Changing jets to make more HP

[kenmyfam]

Re: Changing jets to make more HP

Thanks guys. I WON"T CHANGE ANYTHING!!!

Wow !!!!! look what you started !!!

 

[Craig-]

Re: Changing jets to make more HP

so if I put 1996 115 hp carbs and throttle bodies, and 1996 115 heads on my 1997 90 hp block and adjust the timing to 115 specs......I wont have a 115 hp motor????

because that si what I am about to try....when I rebuild this motor.


bob

More like a richer running 90, but with that you can advance the WOT timing and maybe get more power out of it if that charge volume will flow through. You can play with jets to tune the A/F ratio but 115hp is beyond reach without port (2 stroke valves) changes. WOT may improve with rpm gain due to ignition timing, but lower rpm ranges will most likely suffer. Volumetric efficiency is the key.

 

[bob johnson]

Re: Changing jets to make more HP

More like a richer running 90, but with that you can advance the WOT timing and maybe get more power out of it if that charge volume will flow through. You can play with jets to tune the A/F ratio but 115hp is beyond reach without port (2 stroke valves) changes. WOT may improve with rpm gain due to ignition timing, but lower rpm ranges will most likely suffer. Volumetric efficiency is the key.

everything that I have read says that the block for the 90 and the 115 are the exactly the same...

I have seen several rebuilt blocks on ebay and they have all said the 60 degree eagle V4 block can be used for either the 90 or the 115.

I am under the impression the heads( and compression) and the carb size, is the only thing different..the timing is the same for each, I just looked that up in the manual...

bob

 

[ezeke]

Re: Changing jets to make more HP

Sometime when you have nothing to do, measure the intake ports on a 90 and a 115, you will find that they are not at all alike.

 

[Faztbullet]

Re: Changing jets to make more HP

Ezeke is correct that port timing is different... notice below that the reman companys know its different and offer them seperate.

Catalog No Description *Retail Price Core Stock
OM-PD4-01-R OMC Reman Powerhead 90HP 60 Degree 1995-2000 Call
OM-PD4-02-R OMC Reman Powerhead 90HP 60 Degree 2001-2006 Call
OM-PD4-04-R OMC Reman Powerhead 90HP 60 Degree 1998-1999 Ficht Call
OM-PD4-05-R OMC Reman Powerhead 75/90HP 60 Degree 2000-2005 Ficht Call
OM-PD4-08-R OMC Reman Powerhead 115HP 60 Degree 1995-2000 Call
OM-PD4-09-R OMC Reman Powerhead 115HP 60 Degree 2001-2006 Call
OM-PD4-11-R OMC Reman Powerhead 115HP 60 Degree 1998-1999 Ficht Call
OM-PD4-12-R OMC Reman Powerhead 115HP 60 Degree 2000-2006 Ficht

 

[bob johnson]

Re: Changing jets to make more HP

Sometime when you have nothing to do, measure the intake ports on a 90 and a 115, you will find that they are not at all alike.

I just had the heads off the 115 two weeks ago!!!!!!!!!!!

I am not about to take them off just to measure..

ill rebuild the block and install it back on the midsection and wait to install the carbs and heads until i determine I am going down a worth while path


I just bought the carbs and throttle bodies for a 115 for $200...they should be here tomorrow.

I already have an extra pair of 115 heads..


PS: you probably do...but just to clarify....you know these blocks are from the eagle series 60 degree motors of the mid 90's and later...

not just any 90hp and 115hp!!!!!


bob

 

[bob johnson]

Re: Changing jets to make more HP

Ezeke is correct that port timing is different... notice below that the reman companys know its different and offer them seperate.

Catalog No Description *Retail Price Core Stock
OM-PD4-01-R OMC Reman Powerhead 90HP 60 Degree 1995-2000 Call
OM-PD4-02-R OMC Reman Powerhead 90HP 60 Degree 2001-2006 Call
OM-PD4-04-R OMC Reman Powerhead 90HP 60 Degree 1998-1999 Ficht Call
OM-PD4-05-R OMC Reman Powerhead 75/90HP 60 Degree 2000-2005 Ficht Call
OM-PD4-08-R OMC Reman Powerhead 115HP 60 Degree 1995-2000 Call
OM-PD4-09-R OMC Reman Powerhead 115HP 60 Degree 2001-2006 Call
OM-PD4-11-R OMC Reman Powerhead 115HP 60 Degree 1998-1999 Ficht Call
OM-PD4-12-R OMC Reman Powerhead 115HP 60 Degree 2000-2006 Ficht

I am DEFINATELY not trying to get into a pizzzing match, because I really appreciate all you experienced guys helping out...

but I am THINKING, because the POWER HEAD...has HEADS on it ...makes it one or the other

if the power head was sold sans heads...it would be the same part number...I am THINKING...

from what I have garnered since i bought these two motors...

this info about the actual ports being different in the block, is the first i ahve heard.... and could dispell, my thinking for sure.


thanks again...and sorry to the OP if i chased this thread off its course.

even if it is kinda relevant

bob

 

[Craig-]

Re: Changing jets to make more HP

everything that I have read says that the block for the 90 and the 115 are the exactly the same...

I have seen several rebuilt blocks on ebay and they have all said the 60 degree eagle V4 block can be used for either the 90 or the 115.

I am under the impression the heads( and compression) and the carb size, is the only thing different..the timing is the same for each, I just looked that up in the manual...

bob

The crankcases have different part numbers because they are not the same.
I would like to here how your rebuild works out, I like your idea. The 90 is right on the lean edge but a stout motor that should handle higher rpms if the charge volume will flow through it. Go for it and let us know.

 

[bob johnson]

Re: Changing jets to make more HP

The crankcases have different part numbers because they are not the same.
I would like to here how your rebuild works out, I like your idea. The 90 is right on the lean edge but a stout motor that should handle higher rpms if the charge volume will flow through it. Go for it and let us know.

where are you finding crankcase part numbers????

i couldnt find just the crankcase.

they listed the crankcase assy.

but that includes the heads... again, which makes them different...because for sure the heads are different. so the ASSEMBLY has....DIFFERENT part numbers.

I welcome more input here...because i dont want a headache of mixing and matching jets because this isnt a bolt on change... which i was thinking it was.

this motor will essentially just be a back up to the 115 i now have on my boat. i figured id make the rebuild a 115 to.. so there is no change if somethign happens to the currently mounted motor.

that way my down time is going to be a weekend max..


bob

 

[ezeke]

Re: Changing jets to make more HP

Cylinder and crankcase assembly is usually number 1 in the list of parts accompanying the cylinder and crankcase diagram. It does not include cylinder heads under that part number; those are listed separately.

In the instance of the 115, the 90HP crankcase is listed first with its part number, then the 115HP with the different part number: http://shop.evinrude.com/

 

[bob johnson]

Re: Changing jets to make more HP

Cylinder and crankcase assembly is usually number 1 in the list of parts accompanying the cylinder and crankcase diagram. It does not include cylinder heads under that part number; those are listed separately.

In the instance of the 115, the 90HP crankcase is listed first with its part number, then the 115HP with the different part number: http://shop.evinrude.com/

OK I just talked to the tech at SHOP.EVINRUDE.COM

and he told me that the crankcase is the exact same, no porting difference...whew!!!

and as for the cylinderand crankcase assy, listed as #1... they both include heads, which is why they part number are different..

kinda makes sense, almost everything on the page is probably included in the ASSY

just like a lower unit ASSY...you can buy it all together, or just specific parts.

well i chased it down..

i feel better now about not having that"not really knowing " feeling

he told me the same holds true for the V6 egale 60 degree motors

only difference on the V4 was carbs, throttle body, and heads

sorry for the wide side track...guys

learning more everyday

so my $200 for 4 carbs and throttle bodies, seems to be back into the "good idea" catergory

now onto picking pistons, wiseco or BRP...

take care

bob

 

[Craig-]

Re: Changing jets to make more HP

OK I just talked to the tech at SHOP.EVINRUDE.COM

and he told me that the crankcase is the exact same, no porting difference...whew!!!

and as for the cylinderand crankcase assy, listed as #1... they both include heads, which is why they part number are different..

kinda makes sense, almost everything on the page is probably included in the ASSY

just like a lower unit ASSY...you can buy it all together, or just specific parts.

well i chased it down..

i feel better now about not having that"not really knowing " feeling

he told me the same holds true for the V6 egale 60 degree motors

only difference on the V4 was carbs, throttle body, and heads

sorry for the wide side track...guys

learning more everyday

so my $200 for 4 carbs and throttle bodies, seems to be back into the "good idea" catergory

now onto picking pistons, wiseco or BRP...

take care

bob

So the difference is $180 dollars worth of heads, yet they charge $1,583 more for the 115 crankcase assembly.
I think the heads are just shaved 90 heads, and they charge $90 apiece more for them, so if that's true, your scheme should work.
I still think the ports are different but I've never measured them. There must be a moder on here that knows for sure, the larger charge volume has to flow all the way through. Could be that the 90hp ports are oversize and if that is the case, higher compression should boost horsepower with higher octane fuel to avoid detonation. I might try that idea and run 105avgas, no alcohol worries either.

 

[bob johnson]

Re: Changing jets to make more HP

So the difference is $180 dollars worth of heads, yet they charge $1,583 more for the 115 crankcase assembly.
I think the heads are just shaved 90 heads, and they charge $90 apiece more for them, so if that's true, your scheme should work.
I still think the ports are different but I've never measured them. There must be a moder on here that knows for sure, the larger charge volume has to flow all the way through. Could be that the 90hp ports are oversize and if that is the case, higher compression should boost horsepower with higher octane fuel to avoid detonation. I might try that idea and run 105avgas, no alcohol worries either.

the heads are not just shaved.... i fly cut some extra 115 hp heads i bought . I also took a head off the 90 hp to compare them while i was flycutting the 115 heads..

the chamber is about .080" deeper on the 90 hp...but the wall thickness into the water jacket at the bottom and the top is the same thickness...so if you tried to cut that .080" off to get 115 hp heads, you would blow out and break into the water jacket at the ends of the 90 hp head!!!


so they are cast different for sure...

the guy at evinrude took quite a while to investigate....he must have gone and found some casting numbers...dont know for sure...but i asked if they sold the sleeves for the block...

they would be different if the ports were different...but he said BRP doesnt sell sleeves!!!


bob

 

[Faztbullet]

Re: Changing jets to make more HP

Well the only thing I can say is that "tech" dont know squat, the sleeves in a 90 & 115 are different and port height is .100 difference. The 90 is 1.753 vs the 115 which is 1.673. Heck you can feel the difference with your finger if you feel into the exhaust port as the sleeve hangs deeper into the exhaust cavity,also most like a lip. The 115 has had 3 port changes and latest and greatest is the "ficht" design. Sleeve part #'s are :90hp=1097psa and 115hp =1098psa.

 

[DKennimer]

Re: Changing jets to make more HP

After reading all this, I just want to know the end result.... You guys are very knowledgeable about all this stuff, wish I knew a tenth!!!

 

[daselbee]

Re: Changing jets to make more HP

Well the only thing I can say is that "tech" dont know squat, the sleeves in a 90 & 115 are different and port height is .100 difference. The 90 is 1.753 vs the 115 which is 1.673. Heck you can feel the difference with your finger if you feel into the exhaust port as the sleeve hangs deeper into the exhaust cavity,also most like a lip. The 115 has had 3 port changes and latest and greatest is the "ficht" design. Sleeve part #'s are :90hp=1097psa and 115hp =1098psa.

Fazt is exactly right. Exhaust port height changes are part of the HP difference. BRP does not sell sleeves. Fazt is quoting part numbers from Advanced Sleeve. I bet you can get them from LA Sleeve too.

I too asked a BRP tech why the warning horn on a System Check system wasn't working. He didn't know that the engine had to be running. At the time I didn't know that fact either. Now I do.

Last time I will rely on BRP techs. Plenty more knowledge right here.

 

[Craig-]

Re: Changing jets to make more HP

so they are cast different for sure...

bob

I'd have to cc the chambers to see what the gain could be... but anyway the other comments are saying the port timing is different on the sleeves, at least on the sleeves he is talking about. Maybe the stock ones are the same, the only way to know for sure would be to measure what you have.

Throw it together and let us know how it works. If the comp test was good leave the bottom end alone and see what just the head and intake changes make.

 

[bob johnson]

Re: Changing jets to make more HP

thanks for chiming in fazt.... maybe that is what it really takes someone who has put their hands on both..I could do that , but Id have to pull the heads i JUST installed on the 115...dont really want to do that...I have'nt even ran the boat on the water yet, since the new heads went on..

I had thought the answer might lie in the sleeves....

the lady I bought the heads and carbs from has the block but the clamshell bottom half was damaged.....I didnt think it was worth anything ( the block) with out a matching bottom end!!!

I was contemplating offering a small amount for it, just to check.
But now fazt chimed in....no need

I could check on his figures too...if my 90 measures as he says then his numbers most likely apply to all the blocks...

sooo then....is it worth while bolting up the 115 carbs and 115 heads onto this 90 hp block????

knowing I dont want a monster custom tune headache.... at this point I aM IN FOR THE HEADS AND CARBS

Id appreciate a few sentences of advice on how that effort might go...

could i mssage the ports with a dremel tool prior to taking it to the machine shop for boring?? and then just deburr juditiously afterwards??

thanks
bob

 

[Craig-]

Re: Changing jets to make more HP

I think you will still make more hp but the power band will be lower, improving acceleration but fall flat on top end. You probably should back off on the 115 ignition timing advance spec, start at 22-24 and bump it up in trial. 24 to 28 might not do much if it falls flat, so may as well keep it cooler. Retarding the timing from 28 will make the power band smoother in the mid-range. It will probably like a higher pitch prop.

Tweaking the ports is dangerous unless you know about the working of gas dynamics, all I know is if you do it wrong you can really screw it up.

 

[bob johnson]

Re: Changing jets to make more HP

Well the only thing I can say is that "tech" dont know squat, the sleeves in a 90 & 115 are different and port height is .100 difference. The 90 is 1.753 vs the 115 which is 1.673. Heck you can feel the difference with your finger if you feel into the exhaust port as the sleeve hangs deeper into the exhaust cavity,also most like a lip. The 115 has had 3 port changes and latest and greatest is the "ficht" design. Sleeve part #'s are :90hp=1097psa and 115hp =1098psa.

right on...I measured one exhaust port and it was about 1.775"...but that is with a digital caliper by feel...because I was just using my finger tip to stop the end of the caliper


the 115 would be higher huh.....


what to do, what to do.....Ill rebuild first and sort that stuff out later

bob