More food for thought - progress report

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Geraghty

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Joined
May 16, 2003
Messages
1,636
More food for thought.......Once again I am not trying to start a pissen' match......That is not my intent....I am attempting to get a very "user friendly inexpensive outboard" for the new RC nitro boater.....

Well , here is the latest progress report on the " inexpensive outboard nitro motor project".....
I have learned a lot and I will periodically pass on what I have experienced during this effort.....
This current Corona Virus mess has really curtailed a smooth resolution to this effort....I have run into some purchasing and delivery roadblocks that are going to take some time to resolve......
To date , I have bought and will be testing several different .28 motors....
We have attempted to test the "Hobao" .28 motor and the Hobao rotostart/pull start system is a design nightmare....The Hobao design is different from all the other PTO rotostart/pull start designs on all the other motors I have obtained....If you decide to try this effort my recommendation is stay away from the Hobao motor.....
There a ton of big block SG shaft car motors to pick from so staying away from the Hobao should post no problem for the people who want to join in this approach to nitro RC boating....

Turns out there are several motors that would serve this effort well and all will fit in the Lawless outboard adapter and all have the SG shaft....
These are the displacements of the motors available.... .20 , .21 , .25 , .28 , & .31......I am sure there are more that I just haven't ran into yet...The motors I have all are very well made.....I have had them all apart and my survey of the motors has come to the conclusion that all are of magnificent quality in materials and workmanship....When you think about it all the RC nitro car motors really get tortured by there users....
In fact Novarossi has joined the lower priced .21 rotostart car motor market and it is available on ebay....

https://www.ebay.com/itm/Novarossi-...785162?hash=item2ce7a3130a:g:~u0AAOSwwKNdqVLnI have one of these motors also and have had it apart and my conclusion is "all" the motors I have bought look the same in materials and workmanship.....

What I have learned.......

1] Break in for these car motors is very important....15 or 20% fuel is just fine....In fact these low nitro fuels perform very well and are a lot easier on motor internals....I.E. bearings....Run the motors the way they come out of the box....."DO NOT TAKE OUT HEAD SHIMS".....

2]Patience , patience , patience.....follow the motors manufacturer recommended break in procedure....

3]This is a good idea for all the motors you use in nitro RC boating......get a IR thermometer and use it during break in....

https://www.ebay.com/itm/Autocraft-...537491&hash=item42148fce71:g:AWMAAOSw1g1dL0mr
4]Finding a rotary carb for these motors can be a bit of a challenge.....They are out there....If all else fails find a K&B Black ,Gold or Red and make an adapter for the motor you chose....Choosing a max bore for this effort is not as important as launch and reliable come back to the dock performance....These motors come with slide valve carbs and we are working some throttle linkage...more to follow on this subject.....

The new prototype Zipp tunnel boat is about 90% complete and I should be getting it in about 2 weeks.....Presently my test pond is drained dry and being dredged and the spillway is being rebuilt.....When I get the boat and motor combo ready to run we will get it done somehow.......As long as this effort has interest I will continue going forward......

I am also working on a very quiet small muffler for this effort....more on that later also....

This "Hobao" rotostart / pull start PTO fiasco has really thrown a stick in the spokes of progress here....We will get a video as soon as possible.....

When all this is said and done I will put together a tutorial of all I have experienced and where to get it.....
 
Rod..
Just a fyi....the thunder tiger .21bx-r
and the .28bx-r are the exact same block sizing....and work on a T.T. lower..
Both engines are buggy engines and quite inexpensive...and no flex shaft to deal with..and I'm using the carb off the o.s. outboard...waiting for some warm weather to go play.
 

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Shazaam!!!!......I am very pleased...first runs with a .28 car motor ..... motor right out of the box....

Specs....164 EXH - 118 INT with at .015" ...23 degrees of blow-down right out of the box.....I haven't checked the crank timing but you know it has to be very user friendly......

K&B stock Gold .312" carb.....We changed the carb to a rotary K&B carb for ease of rigging on this test platform.....no 3rd channel.....

This motor was run on David Halls Lynx on a O.S. lower unit....... The set -up was still a bit tight on the boat with the 1515 ABC prop.....

All the .28 car motors have a ton of bottom end performance so bigger props are probably in the works but we will have to see....

Muffler was a $13.00 car pipe off of ebay.....I am working on a lot better quieter muffler......... This whole project is still evolving as we speak and we are just getting started.....

$70.00 motor..... $40.00 adapter motor mount..... Pipe is a modified $13.00 car muffler of of Ebay...... for a grand total of a $123.00 in this outboard powerhead....

There remains a lot I want to try and test but I am confident there is a strong 50+mph boat here with a " box stock pull start .28 car motor"...... These size car motors mounting platform is also available in .21 size....just saying...

I really want to thank David Hall ,Fred Howe of Lawless and Mike Walker for their help.....I couldn't have done this without their help......



1st run



2nd run

The motor is still tight but you can hear it wants to run....a good break in regime is very important on these car motors.....


The Zippkits 30" tunnel effort is still going forward at W.O.T...... The initial boat is about 90% done....waiting for a ABS cowl from dumas for the prototype....
I still have a ice covered pond so I have time to get the new tunnel ready to test.....

Maybe we can cultivate some new interest in RC "nitro" boat racing.....this all remains to be seen.....

"What you think is best isn't necessarily what works best"
 
All progress reports will be posted in the original "Food for thought" thread.......
 
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