40hp out of 20..Possible?

[andrew k]

i have a 2000, 20hp merc, i've been doing my own work on it to get the most horses out of it possible, i've bent reeds, drilled exhaust, changed to a 25 carb, and last year i tore my motor apart with intentions of pot and polishing. well i polished what i could but besides around the reed block, it looked a little tricky to port. and i didn't know how much to port. anyways i put it back together and it ran a bit better but not enough. so this year i inquired about potr'npolish to a couple of mechanics. one guy tells me that if i send my powerhead to him, for 1500$$ he could give me 40 horses. think this is possible? i thought i had done whatever i could, maybe i was wrong.

 

[WillyBWright]

Re: 40hp out of 20..Possible?

For $1500, you could just stack another powerhead on top for 40Hp. Out of a single 18/20/25Hp powerhead? Bullschidt! If it could be done, Merc would've done it.

 

[andrew k]

Re: 40hp out of 20..Possible?

well people modify mercury motors all the time. obviously mercury is holding back on a few things. no disrespect intended, but how come mercury didn't correct little things like the casting behind the reed block, and the casting on the exhaust. i polished these things up and gained 2hp. then i opened the reed buttere a couple millimeters and gained a couple more horses. think mercury would have thought of that. dont get me wrong i'm a strong merc fan, i wouldn't run anything else. i believe murcry builds the fastest motor "out of the box". i'm just saying i believe that they do sacrafice some power for things such as sound reduction.<br />and of course stamina. but i'm not a fisherman i'm a racer.<br />my 2 cents<br />atk81

 

[DHPMARINE]

Re: 40hp out of 20..Possible?

Would your boat accomodate a second 20hp outboard ? (twins)? We have a customer running twin 20hp 'rudes on a SmokerCraft.Real sweet fishing machine.<br /><br />IF the hp is doubled I would expect short engine life.<br /><br />DHP

 

[andrew k]

Re: 40hp out of 20..Possible?

thanx dphmarine<br />but i run a 15ft 100lb flat bottom plywood boat, theres just not enough room for another motor.<br />atk 81

 

[WillyBWright]

Re: 40hp out of 20..Possible?

A few more Hp I could believe, but to guarantee doubling the power???? NOT!!! That crank would snap like a twig if the gearcase didn't grenade first.

 

[Silvertip]

Re: 40hp out of 20..Possible?

Curious as to how you know you picked up 2HP by tweaking the reed block. Do you have access to a dyno?

 

[phatmanmike]

Re: 40hp out of 20..Possible?

he just knows! dont question him!

 

[phatmanmike]

Re: 40hp out of 20..Possible?

heck i just sold on ebay a 40hp twin cylinder mercury outboard for 400 bucks. thats certainley a lot easier and cheaper than having some guy "tweek" a 20 into a 40.

 

[cobra 3.0]

Re: 40hp out of 20..Possible?

Yeah but then the only thing he would be left to polish and tweek is his toe nails.

 

[andrew k]

Re: 40hp out of 20..Possible?

hahahahahahahahahahahahah<br />boy u guys get ugly fast, i was just speaking from my point of view, no i don't thik it is possible to double the hp, i'm just saying theres always room for improvement, i considered buying a forty once but it would be like giving up. i've got a few johnson rivals out there that are not going to let it down until i get by them. be sides i don't think its time for a manicure...<br />atk81

 

[andrew k]

Re: 40hp out of 20..Possible?

by the way anyone ever hear of chamber cumbustion? a guy was trying to explain it to me. seems like a tricky experiment.

 

[WillyBWright]

Re: 40hp out of 20..Possible?

No, but I have seen pistons with a hole on the side on old Chryslers. It may have been what turned a 35/40Hp into a 45/50Hp? I also used to work on Harley Davidson golf cars and we used an aftermarket performance piston with the same hole. The hole was about midway on the skirt and would've passed the center intake port. I believe they were 5/16" to 3/8" holes, but I never measured. I don't know what drilling holes would do to balance either.<br /><br />I don't know if they're available for that motor, but boyesen reeds might help.

 

[andrew k]

Re: 40hp out of 20..Possible?

i've already cut my pistons, seemed to help a bit, you just take a coupl millimiters or the bottom lip of the piston and they top, where it aligns with the ports. this will give it a little more gas a little quicker, and it lets exhaust out a bit quicker. seemed to pick up the revs some too.<br />atk81

 

[cmyers_uk]

Re: 40hp out of 20..Possible?

Here's my two pence worth. An out of the box engine is designed to meet certain criteria like reliability, economy , emissions etc. There are always gains that can be made by compromising one or all of these. In my view to wring the last ounce of hp out of something is a) expensive and b) unreliable. So unless you are racing in a 20hp class why bother. However if you have the money, time and inclenation enjoy the challenge I would be very interested in your achievements especially if they are dyno tested and measured against $'s. i.e $500 brought be new pistons and 5hp. <br />Have fun keep us informed.