New member and new Suzuki owner DF40A

[mrpister]

Good news. I am itching to try the 60hp holder. I have a 16" pitch prop waiting...... Two more months for the ice to go out here. Argh.

[Moonlighter]

Ok back from tinny test Suzuki DF40A upgrade trip.

Flipping heck, that motor goes hard now!!

We used to pull 5400 WOT, now we pull 6100 and not even trimmed out much, 50km/hr.

She flies! Accelerates hard onto the plane and if you open her up at cruise revs it jumps up instantly. Goes fantastic.

So very happy with the upgrade!

The motor just sounds strong.

[Salty01]

As Grant said been lurking around here for a while, great site for info.

Did the mod on my DF40 and as Grant posted, *** what a difference 6200 with throttle to go, so a new prop was in order. Got a 11.4x15 C-Plus from Solas and took it for a run 5450 and 5500 trimmed out .

So next day I drive an hour up the coast for a swap no point going the 14 so went for a 13x11.6 C-Plus. Test run got 5850 with 5950 trimmed way out, probably not the best but I don't want to go for a 12. Picked up 7kmh and better hole shot so happy with that but was hoping for a little more.

Looks like the blade style and cupping on the Solas props adds two or more inches pitch over a OEM Suzuki prop - 13 Solas = 15 or a 16 OEM.

Could try a 4 blade but for now will keep the 13, boat is a 4.55 mtr Polycraft plastic fantastic so it is quite a heavy boat for its size.

Cheers Salty

[redlowrey]

I wonder what sought of air fuel ratio these engines are running at wide open throttle now, might bite you on the arse down the track. It would be interesting to see the colour of the porcelain of a spark plug after a hard run, my guess it would be snow white.

[Moonlighter]

I wonder what sought of air fuel ratio these engines are running at wide open throttle now, might bite you on the arse down the track. It would be interesting to see the colour of the porcelain of a spark plug after a hard run, my guess it would be snow white.

Not many opportunities to run WOT in small 4-4.3m tinnies and poly's, Red, as you would well appreciate. Rare indeed, and scary at 50km/hr in boats that size unless its dead calm!

All of us have done WOT runs simply to check if the props we have are still the best option for out of the hole and cruise performance. I doubt very much if anyone is going to be doing extended WOT runs in the future, i certainly wont be.

Apart form that, the motors all have MAP sensors and i think that they will allow the ecu to compensate fuel mixture quite nicely.

[redlowrey]

This is right moonlighter, but the map sensor runs at around 1 volt at idle and 4.5 volts wide open throttle, nothing is going to change with the map voltage at wide open throttle, the ecu will still only see 4.5 volts and with the restrictor removed a lot more air bypassing the throttle plate. It obviously works, it would be interesting to know what the air fuel ratio is at wide open throttle max load.

[mrpister]

From what I have read, more than the MAP sensor is responsible for fuel flow.

There are sensors for engine rpm, throttle position, coolant temperature and ambient air temperature involved.

I may well be wrong, but if the DF40A ECU adjusts fuel flow for the usual WOT max of 5800 rpm, I would guess that when the ECU sees 6100 rpm, it would increase fuel flow to compensate.

When I ran WOT with the 50hp restrictor for quite a few hours, Suzuki's SDS diagnostic tool saw no overheat conditions. Not even close. Granted, that was not the 60hp silencer holder, but I was still running well above 6,000 rpm for long periods.

My guess is the ECU differences, for the 40 and 50 at least, are just the rev limit spec.

[redlowrey]

The map sensor is the main sensor for fuel to the injectors, the inlet air temp sensor is only a trimer, and coolant temp is there for cold start and over heat conditions. These engines run in open loop and the ecu would not have any idea if the engine was running rich or lean, and your sds will tell you jack squat about what the air fuel ratio is. These engines have all got different ecu part numbers and the sixty hp has got different part numbers for the injectors. As I said in my first post I would think they would be running leaner than they should.

[pafnuc]

Anyway: IMHO for testing hi-octane fuel is good idea. If we go to lean knock combustion is possible.

[Moonlighter]

When you look up the part numbers for the ECU's on this forum, it says the 40 ECU is also used on the 50 and 60, and the same thing is said for the ecu's on the 50 and 60 - that they are also used on the other motors.

Is that a giveaway that they are actually the same?? Would certainly suggest so!

Red, no doubt we will all need to keep an eye on spark plugs to see if there are any signs of excessive lean running. The extra power thats evident certainly suggests a lot more fuel is being injected, though. I suppose the other way of field checking would be to look at fuel flow rates at the higher rpm's. I already have a N2k network set up on my small boat, not linked to the engine, maybe I might think about getting an interface cable and connecting her up sometime. Then would need to do a comparison between the 2 silencers.

[allycat]

OK Red point taken, the problem I had was getting out of the hole, it used to jump initially and then have the feeling that someone threw out the anchor and felt "choked", I'd have fishing mates having to jump to the front to get it up on plane and was just damn embarrassing as it dragged its ass for a 100 metres or so trying to get going. The enquiries I made to dealers was that there was no way this could be modified but for $3k changeover they would trade my 30hr old engine on a 60hp, There had to be another way! The trouble with using a big engine derated is the weight when used on smaller hulls causing the transom to "bear down" and be difficult to get on plane so the difference it has made getting out of the hole is nothing short of amazing, I don't plan to use WOT so much as to get going from a standing start so when cruising the throttle won't be providing anymore air than before with the restrictor in place. I don't expect any issues as I have run with it for a while now and all inspections have shown nothing out of the ordinary. By the way you seem to exude extensive knowledge on Suzuki are you a Dealer?

[2014DF25ARS]

This thread is focused on the 40-50-60 series motors, but I will report results from a test I did this past weekend with the DF25A motor I have on my 13-ft aluminum runabout. My boat weighs about 250 lbs empty without the motor. The DF25A and DF30A share a common 3-cylinder platform.

For around $5 I bought the non-restricted version of the air intake "seal" and installed it in my motor yesterday, supposedly converting it from a 25 HP to 30 HP motor. So in theory, I'm comparing performance with a 25 HP motor to performance with a 30 HP motor.

I currently have a 12-pitch, lightly cupped, stainless "Turbo Hot Shot" prop on my motor.

With a co-pilot in the boat (crew = 2 = probably 350 lbs load), we went upstream and downstream about 1/2 mile in the river near my home town. There was a moderate wind blowing downstream, so when we ran upstream we were running against more wind... I don't know the windspeed; it was enough to rough up the water, but not close to whitecaps. First we ran the "stock" motor, then pulled the boat out of the water and swapped from "Restrictor" to "Seal" in the parking lot - took about 15 mins - then re-launched the boat and tested the "30 HP" modification.

In the 25 HP engine configuration:

Upstream WOT we saw 5650 RPM and 26 MPH
Downstream WOT we saw 5750 RPM and 29 MPH

In the 30 HP (?) engine configuration:

Upstream WOT we saw 5750 RPM and 27 MPH
Downstream WOT we saw 5850-5900 RPM and 30 MPH.

When I'm alone in my boat, I hit 5000 RPM on plane from a stop in about 2.5-3 sec. With a second person onboard, it probably takes about 4 sec to reach 5000 RPM on plane. To be honest, I can't say that I felt a significant difference in "hole shot" after installing the 30 HP gasket.

Bottom line: I found about 100-150 RPM and approx 1 MPH difference between the 25 HP vs a 30 HP (I think) motor.

I included photos of the "Restrictor" that sits in the airway of the 25 HP motor, and the "Seal" that sits in the same location in the 30 HP motor, and one of my 3 spark plugs after about 30 mins running around with the "30 HP" motor mod.

[mrpister]

Thank you for sharing your results. Even though it is a different displacement, I think we can all agree that the air restriction on otherwise identical motors restricts the maximum performance available.

About two more weeks here in frigid Canada and I will be able to try the 60 hp silencer holder on my 40. Assuming the ice is out.

I am going to test two different prop pitches, as I found a dealer who will let me try a 15 and 16 OEM Suzuki aluminum.

Stay tuned.

[pafnuc]

I can't wait for results of your tests. Especially the difference betwen 15 and 16 props. Good luck mrpister.

[allycat]

This thread is focused on the 40-50-60 series motors, but I will report results from a test I did this past weekend with the DF25A motor I have on my 13-ft aluminum runabout. My boat weighs about 250 lbs empty without the motor. The DF25A and DF30A share a common 3-cylinder platform.

For around $5 I bought the non-restricted version of the air intake "seal" and installed it in my motor yesterday, supposedly converting it from a 25 HP to 30 HP motor. So in theory, I'm comparing performance with a 25 HP motor to performance with a 30 HP motor.

I currently have a 12-pitch, lightly cupped, stainless "Turbo Hot Shot" prop on my motor.

With a co-pilot in the boat (crew = 2 = probably 350 lbs load), we went upstream and downstream about 1/2 mile in the river near my home town. There was a moderate wind blowing downstream, so when we ran upstream we were running against more wind... I don't know the windspeed; it was enough to rough up the water, but not close to whitecaps. First we ran the "stock" motor, then pulled the boat out of the water and swapped from "Restrictor" to "Seal" in the parking lot - took about 15 mins - then re-launched the boat and tested the "30 HP" modification.

In the 25 HP engine configuration:

Upstream WOT we saw 5650 RPM and 26 MPH
Downstream WOT we saw 5750 RPM and 29 MPH

In the 30 HP (?) engine configuration:

Upstream WOT we saw 5750 RPM and 27 MPH
Downstream WOT we saw 5850-5900 RPM and 30 MPH.

When I'm alone in my boat, I hit 5000 RPM on plane from a stop in about 2.5-3 sec. With a second person onboard, it probably takes about 4 sec to reach 5000 RPM on plane. To be honest, I can't say that I felt a significant difference in "hole shot" after installing the 30 HP gasket.

Bottom line: I found about 100-150 RPM and approx 1 MPH difference between the 25 HP vs a 30 HP (I think) motor.

I included photos of the "Restrictor" that sits in the airway of the 25 HP motor, and the "Seal" that sits in the same location in the 30 HP motor, and one of my 3 spark plugs after about 30 mins running around with the "30 HP" motor mod.

Although the increase is not going to be as great ( 5hp max at best ) it would be a lot harder to "feel the difference" given the only increase will be 5hp or less, never the less an increase was noted which is great, with the 40hp going to 60hp the difference on my boat is very substantial even though there is a chance it may not be reaching the WOT specs of the true 60hp it is an entirely different boat and the increase is soooo great it is impossible not to notice even down to the growl it now puts out when opened up. this mod may not suit everyone especially if you are abiding by warranty requirements but for me I can't go back now it's too good. Cheers and good luck.