Mercury V6 HotRodding 101

[AxisMoto]

Having never modified or "tuned" an outboard (beyond normal maintenance), I am trying to learn details and theories on hotrodding Mercury V6s.

I have a 1979 BlackMax 175hp. I am assuming this is a 2.4L motor. It has 200hp(?) carbs with velocity stacks, nose cone with LW.

What powerheads can I swap onto my mid and lower? What is the best choice (bang for the buck)?

What are the choices for improving the performance/power of my 175? What can I hope to get for final horsepower?

(My real question is what is the best way to get 250+hp to the prop? (...other than buying a new motor...)

Thanks
-David

[Jay Smith]

I'll try to be gentle David , Junk the complete 2.4 and opt for a newer 2.5 in its entirety........

[mike v]

cool stuff

[The Big Al]

No replacement for displacement!!!

[heath brinkley]

the only way to replace your displacement, is to displace your wallett. If your can't afford it remember your talking about 9 c.i. It's not like your replacing a 283 small block with a 427 inch small block.

[The Big Al]

I need to know what part of what we do does NOT effect the wallet!!:rolleyes:


I need to know what engine or boat that is!!!!:confused:

[Rickracer]

Comparing it to car motors, a closer example would be comparing an '80s 350 Chevy to a new LS1 or LT4. There are 300 horse 2.0s, but they are behind the liner motors too. You can make some serious, reliable power with a 200 2.5 fishing motor with the right mods. :cool:

[heath brinkley]

All aspects of what we do affect our wallet, BUT, he just laid out money for his rig and is asking advice, and our best reply is junk it for a 2.5. If you want to go faster than anyone on this board, yes you need a 2.5, but if you want a fast boat (100+) can it be done with the 2.4 you have, Yes. I agree a 2.5 is a better motor, but not if you have a 2.4 already paid for. I AM however, assuming your working on a budget since your asking what can be done with this motor instead of a 2.5.
Like Big Al said, what kind of boat do you have.

[T-REX]

Congradulations Heath, a man that uses hiz head instead ov sumbody elses wallet...Az tha conversation haz been heeted befo, 200HP iz 200Hp!!!...On a super light boat, sumtimes tha higher torque ov a higher torque motor will actually hurt performance, instead ov help it, unless U know how to deel wit it...From this manz post He iz try'in to leern to mod HIZ motor himself, and NOT find a new place to dump 10K on a new motor...Tha statement "Other than buy'in a new Motor" kinna made me thank that way...

Axismoto, If your wanting to do tha modz yourself, U need to reed, and leern before ya start, so ya don't wind up wit a 100hp, 200!!...I'm sure if U do a search on here, there are artiklez about pump'in up a 2.4...if ya kan't find one, they'z a artikle on the projects section ov tha BYUBOYZ.com that covers sum mods to a 200 2.4, that will step up HP without take'in away your reliability...If U are juss want'in to know what it takes to pump up tha 2.4, and are going to pay sumone to do your work, then buss out tha wallet and spring for a 2.5...either way, and even if ya do tha work yaself, it will cost ya money...MPH=cubik dollars!!...But doing all U kan, and juss buy'in parts iz a lot cheeper than juss send'in it to sumone to do it for U...OB's iz like dat firss piece ov tail...U reel nervous tha firss time, but it gitz easier ever time afta, az ya git mo familiar wit it!!!!...REX

[Fish]

firss piece ov tail... LMFAO!!!! :D :D :D

Seriously tho,
David there might not be anyone on earth that knows more about these motors than rex, or at least he is in very elite company. I think this is the article he was talking about. If not, it is a great read anyway. good luck,

fish

T-Rex Cherry 2.4 Article (http://www.byuboyz.com/boats/cherry.html)

[heath brinkley]

OB's iz like dat firss piece ov tail...U reel nervous tha firss time, but it gitz easier ever time afta, az ya git mo familiar wit it!!!!...REX

now that's funny, I don't care who you are. :D

[lokinutz]

AxisMoto,
Don't forget about working on your setup. I got some great advice from the man who built my boat and got about 8mph just by setup and prop change. I don't know mercs, but like T-Rex said, do a search on this board and you can read for days about this stuff. I live in Mesa, we will have to meet up sometime.

[AxisMoto]

Thanks for all the replies.

My boat is a 19ft Sterling Tunnel. It is similar to a Liberator (in terms of lines and layout). I assume it will be on the heavier side (700-900lbs hull). The motor is a 79 Black Max 175, with some sort of carb upgrade (maybe 200hp carbs? no choke?) and velocity stacks. It is running a 23P prop, Bob's cone and LW, and runs 71mph, but I don't know at what RPM.

Yes, I am definitely looking to do the work myself. While a total newbie to outboard performance (I owned a pair of 2.4s on a 32ft Stinger center console, but never touched them), I have a fair amount of hotrodding experience. I own SR Axis, which is a motorcycle shop in Phoenix - I used to race, and have two podium finishes at Daytona Race of Champions in addition to over 300 carreer victories in Lightweight Superbike classes. I have a complete machine shop (mill, lathe, etc), in addition to $30k worth of hand tools. And, if you are looking for a 400hp 2.5L V6 twin turbo Maserati motor, converted to fuel injection, I have two that I built to put into a race car that I never finished... ;)

While I appreciate your point, the idea of junking the 2.4L to start over with a 9cc bigger block, especially considering the resources and skills that I have, is kinda dumb.

The goal is to have a boat that runs and drives "nice", and has the ability to blast to 90+ when the opportunity arrises. I'm thinking that just beefing it up a little, making sure everthing is healthy, and putting a 100hp shot of Nitrous on it will get me (almost) what I want... Although, that would mean running a 28 or 29P prop, which would be fine "on the bottle", but might be too much drag on the motor under normal use...

Thanks for all the help.

-David

[Rickracer]

And does it have the newer style (bolt holes closer to the edges as opposed to the bolt bosses on the cylinder itself) heads? If it's an older style 2.0, you'd be better off to shop for a later 2.4 or 2.5 to start your project with. If it's a 2.4, den go for it. :D :cool:

[rob@umt]

even with knowledge and experence you will be money and a lot of trouble ahead to get a 2.5 ltr fishin motor block to start with. They are cheap and you can use a lot of your older stuff off it from your 2.4.

[AxisMoto]

Ok, if anyone has a good deal on a 2.5 fishing motor block, I'm interested.

Otherwise, I'm going to play with this for awhile...

-David

[AxisMoto]

First, those who thought the late 70s 175s were 2.0s was correct. Thus, trying to do anything serious with this block is not a good plan.

So, until I find a smokin deal on a good hot rod single, I picked up a matching 2.0 and am going to rig twins. :)

-David

[AxisMoto]

I read through the 17 responses, and realize that no one really answered the question.


I build a lot of racing motors (for motorcycles). One of the popular units we work on is an EX500, 499cc twin, 4 valve per cyl heads. The answer (in terms of this motor) is:

1. remove stock exhaust, install 2-1 Muzzy pipe, Factory carb kit, K&N filter (adds 4-10hp)

2. change stock gearing to lighter sprockets with better ratio (no "real" power, feels like an extra 10hp, much faster 0-60mph)

3. install intake cam, match intake ports and smooth intake path (be careful to remove minimal material, also you don't want smooth - your tool marks and slightly rough finish is fine) (adds another 2 or 3 hp, greatly improves throttle response)

4. install exhaust cam, find expert to degree cams (having both cams will put another 10hp into play, but this is give or take, as not doing it right will kill the motor, or just make it slow - an expert will only charge $50 to $200 to do this job, and it is money well spent)

5. use Mike's pistons (custom, about $200 each, not a problem since you only need two) and bore the cylinders over .050 (good for 5hp more)

6. install a set of my custom rods (about $800/set, billet titanium) (no real power, but great for the cool factor), lighten and balance crank, etc. (at this point, we are getting near the point of diminishing returns - we got 10hp with $500 to start, the next 10hp cost $1500 more, and the next 10 will be $2500+... the motor has about 45hp in stock trim, $1000 will get you 55hp reliably, $2000 more to get 65hp, and a lifetime pursuit to get over 70hp...)

The point is not that I know the recipe to build a good EX motor, but more that someone out there has the same list for Mercury outboards. PLEASE share this with us, as I have time to work on my motors (as my hull is on hold until fiberglass and resin arrives next week...)

Thanks for all who helped earlier. For the record, I bought a second motor and am putting the twin 2.0Ls on my boat. You can't find a more reliable or cheaper way to double the power! (No, we don't need to go into the twins/single argument here, it is well represented elsewhere on the site...) Now, if I can just get my twins to run "well" (sound nice, clean reliable power), I'll be jammin'...

-David, AxisMoto

[Alan Power]

The best article your gonna get...

http://www.byuboyz.com/boats/cherry.html

It should apply to a 2.0 also, if your unsure ask T-rex.
Also that 2.0 is steel bore so you could port it!

I'm not the person to advise you on this but I have asked similar questions to yours in the past, with similar results.
From what I gather there is no formula for building a V6 merc, just referances to what others have done. And what works for one guy may not work for you!


http://www.byuboyz.com/boats/cherry.html
(My real question is what is the best way to get 250+hp to the prop?

100 shot of juice, would be the cheapest and easiest way to get you there and you have a spare motor for when.....

But if you do want to build your motor up yourself try asking more spacific questions. What kind of boat is it? What's it used for, lake boat, drag, cruisin'?

Start at the bottom and work up, heres a list of possible mods you could do, you need to choose which ones would work for you and which ones will compliment each other.

Torque tab, relieve exhaust, remove can from mid, match or widen exhaust plate to block, dry-stack, cut exhaust chest (works better on lighter boats), Tighten heads (first thing I would do) angle cut rod slots, 1" spacer on intake, change to horizontal fron half, 5 petal reeds, cross drill intake (I have one of these and hate it, idles sh*t and dificult to tune), try diferent carbs (find a set that might work for you (WH22) ), velocity stacks. Stock cooling should be left alone unless your going all out all the time from what I've read.

Do a search on all of the above and read up on them, theres tons of info here and your original question has been answered many times, it's just in diferent places. You have to go find it.

Hint... search posts by T-rex, mercman, greg moss, US1, you get the idea...

Alan

[Fish]

LOL, great minds think alike :)

[AxisMoto]

It's funny how learning works - I've read that artice 5 or 6 times, and until today I didn't realize just how detailed it was (and yes, it offers a good "recipe" for the type of mods that I want to do).



The setup is a 19ft Sterling tunnel (center sponson type), twin Mercs with Bob's and low water pu, also transom water pu (setup like Wildman's Liberator). The boat is very light, and I'm hoping to spin 32P cleavers on my 2:1 lower units. Counter rotating.



This is a performance pleasure boat (NOT a race boat). I don't want to build grenades - the motors must start and idle reasonably well. I want smooth, solid power throughout the rev range, with a slight bias towards top end scream (but I should be able to get most of that simply by being able to spin it faster...)



I'm assuming that it ran low 6000 range in stock trim, and would like to be able to comfortably spin about 7500... (these are just educated guesses - guidance would be appreciated)

Thanks for the continued education.

-David, AxisMoto

[Alan Power]

Cutting your exhaust chest should move power up your rpm, but you lose power down low. You might make up for low end loss with the twin motors, I don't know, ask some of the guys that run twins US1 has twins on one of his boats, you could also ask him about the application of his portmap to a 2.0 but I dont know if that's what you would realy want.

Another mod that might wok for you is 'D' porting and matching the ports in your pistons, do your motors have finger ports?

Also, I don't think it wise to turn the stock cast pistons higher than 7g, but if you could spin a pair of 30/32 cleavers to 7000 rpm you would be hauling ass, not sure if those motors would spin a prop that tall.

I don't like what's been done to my motor before I got it, cut exhaust chest, crossdrilled intake, bigbore carbs WH15 with 28" big ear chopper. This does not work for holeshot or idle. It doesn't start too easily either and idles at 1200 rpm but it does pull like a train when/if you get on top.

Have fun and do your reading before your cutting, let us know how you get on. I'm only learning this stuff and love reading all I can on it.

Alan

[Alan Power]

http://forums.screamandfly.com/forums/showthread.php?t=50441&highlight

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=5314

http://forums.screamandfly.com/forums/showthread.php?t=20332&highlight=

http://forums.screamandfly.com/forums/showthread.php?t=12416&page=1&pp=15&highlight

http://forums.screamandfly.com/forums/showthread.php?t=7533&highlight=

http://forums.screamandfly.com/forums/showthread.php?t=6322&highlight=

http://forums.screamandfly.com/forums/showthread.php?t=6147&highlight=

[freddyspens]

you know mr axismoto, when i 1st got my lil 2.0 175hp motor i think it was only pulling maybe 5800rpm and maybe a lil more at times but it seemed like it hit a wall and just wouldnt rev out over 6grand.. it really should have revved to the moon cause i was running a really low pitch prop, much smaller then ideal.. now after going through it and cleaning up and matching as well as flowing the exhaust ports, advancing the timing(i forget cause its been a while but i am thinking something like 24degrees btdc ,with 93octane always ,but double check that and also make sure the timing mark is set correctly cause id hate to see ya burn a piston up) and removing the bs idle stabilizer box...after that the motor was pulliing a 24chopper around 7500rpm no problem.. i also removed the can and drilled 5holes on each side of the mid down low which i dont believe helped revs or anything but it did help the boat to JUMP out of the hole-- and i mean jump cause the boat almost completely leaves the water on take off now-- i put a few very easy break in hours on a AWESOME 14peddle 2.5 200hp motor but it has stock mid and can and even with at least 50hp more then the 2.0 it didnt come out of the hole anything like the drilled mid!! of course once on plane with that stock mid 2.5 ,going anywhere from like 10mph to around 50mph, when i hit the gas the boat would literaly JUMP out of the water and pull like one of the fastest sports cars i have been in-- def not a gixxer1000 but never even been in a boat that put me in the seat like the little bit bigger displacement 2.5 does!!
oh, and cut heads definately make a good difference in power and about 145lbs is tops with 93 pump gas or more if ya wanna make sure u have race fuel or something higher then most pump stuff...and one more like was mentioned is running a horizontal front cause they supposedly flow better from a lot of peoples advise i have gotten although i didnt get a chance to put one on mine. it suks i have my 175 2.0 sold cause i just got cut heads in a trade for some other parts and i didnt even get to try them out as well as a few other things like the horizontal front with 4petal plastic coated cages!! i am supposed to pick up an old F1 champ race motor rolling assembly this week and that should really make whatever light lil boat i put it on fly!! hope that helps but like most said-- type in 2.0 mods and merc mods or whatever in a search and read read read!!! between the reading,talking with rex and a few other really frigging experienced and cool guys here i learned a LOT --and then even with just the few things i did to this 2.0 motor and fine tuning it(never even got to port and match the intake side yet!!) i really got my motor running sooo much stronger and pulling at least another grand or a lil more.. :D well sorry for the book but i hope that helps a bit... good luck-- sean

[AxisMoto]

Sean (and all...)


Thanks for all the great info - I am definitely learning. I have acquired a couple of "parts" motors from Ebay, so I'll have some practice parts. (And, if anyone is looking for misc items, I'll probably have some leftovers...)

The project continues....

-David, AxisMoto

[AxisMoto]

Ok, so I've been educated. I should have listened. The only thing that my foray into trying to hotrod 2.0L motors achieved was that it made the 2.5L parts cost a lot more (as I had to pay for the 2.0 parts first...)

Here is the story - I started accumulating parts (a couple of blown 150hp 2.0s, my original 175hp 2.0, at least one clean 2.0 block, etc.)

Well, in my travels, sure enough if I didn't run across the following - first, a complete, running 1999 2.5L 200hp EFI motor for less than $2000. Ok, this is cool, but it makes for a drastic change of direction needed...

And then, a complete 2.5L powerhead with EFI came available for $600! This will bolt onto my mid/lower, and we have a pair!

So, the advice was better than any of us could have imagined. IF you have the strange desire to put together hot rod 2.0 motors - meaning you are going to build several, accumulate some parts to learn on, and see what happens - then STOP! - you will be well ahead of the game to use 2.5 parts instead, as they aren't really that much more expensive, and with the exception of the problem with nicosil sleeves, are easier to work with, etc.

The wisdom of this board never ceases to amaze me...

-David, AxisMoto
19ft Sterling Project with twin 2.5 EFIs...

[dompie99]

I took me a while to respond to any thread since i got in this S&F but i will try to resume my thoughts.

I'M part of the guys that were also, at one point and time, in a race business (car and drag racing) and succeded to pull out 500hp or more out of a 350 ci chevy engine ( at rear end) without much difficulties.

But when it comes to get informations, definite points, straight to the point answers as of '' How to twist an engine : 2.0L, 2.4L 2.5L to get more HP for the Cubic inches. it looks like were asking for the Gold MIne route or the Philosophal stone ( My feelings)

I'm in no doubts that there is a whole bunch of VERY KNOWLEDGEABLE PEOPLE on this forum and there is no doubts in my mind that they would eat my boat/rig for lunch at breakfast and would have any left for desert on the same eating period.

I Asked, a while ago, some questions about an Hydro (Vision) with a 150 HP and the mods that i should do in order to get more output outa this V6.
They pointed some threads here and there but my feeling is that the reals answers are not what we expect and/or they wana keep their secrets for themselves wich is quite alright BUT say it at the first or second reply so we wouldn't be expecting something else that our own findings out of the Jenings 2 stroke manual and the old '' try and error '' stuff that we were kind of used to when we started in the drag racing stuff 20 years ago.

I'm sorry to put it that way and apologise for the directness of my statements but that's the way i felt 3 months ago and this feeling is revealing again to me at the reading of this POST.....


Jacques

Lachenaie Marine

[dompie99]

I DON't know if it resumes your thoughts TOO but that's the way i felt it.


:eek:

[TAXXIVADER]

sooner or later sumptins gotta give , yoo'll get the bug & ya old engines gettin the tug...................
mo power & mo speed = less cash 4 ya kids to feed..........just bein honest.....................:cool:

[dompie99]

OUpsssssss.

You see, i believe that it's not ALWAYS the same '' kid '' that ask questions and wana get a free bee i know.

But the site, and the forum gets to be known by a whole lot of people and more it goes, more people wana get their hands on the THING themselves wich is quite alright for me.....

Just an opinion.

Jacko