What Pipe for OS 18?

[BobBonahoom]

I have an OS 18 TZ (car engine) that I converted to marine use. Can anybody tell me what pipe(s) work and at what length when used in a JAE 12 size rigger?

What about props?

Bob Bonahoom

 

[RodneyPierce]

The best pipe I found on the .18 TZ was an OPS 3280 .21 pipe. Run it as short as you can.

 

[Glenn Quarles]

Jerry D is running the pipe I designed for the Miss Vegas Deuce (the Super Tiger pipe) in his sport 18 boat and it seems to work really well.

GQ

 

[BobBonahoom]

I saw that Supertigre pipe and wondered about it. 3280 is easy to try also. I guess it is close enough to a 21 that a 21 pipe should work.

Thanks!

 

[BobBonahoom]

Glenn,

Is this the pipe Jerry is using: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXWPL9&P=7

 

[George Taylor]

I have the same exact boat. I use a Mac pipe, 3.5cc high nitro. Glenn Quarles told me to cut it short. 2 1/2 inches from glow plug to cone of pipe. Works great a this length. Engine tunes and launches great. I still have the air cooled head on it with all the fins but 3 cut off. Runs great.

 

[BobBonahoom]

George,

Is that this MAC pipe: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXZ558&P=7

 

[RodneyPierce]

I also ran the MACS pipe, but it was no comparison to the 3280.

 

[Kevin Krogness]

George,

Is that this MAC pipe: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXZ558&P=7

RC car kings used to stock that and the 12-15 pipe.

 

[George Taylor]

it's a Mac 1324 that I use.

 

[Glenn Quarles]

Glenn,Is this the pipe Jerry is using: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXWPL9&P=7

Bob, yes that is it.

GQ

 

[BobBonahoom]

Thanks everyone. I have an OPS 3280 on hand so I am going to start with that.

 

[jken1995]

Not trying to steal the thread, but I just have a quick question. Is there a thread on converting the OS 18TZ for marine use? I am interested which crankshaft would be needed, is the timing left alone, which cooling head is used, and any other information that would be needed. I appreciate any help.

Thanks,

Jeff

 

[George Taylor]

Jeff, I removed the pull start and replaced the crank with the stock crank without the "nipple" for the pull starter. I use the air cool head with all the fins cut off but 3 fins. It cools fine and runs good. I have left the motor "stock" as of now. I have it in a JAE 12 rigger.

 

[jken1995]

Thanks for the info George. I notice there are two different versions of the 18tz. Is one better thant the other? Also, what did you use for the flywheel? Finally, I would be using this in an enclosed cowling so the water cooling will probably be needed. Do you know which cooling head would work? Thanks again for any help.

Jeff

 

[George Taylor]

this is the engine i'm running,

O.S. 18TZ-TX ABC Turbo w/11L Rotary Carb

this is the flywheel.

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMAJ2&P=Z

If it is under a cowling just leave all the fins on the air cooling head, that's what is made for a car under a cowling. Look at Tower Hobbies, they have all the parts needed to convert this to marine. you will see two crankshafts, one for a pull start, with the nipple, and one with out. This crank with work with the flywheel. You will need a back plate if you are not going to use the pull starter.

 

[jken1995]

Thanks for help George. This little engine really seems to be the way to go for .18 size engines. Looks like any easy conversion.

Jeff

 

[George Taylor]

Just make sure you have the pipe at the right distance. I could not get mine to launch or run consistent until I talked to Glenn Quarles with nova rossi and he told me to make the pipe short, glow plug to the "cone" wide part of the pipe 2 1/2 inches on the .18 motors. As soon as I did it ran great and is fun to run.

 

[BobBonahoom]

Here is how I converted my OS 18. I cut the pilot part of the crankshaft off leaving just the 1/4-28 threads. A NovaRossi 12 flywheel and crank collet fit perfect. (I also used a 1/4-28 Flexhex for the wire drive). A NovaRossi 12 air cooled top piece fit right on. Finally, I used a Nova Rossi 12 carb fitted with a 360 degree brass barrel with a 0.270" bore and one of the "hot rod 12" needle valves that Glenn sells. I had to make an aluminum collar in the lathe to press over the Nova carb because the OS carb has a bigger OD on the part that goes into the engine.

It runs really well in my heavy JAE 12 (2.3 lbs without fuel). I am using a wire drive and ball bearings with no strut. I just glue a brass tube to the ski instead.

 

[BobBonahoom]

Forget to mention, I put an AB 21 pipe on at about 7" and it works well.