merc 200 power questions..

[riverfun]

I have a 91 merc 200 and would like to know if anyone has any suggestions to increase performance on it without going overboard... alos what does removing the can in the exhaust do?
thanks for any help..

[mikes19v]

kind of boat?

[Georgia Boy]

Some say it will hep get on top a little faster. The main thing is it will make it louder which sounds better in my opinion. If you pull the can you will need to drill the midsection to relieve exhaust above the water. as far as perfromance goes nothing builds power faster than putting on a set of tighter headsIt is relatively simple job, but that also might mean you may have to run AV fuel which is expensive. So you have to decide if it is going to be worth it. I am sure you will have plenty of other ideas from the others on here. What kind of boat are you running and what kind of set up might help with some answers. Good Luck. ~GB

[rock]

The best thing you can do is a search on this site.There is an absolute library of information on making an outboard run better. Good luck.
Rock

[riverfun]

The boat is an 18 baker v and I am running a mirage 19" prop at the present time....thanks for the info

[pyro]

What other props have you tried? Your 19p Mirage is mainly a ski prop. You will run out of useful (and safe) RPMs around 60 mph. Those aren't really a good performance prop to start with.

Get ahold of a decent 26p or 28p Mazco RE or a Big-ear 14.5" diameter Chopper first. Do some long top end passes in calm water, play with motor height, and get a baseline for comparison. Pay close attention to RPM. You want RPM's on a stock 200 to be ideally between 6000 and 6500. Use a GPS for reading your speed. Post some numbers. You may find that it gives a pretty Scary Fast ride just the way it is.

Eventually you may still want more. That's fine. Search the forums for relevant topics, try searching for:

200 mods
200 performance
200 heads cc

...etc.

Use more words to narrow down your search.

-Chad

[riverfun]

props seem to be the way to get the speed up.... how do these 26 28 props do getting out of the water.... and whats the deal behind the chopper props I hear alot about them.

[pyro]

Higher pitched props are slow out of the hole. you are "spoiled" from running that ski prop! I'll bet it has great holeshot.

Choppers, Mazco RE, Hoss, ET, Cleaver, are all types of "over-hub" props, made mostly for performance applications. Choppers and other round-eared high-rake props are made for bow lift. ET's run flat with lots of holeshot and acceleration, and cleavers lift the stern while offering little bow lift.

Choppers in their stock form will flood the blades with exhaust on takeoff, which causes massive high-RPM ventilation. This is the way they are. Some modification can greatly improve this trait.

Chopper pictured below:

[riverfun]

what do you know about four blade props.....comapared to the three....

[quickonstep]

4 blade props wont really give you any more difference.. cept a bit better holeshot...

but if you have a 26 inch 3 blade prop that is 14 inches in diamiter and the same thing in a 4 blade prop (26p 14" around) the 4 blade will essentially be faster.. why? when you add a blade, you get more of a "biting surface" on the prop to the water..

Basically, if you have a 4 blade 26p prop and you want a 3 blade to run the same, then you have to up the pitch 1 inch.. so a 26p 4 blade = a 27p 3 blade

get it? got it! good :P

Jesse

[Georgia Boy]

Quickonstep, Is that a rule about the 4 blade being faster than 3 blades of the same pitch or just with certain types of props? The reason i ask, is that I usually run a 21 pitch 3 blade on my inline. however when skiing etc. I usually use my 19 pitch 4blade, The reason I ask is because the 4 blade is around 10mph slower on the speedo than the 3 blade 21. ~GB;)

[quickonstep]

if the diamiters are the same, then essentially the 19 p 4 blade would be the same as a 20 p 3 blade

Jesse

[pyro]

4-blades have a bit less steering torque also, because there's always 2 blades in the water, there's less sideways force on the propshaft.

The most popular 4-blade seems to be the Merc Trophy Plus. This is a thru-hub prop with a small hub tube (like XR6 gearcase size) that allows a little exhaust to pass over the hub when it's used on a regular size case. They are only 13.75" diameter, but they have excellent bow lift, right out of the box, maybe more lift than a chopper. But with pitches 25 and higher while carrying passenger weight, some motors may have trouble spooling it up from a dead stop, or a bit of "bog down" out of the hole, because of the blade area and the lack of heavy exhaust ventilation. For solo driver runs, a higher-pitched Trophy Plus like 25 to 28 will provide an excellent balance of holeshot, acceleration, bow lift, and top end. The trophy has great bite and runs well at higher engine heights as a surface prop for top end. The lower-pitches like 19 to 23 are excellent ski props, they give quick holeshot even with a heavy load, with the same weight-carrying lift for short WOT runs to thrill your load of friends. The trophy can run even better with some professional balancing and tweaking.'
The Mazco HP4, Hydromotive TX4, and Powertech TRO4 are all styles very similar to the Trophy, most have mixed reviews.

OMC makes or "has made" a 4 blade called a Renegade, I believe. I don't know anything about them. Sorry.

The Tempest is a good prop on some hulls. It is a full-sized thru-hub with a somewhat flat and "raked" (swept-back) trailing edge. They have a bit of stern lift in addition to good bow lift. They run best on heavy loaded bass boats and heavy vees such as 20+ foot Checkmates.

Read this. The chopper story:
http://abiossa.gearhost.net/adamsdock/chopper.html
The big-ear or is probably the best choice for this style of prop. Lots of bow lift. Big performance improvements with some common modifications like weedcutter removal and trailing edge cupping.

The Merc ET is basically a chopper with the "raked" round trailing edge removed. Picture a chopper with no blade area extending past the end of the hub. They have no weedcutters. You can have one made from a big-ear chopper (a "cut") or as a new "original" or "true" ET. They have excellent holeshot and acceleration with light loads, but less bow lift than a big-ear chopper.

The basic "Cleaver" style prop has a thin leading edge and a radically thick, flat, squared-off trailing edge with very little rake. These props have little or no bow lift. They lift the stern of the boat to keep the hull "loose" and dry. They run well on light tunnel boats and on some pad-vee hulls 18' and under.

There are many other "custom" modified cut styles made from a stock chopper, such as Alabama, Allison, Bullet, Yammy, drag hybrid, etc. These have a certain amount of blade area material ground away and re-shaped, and/or blade thinning and cupping.

The Mazco RE3 (3 blade) RE4 (4 blade) has thinner blades and smaller blades, without the "weedcutters" that the merc choppers have had. Their performance traits are between the big ear and small-ear, with excellent top end and low slip % on light hulls. The RE4 (4 blade) supposedly carries more weight, with better holeshot. The Mazco RE is known for cracking and throwing blades with higher-horsepower motors. Any edge nicks should be filed "clean" to help prevent cracking. These props are very fast with the right setup.

Mazco also makes a Cleaver. It has a decent bit of rake and very clean, thin blades.

There are also a number of independent prop shops that produce custom round-ear (and cleaver style) props from their own designs, such as Hoss, Spinelli, Ron Hill, etc.

The SRX is like the OMC version of a chopper style prop. Similar traits, excellent top end.

The OMC Raker is a high-rake 3-blade thru-hub prop.

There are some other thru-hub 3-blade props as well, such as Laser II, Mirage, Bravo, etc. These are use mostly as ski props on performance outboard boats.

do some searches on these styles of props and do some reading. I'm mostly just quoting what I've read, so someone correct me if I'm wrong about any of these props.

-Chad