anatomy of a burndown

[kev]

His Banshee used a aftermarket head that also used O-rings. It was a super-high quality head, just the bad one out of the bunch I guess.

Thats a whompin air compressor for sure. How were you able to handle the engine with it hot enough to distort metal? Also, did you do the test right there or did you haul it somewhere and do it?

 

[bwalker]

Thats a whompin air compressor for sure. How were you able to handle the engine with it hot enough to distort metal? Also, did you do the test right there or did you haul it somewhere and do it?

Yes, I did it right there. Actually about 20 feet away, but you get the picture. It wasnt that hot. Maybe 100 degress give or so(Room temp was just over 100). Leather gloves are all I used to handle it, but not because of the heat. It was abit dirty from belt dust etc. This temp is consistent with what the operating temp of the motor is. Maybe a little on the cool side, but close enough. BTW onnyour freinds head did he notice the o rings where damaged? How did it leak enough air into the cylinder to lean it out and cause seizure withoutsucking major amounts of coolant also.

 

[kev]

The O-ring showed no damage at all, even after we were able to hear air puffing around it.

The way the banshee engine is designed leaves areas 2 inches or more without a water jacket thru it. The water jackets are kinda like this ( ) The warpage was occuring in one of those areas, between 2 head bolts.

 

[bwalker]

On this engine it uses a dome with a ring that fits around it that locks the dome and cylinder together. The dome cylinder interface is sealed by two o rings.After the dome assmbly is in place a large water jacket covers the whole assmbly. It is sealed by a o ring at the base and a o ring by the plug boss. With this sytem it is impossible for the motor to suck o\air through a leaking head o ring. A head o ring failure would result in a coolant leak directly into the cylinder.

 

[Gypo Logger]

Hello in there, Dennis, is that you? Buddy! Where have you been?
I'm very, very thirrrrsty.
John

 

[bwalker]

Also, was the exhaust blocked in any sort of way? Is the radiator fins distorted or bent? If there is a water pump on it, was it working efficiently?

Exhaust was fine, It doiesnt have radiatore so the fins are not a issue and the ater pump is fine. You may not have seen in a earlier post I mentioned that I have a coolant temp gauge as part of my intsrumentation. It was reading nwithin the normal range when it blew.

 

[My2cents]

Ben, when are you puting it back together? when's the test run?
I have given my opinion on this problem,reguardless I am still interested in the final diagnosis whether I am wrong or not.

 

[bwalker]

My engine guy is putting it back together next week. BTW did you see my post about how the head is configured in way thata head o ring leak would only result in coolant leaking into the chamber. It can not leak air from this sort of leak.

 

[Dennis]

Gypo...yep I am here watching...

The reason I have let this off topic carry on without one mention of a chainsaw, is because of the principles metioned herein. Most of the principles these guys are talking about can be applied to our (chainsaw) world. And I do think that alot of it is good discussion.

Thirsty as well laddie...

 

[dbabcock]

I want to talk about things made from rubber and latex. Since chainsaw sparkplug boots are made from rubber is this OK, Mr. Moderator?

 

[My2cents]

You have to be kidding?? Look who's calling the kettle black!

Ben, I suggested it is a small cyl crack, although I not convinced with your O-ring theory. I would have inspected the metal surfaces of the head and cylinder under magnfication looking for a very small dark track between the cylinder and water jacket.

 

[bwalker]

I know the head is crack free as it is andozed and would show any crack easily. The cylinder will be inspected by my guy prior to rebuild. He is very thorough so I am sure he will find any crack if there is one. In both of these locations sucj cracks would leak coolant into the cylinder. The only plass air can enter is from the basegasket, crankveal, reed gasket, manfold gasket or the cylinder casting around the transfer area(not likely). Any other crack or faulty gasket that resulted in a leak would leak coolant into the combustion chamber. All of this talk of leaks is moot anyways as it has been leak down and passed.

 

[glens]

Ben,

I agree that it's not likely to be the problem in this case, but your language seems to preclude the situation where combustion pressure could squeeze through an opening of some kind which would in all other cases provide an adequate seal.&nbsp; If it were the case that the coolant were being kept away from the cylinder side of the jacket by a barrier of hot gas, the cylinder could overheat locally, but the temperature of the coolant would indicate the situation to some extent.&nbsp; You say that did not occur, but it <i>could</i>, which is the point My2cents is making.

Glen

 

[dbabcock]

Hey Ben,
Think that this was caused by detonation? LOL... center cylinder, 1107 D&D TCat.

 

[bwalker]

ouch. Is that the small end of the rod Im looking at? What casused this?

 

[dbabcock]

What you're looking at is what's left of the piston skirt from the exhaust port side. Problem was caused by using non-coated cast pistons with a motor making about 225 HP. Everyone talks about the somewhat mythical 130 MPH lake sled. I radared myself on this one at 132.2 on hardpack.

 

[bwalker]

Doug, I know Wiseco pistons scare the bejesus out of most people, but in this case it would probaly be a better choice. A forged piston will not crack like this. Many of the aftermarket big bore kits use Wisecos because they will make small, custom runs of pistons for them. BTW the problems associated with wisecos are usually brought on by piston to cylinder clearances that are too tight for forged pistons.

130 is smoking fast for a sled. The fastest I have radared my 800 is about 115. You would be suprsied at the idiots that think their sled will do 130 only to find out it barely pulls 100 on the gun.

 

[dbabcock]

Yes, I ended up with forged Wiesco's in it. The skirt clearances were OK with these particular pistons and they lasted for over a year until I sold the sled. 115 with your 800 Poo is doing well. When my MX 800 was stock except for 192 studs, it ran 109.4 before the 8 hour breakin timing advance and 111.8 after. The fastest I ever had by MX 800 with the mods was 115.3. Years ago, my stock '97 Mach Z ran 118 at 1500' altitude. My son's '00 MX 500 ran 92.2 at 1500' with him on it at 100 lb.. My wifes '97 Grand Touring 500 eeked out about 82 MPH. Will have to radar the '03 ZR900 when I get a chance, as well as the new REV.

I call my Stalker ATS radar gun the Bullsh!t Detector. It's nice because I can interface it to the laptop and then let the computer post-process the raw data to obtain anything I want. Time to distance, speed vs. time, accel vs. time, etc. BTW, as a reference point, with 660 ft gearing and clutching, the drag sled does 0-60 in just over 2 seconds. Now that's shoulder dislocating hookup!

 

[bwalker]

I call my Stalker ATS radar gun the Bullsh!t Detector. It's nice because I can interface it to the laptop and then let the computer post-process the raw data to obtain anything I want. Time to distance, speed vs. time, accel vs. time, etc. BTW, as a reference point, with 660 ft gearing and clutching, the drag sled does 0-60 in just over 2 seconds. Now that's shoulder dislocating hookup!

I would love to have the staslker stats system. I imagine it would be pretty useful for clutching a sled. It sure beats the ride and feal or butt dyno method.

 

[My2cents]

Ben, what ever became of this highly debated topic??