90 E90JELOR convert to 115 HP

[btomlins]

I need a little more HP for my jet boat and want to know if I can gain some HP on my 1995 E90jelor by adding some 115 parts? Exhaust Manifold maybe?????

 

[flyingscott]

If your motor is a factory jet, it is already a 115 powerhead maybe more.

 

[interalian]

More to it than that. Exhaust, carbs, intake porting are the differences. Exhaust by itself would make little difference as it needs to manage the extra flow you'd get with bigger carbs and enlarged ports. Synergistic is the word.

 

[btomlins]

Ok, larger ports on the intake manifold?

 

[interalian]

No, larger ports in the cylinder wall. Intakes are the same for all HP versions. I just did a 90-140HP upgrade using a 140 block, carbs and exhaust. All other parts were the same. My donor block was a '79 and the 90 was an '82. The ports between the two blocks was night and day, size wise.

Even though yours is a 1995, it's still the same powerhead mechanically, although in newer years they were prop rated rather than flywheel rated, so your 90 is more like a 115 of my era.

 

[emdsapmgr]

The most complicated upgrade is the exhaust system on the rear of the powerhead. Your block is called a "flatback" and is missing additional machining and exhaust parts. Once you get the porting to match, youll have to let a machinist add the bubble back exhaust parts. This is a pic of a typical bubble back exhaust system..

 

[flyingscott]

Put up a pic of your powerhead from all sides.

 

[racerone]

90 hp should be adequate.--------Is your motor running properly ?---------Compression test done ?

 

[bob johnson]

The most complicated upgrade is the exhaust system on the rear of the powerhead. Your block is called a "flatback" and is missing additional machining and exhaust parts. Once you get the porting to match, youll have to let a machinist add the bubble back exhaust parts. This is a pic of a typical bubble back exhaust system..

he has a 60 degree looper motor , not a crossflow.....

I did this conversion..... I made my 90 hp ocean runner into a 115 hp....since I also had a 115 block, I could measure the port size and location on the clylinder sleeves, and match them..i ported out the sleeve with a foredom tool, I installed 115 heads( which were much shallower in depth) and I installed 115 hp carbs and throttle bodies.....I think that's the only difference, except for Intruder and Fast strike versions(GL models)... they rev higher and are said to have 15 more hp than stated....but it doesn't appear to come from the carbs or heads...maybe from the ignition system....not sure.

you cant really look at the parts interchange sites like evinrude.com...because if it PHYSICALLY will bolt on...they say it is interchangeable...as do the outboard rebuilders... they say they sell a rebuild powerhead that first BOTH a 90 hp and a 115 hp!! ha ha ha........what a joke

 

[interalian]

Put up a pic of your powerhead from all sides.

Indeed.

 

[emdsapmgr]

Interesting. If you go out to the Evinrude/Johnson electronic parts cataglog and put in "e90j", the model number factory system comes up with a crossflow parts list. Even though the model is not listed in the normal viewing screen

 

[btomlins]

The motor is on a 17' roughneck jet boat. it has "gained some weight" with all of the trolling motor batteries, fishing deck, electric trolling motor. 3 adults etc. It was rebuilt a couple of seasons ago and it just seems a little sluggish. Runs fine but seems underpowered. The 90 hp model number E90JELOR refers to it as 90 hp 1995 Evinrude Outboards 65 [ E90JLEOR ]"but its de rated to a 65 hp by changing to a jet drive. Doesn't seem to be getting to full RPM. Thought it might be a hp issue but now wondering if it is an impeller issue. I talked to a reputable jet drive company and the impeller I have is what's recommended (7 3/8") but seems a bit much. Not sure if I could go to a (7 3/16) to get a litte more RPM? Could be just top much weight?

 

[racerone]

Not sure what post # 9 is all about.-------If it smells like a crossflow and looks like a crossflow , then---

 

[flyingscott]

Here is what is being missed. A factory jet is generally 30% less power than a comparable prop motor. So to get a 90 hp jet you already have a 115 powerhead. If you look up the parts for it you already have a bubble back exhaust. The only way you are getting more power out of that motor is to replace it with a v6. Put up the pics just to make sure

 

[bob johnson]

Usually the crossflows have a T or an M in the model #...but from the parts diagram the motor is a crossflow.....

sorry for the confusion...



to the OP:... if your boat seems underpowered by that jet..one reason maybe that the foam is full of water.... I have a 2070 Roughneck, and this past summer I tore the whole boat aprt and cut out the factory foam... each 1 square foot of foam weighed between 14 and 17 lbs!!!!!!!!! it was SATURATED with water.....my boat was hundreds of lbs overweight because of the water the foam was holding...

bob

 

[btomlins]

It is a 90 hp crossflow powerhead. It gets de rated to 65 hp by adding the jet drive. See the 65 hp engine cover. I never thought of the foam saturated. I guess I should weigh the entire set up too. My original question was, can I add the exhaust, carbs for a 115 powerhead on my 90 hp power head and get more than the derated 65 hp out of it?

 

[interalian]

What's the carb throat size? That's cast into the front of the upper part of the carb where it bolts to the silencer. Adding a bubble back exhaust requires the addition of the exhaust chest fillers, and optional machining of the rib in the bottom of the block for flow. But without enough intake porting, you won't get full benefit.

 

[emdsapmgr]

The 115 has the following upgrades from a 90 block: larger carbs (1 5/16" throats). Oversize porting both exhaust and intake. Bubble back exhaust application. The heads are the same between the two engines.

 

[bob johnson]

Wish I could help, I had thought the model was a looper!, and since I did the conversion, I jumped in, but I have never worked on a crossflow other than taking the cover off and looking at one!!!! Good luck..... for all the work involved.....id think a much more sane route is a different motor all together.

 

[interalian]

Or find a running 140 from the '80s, pull the powerhead then plunk it down on your leg.