# 440CC Honda clone , anyone using any of the big singles for Ultra light?

### Help Support HomeBuiltAirplanes.com:

#### Armilite

##### Well-Known Member
Aircraft need continuously rated engines. Hopped up engine power figures are rarely tested for even 1 minute. Race aircraft have had numerous hopped up engines. The TBO reliably suffers attrociously. A 440 is based on a 13ish HP engine. More than doubling the thermal load needs more than a few stronger parts, or something will give.
===========================
A Stock 440 is 18hp! These different Honda/Clones Engines are being used around the World on Real Aircraft with 5000-5500rpm takeoff, so your Arm Chair Mechanic baseless assumptions are wrong. What kind of TBO do you expect from a $350 Engine with$400 in Upgrades? These Type of Honda/Clone Engines used on Industrial Mowers see well over a 1000 hrs. Learn How to Build One for Racing/Airplane use & Maintain it.

#### Armilite

##### Well-Known Member
error in assumptions!!! the rpm where the prop absorbs 75% POWER is about 90% of the max power rpm, not 75%. The engine output is governed by the propeller rule, and that is exponential, not linear. Look at any aircraft engine with a fixed pitch prop and the 75% power is at roughly 90% of max rpm.
================================

Your Cruise Rpm is usually set at 75% of the Engines Max rpm rating. You can change the Power Band up or down, with different CAMs, Lifts & Duration, Tuned Header Exhaust, Carb Size, etc. As I said, IF you Build the Engine for 5000rpm x 75% = 3750rpm would be your Normal Crusie. You can use higher or lower of that Bar! You Prop that Engine to use it's Max Thrust at that 5000rpm! So for the Clone 460 Single making Max 37.37hp@5000rpm for Takeoff, at 75% Power = 3750rpm, it would be making about 31hp and Max Torgue was made at 3800rpm! Until you Build one and install on your Airframe of choice you will have to see what if any Cooling Issues you have. You can do all of these different Engine Coatings yourself, just as you can do all the Bolt-On Upgrades yourself, so it's easier to do it right the first time when you build it. For Aircraft use, I wouldn't use that 307 Cam they used. Makes Good hp. You can see in this 460 Dyno Print the Power Band is too low. It Averages +2.4hp per +200rpm till 3600rpm then starts losing Power. Stock CAM is .246 Lift - .246 Duration. For Airplane use, you want a Wide Lobe Separation.

#### Attachments

• 80.1 KB Views: 6

#### TiPi

##### Well-Known Member
Log Member
sorry, you are wrong. Put the propeller power absorption curve over your power graph so that peak prop power meets the peak hp and rpm and then see where your rpm is when the prop curve crosses the 75% power mark. It is NOT at 75% rpm.

Couple of examples:
Rotax 912: peak power at 5,800rpm, cruise rpm 5,200 (89.65517%)
Continental A75: peak power at 2,600rp, cruise rpm 2,350 (90.38461%)

Last edited:

#### cohocarl

##### Member
F.W.I.W., Last spring I ordered & built a Vegas Carts 460 kit . Mainly because I love building engines and to place in the carcass of my Yamaha Apex that I had intended to remove it's engine and use for another purpose , but plans changed. Link to 4 pages of individual parts.
The 460 runs fine, although even with it's balance shaft it is a shaker. (I even opened the case again to verify I had the balance shaft timed right.) I installed two charging coils which are +/- 3 amp each with stock flywheel.
Rods & flywheels seem to be clone engines weak points. And unsure if aftermarket billet flywheels have provisions for charging coils.

#### n3puppy

##### Well-Known Member
Protech
As a racer I am sure you know that running 75% power does not mean 75% RPM
5000rpm@ 75% power does not = 3750rpm, 5500rpm @ 75% power does not = 4125rpm.

Unfortunately, almost all Dyno tests are run using wide open throttle (WOT). They have little to do with real life loads/power settings. But some people still make that basic mistake since few results are published at carb settings less than WOT

In real life, industrial engines are governed to 3600 rpm at all load levels - 5% to 100% - none are rated 100% power continuous
Generators are good example - 420 cc/ 13hp clone 9500watt starting, and only 7250watt continuous - BOTH at 3600rpm. Fuel consumption is listed at 8 gallons / 13 hrs at 50% power - Also at 3600rpm

As TiPi has indicated when Flying - climbing with the throttle fire-walled, then reducing power to 75% in level flight does not necessarily result in a corresponding RPM change.

Honda rates their 390 12hp peak @ 3600, but only 9.5hp continuous @ 3600
Big bore it, add a cam, increase the RPM ... All will add hp, but none increase thermal capacity.

That often quoted 460 with 37.37hp @ 5000 rpm is peak hp
But 13ish hp output is where it will most likely run continuous without heat soaking - regardless of RPM (unless there are major modifications to aid cooling)

Changing springs, rockers rods, etc can help with higher RPM operation - Which raises PEAK horsepower.
But it does not help with the continuous power limiting factor of heat. Every extra hp means more BTU's of heat to dissipate
Double the HP- Double the heat.

#### TFF

##### Well-Known Member
Naturally aspirated, 75% power in aviation is pretty much a measure of loss in power due to loss in manifold pressure at full throttle at the altitude you can only make 75% power at, properly leaned. It is not throttling back to 75%.

#### pictsidhe

##### Well-Known Member
I wish someone with more money than sense would buy one of these hopped up kart engines and strap it to a test stand with an Eiffel club. But, would they have the nads to tell us how long it lasted at 75% of claimed power?

Unfortunately, 'failed' experiments are far less likely to get reported. That's a real shame, people learn far more from what didn't work than what did.

#### pictsidhe

##### Well-Known Member
F.W.I.W., Last spring I ordered & built a Vegas Carts 460 kit . Mainly because I love building engines and to place in the carcass of my Yamaha Apex that I had intended to remove it's engine and use for another purpose , but plans changed. Link to 4 pages of individual parts.
The 460 runs fine, although even with it's balance shaft it is a shaker. (I even opened the case again to verify I had the balance shaft timed right.) I installed two charging coils which are +/- 3 amp each with stock flywheel.
Rods & flywheels seem to be clone engines weak points. And unsure if aftermarket billet flywheels have provisions for charging coils.
It's possible that different weight parts are fitted. If the crank and balance shaft weren't altered, it will shake more.

#### Vigilant1

##### Well-Known Member
================================

Your Cruise Rpm is usually set at 75% of the Engines Max rpm rating.
As TiPi (patiently) pointed out, this is incorrect. With a fixed-pitch prop (with or without a PSRU), 75% power will occur at about 90% RPM. Unless you are going to use a variable pitch prop, the power shown on the engine's dyno curve can be achieved (i.e. matched to the prop's power required curve) at just one spot. You can choose where that spot is, but the physics of how a fixed pitch propeller works will dictate the power required at all RPMs.
Regarding continuous HP these engines can provide in aircraft use, their ability to shed heat (and thereby maintain reasonable CHTs) is almost always the limiting factor. Any cart racer can buy new rods, stronger springs, a more radical cam, shave down the head, etc and turn the engine at higher RPMs to obtain more power. And, with regard to continuous HP, that means less than nothing, because CHTs will skyrocket as the designed capacity of the head (fin size and general architecture, etc) to shed the additional heat from burning that additional fuel is exceeded.
Please buy one of these engines, fit a test club to it (much more accurate than a dyno in replicating the behavior of a propeller load), and see what happens when you hop one up. Measure the CHTs. Don't stand too close to it while you are harvesting those extra HP that you believe are available but that everyone else is apparently too dull to recognize.

#### Protech Racing

##### Well-Known Member
A couple of points .These are double roller bearing cranks. I have not seen any forged cranks other than maybe the Honda.
Thrust is taken by these roller bearings. I would not apply prop thrust directly to this engine.
I would never direct drive any small crank , 1 or 2 cyl engine. The crank speed variation is too high and **** will break every time . ( see VW with wood prop VS carbon 3 blade prop and crank failures)
I like these due to the weight of possibly sub 70#. These could swap onto plane with the old school 447/503 Cuyuna, etc And maybe lose a couple of pounds with less muffler, fuel,etc.
I like the possible 500cc from boring and or the large bore bare block. CCs make torque. Torque good.
The V twins are a really pretty little engine also but real world weight looks like 95# or more and not many UL have that much room to actually make 254# with a 100# engine.
I am maybe a year away from building one of these. I have to get my business back up and running and clear out the backlog of my customers that have been so patient. Lucky for me , what I do cant be bought on Amazon or at the local oil swapper shop.

I hope the buy the spars in the next few weeks for the BREEZflyer.

#### Protech Racing

##### Well-Known Member
My build /test sequence would leave the compression near stock,as that builds heat faster than RPM. I'll see how it runs at 9/1 and go from there. Street fuel with E10 or 15 will also run cooler and make a touch more power than E 0 fuel or 100LL av gas.

#### poormansairforce

##### Well-Known Member
There's another problem here. If you're going to insist on taking the blower and ducting off then you're going to have a lot more problems cooling it even if it's stock. And if you increase the horsepower then what do you do?

#### Vigilant1

##### Well-Known Member
There's another problem here. If you're going to insist on taking the blower and ducting off then you're going to have a lot more problems cooling it even if it's stock. And if you increase the horsepower then what do you do?
If the HP is being increased above stock, the baffling/ducting is very important. Just hanging the heads out in the breeze will be far less effective than fitting proper cooling tin to keep the airflow moving through the fins rather than around them. Removing the blower can work even at higher HP outputs IF there is enough available dynamic air pressure to move the air through the baffling/fins. It works okay with cleaner/faster aircraft (Luciolle's, SD-1's, etc), especially if there is a tractor prop to help out. With a draggy airframe and at continuous HP above stock, a fan is likely to be a requirement. The stock centrifugal blowers on these engines do a good job of generating CFMs against pressure (the back pressure is a byproduct of keeping the air close to the fins where it can do the most good).

Last edited:

#### Protech Racing

##### Well-Known Member
The air boats are not using fans . Pusher style . I'm sure the duty cycle is maybe 70% and not 100% per airplane.
But , of course keeping it cool requires some air control around the head.

#### poormansairforce

##### Well-Known Member
If the HP is being increased above stock, the baffling/ducting is very important. Just hanging the heads out in the breeze will be far less effective than fitting proper cooling tin to keep the airflow moving through the fins rather than around them. Removing the blower can work even at higher HP outputs IF there is enough available dynamic air pressure to move the air through the baffling/fins. It works okay with cleaner/faster aircraft (Luciolle's, SD-1's, etc), especially if there is a tractor prop to help out. With a draggy airframe and at continuous HP above stock, a fan is likely to be a requirement. The stock centrifugal blowers on these engines do a good job of generating CFMs against pressure (the back pressure is a byproduct of keeping the air close to the fins where it can do the most good).
I was assuming he was talking about an ultralight style airplane at slower speeds. A little math shows the difference.

#### pictsidhe

##### Well-Known Member
Anyone building a 103 using the appendix calculated power instead of measuring speed may want to keep the fan. Engine power is its output power. Do you want to use some FAA counted prop power to blow air through your fins, or the uncounted power a fan takes?
The baffles on these things are functional rather than efficient. You could do a lot better, even just taping gaps on the stock ones

#### sigrana

##### Well-Known Member
I would like to use 2 of these Honda clones. Duromax 440 18 HP. Modded up a bit with compression, cam, roller rockers, billit rod, etc. Looks like they should make 30 ish HP at 5000RPM.
The FWF weight might be 55# each or less. That would give a pretty good power/weight ratio.
Looking for redrives now.
They weight 77 lbs and they are supposed to work at a maximum of 3600 rpm but not constantly. Even if not biffed, they are not long lasting engines. The lubrication is a splatter type. They are supposed to be running at a standard 2800 rpm. I would be very careful to use them above 3600. Remember, they are NOT Honda, but just copies. I had many Honda copies in the past and they are not really reliable. Keep as well in mind that single cylinder engines of this type vibrate a lot and it is not advisable to use them on aircraft.

Last edited:

#### n3puppy

##### Well-Known Member
Aircraft need continuously rated engines.
A 440 is based on a 13ish HP engine. More than doubling the thermal load needs more than a few stronger parts, or something will give.
===========================
A Stock 440 is 18hp!
Was wondering what Duromax did to make their engines higher hp than other clones - and the original Hondas

Accepted Engineering Standard - 1kw = 1.34hp
From Mfg websites
Honda Engines | Small Engine Model Information

Honda iGX 440. 12.7hp (9.5kw) @3600 1.34 hp/kw
Duromax 440. 18hp (9kw) @3600. 2.0 hp/kw

Honda GX390. 11.7hp (8.7 kw) @3600. 1.34 hp/kw
Duromax 420 16 hp. (8.5 kw) @3600. 1.88 hp/kw

Honda GX190 5.5hp (4.1kw) @3600. 1.34 hp/kw
Duromax 208. 7 hp. (4.2kw) @3600. 1.67 hp/kw

Pretty much proves don't believe what you read until you do your own research.
Especially on the Chinese Clones that are not tested to any legitimate spec.

#### pictsidhe

##### Well-Known Member
Was wondering what Duromax did to make their engines higher hp than other clones - and the original Hondas

Accepted Engineering Standard - 1kw = 1.34hp
From Mfg websites
Honda Engines | Small Engine Model Information

Honda iGX 440. 12.7hp (9.5kw) @3600 1.34 hp/kw
Duromax 440. 18hp (9kw) @3600. 2.0 hp/kw

Honda GX390. 11.7hp (8.7 kw) @3600. 1.34 hp/kw
Duromax 420 16 hp. (8.5 kw) @3600. 1.88 hp/kw

Honda GX190 5.5hp (4.1kw) @3600. 1.34 hp/kw
Duromax 208. 7 hp. (4.2kw) @3600. 1.67 hp/kw

Pretty much proves don't believe what you read until you do your own research.
Especially on the Chinese Clones that are not tested to any legitimate spec.
Ahh, but the Duromax aren't a Chinese company making clones. They are an American company making clones.

Extracted from the XP18 manual:

Rated Power (KW/rpm)
9.0 kW (18.0 HP) @ 3600 rpm
Compress ratio 8.5 : 1
Max Torque
19.55 ft. lb. @ 2500 rpm

Now, max torque is quoted as 19.55 ftlb. If it still had that much torque at 3600rpm, it would have 13.4hp...

#### Armilite

##### Well-Known Member
Was wondering what Duromax did to make their engines higher hp than other clones - and the original Hondas

Accepted Engineering Standard - 1kw = 1.34hp
From Mfg websites
Honda Engines | Small Engine Model Information

Honda iGX 440. 12.7hp (9.5kw) @3600 1.34 hp/kw
Duromax 440. 18hp (9kw) @3600. 2.0 hp/kw

Honda GX390. 11.7hp (8.7 kw) @3600. 1.34 hp/kw
Duromax 420 16 hp. (8.5 kw) @3600. 1.88 hp/kw

Honda GX190 5.5hp (4.1kw) @3600. 1.34 hp/kw
Duromax 208. 7 hp. (4.2kw) @3600. 1.67 hp/kw

Pretty much proves don't believe what you read until you do your own research.
Especially on the Chinese Clones that are not tested to any legitimate spec.
===================================

There are over 20+ different Brand Name Clone manufacturers whose Engines are based off Honda Engines, but not the same Spec's! They don't all use the same Compression(CR) or CAM. Some even have different Size IN/EX Valves which all effects the HP made. 3600rpm rating is the Standard for Industrial Tools and is the only thing that is Standard between them and Bolt patterns. If you knew how to build Engines you would see these differences! Besides Hondas, Duromax has the best Engines in my opinion. Lifan is good also. Not all Clone Brands are sold in the USA. The Duromax 440 is rated at 18hp, I saw the other day they have a new 460 Single coming out that is also rated at 18hp.

They also have a New:
DuroMax XP23HPE 713cc 23-Hp V-Twin Electric Start Engine
XP23HPE
 Compression Ratio: 8.5:1

#### Attachments

• 70.4 KB Views: 8
• 70.7 KB Views: 8