ECU for 20hp - Page 2

Limecc · 30 January 2020, 10:35

Quote:

Originally Posted by Fenlander

And that's why for a newish £2000+ outboard I'd not risk experimenting for a possible 1kt increase in top speed.

Well researched. Notwithstanding, if someone is willing to forego warranty and accept the cost, swopping just 3 components and prop gives an identical engine, increased power with no increased risk of harm.

The 15 and 20 power/torque curves are probably the same until higher rpm's when the mechanical air intake restriction and electronic rpm limitation have an effect.

15HP = WOT 5000-6000rpm
20HP = WOT 5300-6300rpm

Fenlander · 30 January 2020, 10:52

>>>if someone is willing to forego warranty and accept the cost, swopping just 3 components and prop gives an identical engine, increased power with no increased risk of harm.

Oh yes agreed... then it just becomes a financial decision of £450ish, possible future sale issues and warranty loss for 2kts.

Fenlander · 30 January 2020, 10:58

>>>The 15 and 20 power/torque curves are probably the same until higher rpm's when the mechanical air intake restriction and electronic rpm limitation have an effect.

I'd wondered similar... that in the usual UK sea conditions at mid range speeds there would not be a lot of difference... only if you were doing flat water WOT speed trials.

Suzuki themselves give a slightly unusual performance figure for these OBs... from a standing start to reaching 165ft distance covered. At 7.1sec the DF20 is just 0.4 sec quicker than the DF15 which I reckon you'd hardly notice without a stopwatch.

Limecc · 30 January 2020, 11:11

Quote:

Originally Posted by Fenlander

My guess is the fuelling on the 20hp ECU will be altered for the extra airflow... possibility you might be running far too lean with just the restrictor out and existing ECU given this is already a lean burn engine. This could damage the engine.

My guess is the fuelling is broadly the same. Most of that extra 5HP will be produced at rpm's where the 15 is not allowed. If there is increased airflow then the Mass Airflow Sensor will detect it and adjust.

Also, doesn't the lean burn feature only apply for part-throttle? More of a marketing ploy anyway. Fuel economy will be no better than a non-lean burn Tohatsu.

Lol. Go for it and order the parts Cumbria!

Limecc · 30 January 2020, 11:45

Quote:

Originally Posted by Fenlander

Suzuki themselves give a slightly unusual performance figure for these OBs... from a standing start to reaching 165ft distance covered. At 7.1sec the DF20 is just 0.4 sec quicker than the DF15 which I reckon you'd hardly notice without a stopwatch.

Without an identical prop you can't compare.

Fenlander · 30 January 2020, 11:50

>>>doesn't the lean burn feature only apply for part-throttle

Yes that is how Suzuki describe it but they also publish that it starts rising to a lean burn from about 1500rpm and only drops away from that lean condition above 5500rpm.

The most lean phase is if you are able to maintain between 3000-5000rpm on a moderate throttle.

I don't know if you found it with yours but I could always feel the effect on my DF20 in what I called a slightly non-linear feel to the throttle in use.

Pikey Dave · 30 January 2020, 13:59

Another thing to consider is the way outboards are rated using the ICOMIA standard. Your 15hp might actually be 16.5hp and my 20hp might only be 18hp. Judging how they (Suzuki) rebadged a 115hp as a 140hp, as in the DF140, I think they take full advantage of the leeway that ICOMIA allows.

Fenlander · 30 January 2020, 15:42

Oh no... don't stress Cumbria... he might only have a 13.5hp!

Pikey Dave · 30 January 2020, 16:35

Quote:

Originally Posted by Fenlander

Oh no... don't stress Cumbria... he might only have a 13.5hp!

I know, and I might have a 22hp

beamishken · 30 January 2020, 16:40

Easy answer Pikey meet cumbria for a jolly & swap ecus see how much difference it makes.
Settle the argument

Pikey Dave · 30 January 2020, 17:56

Quote:

Originally Posted by beamishken

Easy answer Pikey meet cumbria for a jolly & swap ecus see how much difference it makes.
Settle the argument

My ECU is staying where it is thank you very much. Warranties work both ways[emoji57]

beamishken · 30 January 2020, 20:41

Quote:

Originally Posted by Pikey Dave

My ECU is staying where it is thank you very much. Warranties work both ways[emoji57]

Understandable [emoji106]

Cumbria · 31 January 2020, 08:32

Lol the 13.5

Meeting up with a few chaps next week with 20s. Will compare and will try a few new props to check diff.
Might even try a ss prop :-)

Fenlander · 31 January 2020, 09:45

Good idea... it's only trying another OB on your boat and getting a feel for it plus some two way GPS speeds that will tell you if the 20hp is a worthwhile improvement for what you are looking for.

If you do prop swapping too posting up the revs and speeds achieved on here is a great resource for folks in the future.

Cumbria · 31 January 2020, 10:06

Defo post , ordered a rev counter as well.

Ordered 2 more different props . Also trying to get a ss to try

jeffstevens763@g · 31 January 2020, 10:29

Quote:

Originally Posted by Cumbria

Lol the 13.5

Meeting up with a few chaps next week with 20s. Will compare and will try a few new props to check diff.
Might even try a ss prop :-)

thats the way to go a SS prop has the potential to give 5% more performance too

Searider · 31 January 2020, 16:32

Quote:

Originally Posted by Limecc

My guess is the fuelling is broadly the same. Most of that extra 5HP will be produced at rpm's where the 15 is not allowed. If there is increased airflow then the Mass Airflow Sensor will detect it and adjust.

Also, doesn't the lean burn feature only apply for part-throttle? More of a marketing ploy anyway. Fuel economy will be no better than a non-lean burn Tohatsu.

Lol. Go for it and order the parts Cumbria!

There isn't a Mass Airflow Sensor.

Throttle position sensor and manifold absolute pressure sensors primarily determine fuelling.

Highland Haggis · 31 January 2020, 22:48

Be careful with ss prop if u hit something underwater or a sudden stop you take the chance of damaging your gear box and the difference on a small outboard would be minimal but I could be wrong with the last comment someone will be along shortly to explain more on prop slip on a small outboard compared to a large outboard my understanding is 5% to 15% slip but sure someone will confirm this more hope you make the right choice Cumbria all the best HH

Poly · 01 February 2020, 07:49

Quote:

Originally Posted by Highland Haggis

or a sudden stop you take the chance of damaging your gear box

I’m with you on hitting something under water. I’m skeptical that the gearbox suffers and harm from a sudden stop - it’s spinning a prop in fluid, surely it just slips?

Cumbria · 06 February 2020, 13:04

Very interesting

On Ullswater yesterday with 2 others who both had 20s.

Tried different props between us all including a go with as.
Prop makes more of a difference than the 15 to 20 hp.
Need to match prop to what doing .

Did have 3 fat blokes up at one point and 2 knots difference but had not changed prop for this.

When similar props than max 1knot difference.

Still investigating the possibility of up to 20 , I think it's the ECU and restrictitor .. but not much of a difference