merc 3.0L and merc 3.0LX.. ???

[trog100]

i am basically a new boater with a small 20ft cuddy cabin type boat.. the L and the LX is puzzling me.. from what i can gather the LX has longer reach plus projected nose spark plugs and smaller ports and i think the L is the same head that was used on the 2.5 mercruiser engine it uses standard nose and reach spark plugs. i am just kinda puzzled as to why the two different types.. i have done a bit of searching trying to find out but there seems surprisingly little information as to the "why"..<br /><br />did one come after the other.. ?? does one have some hidden advantage i cant think of.. ??<br /><br />incidentally i have replaced the standard nose plugs in my 3.0L with the projected nose type and in a hotter heat range cos i do a lot of river cruising (8 m.p.h speed limit) and the engine didnt seem too happy with extended 1000/1200 rpm stuff.. i do give it a blast every so often when nobodies about.. he he <br /><br />can anybody clue me in as the why there are two diffent cylinderheads on these engines..<br /><br />trog100

 

[Don S]

Re: merc 3.0L and merc 3.0LX.. ???

The LX is listed as 135hp, whole the L is listed as 115.<br />I haven't compared all the parts, but there are more than just a spark plug change to add 20 hp.

 

[trog100]

Re: merc 3.0L and merc 3.0LX.. ???

Hello Don S.. i have seen the difference in 115 and 135 quoted someplace but mostly the the 3.0L gets quoted as 135.. in fact the 3 litre merc with no mention of a difference just mostly gets quoted as 135 hp.. <br /><br />the merc manual when it refers to electronic ignition seems to mention the LX version.. with the L it just mentions points..<br /><br />i have seen forum comment along the lines of the fact that the L uses the same head as the older 2.5 merc whereas the LX uses the "3 litre head".. but whats the "3 litre head" he he..<br /><br />the mercruiser manual (the pdf files u can get at on boatfix.com) mentions different sparkplugs (3/4 reach on the LX as opposed to 1/2 inch on the L) and the only other mention refers to oil seals on the valves the L has them on all valves the LX only on the Inlets I think..<br /><br />as u say sparkplugs wont make any HP difference.. they are both different castings thats for sure and i think the LX has smaller ports and thicker sides hence the need for the extra 1/4 inch reach on the plug.. all other parts such as valves and stuff seem the same..<br /><br />i would have guessed that the LX simply came later but i think both engines are still current.. ??<br /><br />kinda funny really but the engine is as common as muck but i havnt been able to find out the why of it.. he he<br /><br />the 115 hp (sometimes) quoted for the L does seem a bit low when compared to HP figures quoted for the 2.5 and older mercs.. and the L seems to be the most common of the two.. it might be as simple as the fact that the LX is the only one that comes with electronic ignition and perhaps fuel injection (is there a fuel injection version i am not sure) instead of a carb.. dunno..<br /><br />i might seem a bit pedantic but mysteries always get me going.. he he<br /><br />thanks for your answer..<br /><br />trog100

 

[trog100]

Re: merc 3.0L and merc 3.0LX.. ???

the more i look the more confused i get.. he he.. depending on year of manufacture it seems the "L" can have either cylinderhead but the "LX" only has what is refered to as the 3 litre cylinderhead..<br /><br />i am still kinda puzzled as to why the 2.5 litre head has been bunged on the 3 litre engine in the first place.. but there ya go.. he he he<br /><br /> http://www.boatfix.com/merc/Bullet/97/97_06.pdf <br /><br /><br />trog100

 

[trog100]

Re: merc 3.0L and merc 3.0LX.. ???

okay.. it seems that starting 1990 merc came out with the engine they called the 3.0LX at the same time it seems that they chose to downgrade the performance of the engine that didnt have the "X" stuck on the end.. they seem to have done this by bunging the old 2.5 cylinderhead onto the 3 litre engine.. this seems to have dropped the HP from 130 down to 115..<br /><br />sometime later after 1994 i think they stopped doing this and went back to useing the proper cylinderhead on the engine commonly known as the 3.0L..<br /><br />assuming that they didnt just have a whole bunch of old 2.5 cylinderheads laying about they wanted to use up.. he he.. i only think this was to make the "LX" relatively better than the earlier none "LX" version.. <br /><br />i think that the hybrid 3.0L (115 hp) only existed between 1990 and 1995 after that they quitely went back to useing the proper cylinderhead and the power output went back up to 130hp-ish where it had been since the year dot..<br /><br />clear as mud aint it.. he he.. <br /><br />course i could be wrong in my supposition as to the "why".. but it does explain why there isnt much said about exactly what the difference is between the "L" and the "LX"..<br /><br />trog100

 

[Bondo]

Re: merc 3.0L and merc 3.0LX.. ???

clear as mud aint it.. he he..

Ayuh................<br />And,<br />They're All the New Up-Dated Improved Version of the Same Old 181cid, 3.0l, 140hp motor.............

 

[trog100]

Re: merc 3.0L and merc 3.0LX.. ???

the HP figures quoted for the hybrid 3.0L (115hp) dont make a deal of sense either.. 2.5L engine which used to be called a 120 which i assume refered to its HP.. gets swopped for hybrid 3.0L which in actuality 3.0L block with 2.5L head stuck on top) and gets quoted at 115 hp.. <br /><br />it figures to me that upping the capacity of their new "bottom of the range" engine by 20% even thow u do use the same cylinderhead would up the 120hp starting figure of the discontinued 2.5L to 135 to 140 ish..<br /><br />i can only assume merce hp figures are more to do with marketing than the actual power output of the particular engine..<br /><br />as u say.. in forty years they aint exactly changed a lot.. he he <br /><br />trog100

 

[Don S]

Re: merc 3.0L and merc 3.0LX.. ???

Originally posted by trog100:<br /> course i could be wrong in my supposition as to the "why".. but it does explain why there isnt much said about exactly what the difference is between the "L" and the "LX"..<br /><br />trog100

One of the reasons you won't find many comparisons is because people usually have one or the other and want to know how to fix what they have, not speculate what the differences are between the two.<br />Do you know what the answer to the universe is? If not, I will give you the answer.... it's 41. but you would have to read all four (4) books of the trilogy to find that out.<br />Anyway, back to the 3.0, if you check out some of the many web sites on GM engine hotrodding, you will find out more information on the actual differences between all the 3.0L GM engines.<br />Remember, Google is your friend.

 

[trog100]

Re: merc 3.0L and merc 3.0LX.. ???

jeesh Don u dont have to tell me about google.. i would say that over the last week ever since my curiosity got tickled (it got tickled mainly cos i couldnt find the answer to what at first seemed a simple question) about fifteen hours of googling (i should get a life..he he) have gone into trying to find the difference tween the 3.0L and the 3.0LX.. he he he.. i spent many an hour googling.. read whats readily available on this forum (and some others) as well.. <br /><br />all my googling and forum reading turned up basically bugger all.. which of course tickled my curiosity even more.. i always smell a rat when i have difficulty finding the answer to a simple question.. he he..<br /><br />as a last resort i even asked on here.. that produced less than my googling.. i never get usefull answers when i ask quetions on forums mainly cos i do my googling first and only (as a last resort) ask questions that not many b-ggers know the answer to.. its the problem with being a clever "googling" bugger.. i should learn better.. he he he..<br /><br />anyways i now know enough to satisfy my curiosity as to the differences tween the "L" and the "LX" (and why there is confusion and no simple amswer) and i am happy as to my assumption as to the "why".. pretty "simple" really.. merc (or GM) decided to save some money by not making 2.5 litre block/bottom end pieces.. after the 2.5 got dropped pretending the new hybrid 3.0L fitted the same slot (120HP) in their line up saved somebody some money and didnt decrease the number of options merc had on offer..<br /><br />i was probably a GM decision to stop turning out the 2.5 bottom ends anyway.. they have to make em..<br /><br />tell u what thow dude i do find it odd that many others havnt ask the same question that i did.. if they had my googling would have turned up some answers.. the only reference i came across was some guy asking about what sparkplugs should be used and why.. with an answer from another guy who (wrongly) said that the L used the 2.5 head and the LX used the 3.0 head (he was partly right of course cos during certain years (early nineties)it did.. the problem being that during most of them 74 t0 89 and later than 95 it didnt) he also said that many a wrong sparkplug has been fitted to many a wrong engine and the only real way to tell the difference was to measure the thread depth in the plug hole.. he he <br /><br />course after all my googling we now know a better way dont we.. least those that take the trouble to read my lengthy blathering do.. he he <br /><br />diferences that "matter" to the average dude.. two different sparkplugs same thread diameter (14mm) but one standard length thread (1/2inch) with standard nose.. the other (3/4inch) reach with projecting noise.. an overall difference of 3/8inch) poking into the cylinder hmmm.. an 89 3.0L takes the longer one a 90 3.0L needs the shorter one.. hmmm.. "many a wrong plug has been put into many a wrong engine".. well yes i can see why.. also gonna hazard a guess here and say that even if that long reach plug has been fitted to the head that should have the short one it has still missed the pistons and valves which in theory it shouldnt do.. hence no scandals about busted 3.0Ls..<br /><br />nah.. these are the sort of questions that folks should ask.. not quite in the same esoteric league as the answer to the universe..<br /><br />my answer to the "why" in the end came not from manuals or google but from mercruiser service bulletins.. u know the things that get sent out to dealers telling em about all the c-ck-ups.. err alterations.. and how to fix em.. he he he.. must be a moral in here somewhere.. whoops..<br /><br />u have to laff<br /><br />trog100

 

[Bondo]

Re: merc 3.0L and merc 3.0LX.. ???

trog100,<br />You seem to have Way Toooo Much Time on your Hands...............<br />I can tell you from experince,<br />There are Way More than 2 heads used on the 3.0l engine..........<br />I've Seen 6 Different Heads.......<br />Most are interchangable......<br />Different Port sizes,+ heights....<br />Different Plug Hole locations,+ sizes.......<br /><br />Trying to determine the differences in motors by the parts book Doesn't always work...............<br /><br />I too think the HP ratings are more of a "Marketing Ploy",<br />Than "Actual" Horsepower.................................

 

[craze1cars]

Re: merc 3.0L and merc 3.0LX.. ???

"I can tell you from experince,<br />There are Way More than 2 heads used on the 3.0l engine..........<br />I've Seen 6 Different Heads.......<br />Most are interchangable......<br />Different Port sizes,+ heights....<br />Different Plug Hole locations,+ sizes......."<br /><br />I see now after looking back that I've restirred an old hornets nest on this topic. This quote right here is the EXACT info I'm looking for.<br /><br />So here's the crux of my question: Which of these 6 heads has the best port sizes/heights/plug hole locations/etc to make the most HP out of the 3.0 block? THAT's the head I want to find as the starting point for my "experiment" that's I've discussed my other another very recent post.

 

[trog100]

Re: merc 3.0L and merc 3.0LX.. ???

the 64.000 dollar question hey.. he he <br /><br />not as u stand a hope in hell of getting the kinda answer u are after..<br /><br />merc seem to have a simple policy.. if u want more power u fit a bigger (still low powered) engine..<br /><br />with cars we all expect engines of any given size to bung out more power.. use less fuel or a combination of both as the years pass.. and on top of that get more reliable.. with boats it seems to be different.. we really do have pretty much the same engines as we had forty years ago.. 1960's vintage cast iron block.. cast iron head.. over-head valve push-rod engines that were new technology forty plus years ago..<br /><br />errr.. what the f-ck is an overhead cam.. the rest of the world invented and put em into common none exotic usage back in the seventies.. boats aint got there yet.. bless em.. he he he<br /><br />still it could be worse.. we could still be stuck in the fifties.. cast iron blocks.. side valve type engines with flat top cast iron heads.. he he he.. <br /><br />my logic goes like this.. merc might well have used many different heads (no real big super-duper differences thow) on that venerable old four banger.. but it seems very clear that their reasons for doing so had bugger all to do with increased efficiency.. or getting more power out of the old beast..<br /><br />i think your two main choices here would be between the older 3 litre head (before 89) that takes standard reach plugs or the newer 3 litre head that takes long reach plugs.. thow for all i know after the LX was dropped in 94 merc might have gone back to useing standard reach plugs.. dunno.. but i dont think u can assume that "newer" means "better" it could well just mean "cheaper".. who knows.. i certainly dont..<br /><br />i aint suggesting by the way that the plug reach will make any power differences on its own.. but it does require a positively different casting..<br /><br />still any more info u turn up is interesting.. make sure u let us know.. he he <br /><br />i just got told "i have too much time on my hands and think too much".. he he <br /><br />trog100