A/A 45

[Al Hobbs]

Just let me know you want one, or you can get them from Jerry Crowther at Seaducer or Troy Davis in California. In England they are available from Graham Morgan. In Europe they are available from Ready to Win Models. In Australia they are available from Steve Winks.

I think the reason that they used the MACS 10cc pipe is that is what was on the boat when they went to the pond. Remember, this was the first time the engine and boat combination had even been put into the

water.

I expect them to do further running with other props and pipes to see what they can get out of the engine. I was happy to see the engine start up, run, take the boat around the course and come back the first time in the water.

After the engine has some run time, we'll have a better idea of what is possible.

Al Hobbs

 

[Al Hobbs]

I plan to run May 1 at the Calgary District 16 race. I'll run an old rigger, with the A/A 45 using a parabolic pipe, 1457 prop, and 50% nitro fuel.

 

[Duck899]

I plan to run May 1 at the Calgary District 16 race. I'll run an old rigger, with the A/A 45 using a parabolic pipe, 1457 prop, and 50% nitro fuel.

Al, if I'm not pitting, I'll get video....

 

[Al Hobbs]

That could be the Kiss of Death!

 

[tnrcboatracer]

What other pipes have tried why a Macs 10cc pipe why not a 7.5CC pipe or a Parapolic type pipe.

Just after some other pipe suggestions.

Thanks

Steve

It was also run with a CF Squarewave. Got a 19 sec set out of it, with lots more prop available. From hte sound of the video, it is still rich as a pig.

 

[julianconde]

interesting too bad i dont run anything 45 size inboard lol.. :lol:

 

[julianconde]

im a 3.5cc guy h34r:

 

[Rokieboater]

Got my AA .45 today. I will put in rigger tomorrow and test it Friday. I will test both the OPS pipe and an Andy Brown Parabolic Pipe. I will post my results on Friday.

The motor looks absolutely beautiful inside.

Al I need another motor. Can I order from you or should I get from you distributors?

Robert Holland

 

[Al Hobbs]

I need to clarify somehting. The finished A/A 45 engines have not arrived yet. Rokieboater pulled a brand new MAC 45 out of his boat so that I could verify new A/A 45 parts with a new MAC 45 engine.

I promised to replace the MAC with an A/A. Of course, the A/A engines were delayed and Rokieboater needed an engine so his boat would be ready for a race.

While I was in Italy, I put together an engine for Rokieboater. It does not have the cosmetic touches that the A/A 45 engines will have. But, Rokieboater has an engine to replace the new MAC 45 he was so gracious to send me.

Al Hobbs

 

[JSCARPINO]

Hello Al

I want a 45 engine from you, but will have to wait until you get the angled carb set up.

The engine does not fit into my SGX Eagle without hitting the rear Sponson tube...

I want one though when that is released....

Let me know...

Thanks

Joe

 

[Al Hobbs]

Hi Joe,

The MAC type drum rotor will be available and I'll make sure to post it on IW when they arrive.

Thanks,

Al Hobbs

 

[Bill Gibson]

Hi Joe,

The MAC type drum rotor will be available and I'll make sure to post it on IW when they arrive.

Thanks,

Al Hobbs

Glad to hear about the drum rotor also Al........the way the fuel tank sits in my Sport 40, i need the ramp! Now i can just drop the motor in!

 

[Al Hobbs]

Rossi has shipped the first case of A/A 45 engines. They should arrive here on Monday or Tuesday. The second shipment will follow with engines using the MAC style rotor assembly. I have told Rossi to start production on the next run of 100 A/A 45 engines. They should arrive in June.

I will start shipping out orders this coming week. Thank you for being patient.

Al Hobbs

 

[Martin Hamilton]

Al have you seen how Axe Rossi produce the fit of pistons to liners, I was told by rather than the old way of producing slightly diff size pistons and then matching by hand. In the UK the 10cc tether hydros had 50 piston and liners made by Axe Rossi to fit the OPS 60 5 port motors which are no longer produced by OPS. And that the machine that grinds the piston measures the relevent liner and grinds the piston to suit . Just curious if this is how they do it. Regards Martin.

 

[Al Hobbs]

I did watch them manufacture liners and pistons. The liner is machined out of an alloy. Then it is ground. After the inital grinding, it is sent to be chromed, The chrome operation is not done at the Rossi factory.

When the chromed liners return to the Rossi factory, they are ground a second time to produce the required surface. The finished liner is placed on a mandrel that measures the liner in microns. The mandrel is connected to the CNC machine which makes a piston for that liner. Alfredo verifies the piston/liner fit by hand. He has been doing this for more than 30 years.

Once the piston/liner assembly is approved, that piston and liner are never seperated again. There are no bins of pistons and bins of liners.

Rossi does several things differently than the other facories I visited. The liner is ground twice, before chroming and after chroming. A particular piston is made for each particular liner. The fit is tested by hand and the pistons and liners are not seperated.

In addition, you can take the liners from several different manufacturers and there will be differences in color, depending on the type of alloy used. Brass will actually move under pressure. When your engine is running hard, if the sleeve is just brass, it will expand and you will lose some compression. The higher the quality alloy, the less the liner can expand and the higher the compression while the engine runs. We are talking very small increments, but there is a difference.

You can also see the difference in the grain of the aluminum pistons. The more coarse the grain, the lower the quality. The best piston material I've seen is the high silicon content aluminum that Kalistratov used. Rossi's piston material quality is close.

I hope that this answered your question.

Al Hobbs

 

[John Knight]

Al,

Do you know the silcon content of the A/A pistons? I was told that most manufacturers use 20% while others doing the high silcon content were using 30%. The 30% ones can become more brittle but will outlast the 20% ones 3+ to 1 in durability. Interested in finding out where the Rossi factory has in theirs.

 

[Martin Hamilton]

Al many thanks for your reply. Re piston materials most cast pistons are around 20% silicon, I know of some old OPS pistons that were analized in the lab were 19% silicon. Ive also used in the past a material called Vanasil which is 21-23%, Vanasil is a trade name and this is what K&B use to use not sure if they still do. Most of the Italian engine manufacturers and some of the Russian specialist speed engine manufacturers get their 30% billet material from a company in Holland called RSP Technology. This involves a process where the material is heated and sprayed onto a copper mandrill its then removed and pushed through dies to form a solid billet of the required diameter. This is also the material i believe Brad Christy uses. Regards Martin.

 

[Al Hobbs]

One thing I found out earlier was that some of the Italian manufacturers did not consistently use the same piston material. So you could see anywhere from 15% to 22% silicon content.

Kalistratov used 22% for his standard pistons and 30% for special order pistons. The 22% was used in the cast pistons. The 30% was used in the barstock pistons. I was bringing in slightly oversized pistons of the 30% material. It took forever to lap them in, but they would not wear out. It depended on how much you hated lapping in the pistons. I was never aware of any problems caused by brittleness.

It is also more difficult for the engine manufacturer to use 30% material. The 30% silicon wears out his tools faster than lower silicon material. The 30% material is more expensive to buy, and more expensive to machine.

I was told at the factory that the A/A engines have 22% silicon content piston material.

I do think that the best check for you to make is to inspect the material grain in your pistons. If you look closely you can see small dark spots. The bigger the spots, the coarser the silicon, the lower the cost and often the lower the silicon content. If you are one of the few people with a Kalistratov 30% silicon content piston, you can see how fine the material grain is, especially when compared to a low cost piston.

I do know that the 30% silicon content material is commercially available from different suppliers. I do not know what the various manufactuers call their products. I do know that some after market piston suppliers offer this high quality material. However, if you are a mass producer, the additional cost of the 30% material adds up to a lot of money over time. If you are a mass producer, trying to keep your costs and prices down, you would not use such a high priced material.

Al Hobbs

 

[Martin Hamilton]

Al something i have found in tether hydros where we need a lot of torque lower down on the launch period,Is that the high silicon (30%) does not work as well as say around 20%+ silicon 0n FAI fuel (no nitro). I believe that the 30% pistons dont expand enough when hot and dont make as good a seal in the liner which is critical on FAI fuel. Ive also found that shallow tapers in the liners work better in my applications than some of the very steep tapers used in a lot of motors now. Which is great for nitro fuel and higher revs. If you look at some of the very nice but very expensive Russian say 2.5cc speed motors that are designed to use FAI fuel they use very close fitting pistons with no oil grooves and very shallow tapers in the liners. As soon as the piston closes the exhaust port the piston is making perfect compression with no leaks what so ever, The steeper taper liners do not do this until the piston is around 4mm above the exhaust closing. Ive found on my .21 motors the taper per 10mm =.394" of liner length is .0006"- .0008" to be what i use, Most .21 motors now use around .0016" per .394" liner length. Martin.

 

[Al Hobbs]

Yes, the amount of taper is very important. The Kalistratov engines had very little taper as compared to engines made in Italy.

One of the reasons that one manufacturer has more taper than another is its inablility to machine the tolerances required for little taper.

They let the piston wear into the taper.

When there is little taper, the piston must have a better fit. It is the fuel that then makes the piston to liner seal.

I do not know the difference between 30% and 20% expansion rates when heated. But, I do believe you when you say that 30% silicon material does not expand at the same rate as 20%. We know that aluminum expands. I don't know if silicon expands much or at all when heated.

I would think that if the 30% piston is machined properly, it does not have to expand to make a seal. But, I really don't know. Just my thought.