be curious to see the hard data. Best of luck.

dereknkathy

the more efficient exhaust will slightly increase engine efficiency. you might see a 4 or 5% overall increase in fuel efficiency. 1-2% cuz you made engine flow better. the rest cuz the stern is lighter and planes easier.

Unlimited jd

iTrader: (5)

Well if bsfc is what your after you should go injected with vortec style heads with fast burn chambers, etc.