ShadowHawk

Anyone have any idea about how long an engine should last? I treat mine really well and put all the after run oil and stuff in it. I do my job to see that it stays clean of dirt, but I have never really opened it up (don't trust myself) other then taking off the heat sync and the piece that holds the glowplug in place (something called a button) to clean out the heatsync out really well. Is there anything else that I should do to take care of the engine, and how long should they last?? Do they usually last a while? Do they need parts often??

KyleSch

If your running it slightly rich and taking good care of it maybe 4-5 gallons before you start seeing the compression drop.

You should not open up the engine to remove dirt since there won't be any dirt to get out of there if you have taken care of it. If there is dirt in there your engines trashed anyway If you wanna clean out the grease and stuff WD-40 works very well, take off the glow plug and header you spray (alot) WD-40 in the engine with the piston above the exaust opening. Let it sit for 10-15 minutes. Pull the pull starter while the engine is upside down, it gets rid of most of the grease and oil left from the fuel.

ShadowHawk

What happens when the compression drops?? What can I do to get the compression back up?? Is a compression drop a really big deal if just using the car as a play ride.....I'm not into racing, I just don't like the idea of having to put a new engine in my car every few months or so....I tend to take mine out a lot, but I do my best to take care of it.....I run it rich on the low end, but not so rich on the high end, but I don't run it full throttle very often! I guess I was just kind of curious as to how much maintenance these engines really need and how long they will give me a good time!

ShadowHawk

I really didn't take the engine apart to get the dirt out of it....I just took the heatsync off the top of the engine to get the crud and grease out of the heatsync where the glowplug goes....I can clean out the fins without removing it, but I just wanted to get toward the bottom where the glowplug sits so stuff wouldn't get into the engine....Not only that, but I could spray the WD-40 on the heatsync to get that cleaned up without fear of the WD-40 going into the engine and taking the dirt with it!

KyleSch

Yes the compression is vital. What the engine does is get the fuel and air from the carb. Then the piston goes up and compresses that air/fuel mixture enough so it ignites shoving the piston back down to have it repeat over again. When the compression drops the piston can't compress the air enough and it will have problems igniting the fuel/air mixture, so you will see a big drop in power, idle problems, tuning problems, and finally an engine that won't run. You can check compression by turning over the flywheel, you should feel a definite cycle from easy to turn to harder and harder then it should give out.

Good news is most of your engine is fine, all you need to replace is your piston and sleeve which will cost you around 40 dollars on a non race engine, up to 90 or more on a race engine.

adeoliver

My Feedback: (4)

LOL well for one it all depends on what engine you run. THe cheaper the engine generaly means the less life it will have, not always though. If you always monitor the temps, keep it clean, and rid the engine of excess gas each time you put it away it will last sometime. Now for instance I used to run the os.12' and 15's and usualy got anywhere from 2.5 -3 gallons out of them, now on some of the .21's I have ran Ive got up to 6 gallons on a couple hyper .21 4 ports and 5 gallons out of a couple 8 ports, and have also got 6 gallons out of one of my XTM.247's, my current .247 is rounding 1.5 gallons which is just about its final brakein and is starting to show some serious signs of power, it just keeps getting stronger and stronger. Now Ive heard some of the higher dollar engines like the RB ws7 getting something like 15 gallons+.
What ever your case is, just make it a point to put a new conecting rod in every 2 gallons or so because it will stretch and eventualy fail(snap)

KyleSch

2.5 - 3 gallons? You must really of run those things hard! Yeah some really expensive engines can last 10-15 gallons.

And no you don't need a connecting rod that often, every other piston/sleeve rebuild is good. (like 10 gallons)

nitroman88

My Feedback: (5)

If you run fuel with low amounts of oil your engines wont last long. most of the car fuels have about 9-15% oil. The fuel i run has 18-20% also depends on how much nitro you running and in what temp but generally 5-6 gallons it about right but im ecpecting about 7 out of my engines.

adeoliver

My Feedback: (4)

Um ya 2.5-3 gallons out of the cv engines. That was with normal running, the sleeve and pistons in those engines are junk, and they wear out to fast, now if your getting more out of them, then you are taking it very easy. As for the connecting rod, I dont know about changing it every other rebuild, but the smart thing to do is to change it at least everytime you rebuild, I sugjest the next time you buy a new engine, messure the rod, run 2 gallons through it and messure it again, any increase in the length is a key sign that it will need to be replaced!! I only speak from expierience here, not from what Ivew read or heard!!

gubbs3

My Feedback: (1)

2-3 gallons out of a CV isn't that great. I know several guys that got six gallons through them. Just don't run them lean. Compression is vital for an engine to run right. As much as the fuel mixture needs to be compression in the cylinder the crankcase must be pressurized on the down stroke to deliver the charge into the cylinder. Without that it won't run at all.

ShadowHawk

Other then turning the flywheel by hand, what are some other signs of compression drop?? I can't really tell for sure what the compression should feel like when turning the flywheel so I'm not sure if it is loosing any or not.....Are there any serverly noticeable changes in the engine that tells you that it is loosing compression and is about to fail?

KyleSch

It won't idle well, won't have as much power, hard to tune, difficulty starting, basically everything that can be wrong with the engine running will happen

gubbs3

My Feedback: (1)

When you turn the flywheel with your finger turn it until you feel some compression but don't go over the top. Just keep some pressure on it and if it slowly goes through the cycle it may be time for a new piston and sleeve.

BUGGIES_R_US

Good information here..

Some engines also have heads made of special alloys or ceramics and these engines tend to last a good 10-15 gallons.

Only thing is, it takes about a gallon to break in in all the way!

I started full throttling my HPI at about 6 tanks. That thing really screamed, but I could tell it still needed to break in some more to pull out the revvs!

Dont forget.. temperature changes a lot depending on what engine it is your talking about.

Most RTR engines run well around 235-250.
But you can run the ceramic engines at that temp only after a few tanks!

And I was talking to a friend, he told me that runs his engine at 275 and runs in the 300s often while racing.. and it lasts em over 10 gallons!

Of course.. ya gotta pay $350-400 to get an engine like that. Ouch! lol

ram

WhiskyVR-4

your best bet is to buy a compression gauge (both dynamite and hobbico make them) and check your compression. Take note of what it is, and monitor that as you run more and more fuel through the engine.

You really should keep a notepad handy when you run your car. Keep track of carb settings, suspension geometry changes, engine temp, compression (both cold and warm), weather (not just temp but humidity and pressure), etc.

I gurantee that if you keep good, clearly organized notes about how the car ran in different weather and different carb settings and such you will get a VERY good feel for your car in a hurry.

adeoliver

My Feedback: (4)

Very very good point!! I use to monitor it all just as you stated, until I got a good feel for these engines. But I agree this is a very good Idea for those still learning how to tune a 2 stroke.


And as for 2.5-3 gallons being bad, I know but it was the same with every one of them. I was also running them at around 240-270, and yes they were lean, cause I was in a hurry LOL!! However I do know that some folks out there have squeezed 5 or so gallons out of them which is very very good, but not likely for most of the engines, considering the rear bearings tend to come apart after about 2.5 gallons!! I guess it all depends on how you run them, cause I am a die hard basher, and normaly dont stop until something breaks.

BUGGIES_R_US

Wow.. I still dont understand how a compression guage would help me tune an engine.

IS there an optimum compression range for every needle setting or something?

What would a compression number tell you?

Thanks
ram

dbow

My Feedback: (1)

A compression measurement should be taken when the engine is new and when its at operating temperature. This will give an starting indication measurement to go by.

Its a good idea to check the compression from time to time to see how far off from the original number it is.


Someone stated earlier that an engine showing compression loss will not idle correctly etc.
This is not a true statement, if the engine was that worn out, it would never be able to hold fuel in the line up to the carb to get started. Even if you put fuel into the carb it would not start.

From my experience a loss of compression will yield engine failure. In that the engine will start, idle and run as it always has, however once the engine reaches the upper regions of the temperature range (normal operating temperature) then engine will just all of a sudden stall.
Numerous attempts to re-start the engine fail. Thing is that if you wait a few minutes the engine roars back to life and we began the cycle again.

2 things are happening to cause this behavior. First, once the temperature gets up to where it needs to be, the sleeve expands. Normally the engine runs great, however with worn internals the parts no longer have a tight fit like before. Thus there is loss of compression and the engine stalls. Attempts to re start fail because the engine cannot hold or pull fuel because of the heat.

Secondly the engine cools, it starts fine again, the internals shrink and once again there is a tight fit in the internals.

The amount of fuel that goes through these engines is an individual basis, each engine is different and tunes a little different.
Each owner has their own preference of fuel and maint routine.
Climate, frequency of run time, and your behavior with the model all affect its lifespan.

The bottom line is like anything else, take care of it and it will take care of you.

Work smarter not harder.

Dbow

KyleSch

Dbow, problems will occur if you try to idle it at operating tempurature. It may start fine but once it gets up and past 200 degrees or so chances are it won't idle anymore.

WhiskyVR-4

I wasn't suggesting that a compression gauge will help you tune an individual engine, per se, but it will help show you how worn your internals are, and in the long run it can help you try to coax more life out of your engines by running them a little differently. In addition, it can help you determine the relative effect of adding or removing head shims. In my view, more info is better than less, and compression is certainly useful info on any internal combustion engine. Besides, they are petty cheap, its not like I'm telling the guy to buy a dyno or anything

speedracer0_7

from what i've seen motors don't last very long, about 10 to 15 hrs. run time on a piston and sleeve. i suggest checking the rod after each gallon and if u detect any play at all replace rod and measure rod pin on crank. 4 some reason airplane motors never seem 2 wear out, more oil and cooler cleaner air i guess

nitroman88

My Feedback: (5)

One reason airplane engines last longer is beacuse The people that fly planes(like me) use fuel with lots of oil and only about 10% nitro. The reason people are only getting 2-3 gallons out of car engines is beacuse they are using 20-30% nitro with 8-15% oil(thier may even be lower oil percentages). With this fuel a engine will produce more horsepower but It wont last near as long as a engine running on high lube fuel. I really dont understand why people can spend 200 dollars on a engine and then fry it in 3 gallons using fuel with high nitro and low oil precentage. Lets not turn this into a fuel thread as thier is already another active one going on but fuel plays a major part in how long a engine will last.

speedracer0_7

shore you're rite nitroman, when i was flying i was'nt competing and what little competing i did do was thermal gliders which is more like a timed landing. with the cars i've pretty much always competed at the races, probably more than a thousand races over a 20 year period. when i got my first nitro car i used 10%nitro and 20% oil and although the motor ran it didn't run that good compared to the tank of blue thuder someone gave me at the track. the small motors seem 2 like at least 20% nitro they just run and idle better. when u have 2 much motor a restrictor and 15% nitro make it much easier 2 drive

BUGGIES_R_US

Very good point. Thats why I'm kicking down to 15%+ extra oil next gallon

But.. I need castor oil, cant find it anywhere.

Maybe I'm just gonna buy it online. I'll go check klotz now.

ram

nitroman88

My Feedback: (5)

I have ran the 10% with 18% oil in my cars and boats and it worked qiute well. now I have moved up to 20% nitro. and it seems to give alittle snappier throttle response and a noticable top end. bottom line is when the nitro content is higher and the oil content is lower, the engine wont last as long. This si why Im running the 20% airplane blend now, because it gives me half syn and half castor and a hack of alot more oil then most of the 20% car fuels give.