By Passing the Rev-limiter

[Emustard]

Hey just wanted to know if any one can help answer this question, can I by pass my rev-limiter in my 1990 20hp evinrude?

Rev-limiter cuts in at 6100 rpms can I can't I wire or disconnect something?

[MWhite]

Hey just wanted to know if any one can help answer this question, can I by pass my rev-limiter in my 1990 20hp evinrude?

Rev-limiter cuts in at 6100 rpms can I can't I wire or disconnect something?

dont know on that year model,,u may have to go to a late 80's eletronics if u cant find a way to by pass the limiter

[Emustard]

I could go out and by a non rev-limiter for 150-200$ but just wanted to know if there was a cheaper way. There has to be something or someone that can shed some more light on this.

[omcstratos]

I know on yamaha's it's called the "gray wire mod". If you want to take a gamble, cut it and see if it works. You might could solder it back together if it didn't work...
Actually you should be able to pull the wires straight out of the connector without cutting at all. They slide in the rubber multi-pin connectors.

You should be able to find some used electronics somewhere around.
I replaced my powerpack for a $90 cdi unit, I don't think it is that expensive and it seems to work just fine.

[Emustard]

Thanks I might try that this weekend, a new cdi is about 150-200$ to get it shipped to canada so if there is a cheaper way like cutting a wire, I'm all for it.

[pdt]

can I ask why people want to go past the rev limiter ?
is the power still going to be in the region past the limiter ?
or is this mainly done when the port timing has been changed, obviously the engine can rev higher, but will it produce the horses once it goes past a certain point.

would it no be simpler to just put on the next pitch prop and keep in original power-band if piston /bore work has not been carried out.......

[Emustard]

The reason I want to go past the rev limiter is because I just bought an 18pitch cleaver and am already hitting the rev limiter with it and I don't want to buy another prop so soon. Started with a 13 aluminum could hardly turn 5 grand now with a 18 stainless steel cleaver in hitting the rev limiter at 6100rpms. People go past the rev limiter mainly because the engine will still create power, even above its rev limiter. The manufactures put a revlimiter in to increase engine life.

[pdt]

Yes I understand it can go above the rev limiter, but at what revs is the powerband ?
its not a continuing thing, there is a band that runs ceretain revs to create power, then once it goes past a certain point the power drops off.
would a tweak in the prop not be a better idea ? so you still have plenty of power and torque etc..18 inches of pitch is a fair bit for a 20hp, what diameter is the prop
and how high do you run it.
any pics of the engine on the boat ? sounds like a pretty cool boat engine set up to be getting those revs

[HankFrazier]

Yes I understand it can go above the rev limiter, but at what revs is the powerband ?
its not a continuing thing, there is a band that runs ceretain revs to create power, then once it goes past a certain point the power drops off.
would a tweak in the prop not be a better idea ? so you still have plenty of power and torque etc..18 inches of pitch is a fair bit for a 20hp, what diameter is the prop
and how high do you run it.
any pics of the engine on the boat ? sounds like a pretty cool boat engine set up to be getting those revs
when u unhook the rev limiter and run your motor with no oil in the gas at high rpm's it allows the pistons to stick to the cylinder walls this then allows the rods to stretch and increases the stroke and that helps the low end torque and u can accelerate faster. the trick is to know how much to stretch those rod's.

[pdt]

when u unhook the rev limiter and run your motor with no oil in the gas at high rpm's it allows the pistons to stick to the
cylinder walls this then allows the rods to stretch and increases the stroke and that helps the low end torque and u can accelerate faster.
the trick is to know how much to stretch those rod's.


now that is a wonderful explanation ;)

[omcstratos]

can I ask why people want to go past the rev limiter ?
is the power still going to be in the region past the limiter ?
or is this mainly done when the port timing has been changed, obviously the engine can rev higher, but will it produce the horses once it goes past a certain point.

would it no be simpler to just put on the next pitch prop and keep in original power-band if piston /bore work has not been carried out.......

Speed is all about RPMs. The more you turn the faster you can go. By throwing a larger prop on, you will decrease your RPMs and put a bigger load on the motor. Once you find the best prop, you do all you can to get the highest revs with it.

[pdt]

its only the more you turn the faster you go within the power curve

[omcstratos]

If I can remember correctly, He has modified the motor at least raising the compression and something with the exhaust tuner. I wouldn't be surprised if his motor made a little more power on the top end.

As much as you talk about the power curve and other things, if I knew any better, i'd say you might go by the name Phill

[Chairman]

Try Tim's Outboard in Hackensack, MN. 218-682-2331. They have a large inventory of used parts, and they ship. Make sure the pack does NOT have "6100" printed on it -- that's the limited version.

[MWhite]

its only the more you turn the faster you go within the power curve

If u know so much phil why u keep asking silly pointless question? Then when someone does answers u, u dont believe what they tell u,, cause it dont meet your theory.... someone wanting to turn more rpms and run faster will unhook the rev-limiter so the motor can turn up more and get more out of there engine,,, it dont take a rocket scientist to figure that out.. No one can ever explain nothin to u, and no explanation is ever going to meet your thoughts or understanding, u just dont comprehend things.

[pdt]

I have said nothing wrong
just stating that a tweak of the prop could be better if the engine was not a worked on engine.

everywhere on this forum there is mention of the power in a given rev range of the engines, why would this be so different to all the other posts about power/speed increases ?
I agree it don't take a rocket scientist to work it out, IF the engines power band has been taken further up the range, that is basic engine power theory.
There is plenty of people who would say to go up a prop rather than exceed the rev limiter.
I only asked why Mike.

[omcstratos]

I have said nothing wrong
just stating that a tweak of the prop could be better if the engine was not a worked on engine.

everywhere on this forum there is mention of the power in a given rev range of the engines, why would this be so different to all the other posts about power/speed increases ?
I agree it don't take a rocket scientist to work it out, IF the engines power band has been taken further up the range, that is basic engine power theory.
There is plenty of people who would say to go up a prop rather than exceed the rev limiter.
I only asked why Mike.

People that cut the rev limiter wouldn't do it if it didn't help.

To answer your question, "Can I ask why people want to go past the rev limiter? ...would it no be simpler to just put on the next pitch prop and keep in original power-band if piston /bore work has not been carried out.......?" I would say you are probably a person that would be better off to stay with a stock powerhead and play around with props that run within your powerband. Keep the more complicated setups to people that know their stuff better.

And if you ask a question on here, take in the answer instead of challenging it with your own logic.

[pdt]

ok
this is to omc stratos
what is your top revs and what power does the engine produce at these revs ?
what is the powerband range now ? and what was the original range for the powerband ?
that's pretty easy to answer I imagine,its not a trick question im serious as this would prove a very valid point that is not coming across on here,

[Chairman]

Racing GT Pro (OMC 32.8, 30/35hp), I've always had the best results running in the 6400-6800 rpm range. However, the 20hp version of this powerhead is seriously restricted at the intake, so results may be different.

[Fast Fred]

as torque falls off, the hull also gets lighter, cuzz of air intrapment ( the style of hull will determiner how much lift you get) rpms give her legs to advance in speed. example; torque starts to falls away at 58-6200rpms, but she is still makin more hp up to 7800rpms, she is fastest at 8000, torque is long since fallen off:cool:

[pdt]

how is the hp calculated if the torque has fallen off by 1,600 rpms ?
this is a huge gap away from the max powercurve !!!!!

ive never ever come across an engine that develops its highest power at its highest rpms before, not even on race bikes and race cars.

[omcstratos]

how is the hp calculated if the torque has fallen off by 1,600 rpms ?
this is a huge gap away from the max powercurve !!!!!

ive never ever come across an engine that develops its highest power at its highest rpms before, not even on race bikes and race cars.

Hey, phillnjack, do some research on the internet. There's plenty already out there instead of challenging what's been said here.

[Powerabout]

hp is a calculation from torque and rpm so clearly hp can climb when torque goes down

[zul8tr]

Rev limiters are installed by the factory to keep the engine at the rpm they feel is reasonable for the multiple uses intended without over rev for warranty claimes for a damaged engine. These outboards can run quite well above the rpm the factory limits them to as hp increases above max torque to a point then drops off, but the owner would be out of warranty if the limiter is disabled, but in Emustard'd case his 1992 warranty is way gone, he should so go for more revs and more pitch if the engine power is there.

As an example with my race 1972 Merc 25ss 2 cylindere Mercury (no rev limiter) states in the specs max recommended rpm = 6600. Well that didn't win races so all us 25ss guys raised them up increased the prop pitch and ran these engines at 7100+ with more oil than the recommended 25:1 and much greater speeds.

[Powerabout]

Rev limiters are installed by the factory to keep the engine at the rpm they feel is reasonable for the multiple uses intended without over rev for warranty claimes for a damaged engine. These outboards can run quite well above the rpm the factory limits them to as hp increases above max torque to a point then drops off, but the owner would be out of warranty if the limiter is disabled, but in Emustard'd case his 1992 warranty is way gone, he should so go for more revs and more pitch if the engine power is there.

As an example with my race 1972 Merc 25ss 2 cylindere Mercury (no rev limiter) states in the specs max recommended rpm = 6600. Well that didn't win races so all us 25ss guys raised them up increased the prop pitch and ran these engines at 7100+ with more oil than the recommended 25:1 and much greater speeds.
That works on light boat where you decrease the drag so dont need the torque and the engine will either have a same hp or more as the rpm goes higher

[Powerabout]

Hey just wanted to know if any one can help answer this question, can I by pass my rev-limiter in my 1990 20hp evinrude?

Rev-limiter cuts in at 6100 rpms can I can't I wire or disconnect something?
there is a service bulletin showing where to drill a hole in the pack to disconnect the rev limiter if it has one
or just use an earlier pack as they didnt have limiters

[Emustard]

Hey thanks for the tip, I ended up buying a no-rev limiter from CDI. installed it this weekend and it worked great hopefully some more runs this weekend. Thanks everyone for your help.

[Fast Fred]

you can drill it, but if you miss, always used the non rev limiter box my self. stock 75hp omc 49cubes, hp and torque peak together at about 5800rpms, after that torque starts to fade or fall off, hp however holds at 75hp all the way to 7800rpms then hp starts to fade, stock, out the box,:cool: gots to go fix boats........

[Fast Fred]

:cool:55hp omc head is not a good choice, someone asked

[Powerabout]

you can drill it, but if you miss, always used the non rev limiter box my self. stock 75hp omc 49cubes, hp and torque peak together at about 5800rpms, after that torque starts to fade or fall off, hp however holds at 75hp all the way to 7800rpms then hp starts to fade, stock, out the box,:cool: gots to go fix boats........
no argument there Fred
I am surprised the 75 makes power to 7800, so light boats prop'd over 7500?

[pdt]

well the 75hp 3 cylinder omc engines in Europe never came out the box revving at 7800 that's for sure.
must of been specials that revved that high
.or is this free running in neutral !!!!!!

[Fast Fred]

:cool:sorry to to see you are still havin a bad time with yourself, anyhoo, the " special" ones made more hp than 75, had a stronger torque curve...........:cool: