Piston Longevity of a Busa

[fabr]

I still see signs of detonation on the crowns. here's a better read on detonation.

http://www.contactmagazine.com/Issue54/EngineBasics.html

[Enemy]

For reference

#3 Plug

[fabr]

For those not interested in the whole read here is just one paragraph from it.

DETONATION INDICATORS
The best indication of detonation is the pinging sound that cars, particularly old models, make at low speeds and under load. It is very difficult to hear the sound in well insulated luxury interiors of today's cars. An unmuffled engine running straight pipes or a propeller turning can easily mask the characteristic ping. The point is that you honestly don't know that detonation is going on. In some cases, the engine may smoke but not as a rule. Broken piston ring lands are the most typical result of detonation but are usually not spotted. If the engine has detonated visual signs like broken spark plug porcelains or broken ground electrodes are dead giveaways and call for further examination or engine disassembly.

[fabr]

For reference

#3 Plug

Bottom line is that unless there is something I don't see here your problem was detonation breaking the ring land followed by valve/piston collision due to piece of ring land holding open valve. IMHO

[Enemy]

Another very good read. Had no idea that EGTs react that way to detonation! Cool stuff.

"Engines that are detonating will tend to overheat, because the boundary layer of gas gets interrupted against the cylinder head and heat gets transferred from the combustion chamber into the cylinder head and into the coolant. So it starts to overheat. The more it overheats, the hotter the engine, the hotter the end gas, the more it wants to detonate, the more it wants to overheat. It's a snowball effect. That's why an overheating engine wants to detonate and that's why engine detonation tends to cause overheating."

Remember my cooling system issues I was discussing with ya a while back Fabr? I have a double edged sword going on, not to mention that I am helping the situation with poor cooling to begin with..

Bottom line is that unless there is something I don't see here your problem was detonation breaking the ring land followed by valve/piston collision due to piece of ring land holding open valve. IMHO

Agreed.

[fabr]

For the bad ass engine, you planning on low compression or staying with something around 10.5:1? Reason I ask is that there are 2 schools of thought on this for turbo buggies compared to turbo bikes. What's your opinion?

[fabr]

Another very good read. Had no idea that EGTs react that way to detonation! Cool stuff.

"Engines that are detonating will tend to overheat, because the boundary layer of gas gets interrupted against the cylinder head and heat gets transferred from the combustion chamber into the cylinder head and into the coolant. So it starts to overheat. The more it overheats, the hotter the engine, the hotter the end gas, the more it wants to detonate, the more it wants to overheat. It's a snowball effect. That's why an overheating engine wants to detonate and that's why engine detonation tends to cause overheating."

Remember my cooling system issues I was discussing with ya a while back Fabr? I have a double edged sword going on, not to mention that I am helping the situation with poor cooling to begin with..

Agreed.

Had forgotten you asking ma about that but yes!,that also happens with detonation. Starting to add up now.

[Enemy]

For the bad ass engine, you planning on low compression or staying with something around 10.5:1? Reason I ask is that there are 2 schools of thought on this for turbo buggies compared to turbo bikes. What's your opinion?

Well, since from what I have been reading, only a slight loss in torque going the low compression way on the Busa..That is the way I will go..

Low compression/high boost is much more efficient than high compression/low boost from what I learned from the V8s and superchargers. I think Im going to stick with that theory!

[fabr]

I'm undecided at this point.

[millbilly]

One pic looks like piston fatuge, the next looks like a melt down...?

[fabr]

second is not from his engine unless I misread in which case all I said was BS.

[dsrace]

I believe all the pics on the first page are of enemy's motor but he'll let us know. either way not pretty.

[fabr]

I completely understand that theory as well, I just don't see the signs of it. No pitting on the piston, no aluminum on the plug ceramic. All cylinders, pistons, and plugs look wonderful...except for that chunk missing    Hell, I dunno!

I was leaning towards weak or broken spring cause it is the intake side that hit, and I never installed the heavier spring like has been highly suggested from other builders.

High speed detonation..

[Carlriddle]

Dont think the last pic with the melted piston is his, just a reference.  No way that thing held any compression.  I cant hear crap over about 4k rpm, definitly a good catch.  Everything I've read says short of oil/air change you cant realy abuse these motors.  So much power, so little weight.

 Found 3 busa's in Tampa Fla.

[fabr]

PLENTY BUSAS ON EBAY. aCTUALLY A GOOD SOURCE .