2018 F75 to 90hp

[boatinpete]

Can this engine be converted to a 90 like the last gen were proclaimed to be. Was wondering as I might give it a shot if its possible, anyone know the actual difference?

[ausnoelm]

It won't matter how many places you ask, the answers will be the same, some say yes, some say no, some say try it and let us know, your choice, I think there was a guy on here who tried it, came back with all sorts of incredible figures, most unbelievable.

[boscoe99]

Only difference appears to be the ECU. Stands to reason.

$1213.70 and your F75LB will become an F90LB.

Interesting to note that the F90LB is priced at only $330 more than the F75LB. An expensive way to get the F90LB.

[boscoe99]

It won't matter how many places you ask, the answers will be the same, some say yes, some say no, some say try it and let us know, your choice, I think there was a guy on here who tried it, came back with all sorts of incredible figures, most unbelievable.

It is so easy for anyone to determine the truth. On their own. Apparently they would rather come to the innerweb and get answers that, as you note, are all over the map.

[99yam40]

It is so easy for anyone to determine the truth. On their own. Apparently they would rather come to the innerweb and get answers that, as you note, are all over the map.

and have no solid proof that there was a an increase or how much of an increase there was.
Dyno runs before and after might say, if they did not falsify them

[boscoe99]

I did what the OP could have done and compared all of the F75LB parts to all of the F90LB parts. Only difference was the ECU and the Cowling.

It is quite easy in this instance to up the HP of the F75LB to the F90LB. It is just gonna cost some money. More money than if the F90LB had been purchased in the first place.

Everyone is looking for a free lunch. I mean free HP.

[99yam40]

Yea, my 1st thought was also why buy a 75 if you want a 90

I understand the injectors can dump more fuel, but how do you get more air to go with the fuel

[boscoe99]

Yea, my 1st thought was also why buy a 75 if you want a 90

I understand the injectors can dump more fuel, but how do you get more air to go with the fuel

Good point. I went back and took another look. The intake silencer is different. Add another 60 bucks to the cost to convert.

Guessing that it is more air, more fuel and different ignition timing.

[boscoe99]

[boscoe99]

For about $300 bucks I would certainly have gone with the F90 to begin with.

[panasonic]

Yea, my 1st thought was also why buy a 75 if you want a 90

I understand the injectors can dump more fuel, but how do you get more air to go with the fuel

My thoughts are the engine was designed as a 90 hp and then derated to a 70hp with the use of fuel mapping....the ECU. No changes to the air system where made to derate the engine.

So the 70's air intake system is already capable of supplying enough air that a 90 would need.

All that is required is the proper ECU to bring it back up to a 90hp.

[holmen78]

Like the V6 engines. 200-300hp range can be ECU mapped to 320-330 something.

[panasonic]

My thoughts are the engine was designed as a 90 hp and then derated to a 70hp with the use of fuel mapping....the ECU. No changes to the air system where made to derate the engine.

So the 70's air intake system is already capable of supplying enough air that a 90 would need.

All that is required is the proper ECU to bring it back up to a 90hp.

I posted that with the idea that only the ECU was different on the two different models..

I wonder where I got that information from? lol

[99yam40]

Yea, dumping more fuel without adding more air does not give the proper ratio for burning properly to get the most out of a motor.

my C40 had a high speed miss when I 1st got it.
found out that if I remover the cowling and silencer and ran into the wind I did not have the miss.
turn around and run with the wind it would go back to missing.
replaced the main jets and that problem went away.
someone had drilled the jets out a little.

From what I understand the jets and tuner are different on the 40 and 50 carbed motor back then

just extending the injector on times on these newer motors will need more air too to keep the proper ratio

Do any of you remember the post some time back about a guy swearing all you had to do on a motor was to remove a restrictor plate to increase the HP?
I do not remember if it was carbed motor or injected

[pstephens46]

Yea, dumping more fuel without adding more air does not give the proper ratio for burning properly to get the most out of a motor.

my C40 had a high speed miss when I 1st got it.
found out that if I remover the cowling and silencer and ran into the wind I did not have the miss.
turn around and run with the wind it would go back to missing.
replaced the main jets and that problem went away.
someone had drilled the jets out a little.

From what I understand the jets and tuner are different on the 40 and 50 carbed motor back then

just extending the injector on times on these newer motors will need more air too to keep the proper ratio

Do any of you remember the post some time back about a guy swearing all you had to do on a motor was to remove a restrictor plate to increase the HP?
I do not remember if it was carbed motor or injected

Can’t remember his name but he was some maniac from the Pacific Islands.....typed about as well as BajaKeith.