NM2K

My Feedback: (14)

The amount of compression also influences the length of the pipe setup, in addition to the fuel, glow plug and propeller. Lowering the compression is customary when running a tuned pipe. Your glow plugs and engine will thank you.


Ed Cregger

1QwkSport2.5r

Thanks guys. I don't think this Tigre is as highly compressed as other Tigres. My s90 has a heap more compression than the s29. If need be, I can cut a pop can apart or something and make another head shim. It came with one, .1 or .2mm I believe. What is the max gap can I have between th header and pipe? 1/4"?

1QwkSport2.5r

I'm going to wait to tune the pipe until it has more run-time on it. Its seen a gallon of fuel and probably 60-75 minutes of run time over 20 or so runs. Transition is great, idle quality got significantly better without my "muffler bucket" on it. Lowest idle I saw was 2200rpm, with a really solid reliable idle at 2500rpm or so. I'm keeping the top end pretty rich still, probably 700-800rpm short of actual peak power. This is my first engine with a full pipe, so I'm not sure if its "getting on the pipe" or not, but the new glow plug I put in still looks like it just came out of the package. Mixed fresh 5/20 fuel for it and let 'er rip. I'm pleased so far.

http://www.youtube.com/watch?v=OXPcGVX-OI8

Mr Cox

Run it without a muffler and see what kind of top-rpm you get. Then put the pipe on, you should see an increase in the top revs or else the pipe is nothing but a restrictive muffler at best.

(the needle needs to be altered when doing this)

1QwkSport2.5r

I might try that sometime. Havent ran an engine open faced yet, though some of my engines dont draw fuel really well on their own so without muffler pressure they're kind of a dud. I think this S29 might do okay, but I'm not in a rush to run it like that.

I will say (and I didnt even mount the stock muffler) that the tuned pipe is far less restrictive than the stock muffler. It would have to be. I ran the pipe untuned simply to have "something" there to provide muffler pressure and not choke the engine down to nothing like the stock muffler would obviously do.

Mr Cox

A tuned pipe is more restrictive than a regular muffler. It is this restriction that gives you a back pressure wave that will help, but only at a suitable rpm compared to the tuned pipe length. Outside this tuned rpm, the pipe has no advantage over a regular muffler, on the contrary it is more restrictive.

fujiman

My Feedback: (133)

if the pipe is not adjusted to the proper length for the reversion wave at rpm with the proper nitro, port timing and prop size then the reversion wave will be off, causing a lose of power and rpm. your eng. sounds pretty healthy in you vid. there is a formula to figure the prop pipe length from the mid. of pist. to the apex of the pipe but i'll be darned if i can remember what the heck is is!!!!!!!!!![:@] macs muffle systems mite be able to help tho. the header looks a little long for your engine. you can tune it by shorting the header by a little and then running it full bore. you can tell when comes on the pipe by sound (sounds real wicked) and by tach checks. a little science is involved here!!!!!!! if you change any thing, prop, nitro, plane weight you mite have to adjust the pipe again. can become a real pain in the patoot if you know what i mean!!!!!!!! getting the engine on the pipe is like supercharging an engine by means of the exhaust reversion wave, it actually repacks the cyl. by means of that wave. race cars use a similar science but is different than 2 stk apps. i once had a race plane that i modified fro a foamy sureflite kit, a p-39 airocobra, clipped wings and tail a cut down canopy and a tune piped rossi .40 and it walked away from a sig kingcobra .60 with an OS .61 with a pipe. man when that rossi came onto the pipe you had better be ready cause that thing would accelerate like it had an after burner. it was no contest!!!!!!!![>:]

1QwkSport2.5r

I understand how a pipe works.. Been in R/C for 14+ years. I havent tuned the pipe yet because I dont know what prop is going to work best for my application. I figured using the tuned pipe (which came with the engine from an RCU member) was a heck of a lot better than the stock muffler that you'd think would come with a .15! The stock muffler would probably choke the engine down 3000rpm or more! I've been using a 9x5 prop, but if I tune the pipe to the 9x5 and if I need to run say... a 9x7 in my application, I'll have to order a new header most likely and at this point in time, I can't do that. Once I find what prop pushes my airboat the best, then I'll tune the pipe and get the "boost".

I mean, seriously... Is anyone going to tell me the full pipe is going to be more restrictive than this?


Don't get me wrong - I am not discounting what you guys have said.. I understand its not running at its full potential, but I dont want to have to cut up 3 or 4 headers to figure out what prop is going to do the trick. Who knows.. I might have to go down to an 8x8 or something.. Then I definitely would need a new header since there isnt a 9" prop with the same prop load as say, an 8x8. That is, according to the dia. X dia. + pitch that I've read about in other threads. I can't use any larger than a 9" dia. prop on my airboat the way its built. It was built with a 9" prop in mind, and a .30 sized engine.

fujiman

My Feedback: (133)

i guess we all have been beating a dead horse!!!!!!! i agree with you on the S.T. ''stock'' muffler. really would choke the devil out of your engine. not much of any kind of expansion chamber in that one!!!!!!!!

Mr Cox

The outlet is usually smaller on a tuned pipe compared to a regular muffler, I don't know what you have on yours. The easiest way to check what the pipe is doing is to run the engine without any muffler or pipe. You can then see how much drop you're getting with the pipe or muffler. Other than noise (wear ear protection) there is no problem running without a muffler. On a stand you can put the tank a little higher if you want to aid the fuel draw.

Another thing to consider is the exhaust timing. Competitive engines were often made in two versions, one with "regular" timing to be used with or without muffler and one with a longer exhaust timing to get the most out of a pipe. On a regular timed engine you may not be able to reach a boost compared to open face but you might do better than with a regular muffler.

1QwkSport2.5r

Fujiman - there's a reason I set it up like I did. That stocker isnt worth mounting. The guy I got the engine and pipe setup from said I could tune the pipe for more power or use it untuned as a replacement "stock muffler". As I see it, even as its setup currently, its a win/win since the stock pipe would choke it down so much. When I figure out what prop is going to work best, I'll cut the header down in 1/4" increments and get it in the sweet spot.

Mr. Cox - The stinger opening on the big pipe is 8mm, the stock muffler's stinger opening is 6mm. The outer diameter of the stock muffler is less than 1mm larger than the inside diameter of the big pipe's stinger outlet. It almost fits inside.

I'll try it open face one of these days and see for myself. The s29 has 162* of exhaust timing and 17* blowdown timing.

NM2K

My Feedback: (14)

That looks the same as the muffler that fits my ST G20/15. Sure wish I could buy a couple of those somewhere.


Ed Cregger

1QwkSport2.5r

If you have a good carb laying around that you dont need with a neck size of .622", I'll trade ya straight up for this ST muffler. Its just going to sit in the box otherwise. The bolt spacing looks like 32mm.

Mr Cox

It sounds like you have the wrong muffler then, 6mm is common for .15 engines. As a comparison the Enya .29 has 8.5mm outlet diameter on the muffler.

1QwkSport2.5r

I don't think so. This muffler came with the engine in the box (despite it being so small) and is the reason the previous owner bought the Macs full pipe setup for it. He had 2 of these engines and bought pipes for both but since he was getting out of R/C and concentrating on Free Flight, he had no use for them anymore. I have read other threads detailing the S29 as being a dog and one would be better off trading it in for a different, better performing engine. I can see why they would think it to be a dog.

Here's the thread where they talked about these engines at length. The Como .29 came with a larger "swing" muffler, the S29 the one I posted a photo of.
http://www.rcuniverse.com/forum/m_10...m.htm#10663250
Yes its a .15 sized muffler.. but it had to fit in the box.

The muffler that came with my SS30 has a stinger outlet inside diameter of 7.5mm, but volume-wise its just as small if not smaller than the ST muffler.

fujiman

My Feedback: (133)

sounds like you have a handle on it!!!!!!!!! so do your thing and enjoy your air boat!!!!!! fujiman is now signing off!!!!!!!!!!

1QwkSport2.5r

Fujiman - Thanks a bunch for your opinion and input on my project!

I think I got a handle on it anyway. I certainly dont want anyone to think I'm a know-it-all or against taking anyones advice. Believe it or not, I try to go about things in a logical manner and what I'm doing seems the most logical and cost effective. If my original plan doesnt work, there's always plan B... Order 2 or 3 headers and chop away.

This is the rig my S29 is going to call "home" until I learn the ropes of piloting a plane. I think I'd put this engine/pipe combo on a small Sig Kobra or some other go-fast plane.


I know I know.. I'm a weirdo... I can't help it. I'm always finding ways of using things in a manner of which they were never intended. Keeps the hobby "interesting" for me, and gives me something to work on over the winter. I built this airboat out of scrap materials I had laying around. The dark wood is American Black Cherry and started out as hardwood flooring scraps I brought home from work. Talk about re-purposing.

fujiman

My Feedback: (133)

wow now that is very nice airboat!!!!!!!!! i don't think anyone thot you came across as a know it all or at least i didn't. we all seem to jump in to help, some times where help really is needed or even wanted. strange thing about us rc'ers we love to help out with what we have learned down thru the years.

1QwkSport2.5r

I've noticed that. From my standpoint, it seems a lot of guys tackle engine questions thinking the guy asking the question isnt "in the know" but at least for me, I have a pretty good knowledge of all of this but getting into new areas of the hobby (like tuned pipes) creates other questions. I certainly dont mean to talk down to the "extra" info I got; for me its well received and understood. There really is a method to my mayhem though it may seem like I dont know what I'm doing. When I got my S90K, I read the entire Club ST thread. I think it took me 4 days to read it all in my spare time. It drove my wife nuts - LOL.

I'm always willing to help and try to share what I know and not "what I heard" though sometimes "what I heard" comes from guys with far more experience than I and in that case I trust "what I heard" to be correct.

Thanks for the kudos on the boat. I hope the S29 has enough power to move the boat well. The boat weighs 5lbs even, and is a flat bottom stepped hull design. (kind of a cross between a hydroplane and flat bottom) Now I just need to get it on the water and see what prop is gonna get me that unofficial speed record.

hama743

I have a ST .45 ringed and I need a piston. Could anybody point me in the right direction?
Thanks
Matt

spaceworm

Toysonics say they have ST parts. Might be worth a try. Good luck.

http://www.toysonics.com/super-tigre/

hama743

Thanks so much I will try them.

Matt

hairy46

My Feedback: (1)

Super Tigre and I are just not a match! Bought few of them and just not had any luck with them! That last draw with one was I bought a new 91 for my stick after having to work on it for weeks to get it to run enough to maiden the plane the muffler broke off breaking the casting on the engine itself. metal in the engine also messed up the ring! one flight so far on the plane but have a new engine going on it this week. Magnum 91

jeffie8696

Does anyone know if Tower is dropping ST engines? Iwould love to fix up my G60 and Ihave a part on back order.

fujiman

My Feedback: (133)

try toysonics.com