More 2.5cc Diesels
02-27-2012, 03:53 PM
#1
More 2.5cc Diesels
Enough of the Silver Swallows!
The 2.5cc (.15 ci) engine size has always been at the peak of diesel development.
This would be because it's the size engine for the FAI competition classes in F2A, F2C and F2D.
The pics below show some examples, none of the are really suitable for top league competition but all are nicely made and very powerful.
They also come from a variety of countries.
Pics 1-3 are of a Bulgarian POCOM 15 DIESEL it's a Rossi clone and is ABC. This on looks like it was intended for Free Flight because it has a tapped hole in the venturi cavity for a floodoff device. The venturi has the largest hole that I've seen in a diesel. Haven't run it yet.
Pic 4 is of the Pocom and a 90's model US made Nelson 15 AAC diesel set up for the UK diesel combat class.
Pic 5 shows a Ukrainian Fora 15 diesel mk2 Junior and another low timed Nelson 15 D.
Pic 6 shows a Rothwell R250 Vintage racing diesel from Australia. It's essentially an enhanced Oliver Tiger mk3.
Ray
The 2.5cc (.15 ci) engine size has always been at the peak of diesel development.
This would be because it's the size engine for the FAI competition classes in F2A, F2C and F2D.
The pics below show some examples, none of the are really suitable for top league competition but all are nicely made and very powerful.
They also come from a variety of countries.
Pics 1-3 are of a Bulgarian POCOM 15 DIESEL it's a Rossi clone and is ABC. This on looks like it was intended for Free Flight because it has a tapped hole in the venturi cavity for a floodoff device. The venturi has the largest hole that I've seen in a diesel. Haven't run it yet.
Pic 4 is of the Pocom and a 90's model US made Nelson 15 AAC diesel set up for the UK diesel combat class.
Pic 5 shows a Ukrainian Fora 15 diesel mk2 Junior and another low timed Nelson 15 D.
Pic 6 shows a Rothwell R250 Vintage racing diesel from Australia. It's essentially an enhanced Oliver Tiger mk3.
Ray
02-28-2012, 12:39 AM
#3
RE: More 2.5cc Diesels
Some more:
Pic one Taipan Blackhead, Series 13 2.5cc diesel. Now fitted with a new homemade piston. Awaits running in.
Pic two: Fora Junior mk1. Ukrainian 2.5cc beginners diesel with a few issues. This one has had them fixed up. A superb beginners diesel otherwise. AAC P/l, integral finned liner, push/pull head.
Pic Three: PAW 15 TBR GTS2, perhaps the most powerful conventional diesel available. Designed for British Goodyear racing it has no fuel economy to speak of, but on the same clipped Taipan 7 x 4 as a Nelson diesel comes within a few 100 rpm.
More later,
Ray
Pic one Taipan Blackhead, Series 13 2.5cc diesel. Now fitted with a new homemade piston. Awaits running in.
Pic two: Fora Junior mk1. Ukrainian 2.5cc beginners diesel with a few issues. This one has had them fixed up. A superb beginners diesel otherwise. AAC P/l, integral finned liner, push/pull head.
Pic Three: PAW 15 TBR GTS2, perhaps the most powerful conventional diesel available. Designed for British Goodyear racing it has no fuel economy to speak of, but on the same clipped Taipan 7 x 4 as a Nelson diesel comes within a few 100 rpm.
More later,
Ray
02-28-2012, 12:48 AM
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RE: More 2.5cc Diesels
ORIGINAL: locktite401
Enough of the Silver Swallows!
The 2.5cc (.15 ci) engine size has always been at the peak of diesel development.
This would be because it's the size engine for the FAI competition classes in F2A, F2C and F2D.
The pics below show some examples, none of the are really suitable for top league competition but all are nicely made and very powerful.
They also come from a variety of countries.
Pics 1-3 are of a Bulgarian POCOM 15 DIESEL it's a Rossi clone and is ABC. This on looks like it was intended for Free Flight because it has a tapped hole in the venturi cavity for a floodoff device. The venturi has the largest hole that I've seen in a diesel. Haven't run it yet.
Pic 4 is of the Pocom and a 90's model US made Nelson 15 AAC diesel set up for the UK diesel combat class.
Pic 5 shows a Ukrainian Fora 15 diesel mk2 Junior and another low timed Nelson 15 D.
Pic 6 shows a Rothwell R250 Vintage racing diesel from Australia. It's essentially an enhanced Oliver Tiger mk3.
Ray
Enough of the Silver Swallows!
The 2.5cc (.15 ci) engine size has always been at the peak of diesel development.
This would be because it's the size engine for the FAI competition classes in F2A, F2C and F2D.
The pics below show some examples, none of the are really suitable for top league competition but all are nicely made and very powerful.
They also come from a variety of countries.
Pics 1-3 are of a Bulgarian POCOM 15 DIESEL it's a Rossi clone and is ABC. This on looks like it was intended for Free Flight because it has a tapped hole in the venturi cavity for a floodoff device. The venturi has the largest hole that I've seen in a diesel. Haven't run it yet.
Pic 4 is of the Pocom and a 90's model US made Nelson 15 AAC diesel set up for the UK diesel combat class.
Pic 5 shows a Ukrainian Fora 15 diesel mk2 Junior and another low timed Nelson 15 D.
Pic 6 shows a Rothwell R250 Vintage racing diesel from Australia. It's essentially an enhanced Oliver Tiger mk3.
Ray
The big Bulgarian Bloke is going to need a pressure fuel system. I remember that SS was using bladder tanks in his F1C's in the 80's.
Regards
G
02-28-2012, 01:05 AM
#5
RE: More 2.5cc Diesels
Greg,
Bob Fisher bought it's glow NIB brother about a month ago. Magnificent, as is this one, that's why I bought it (NIB also) when it came up on ebay.
It went unrecognized and I was the only bidder at the base price.
Probably from a custom made batch for their national team at the world champs in the '80s.
I'll make a smaller venturi.
Should be great in a diesel goodyear model.
Ray
Bob Fisher bought it's glow NIB brother about a month ago. Magnificent, as is this one, that's why I bought it (NIB also) when it came up on ebay.
It went unrecognized and I was the only bidder at the base price.
Probably from a custom made batch for their national team at the world champs in the '80s.
I'll make a smaller venturi.
Should be great in a diesel goodyear model.
Ray
02-28-2012, 01:08 AM
#6
RE: More 2.5cc Diesels
ORIGINAL: locktite401
Some more:
Pic one Taipan Blackhead, Series 13 2.5cc diesel. Now fitted with an new homemade piston. Awaits running in.
Pic two: Fora Junior mk1. Ukrainian 2.5cc beginners diesel with a few issues. This one has had them fixed up. A supurb beginners diesel otherwise. AAC P/l, intregal finned liner, push/pull head.
Pic Three: PAW 15 TBR GTS2, perhaps the most powerful conventional diesel available. Designed for British Goodyear racing it has no fuel economy to speak of, but on the same clipped Taipan 7 x 4 as a Nelson diesel come within a few 100 rpm.
More later,
Ray
Some more:
Pic one Taipan Blackhead, Series 13 2.5cc diesel. Now fitted with an new homemade piston. Awaits running in.
Pic two: Fora Junior mk1. Ukrainian 2.5cc beginners diesel with a few issues. This one has had them fixed up. A supurb beginners diesel otherwise. AAC P/l, intregal finned liner, push/pull head.
Pic Three: PAW 15 TBR GTS2, perhaps the most powerful conventional diesel available. Designed for British Goodyear racing it has no fuel economy to speak of, but on the same clipped Taipan 7 x 4 as a Nelson diesel come within a few 100 rpm.
More later,
Ray
That said I have a diesel trivia question.
The three diesels in the pictures each have an important design feature that they share with the Cox TD 15.
What is it?
02-28-2012, 11:51 AM
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RE: More 2.5cc Diesels
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
02-28-2012, 01:20 PM
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RE: More 2.5cc Diesels
ORIGINAL: locktite401
That said I have a diesel trivia question.
The three diesels in the pictures each have an important design feature that they share with the Cox TD 15.
What is it?
That said I have a diesel trivia question.
The three diesels in the pictures each have an important design feature that they share with the Cox TD 15.
What is it?
(Not the best for stunt though.)
02-28-2012, 02:20 PM
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RE: More 2.5cc Diesels
Engine 1 and 3 do not have Peripheral jets in the venturi insert. They have the central bar for best fuel draw. yet, the peripheral jetting, if set up right, has both best draw, and best mixing. If not set up right, it's lousy.
You need to have air entry turbulence. You also need to have venturi exit ejector vortex turbulence to get the perfect mix going. The "De Ridder" solution works well here. It has a airflow step in the entrance, and a steeply cut part in the venturi exit, in which the jets are located.
Pictured is the 3.7mm venturi I modified using an insert in the MVVS 4.5mm venturi. Peripheral jets are 0.6mm
You need to have air entry turbulence. You also need to have venturi exit ejector vortex turbulence to get the perfect mix going. The "De Ridder" solution works well here. It has a airflow step in the entrance, and a steeply cut part in the venturi exit, in which the jets are located.
Pictured is the 3.7mm venturi I modified using an insert in the MVVS 4.5mm venturi. Peripheral jets are 0.6mm
02-28-2012, 03:47 PM
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RE: More 2.5cc Diesels
ORIGINAL: pe reivers
Engine 1 and 3 do not have Peripheral jets in the venturi insert. They have the central bar for best fuel draw.
Engine 1 and 3 do not have Peripheral jets in the venturi insert. They have the central bar for best fuel draw.
But that would be very unusual.
02-28-2012, 04:24 PM
#11
RE: More 2.5cc Diesels
Ok, Engine one: Taipan Series 13 "Blackhead". Standard straight through NVA.
Engine two: A mk 1 Fora Junior which is different to the Fora Junior mk2 also shown above.
The motor has a non standard Cox TD 15 Venturi, Banjo assembly. Normally the Fora Juniors have a single jet Tangental system.
Engine three: A PAW 15 TBR GT2S
The NVA is a SMR (Rothwell) replacement for an OS 15 Glow. It gives a finer adjustment than the standard PAW nva.
No the commonality isn't in the venturi system.
It's obvious just by the pics for the first two engines. The third isn't obvious because most assume that it's something it's not.
That's also a clue to why it out performs more "modern" designs.
Picture Cox TD 15:
Ray
Engine two: A mk 1 Fora Junior which is different to the Fora Junior mk2 also shown above.
The motor has a non standard Cox TD 15 Venturi, Banjo assembly. Normally the Fora Juniors have a single jet Tangental system.
Engine three: A PAW 15 TBR GT2S
The NVA is a SMR (Rothwell) replacement for an OS 15 Glow. It gives a finer adjustment than the standard PAW nva.
No the commonality isn't in the venturi system.
It's obvious just by the pics for the first two engines. The third isn't obvious because most assume that it's something it's not.
That's also a clue to why it out performs more "modern" designs.
Picture Cox TD 15:
Ray
02-28-2012, 04:45 PM
#12
RE: More 2.5cc Diesels
Talked with BOB DAVIS yesterday think he will get a pix of the FOX 15 on with with his head, soon I hope my guess he had to run some more off
and all made here in the USA martin
Fiery hope to get the 2.5 Taipan fired up in the next day or two,
Lets all wish Hobbsy a speedy recovery he tore his Biceps muscle lifting a heavy log a few days ago
and all made here in the USA martin
Fiery hope to get the 2.5 Taipan fired up in the next day or two,
Lets all wish Hobbsy a speedy recovery he tore his Biceps muscle lifting a heavy log a few days ago
02-28-2012, 05:07 PM
#13
RE: More 2.5cc Diesels
Here's another picture of the PAW, this time the front bearing housing.
There's a couple of interesting features. Firstly the slot in the bearing area between the races from the front bearing to the venturi cavity.
It's probably there to suck excess fuel/oil back from the bearing. I'd suggest it also allows a looser fit for the crank.
Secondly the shaft end-float adjustment allowed by the threaded plate that holds the front bearing in place.
This feature is normally only found in F2C diesel engines I believe.
This has nothing to do with the trivia question above although two things all three engines do have in common is TBR and screw in backplates.
That's not it either..
Ray
There's a couple of interesting features. Firstly the slot in the bearing area between the races from the front bearing to the venturi cavity.
It's probably there to suck excess fuel/oil back from the bearing. I'd suggest it also allows a looser fit for the crank.
Secondly the shaft end-float adjustment allowed by the threaded plate that holds the front bearing in place.
This feature is normally only found in F2C diesel engines I believe.
This has nothing to do with the trivia question above although two things all three engines do have in common is TBR and screw in backplates.
That's not it either..
Ray
02-29-2012, 04:09 AM
#15
RE: More 2.5cc Diesels
ORIGINAL: pe reivers
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Also your rpm and power figures seem high for an MVVS 2.5cc diesel. How have you obtained your power figures?
Have you used a ignition improver?
Ray
02-29-2012, 04:35 AM
#16
RE: More 2.5cc Diesels
Here's another, my Spanish Zom 2.5cc mk2 diesel from the late 1970's IIRC. Apparently the Zom's started out as an Oliver Tiger/ Webra 2.5 copy and then were developed on their own design path.
Not a bad diesel but doesn't like hot starting. perhaps a new piston would help but I heard stories that the liner is made of cast iron which complicates the metallurgy of a rebuild.
This pic is off the web and apparently shows a mk1 "Oliver Tiger' like Zom.
Any diesel experts out there know any more about it?
Ray
Not a bad diesel but doesn't like hot starting. perhaps a new piston would help but I heard stories that the liner is made of cast iron which complicates the metallurgy of a rebuild.
This pic is off the web and apparently shows a mk1 "Oliver Tiger' like Zom.
Any diesel experts out there know any more about it?
Ray
02-29-2012, 01:42 PM
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RE: More 2.5cc Diesels
ORIGINAL: locktite401
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Ray
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Ray
02-29-2012, 02:59 PM
#18
RE: More 2.5cc Diesels
ORIGINAL: Recycled Flyer
Ray, is this that semantic jungle we are entering again? All peripheral style venturi systems have a tangential feed to them (it makes little sense to do other wise) and all tangential feeds have a jet on the periphery (bar the spigot hybrid types) but do you really mean that the Fora's simply use the one jet rather than a series of annular ones?
ORIGINAL: locktite401
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangential feed venturi, some of dubious quality.
Ray
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangential feed venturi, some of dubious quality.
Ray
I don't know where you get your information from but in my world a Tangential venturi,as used in many high performance 2.5cc diesel and glows, has a single fuel jet from a NVA positioned Tangentially relative to the venturi.
A Peripheral jet system has many jet holes positioned radially around the "periphery" of the venturi.
My four Fora Juniors had one tangential hole.
I owe Pe an apology here because the 2011 model Fora Junior does indeed have a five holed peripheral setup.
Ray
02-29-2012, 03:34 PM
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RE: More 2.5cc Diesels
My power figures were obtained using MA props, and doped fuel. My standard mixture will not allow high rpm. Fuel mixture for power tests was:
20% oil (putoline cart tech, a castor oil reinforced with synthetics)
40% ether
20% Wynn's Diesel+plus+ treatment, contaning about 7.5% 2-ethylhexyl nitrate; 75% staight run kerosene, some solvent naphta, some naphtalene. (2EHN is also known as octyl nitrate, the stuff that amsoil cetane enhancer is made of)
20% farmlight lamp oil C5-20. Flashpoint >65°C
The standard MVVS diesel engine still has a very tight piston and is not completely run in yet.;
I made two extra peripheral venturis with 6 x 0.6mm jets, like the original 4.5mm MVVS venturi. One of 3.7mm, and one of 3.0mm. I used the Ridder system of breaking the airflow, as can be seen in the pitures I posted. The MVVS venturi which gave me the 0.45hp was unmodified.
This horsepower figure was exactly in line with a power graph I borrowed from an American tester. I forgot magazine and tester name.
for Wynn's, look up www.wynns.eu
PS apology accepted
20% oil (putoline cart tech, a castor oil reinforced with synthetics)
40% ether
20% Wynn's Diesel+plus+ treatment, contaning about 7.5% 2-ethylhexyl nitrate; 75% staight run kerosene, some solvent naphta, some naphtalene. (2EHN is also known as octyl nitrate, the stuff that amsoil cetane enhancer is made of)
20% farmlight lamp oil C5-20. Flashpoint >65°C
The standard MVVS diesel engine still has a very tight piston and is not completely run in yet.;
I made two extra peripheral venturis with 6 x 0.6mm jets, like the original 4.5mm MVVS venturi. One of 3.7mm, and one of 3.0mm. I used the Ridder system of breaking the airflow, as can be seen in the pitures I posted. The MVVS venturi which gave me the 0.45hp was unmodified.
This horsepower figure was exactly in line with a power graph I borrowed from an American tester. I forgot magazine and tester name.
for Wynn's, look up www.wynns.eu
PS apology accepted
ORIGINAL: locktite401
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Also your rpm and power figures seem high for an MVVS 2.5cc diesel. How have you obtained your power figures?
Have you used a ignition improver?
Ray
ORIGINAL: pe reivers
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Also your rpm and power figures seem high for an MVVS 2.5cc diesel. How have you obtained your power figures?
Have you used a ignition improver?
Ray
02-29-2012, 04:55 PM
#20
RE: More 2.5cc Diesels
ORIGINAL: pe reivers
My power figures were obtained using MA props, and doped fuel. My standard mixture will not allow high rpm. Fuel mixture for power tests was:
20% oil (putoline cart tech, a castor oil reinforced with synthetics)
40% ether
20% Wynn's Diesel+plus+ treatment, contaning about 7.5% 2-ethylhexyl nitrate; 75% staight run kerosene, some solvent naphta, some naphtalene. (2EHN is also known as octyl nitrate, the stuff that amsoil cetane enhancer is made of)
20% farmlight lamp oil C5-20. Flashpoint >65°C
The standard MVVS diesel engine still has a very tight piston and is not completely run in yet.;
I made two extra peripheral venturis with 6 x 0.6mm jets, like the original 4.5mm MVVS venturi. One of 3.7mm, and one of 3.0mm. I used the Ridder system of breaking the airflow, as can be seen in the pitures I posted. The MVVS venturi which gave me the 0.45hp was unmodified.
This horsepower figure was exactly in line with a power graph I borrowed from an American tester. I forgot magazine and tester name.
for Wynn's, look up www.wynns.eu
PS apology accepted
My power figures were obtained using MA props, and doped fuel. My standard mixture will not allow high rpm. Fuel mixture for power tests was:
20% oil (putoline cart tech, a castor oil reinforced with synthetics)
40% ether
20% Wynn's Diesel+plus+ treatment, contaning about 7.5% 2-ethylhexyl nitrate; 75% staight run kerosene, some solvent naphta, some naphtalene. (2EHN is also known as octyl nitrate, the stuff that amsoil cetane enhancer is made of)
20% farmlight lamp oil C5-20. Flashpoint >65°C
The standard MVVS diesel engine still has a very tight piston and is not completely run in yet.;
I made two extra peripheral venturis with 6 x 0.6mm jets, like the original 4.5mm MVVS venturi. One of 3.7mm, and one of 3.0mm. I used the Ridder system of breaking the airflow, as can be seen in the pitures I posted. The MVVS venturi which gave me the 0.45hp was unmodified.
This horsepower figure was exactly in line with a power graph I borrowed from an American tester. I forgot magazine and tester name.
for Wynn's, look up www.wynns.eu
PS apology accepted
ORIGINAL: locktite401
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Also your rpm and power figures seem high for an MVVS 2.5cc diesel. How have you obtained your power figures?
Have you used a ignition improver?
Ray
ORIGINAL: pe reivers
I remember the article vaguely, I think I know where it is and will try and find it.
Ray
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
I remember the article vaguely, I think I know where it is and will try and find it.
Ray
They have a crankshaft?
I did some tests with the mehanite piston MVVS diesel venturi size. I know the Fora junior has a 3.8mm 5 jet peripheral venturi.
with the MVVS standard 4.5mm peripheral 6 jet venturi I obtained 0.46 hp (MA8x4 @ 16740 rpm). In this form the engine dislikes larger propellers.
With a smaller 3.7 peripheral venturi I got 16100 rpm, but much lowered fuel consumption and much improved fuel draw. The engine hardly lost power when loaded down with up to 9x5 props (11500 rpm), and was still very well behaved.
Pe, none of the Fora Junior diesels have a peripheral venturi. The dozen or so I've seen have a tangental feed venturi, some of dubious quality.
Also your rpm and power figures seem high for an MVVS 2.5cc diesel. How have you obtained your power figures?
Have you used a ignition improver?
Ray
02-29-2012, 06:04 PM
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RE: More 2.5cc Diesels
ORIGINAL: locktite401
Chris,
I don't know where you get your information from but in my world a Tangential venturi,as used in many high performance 2.5cc diesel and glows, has a single fuel jet from a NVA positioned Tangentially relative to the venturi.
A Peripheral jet system has many jet holes positioned radially around the "periphery" of the venturi.
Ray
Chris,
I don't know where you get your information from but in my world a Tangential venturi,as used in many high performance 2.5cc diesel and glows, has a single fuel jet from a NVA positioned Tangentially relative to the venturi.
A Peripheral jet system has many jet holes positioned radially around the "periphery" of the venturi.
Ray
03-01-2012, 03:14 AM
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RE: More 2.5cc Diesels
[/quote]
Doesn't the Fora have its single jet positioned radially around the periphery also?
[/quote]
Chris,
I'm a bit confused with your question. How can a single jet be positioned around the periphery?
There may only be one jet, and it can be anywhere around the perimeter, but peripheral suggests more than one jet.
Greg
03-01-2012, 07:24 AM
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RE: More 2.5cc Diesels
.
A single radial jet does not make it peripheral. I am inclined to doubt the effectiveness of such a single radial jet. I have experimented with a side NVA, radial to the venturi. Best power was obtained when the jet ended exactly in the venturi centre (+- 0.1mm!!!) The fuel mist was a nice cone that filled the whole venturi.
A single radial jet does not make it peripheral. I am inclined to doubt the effectiveness of such a single radial jet. I have experimented with a side NVA, radial to the venturi. Best power was obtained when the jet ended exactly in the venturi centre (+- 0.1mm!!!) The fuel mist was a nice cone that filled the whole venturi.
03-01-2012, 02:18 PM
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RE: More 2.5cc Diesels
Greg,
perhaps its semantics or me just taking things a bit too literal, but the meaning of 'peripheral' is "Related to, located in, or constituting an outer boundary or periphery."
Can a single point, (such as can be represented by a jet hole) " be related to, located in, or constituting an outer boundary?" I would have thought so but perhaps its simply accepted as not being such in certain circles.
And Ray, yep can post pics of my 2.5cc diesels but do you really want to see a plain bearing PAW that is 35 years old and a reworked Sokol?
I suppose that I do this as it looks like the Hunter Valley championships are going to be called off (I was going to attend and the time can be spent on other things.)
Cheers.
perhaps its semantics or me just taking things a bit too literal, but the meaning of 'peripheral' is "Related to, located in, or constituting an outer boundary or periphery."
Can a single point, (such as can be represented by a jet hole) " be related to, located in, or constituting an outer boundary?" I would have thought so but perhaps its simply accepted as not being such in certain circles.
And Ray, yep can post pics of my 2.5cc diesels but do you really want to see a plain bearing PAW that is 35 years old and a reworked Sokol?
I suppose that I do this as it looks like the Hunter Valley championships are going to be called off (I was going to attend and the time can be spent on other things.)
Cheers.