YAnmar 3GM30F forced air induction mod

[julius222]

OPINIONS WANTED

I am thinking of using a bilge blower to force air into the engine air intake

My reasoning is that:
the original air filter seems small and sounds restricive
it sucks in hot air from the enine vicinity. colder air means more oxygen for the same volume
Forcing more air in should give better fuel consumption by burning more air/less fuel

Using round/close enough good enough numbers so I can use mental arithmetic for my estimates

Engine is 1 litre (0.954)
RPM 4000 (3600)
therefore need a blower that moves more than 4000 litres per minute. Is this right?

Both the Aqua trak and JAg 4 inch bilge blowers move almost 8000 litres per minute. That should prove adequate and provide a little over pressure. They draw 6 amps. With an 80 amp alternator, there is adequate electrical power.

Place the air intake for the blower somewhere cooler than the engine housing

Would this work??
I lose the power needed to produce 6 amps. What will I gain?
Would I get better fuel economy?
What extra stresses are there on the engine by increasing the compression ratio using forced air induction?
Any other risks involved?

Calling all engine experts
Comments please

[a64pilot]

It's not going to do anything truly but waste your time and money. Pressure would be negligible. Takes more power than you can imagine to run a Supercharger, look at the size of a drive belt on one to see how much power it takes
Only way it could hurt that I can think of is if something like a bower piece part got ingested into the engine, that could get expensive.
Even a cool air inlet won't yield enough power difference to be measurable.
Best thing to do in my opinion is to leave it stock and spend that money on frequent servicing.

A high power leaf blower has been shown to increase power on small cars like a Honda Accord on a Dyno though, done I believe more as a joke.

[Azul]

You are trying to get it to burn less than the usual one-half gallon per hour at cruise by making it less reliable?

I've run NOS on a Miata but I still don't see the point ha.

[sailorchic34]

Agree with the others that it's not really going to do anything. The GM engines are old tech, reliable, but not high output, which I think is a good thing. Simple and reliable and a blazing 20 ish HP.

The injection timing is based on atmospheric inlet conditions. Best not to mess that up with a pressurized intake.

Best you should do is run a cold air duct to the outside. The net effect would be minimum on a yanmar GM engine.

[Wotname]

As well as the bilge blower why don't you connect up the bilge pump at the same time. This way you will forced induction air as well as water injection. Bumps up the compression ratio and keeps the cylinders cooler. Stick some water/methanol mix in the bilge for added HP.

Just kidding….

[Rainh2o2]

You won't get better fuel consumption. If you forced enough air in, you will lose power but burn the same amount of fuel...essentially leaning out the mixture. You have to keep the mixture in balance or you will run lean and stall. I don't know about your engine but the reason a cold air intake is supposed to work is the cold denser air can hold more fuel vapors, more air and more fuel in the same suze cylinder produces more power, however with modern computer controlled cars with oxygen sensors, the computer adjusts the fuel to keep factory stoichiometric settings vs polution emissions at bay. actually at times it will lean the mixture if needed to keep within those settings so the cold air intakes are useless unless other mods are made to the car. Not sure if your marine engine would do that but I suspect it would probably just lean the mixture and cause power loss or engine damage.

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[Wotname]

Originally Posted by Rainh2o2

You won't get better fuel consumption. If you forced enough air in, you will lose power but burn the same amount of fuel...essentially leaning out the mixture. You have to keep the mixture in balance or you will run lean and stall. I don't know about your engine but the reason a cold air intake is supposed to work is the cold denser air can hold more fuel vapors so your supposed to get more power, however with modern computer controlled cars with oxygen sensors, the computer adjusts the fuel to keep factory stoichiometric settings so they are useless unless other mods are made.

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FWIW, the theory aspects for the OP's engine is that the throttle lever essentially sets the RPM desired. The amount of air inducted is fixed by engine design and the governor dumps enough fuel into the cylinder to maintain the desired RPM.

So if the OP can get more air into the engine than the engine was originally designed for, the capacity of the engine is now "increased". The throttle lever will still only set the desired RPM and the governor will still dump enough fuel to get that RPM. Will it be more efficient - I dunno but I reckon the difference would be very very slight...

[01kiwijohn]

As an ex Yanmar service manager, looking at some of these replies, I'd advise you to leave the damned thing alone. Use good quality lube oil, change it as instructed, clean the air intake mesh/ screen annually and it'll last a long time. Pull the injectors every 2000 hours or so and have a "qualified" injection shop take care of them. Enjoy!!

[julius222]

Hi

Thanks all for your input
And Wotname..please keep yr sarcasm to yourself..not appreciated.
.
Is there anyone with a good theoretical knowledge of diesels?
We all have a good practical knowledge. But just because we use something it does not mean we realy understand what is happening or what would happen if we made changes.
.
This is my third 3GM and I have been very happy with them. I know how reliable they are...I do understand the conservative "if it aint broke dont fix it"....I'm a tinkerer by choice, hence this thread

Engines, diesel, petrol, marine, truck, ...all have a forced air induction option. Example, My 135 hp Perkins comes with a bolt on turbo kit option.

And doesn't Yanmar have naturaly aspirated and forced air versions of the same engine? 01KiwiJohn. From your service background, CAn you please let me know what the differences are? The engine block is the same? pistons are the same? injetors and injector pump the same? Does the factory just bolt on the turbocharger and leave everything else the same?

So why not a 3gm?
AND WHY ARE THERE FORCED AIR INDUCTION OPTIONS ANYWAY?
(sorry, hit caps lock accidentaly)
Because it provides more power for less fuel
.
I wonder if there is an engineering student out there that can crunch some numbers
Hmmm...what can I remember from high school?
Density is proportional to pressure and inversely proportional to
temperature..
An engine compartment heats up..guestimate 20 degrees from 25 to 45 c so at 100 kpa, air density will decrease from 1.184 to 1.108 so sucking in colder outside air gives 7% more oxygen than using the engine compartment air.

Would an engine room blower providing 7000 litre per minute to an engine
using 3000 litres per minute raise the pressure from 100 to 105 kpa or maybe 110 kpa?
Guestimate a 5 to 10% increase in oxygen with the blower and a correspondingly higher compression ratio.
.
(The volume of the combuston chamber has not changed but you are compressing more air into that volume so...maybe compression RATIO is not the correct term but close enough)
.
The mixture will be leaner but dont you need a leaner mix with higher compression??
.
Higher compression and 10 to 15 % more oxygen has got to make a measureable power difference.
.
A big downside is that the operating tempereature will increase due to leaner mixture and higher compression. Will it get hot enough to burn a hole in the piston?
.
I'm guessing...need some facts
C'mon you guys...someone somewhere...must have enough theory to explain the process



Cheers

[roverhi]

FWIW, when VW turbo'd their old Rabbit Diesel they made over 50 changes to the engine. Even with all those upgrades like oil spray of the piston skirts, the turbo'd engines didn't have a reputation for longevity. You can't get more output out of a given displacement without putting more stress on the internal parts of the engines. Some engines may be able to handle the stress but you won't find that out till the engine fails to blow up prematurely.

Doesn't sound like you are going to listen to reason so have at it. BTW, why do you need more hp out of the 3GM30, pulling water skiers??

[GrahamHO]

If you did; unlikely, manage to increase the power you will decrease the reliability. Yanmar designed the intake for a reason. If they could have got one more horsepower by redesigning it they would. I have a 2GM20 and I guess it's intake is similar.
Your 80 amp alternator (I have the same Hitachi one from a 3GM30 ) is absorbing 1.5 horsepower. There are 746 watts to 1 hp. Watts is volts X amps. So 80 amps X 14 volts divided by 746 = 1.5 HP round figures. You can calculate what your blower might absorb the same way. Your 6 amp blower absorbs around .1 of a horsepower. How is one tenth of a horsepower boost going to make your 30 (27 HP) any more powerful?


What you are proposing is supercharging. When an engine is supercharged it is normal to decrease the measured compression ratio as supercharging will increase the effective compression ratio. That is because the volumetric efficiency is increased. But with a diesel you would also need to inject more fuel to obtain more power.


Boy racers often install a pretty looking alloy cold air intake with a less restrictive air filter in their cars. That's not a bad thing to do. My Nissan V6 has that as standard factory designed in black plastic as do many other cars these days. There are also after market electric blowers designed for the intake, as you are suggesting. But all those things are for gasoline engined cars. All I suspect the add on electric blowers do is to create more turbulence and mix the atomised fuel better with the air. But our diesels are only sucking in air as the fuel is injected in each cylinder during the power stroke.


I've installed an electric fan (wired to the start key) in my Yanmar engine box mainly to cool the alternator which has a smart regulator. It's a large computer cooling type of fan. At the same time it supplies cooler air to the intake which is not a bad thing. Though its improvement to actual power is doubtful. A change in the atmospheric barometric pressure probably makes more difference.


What truck racers ( Kenworth etc tractor units racing on a circuit) do to increase the power of their turbo supercharged trucks (exhaust driven) is to modify or replace the injector pumps to squirt more fuel in their engines. They tell me it drastically decreases the life of the engines but increases the power. They pour out black smoke when they accelerate with the turbo lagging behind the fuel supplied.


I suspect Yanmar have designed their air intake to be able to supply the amount of air required by the capacity of the fuel injection pump. If you did manage to supply more air to your cylinders you would also need to inject more fuel to obtain more power.


I would say "yes" to ventilating your engine compartment by better supplying cooler air.


One more thing. Look at your exhaust system for any restrictions. Is your system (1,1/2" ?) all the way including the water lock and final outlet. I've often seen boats where a bit of plastic pipe extension is jammed in an already restrictive cast bronze exhaust skin fitting. I found my original plastic water lock had 1,1/2" in and out but the hole inside the inlet was only 1". I replaced it with a larger water lock. Improvement to your exhaust system is the best area to obtain the factory power rating. A thin wall SS skin fitting is best as there is little restriction. Don't forget the exhaust system has to carry cooling water as well as exhaust gasses.


Turbo charged marine diesel engines factory designed are a different story and enable an engine to have a better power weight ratio and they absolutely need a good exhaust system. Factory turbo engines are good but I think they add another potential problem area.



Old piston engined aircraft such as the Super Constalation had superchargers plus turbo chargers to maintain power at high altitudes.

[GrahamHO]

Originally Posted by Rainh2o2

You won't get better fuel consumption. If you forced enough air in, you will lose power but burn the same amount of fuel...essentially leaning out the mixture. You have to keep the mixture in balance or you will run lean and stall. I don't know about your engine but the reason a cold air intake is supposed to work is the cold denser air can hold more fuel vapors, more air and more fuel in the same suze cylinder produces more power, however with modern computer controlled cars with oxygen sensors, the computer adjusts the fuel to keep factory stoichiometric settings vs polution emissions at bay. actually at times it will lean the mixture if needed to keep within those settings so the cold air intakes are useless unless other mods are made to the car. Not sure if your marine engine would do that but I suspect it would probably just lean the mixture and cause power loss or engine damage.

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Diesels CANT run lean. There is no air fuel mixture such as 15 /1 in a gasoline engine. In a diesel engine the fuel is burned as it is ignited by the heat of the air compressed in the cylinder. More fuel; more power; less fuel less power. The amount of air induced stays practically the same. ( slightly less air gets in at higher revs)

[farm sail]

Originally Posted by Rainh2o2

You won't get better fuel consumption. If you forced enough air in, you will lose power but burn the same amount of fuel...essentially leaning out the mixture. You have to keep the mixture in balance or you will run lean and stall. I don't know about your engine but the reason a cold air intake is supposed to work is the cold denser air can hold more fuel vapors, more air and more fuel in the same suze cylinder produces more power, however with modern computer controlled cars with oxygen sensors, the computer adjusts the fuel to keep factory stoichiometric settings vs polution emissions at bay. actually at times it will lean the mixture if needed to keep within those settings so the cold air intakes are useless unless other mods are made to the car. Not sure if your marine engine would do that but I suspect it would probably just lean the mixture and cause power loss or engine damage.

Sent from my SAMSUNG-SM-G890A using Cruisers Sailing Forum mobile app

some of that might be accurate for a computer controlle gas engine but totally irrelevant for the diesel engine. yes adding more air even without more fuel will make the engine more efficient, ie make more power with less fuel. weather that gets you any extra power at max is dependent on if there is more available fuel to be burned. most factory diesels run a wee bit rich at full load and could make a bit more power. with more air. if you bump the intake pressure a couple of psi without adding extrs fuel you could increase efficientcy and power slightly without worry. but your bilge blower wont do it. and the cost to doit with a turbo would not be worth the slight gain. now if you boost the air and the fuel along with all the other mods required to keep the engine from melting down you can see some serious gains. but it aint cheap or easy

[GrahamHO]

Originally Posted by farm sail

some of that might be accurate for a computer controlle gas engine but totally irrelevant for the diesel engine. yes adding more air even without more fuel will make the engine more efficient, ie make more power with less fuel. weather that gets you any extra power at max is dependent on if there is more available fuel to be burned. most factory diesels run a wee bit rich at full load and could make a bit more power. with more air. if you bump the intake pressure a couple of psi without adding extrs fuel you could increase efficientcy and power slightly without worry. but your bilge blower wont do it. and the cost to doit with a turbo would not be worth the slight gain. now if you boost the air and the fuel along with all the other mods required to keep the engine from melting down you can see some serious gains. but it aint cheap or easy

Quite right and I'm not contradicting you. But if I were being pedantic I would say they don't "run rich at full load". They smoke with unburnt fuel when they can't obtain full revs and the throttle is fully open. That's different from being under full load and obtaining maximum revs when there should be little or no unburnt fuel. Diesels actually normally induce more air than is needed. It is the fuel that supplies the power. There is no mixture. Fuel is burned practically instantly as a stream of fuel is injected. Almost like a steam engine roughly speaking.

And you are theoretically correct saying bumping the pressure a couple of psi increases the efficiency. That's because the effective compression ratio is increased. However that being the case, why don't manufactures simply make the compression ratio say 30:1 instead of 22:1?
They don't want their motors to blow up; that's why.

[farm sail]

Originally Posted by GrahamHO

Quite right and I'm not contradicting you. But if I were being pedantic I would say they don't "run rich at full load". They smoke with unburnt fuel when they can't obtain full revs and the throttle is fully open. That's different from being under full load and obtaining maximum revs when there should be little or no unburnt fuel. Diesels actually normally induce more air than is needed. It is the fuel that supplies the power. There is no mixture. Fuel is burned practically instantly as a stream of fuel is injected. Almost like a steam engine roughly speaking.

And you are theoretically correct saying bumping the pressure a couple of psi increases the efficiency. That's because the effective compression ratio is increased. However that being the case, why don't manufactures simply make the compression ratio say 30:1 instead of 22:1?
They don't want their motors to blow up; that's why.

I used the phrase run rich at full load for general laymans terms. though most factory engines even those that dont smoke have a slight excess maybe only a % or few when running full throttle at rated rpm. an increase in manifold pressure of just a couple psi can lead to a small improvement in max power with no other mods. Ialso pionted out that there would be other mods needed for the engine to not melt down if you upped the anne with more fuel and pressure.

the reality is that ccompression ratios by them selves mean nothing. what is important is peak pressures. putting it simply if we lower the comp ratio and then raise the manifold pressure by stuffing more air in till we resch the same peak pressure we can now burn more fuel and make more power. yes if you take it far enough you need to start looking at things like piston cooling, inter/after cooling of charge air, block and component strength/durability and all sorts of other stuff. I was zddressing the op question with out trying to be too technical. I assumed he was talking about sealevel use of the engine so I didnt even memtion the use of altitude compensating wastegates to maintain sealevel performance up in the mountains. I supose we could stsrt breaking out pressure maps looking at a/r ratios flow rate boost ratios and so on... but that would be putting the cart before the horse.

best suggestion for the op is no the bilge blower wont do much of anything. and if he want to learn about turbos, I would start at a perfomance auto parts store bookshelf and grab one of the books about turbocharging. read it several times. even though those books dont go much into diesel turboing you will get a good understanding of the dynamics. then if you want to learn more find some book about diesel turboing or pit crew for some tractor pull folks. some of those guys are running 100+ psi manifold pressures