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Aftershock questions..

Old 03-29-2009, 07:53 PM
  #1  
Fordtrucks96
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Default Aftershock questions..

So im the new owner of the after shock. So far i really love it. Got her dialed in and runnin like a top so far. THings ive done so far is, I raised the fuel tank to create a gravity feed for the fuel to the carb, removed the stock pipe and run an open header with a turn down and added the 6v rechargable pack for the car servos. Ive also had to adress the non shifting tranny but seem to have fixed the factory flaw there. I also removed the copper shim under the head to improve the CR.

I want to upgrade to the LST2 fuel tank and try the HPI clutch shoes. Ive read a bunch about trying the HT pipe wich im thinking was a stock LST2 pipe? The one everybody raves about on here? With having the fuel gravity fed into the carb, I dont need the pressure from the pipe to force the fuel so im able to run the open header. I really like this but was wondering if anyone else has honestly tried the open header, then installed a good pipe to see if you loose or gain power? I gained power going to the open header from the stock pipe, However ive herd the stocker sucks anyways. SO i guess my questions are as follows.

Do i want the stock clutch shoes and springs from the HPI .25 engine only? Are they a direct bolt on to my fly wheel and bell?
Has anybody compared an open header to a nice tuned pipe?
Is the stock pipe from an LST2 the one everybody says is the bestupgrade?

Thanks.
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Old 03-29-2009, 09:13 PM
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Airbus 9e
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Default RE: Aftershock questions..

Running without the pipe and the pressure fitting will make your engine run too lean....plus many here have posted saying that you lose a ton of power without the tuned pipe....The stock pipe sucks....You can find the Losi HT pipe that's standard on the LST2 on Ebay cheap.....I got mine for $11, and that along with a set of LST2 aluminum clutch shoes really woke up the M26SS
Old 03-29-2009, 11:14 PM
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Default RE: Aftershock questions..

Almost everything you've done is in some way destructive to the engine and the truck as a whole.

Don't remove a head shim as that can cause piston damage and lower engine life GUARANTEED.
IMMEDIATELY install the lst2 pipe (a.k.a. HT pipe ), gives the engine ton of power and ensures constant pressurized fuel. Probably the best pipe for that engine
Put back the fuel tank the way it was.

Buy a set of dynamite max life clutch shoes or losi long wear clutch shoes as they last for 4 to 5 gallons with very little maintenance. HPI shoes, I wouldn't recommend them as they cost just as much as the dynamites or the losi long wears but you end up getting only 1 gallon of life out of them.
Old 03-30-2009, 05:07 AM
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full maxx
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Default RE: Aftershock questions..

never heard of anyone running without a tuned pipe as these are scavenger engines it needs the back pressure to get the proper fuel mix from the tank (from pressure) and the exhaust ...ditto on the max life shoes and the ht pipe is the cheapest and best upgrade for power...as far as the tranny not shifting it is prob. because of the lack of power from the exhaust missing, all of these do not shift right on the first few tanks anyway ...but it is a great lookin body tho...oh and the way you have the tank mounted , it will not last past your first roll over , which will be soon if not then you ain't driving hard enough
Old 03-30-2009, 02:49 PM
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Fordtrucks96
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Default RE: Aftershock questions..

Well i guess im not sure what to say.... This engine has run really strong without the pipe.. Doesnt run lean at all on the top end. Ive also rolled the truck many times and have not had any problems with the raised tank. I will prolly try the HT pipe just to see what results i get from it. I will buy the aluminum LST2 clutch shoes as well. As for the copper shim under the head, that seems to be a pretty popular thing to do in the RC world as ive read with many other trucks and engines. My M26SS ran much stronger when i removed that..

Ive herd ppl talk about a high compression head button for the .26.. Anyone know any details on this?
Old 03-30-2009, 06:14 PM
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twomanytoys
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Default RE: Aftershock questions..

I would really like to see on video how it it runs. I can guarantee that you dont have anywhere near the power output that the engine is capable of. You need the Pulses of teh exhaust to make it run right and get full power. I can also bet that it is running lean at some point. I have been in rc for over 20yrs and never heard of a nitro truck running without a pipe and running to its full potential. Not sure why you would try to change the whole concept of how the engine works. Does it wheelie? Im sure it wont because you dont have any back pressure. It depends on backpressure for low end torque. ANY 2 stroke engine needs some kind of exhaust.
Old 03-30-2009, 07:44 PM
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Fordtrucks96
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Default RE: Aftershock questions..

Well actually, No it does not wheelie... Ive never had one of these aftershocls before so i had nothing to compare it to. It did, as mentioned before, gain power getting rid of the stocl pipe and running an open header but I will buy the HT pipe and see how that runs. As of now, ive ran about a half gallon through it without touching either of the carb needles. It fires up and runs like a champ!

Does nobody have any input on that high compression cilinder head i herd about for these engines?
Old 03-30-2009, 07:51 PM
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twomanytoys
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Default RE: Aftershock questions..

You dont need a high compression head. Higher compression will just make it predetonate. You wont gain any power with raising compression. If you want more power then get the HT pipe and raise your nitro percentage.
Old 03-30-2009, 09:37 PM
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Fordtrucks96
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Default RE: Aftershock questions..

Is running the 30% over the 20% worth the extra cost? Does it make a big difference then?
Old 03-30-2009, 10:31 PM
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Default RE: Aftershock questions..

You are killing your engine by running no shim and without a pipe. No shim will cause detonation and destroy your piston. No pipe will cause it to run lean, two strokes NEED a pressurized tank to maintain a consistant tune. The pipe also acts as the engine's "valves" for lack of a better word, here's a good example of the pipe's primary function on a 2 stroke:



http://en.wikipedia.org/wiki/Two-stroke_engine

http://en.wikipedia.org/wiki/Scavenging_(automotive)

http://en.wikipedia.org/wiki/Expansion_chamber



Put the shim back in and put the stock pipe back on, then practice tuning. Then get the Losi tuned pipe, the Mach .26 is a pretty good engine for a RTR.
Old 03-30-2009, 11:05 PM
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Default RE: Aftershock questions..

I can guarantee you didn't gain any power taking your pipe off. Do some reading on two strokes and tuned pips and you will quickly see why. People often do engine mods, and then swear it helps, when it really doesn't. "seat of the pants feel" is a poor engine dyno. Your truck is probably a LOT louder now than it was with the pipe, which is probably whats giving you a false sense of more power. But trust me (and everyone else who has replied) You are losing power running with no pipe. The stock pipe may suck in comparison to a "good" pipe, but its DEFINATLY better than no pipe.

The reason a tuned pipe helps a 2 stroke nitro engine, is because it (the engine) has an intake port, and an exhaust port, but the intake port closes before the exhaust port... so not just the exhaust goes out, but a little bit of the new fuel/air mixture. The way a tuned pipe works its pretty complex and could take up several pages, but put really simply, as the engine runs, each time the exhaust port opens, it expels a "pulse" of exhaust, along with a "pressure wave" which travels at the speed of sound (faster than the exhaust gasses go). This wave travels out of the engine, and has the net effect of sucking the exhaust gas out of the cylinder, and drawing a fresh air/fuel charge into the cylinder. It goes down the header to the pipe through the exhaust gasses, and when it hits the cone inside the pipe (if you have a plastic pipe , you can take it apart to see the cone, some people take it out because it makes it louder, but doing that lessens performance, if you have a metal pipe , you should still be able to see it looking inside with a flashlight), it bounces back toward the engine. When you are in the pipe s "ideal" RPM range, the wave comes back right as the port is about to close, stuffing some of the gas back in, some exhaust gets back in (but there was already some still in there from the last cycle anyhow) but more importantly some of the fresh charge that escaped also gets pushed back in.. the net result is that there is MORE fuel/air in the cylinder then without the pipe , which means MORE POWER. its basically supercharging it, but only in a certain rpm range. A longer header/ pipe combo will give more power at low rpm's, while a shorter combo will give its power at higher rpm's
Old 03-31-2009, 10:11 AM
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Fordtrucks96
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Default RE: Aftershock questions..

Well thank you both for the education on the pipe! As stated before I "think" I gained power over the stock pipe but was not convinced a tuned pipe would not be better. I will admit, I didnt know much about the 2 storker. I figured if it was anything like a 4 stroker that the less restriction on the exhaust, the better. I will order the HT pipe, then retune. I guess with a pressure pipe on there I can also lower the tank. With the tank raised it did provide a constant supply of fuel and the truck did run great..I will also order the aluminum LST2 clutch shoes and springs. I also think I will leave out the head shim as I ran the truck before i took it out then i removed it and tested it again before i did the exhause change and really did notice a power change there. Then i did the exhaust work.

Thanks for the replies here guys.
Old 03-31-2009, 01:15 PM
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Default RE: Aftershock questions..

Fordtrucks what body is that? Very cool.
Old 03-31-2009, 04:19 PM
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Fordtrucks96
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Default RE: Aftershock questions..

That body is for the Traxxas slash and slayer.
http://www3.towerhobbies.com/cgi-bin...?&I=LXVUG2&P=7
Old 04-01-2009, 01:43 AM
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Default RE: Aftershock questions..

Nice thats what I was thinking but I thought the slayer was much smaller. How does the body fit? Got a pic from the side? THanks
Old 04-01-2009, 10:31 AM
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Default RE: Aftershock questions..

Fordtrucks96, I promise you that the Losi HT pipe will give you what you are looking for. You honestly don't even need to replace the stock clutch shoes to get the wheelies. Slap that HT pipe on there, get it tuned to run 220-230 with good low end throttle snap off the line and you'll soon get sick of having to flip the truck back on it's wheels from excessive wheelies. The stock shoes aren't too bad for a gallon or so. I believe I had around 2 gallons on my AFT w/ original shoes and it still had plenty of bite.
Old 04-01-2009, 07:35 PM
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Fordtrucks96
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Default RE: Aftershock questions..

Thanks guys for the positive replies. That pipe is on the list...

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