I heard that there were a few safe, simple mods that one can do to a .40-size engine. My only current engine is a Thunder Tiger GP-42 that I got with my SuperStar 40 at a swap meet for $25, unbuilt and unused. I looked up the MSRP for the GP-42 and it's like $50 or $60, so it really isn't the hottest or spendiest engine. I still value it, though, so I want to hear of some safe engine mods.

One I heard about was simply taking the baffle thing out of the muffler. How much power would I gain? An then, what if I added a tuned pipe?

haha sorry this post contributes nothing I'm just stunned at your sig.. haha

take the muffler off and get the tower hobbies muffler, 300 rpm. [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJB16&P=Z]tower muffler[/link]

could remove the head and take out the shim, increases compression but can reduce the engine life.

if your not worried about ruining the engine you can take the sleeve out and polish the exhaust ports.

Something the racing folks know about: On an engine where the head extends down into the cylinder, a tight fitting head (.001 clearance) will give as much as 1000 RPM over a similar head with a sloppy fit. It may be that the head off the next biggest Thunder Tiger engine will match up bolt holes. If so, carefully cut it down to the required tight fit in the cylinder. Another way is to cut the diameter of the part-in-the-cylinder down. Then make a metal band, shrink fit it onto the head, and cut the outside of the band to the requisite diameter.

The simplest horsepower improvement comes from using more nitro in your fuel. If you go up to 20%, you may have to shim your head to reduce the compression, but you will gain RPM too.

the engine isn't designed for the higher nitro so this isn't true. Plus you have to buy club fuel ranging from 10-15% at sanctioned evens so this doesn't help you at the race either, you need to break in the engine on the fuel you plan to use at the race. If you wanna use higher nitro put a couple shims in the head and get a colder glow plug.

Most reliable mod is to get the mounting bolts really loose. Then jerk that loser engine out and throw it away. Then buy and install a decent engine. Problem solved.

I have had 2 GP42s that responded well to a little porting and polishing. I don't have the original muffler but I have been using an OS 40 size muffler without the baffle. I imagine a pipe would work great. I really like TT engines, I have several. It's great fun to tinker and with an inexpensive engine you are not out much if you slip up. (loser engine????)

Some examples of the porting
I just ran it with a Master Airscrew black and got 13,500 on a 10X6. Using Sig 15% champion fuel and a Hanger9 medium plug.

another good mod for any 2 stroke engine is stuff the case. These glow engines already have tight tolerances, but i bet if someone was crafty enough, they could make it tighter. If you start tampering with engines, be prepared to loose one or two. I played with a homelite 25cc for a while, but it did blow up from pushing the limits. no matter what you do, have fun and i hope you learn something in the process.

Try a Macs muffler and more nitro. Play around with props to make sure that you are on the peak of your power curve.

Buy a rev counter to make sure you know what you are getting in terms of RPM.

Delicately spoken, oh fellow Tennessean.

I did also live in Houston for 10 years. Late 70's-early 80's.

I also reccomend the Tower muffler. It is cheap and easy way to get a few hundred RPM. The GP42 is no power house but it should do the trick for the Superstar 40. ANother thing to consider is looking around for a cheap TT Pro 46. I have a few of them I have gotten used for $40 or less. They pop up quite a bit at swap meets and on eBay. I lurk on alot of boards as well looking for classifieds.

Harsh!
But fair, I thought

It's just hard to make SIGNIFICANT improvements on most modern engines. They have been tweaked by the manufacturers already for performance and reliability. If you want to tinker for a few RPM then go for it knowing that you may do more harm than good, otherwise simply buy a better engine which is what I said in my earlier posting.

I would say this guy has made significant increases in his engines output.

Sorry, I thought we were talking about RC engines.

RC engines work on the same principles as their grown up cousins and will respond to mods in similar fashion. They are mostly air pumps you know.
The trick to porting is just looking at the way fuel and air mixture flow, it doesn't like sharp edges or quick turns and it follows a smooth surface better than a polished surface. Also a polished surface will cause the fuel to become separated due to a loss of surface turbulence that keeps the fuel mixed, this is called "drop out". I have ported and polished from small RC engines to motorcycle engines to big V-8s with excellent results.
make the inexpensive low powered engine make the power you want , that is the essence of what we Americans call "Hot Rodding".

DC12V, the biggest boost I ever got out of a OS LA .40 was with a homemade mousse can pipe [MCP].

There is a construction article over at the official SPAD website.....SPADS all the Way?

Anyway, the engine gained over 1000 rpm IIRC. I'll bet your GP .40 is basically the same as the LA .40.

Increasing nitro does also work, like stated before you should have head shims and a tach to see what's going on.

Nitro is liquid torque. Tim's usually has 30% heli fuel in stock.

if you want more power without buying more expensive fuel all the time just get a larger engine to start with.

Combat the Thunder Tiger GP42 has 3 intake ports while the OS40LA only has 2 so I believe the TT has more potential.
It is much more like an OS40FP.

The only thing that might prevent the GP .42 from out performing the OS would be the quality of the parts, then. Years ago I asked a knowledgable guy what the main difference between OS and the OS clones was and he pointed to bearing classification, heat treatment, choice of alloys, etc.
In some cases OS can't be outclassed metalurgically for a competitive price so the under-dogs can try to offer engines that are set to run a little bit harder.....at the expense of reputation for longevity.

Can't complain about mine, it came to me beat to heck and after a good cleanup it ran great. After all a good bushing engine doesn't have much to break. I can remember only one of two bushing engines in the past few years (of many different brands) that I have seen with significant bearing wear. I have seen several ball bearing engines with crunchy bearings. Not to say they are superior but going by the averages I have seen bushing engines tend to be quite durable.