Hey Roloef, what do you make of this....apart from it being the wrong thread and that it's stuffed....hahaha. This happened on the 6th tank, and it was heaps rich...but the temp of the atmosphere was about 37 degree's as usual down here....!! I had it going pretty well and she just stopped on me. I think I pushed her too hard....too early. Ive never had this before ever though. Time to throw in the spare engine I guess. I was wondering, do you think the crank shaft would be ok still, or should I just turf the whole lot....?

I would say an end of life conrod...
Other possibillity is not enough lubrication and builded up to much friction on the crankpin and damaged the rod.

Many rods when not replaced on time can break on the crank pin hole or just above it.

He says its the 6th tank...

Does that mean its the 6th tank of break-in??

Well, modifying engines for better performance does alway mean more stress on the internals and can shorten the life a lot, for sure on cheap engines where not the best materials are used.

Looking on the 1st pic you se a part of the bushing, the surface is compleetly burned so it must be a shortage of lubrication. If it was a bad conrod or fuel I can not tell. If it was a bad rod then the hole for lubrication was blocked, the rod was wrongly mounted or the bushing became loose.

If that is a rear exhaust engine, the piston is modified completely wrong. Those cuts on the piston will not allow the engine to run properly. The exhaust side of the piston skirt must seal against the sleeve at TDC. What made you do that?

Ah... The piston front/rear is symetric (the cuts in the piston looks like indeed a side exhaust), there is a chance the rod was placed in the wrong way.

I have the 353 ct, a 41615 manifold and the 2652 pipe. Now I'm NOT into modifying any inturnal parts in this engine, but seeing how I do have alot of time on my hands and a drimel Is there any benifit from polishing my exhaust manifold, pipe and where it exits the block?
I'm not looking for any big throws of power but polished exhaust I know will help with the flow and maybe fuel mileage. I'm thinking this won't hurt me.
Bob

Pretty nuts hey....!!!

Yea, MGT8.0 side exhaust engine.

Yea, was on the 6th tank from new. I put 4 tanks through it, via Idle. 5th tank was light revs and 6th tank (still on rich settings) I started taking it through passes to open her up a little. About half way through 6th tank I was pushing her a little and she just suddenly stopped. Went to start her up again and it was just locked up.

At first I thought it was seized, but was puzzled as I hadn't changed the factory rich settings yet. I then took her home to inspect and found the bottom of the conrod and bearing shell in the intake port. Immediately I was hooked on pulling her down in absolute amazement. The piston was flush hard against the cylinder head, and the inside of the conrod-bigend looked as though the sleeve bearing had been spinning inside the rod journal for some time...there was scoring and was darkened. The crank pin's steel surface is also heavily scored. That is what I am starting to think anyway....that the sleeve bearing had spun and the lubrication gallery's were not in alignment no more.

There's excessive heat localised, as the big-end was blackened, and the conrod didnt look like it had be typically broken away, it looked as though it was stretched away...(metal became malleable from the heat). There is ALOT of pinch at TDC of these engines at new, but still....I would have thought that after 5-1/2 tanks, most of that harsh pinch would have bedded in. The internals of the 8.0 are huge and strong in general. But still.....just amazes me hey.

Even though I have a wrecked brand new engine....I still think its pretty cool to observe something like this in a device such as this. The conrod was placed with the gallery facing the front to the crank port. I have a brand new MILL in it already (exactly the same), and I will get her turning and burning this weekend. I will be considering a .32LRP for it though, just to see if that will give me the same power and torque figures, as I really do like what the 8.0 does for the MGT. I guess I just got a "one-off" this time.

Thanks guys, you're all great at this stuff and have helped me alot, and at the very least, its something new to look at on this site. ;-)

As Roelof states, widening exhaust port makes for more RPM, and crank induction port for timing makes for better response. I first hand have tried these, and have to say that those 2 mods are the most gains. Matchporting the exhaust is well good, and noticeable. I have a redcat 1/8MT with an SH.28-P6 engine in it with all the mods that Roelof advised me...(sleeve porting, sing grooves, crank timing, exhaust matchporting). That damn thing is totally off the chain....!!! 2nd gear doesnt affect the RPM at all....once it hits 2nd....its all over, and the truck is in the air and on its roof. Its soooooo hard to control on the dirt....instant, 4WD on the spot donuts, turn into 1WD donuts and flat on its roof. Im amazed.

In short.....THANKS ROELOF.....!!! :-D

OK, but will matchporting going to improve my fuel mileage or make it worse for me? This set-up has me worried that I may have trouble making the 5 mins. I have plans on ordering a novarossi (I think its) a 03600 inline exhaust cooler, which is supose to help some with fuel mileage.

Milage can simply solved with testing some pipes or look what others use. The 2013 is an awesome pipe to make the 5min easy if you are alowed to use it (Within the EFRA it is illigal)

Beside that with todays engines it is most of the time difficult to get the 5 minutes so that was the reason for the EFRA to go to a 7 minute qualification to be sure you have to make a fuelstop.

Well that sure sucks! Nothing more that I like doing then running my engine (lean) and out of fuel at the end of a run. Thats not to good for a engine.

I'll have plenty of time during break-in to evaluate run time on the rich settings and a well behaved driving mannor to see if I can make the 5 mins.

I'm still wondering if the match porting is going to help or hurt my fuel mileage though?

It can, sometimes I have seen a better milage after modification but I can not realy tell what will help, in my early days with a small change in crank timing (1 degree both ways) I have seen some results but todays top engines are much larger timed.
I believe de pipes you can get are optimized to work with the factory team engines and so they do perform a little bit less with "standard" engines, getting the right pipe (and that could be one from another brand) can give more result. To give an example, the 2052 on a JP Eagle did give me 4:45 maximum while a 2013 can give me 5:30 on the same engine.

Current Flash engines in combination with a Novarossi pipe are not easy to get 5 minutes. These engines are made to get as much mixture in and to get all the combustion out. Over here the 2013 is not alowed in racing so I can not tell how it performs on current engines.

Get a Novarossi 2601 or a RB 2604 with a Non-conical manifold.... You won't have a problem with runtime again...

This engine came with the C5TGF plug which is a very hot plug, I've got some OS R7s which is a medium plug. I was thinking that I could try the medium plug and run 20% top fuel and see what kind of results I can get out of this for the break in period, (my tinking is) Cooler running temps. with the .30 head shim. This will,... chance the timming up some, but I don't think that theses chances aren't that significant to hurt anything.
If the fuel mileage isn't going to make the 5 mins I'll try the hotter plug with the 16% nitro and see what those results give me.