Effect of a Scratch
 

How much effect will a scratch have on a motor? I.E. a scratch on both the piston and sleeve, and a deep one too

RE: Effect of a Scratch
 

Only a professional can tell for sure. You need to send it to RayARacing. He is the only one who can repair (if possible) a damaged piston and sleeve.

http://www.rayaracing.com/

RE: Effect of a Scratch
 

Based off what Ive seen its hard to tell beacuse my motor is modded and no one has reached the speed I have so its anyones guess as to if the scratch was actually hurting performance.

I knew he could repinch, did not know he could repair.

RE: Effect of a Scratch
 

As far as I know, he is the only one that can bringan engine back with sleeve damage. Of course there will be some that are beyond repair. Call him and discuss it.

RE: Effect of a Scratch
 

I highly doubt he can fix a damaged chrome plated sleeve.

RE: Effect of a Scratch
 

I guess all those high speed runs did your motor in?

RE: Effect of a Scratch
 

Yes they worn the motor out... NO they didnt cause the scratch

Here you can see the scratch at 3 gallons when I found it during the rebuild

http://i1105.photobucket.com/albums/...z_untitled.png
http://i1105.photobucket.com/albums/...redownload.jpg

Now here is the same scratch with 6 gallons thru it, notice the wear and the scratch is more noticable

http://i1105.photobucket.com/albums/...let2/285-1.jpg
http://i1105.photobucket.com/albums/...let2/287-1.jpg
http://i1105.photobucket.com/albums/...let2/288-1.jpg
http://i1105.photobucket.com/albums/...let2/286-1.jpg

Its really really hard to tell if it truly hampered my performance, why because I was still able to reach 59 mph. Im sure there was some power loss but it had to have been minimal at best. The only way to truly know is to have a fresh motor built and try again. Even of the motor was repinched it would seriously yield me another mph or two, but the scratch would still be there.

RE: Effect of a Scratch
 

Definately a major scratch. No repair for that.

RE: Effect of a Scratch
 

Haha yes it is and you can stick your nail in it its so deep

RE: Effect of a Scratch
 

if the engine idles well then the scratch is making very little effect..first place a engine acts up with a bad seal is the idle quality, as well as it will stall coming off throttle.....

RE: Effect of a Scratch
 

Well it idled perfectly and launched off the line great

RE: Effect of a Scratch
 

thats crazy..I have seen engine with much less visible damage run like absolute poop...........and just the same I have seen engines with badly damaged piston/sleeve like yours run like absolute tops.........

RE: Effect of a Scratch
 

run it till it wont run any more and toss it when it dies. that scratch looks like a crack to me.

FYI, when chrome scratches deep, it will eventually flake off, and will kill the engine very quickly.

RE: Effect of a Scratch
 

Yep she had lots of torque steer, was definantly a motor to try the first ever nitro back flip;) trust me I will do it one day. Kinda funny that the motor was designed to move a truck with 4lbs of Baja wheels and yet it ran to 59.2mph:D

The engine has lost alot of power ontop due to the fact it was ran at full throttle for 4 gallons haha. It still runs 57mph consecutively but doesnt quite have the steam to reach 58, 59, anymore. If It was a motor that could have crossed 60mph but I reached that point a little to late. Robin is going to build me another mill with a few tweaks to this motors design.

RE: Effect of a Scratch
 

Not much more damage you can do... run her lean and fast until it dies, then just buy another motor.

RE: Effect of a Scratch
 

4 gals on an engine is nothing.....should not need a rebuild at all at this point and this is your second? What am I missing here? That engine looks like it ingested a circlip or something. Still ran good though????? Just when you thought you have seen everything.......Thanks for sharing your pictures I would not have believed this engine ran like this.

RE: Effect of a Scratch
 

Your correct in the manner that it was early for the rebuild. The reason for the rebuild was my intention to do nothing but HS passes for a run at the Top Speed record for the savage. Piccos are awesome motors that take a good bit to break in and upon the advice from Robin at ERCM. I decided to rebuild so that during a run I wouldnt run the risk or have much greater risk of popping the motor. Regardless of what went thru the motor, the button was still smooth with no dents, divots, scratches or anything. Yes the motor ran like a dream amazingly enough haha.

Heres a vid of the truck running at 59.2mph with this scratch

[youtube]http://www.youtube.com/watch?v=FCnoZDkJiRM&feature=plcp[/youtube]

RE: Effect of a Scratch
 

Seems like she was running just fine....saw nothing wrong with that pass. So your after the top speed record for the Savage, ahhh makes sense now. I have a Savage that is pretty fast, but not that fast. I pretty much keep mine offroad man. I like to drift mine wide open in the gravel....never thought of making it the fastest as it is a big ass truck. I see your running 1/8th scale foam tires all the way around for stability. How fast did you make it on rubber?

If I was going to attempt to make my Savage the fastest I would strap my Clocked Nova Rossi 28-7 in it. Of coarse I would have to figure out how to start it as it is bump only. I think it would surpass the progress you have already made as it is the baddest MONSTER engine I have ever had the pleasure of laying my hands on. Hell, I haven't seen anything even close. This engine does not even sound like other engines, it fricken wails man. FYI I have no intention of making my Savage the fastest.

RE: Effect of a Scratch
 

Haha its cool man no worries...

Actually the wheels im using are Hpi Phaltlines, right out of the box no belting or fishline or anything. As for the record, the record was 52.9mph set by Robin at ERCM but there is one video of a guy at CC racing with a savage that hits 70mph with twin motors, but his is not stock by any means. Traxxas gearing and the motors are modded, but the way the guy radars gun is a little fishy. My time running for the record has shown me a fews things when accuratly trapping speed. GPS is more accurate than the radar gun and the radar gun on average is 1mph faster than GPS.

My truck uses all stock parts that anyone can buy from HPI. The idea behind it was to make the fastest possible savage with all HPI stuff, the only thing different is the CEN ring and pinions, the rest is all HPI. Of course the baddest MONSTER truck engine there is;)...or was[:o] The motor would have easily reached 60mph a gallon sooner with the knowledge I have now but when I get my new mill, 65+ here I come. Oh and that motor is a torque motor not meant for top speed ;)

RE: Effect of a Scratch
 

I can't find the picture of it, but I have a Fox airplane engine that ate a wristpin G-clip.. Actually, it ate 4 different clips scoring the iron piston and steel liner. I put a new piston and liner in it with new clips and it did the same thing. I guess the wristpin floats back and forth quite a bit and pushes the clips out. Anyway, despite having a scratch that goes from the top of the piston to the bottom and a scratch in the liner the entire stroke of the piston, it does still run and idle pretty well. Running it fast and hot with a lot of castor oil in the fuel sort-of varnishes up the scratch masking its leak-down effect.

My Fox engine bleeds cylinder pressure down pretty quickly if you rotate the engine slowly, but sounds normal and has a nice bounce to it if its flipped over quickly.

I'm not surprised the OP's engine still runs with that scratch in it. I'm curious as to how it happened since the wristpin clips are still in place. Glow plug element wire break off at one time maybe?

RE: Effect of a Scratch
 

There was an early run of the 40th Anniversary Fox 35 where the circlip groove wasn't machined quite deep enough causing them to pop out. The check for these is to push the wristpin quite hard and if the circlip came loose, get another piston from Fox :).

RE: Effect of a Scratch
 

I see what you mean about the castor but for 5 of the 6 gallons thru the motor, I ran odonnels race fuel which does not have castor. The last gallon I ran was Werks 30% and that does have castor. As for what I think caused the scratch? Idk it happened during the first 3 gallons so it's anyone's guess

RE: Effect of a Scratch
 

The engine I was talking about is a 1983 Fox .40 series 5 with the small case. Parts aren't available for it anymore. I got lucky and found an RCU member that had a NOS piston and liner for my engine. Regretfully, the clips that came in the piston were not up to snuff. I did finally get the clips to stay in, however I didnt feel that the engine was going to perform to its full potential. With the engine warm, compression bled off very quickly. I suspect that after the rest of the break-in, the idle quality would be poor.

I'm saving this engine to send to Fox using their trade-in program to get a big case Fox .45 or the Eagle IV .60.

RE: Effect of a Scratch
 

That's insane to have a scratch like that and it still runs that good. That pipe sounds freakin AMAZING. Robin, i think it is, im gonna have to hit you reaaal soon for one of those end-bleeds.... Thing screams skillet, nice!

RE: Effect of a Scratch
 

ERCM pipes are the shiznit so are his modded motors