928mac

sorry to here that. Is that true that you should keep them under 6000. mine see's that in town

NoVector

Sorry for your loss; but what a way to go. Are you going to buy a used engine or just a short-block? I always think of buying a spare when 928 Intl has their 1/2 priced sale in December--becuase when I need it, they won't be on sale. Again, sorry...

justaguy

Sorry to hear of your Failure BTDT twice ! Consider Iceman's advice on the OB pan and spacer.
Good Luck
Sean

AO

Hey... at least you have your swaybars installed!

Let us know when you want to pull the motor. We'll get the posse over there and pull it right quick.

IcemanG17

The 6000rpm is just a gauge I use in my 4.7L 16V 928...mostly due to its dying torque curve there really is no sense to go higher than that............

A euro engine or 32V could easily spin higher and many do...but I have had great success using the 6000 guideline....

On the 1st engine in the estate we spun it to 6500rpm many times due to the trans not wanting to shift.....that engine didn't last very long...but I do think its more attributed to the rod bearings starving in the corners than the higher RPM...

It all comes down to what the engine was DESIGNED to do....the 928 engine was designed to make good power through a WIDE powerband...it never was intended as a high rpm screamer.....

I like Doc's idea for a warning sticker.....

cold_beer839

"Lifters is Losers!!!" The Ol' Nascar sayin'

Fix it and hit the track again hard!!

littleball_s4

First, sorry to hear that your engine is blown.

Second, glad to hear you're ok and nobody is hurt. Could have been a much bigger mess.

Third, I am curious as to the seconds before the failure:

-What rpms and g level are we talking about? Rough figures.
-What oil level? When was it last checked?
-Were you on full throttle already? Were you powersliding?
-Were you jumping on the curb?
-Do you remember any sign something was wrong (vibration, noise, power surge...) the second before?

-How many street/racing miles on it?

Sorry to make such painful questions, I know all you want now is pull the thing out and fix it. It's the first blown engine I read of here, and I would like to have a small database to help with the autopsy and help keep the fixed unit trouble free.

Happy rebuilding and again sorry for the loss.

Koenig-Specials 928

For guys like me that drive a little hard on the freeways when there isn't much traffic is around, this is exciting stuff. You guys are our heroes. Sorry about your car but you guys lead exciting lives with these cars. I am sure you'll make 'er badder than before.I am so jealous.

Mike Simard

What an interesting engine failure. Congratulations! Just think of the world of possibilities this opens up. Ahh, a new engine.

I used an engine that had split a cylinder for my 7.0, it seems to happen sometimes.

auzivision

Shoot, that’ll buff right out!

Seriously… glad to hear nobody was hurt... engine blocks are replaceable!

Sharks

Thank you for all the replies of sympathy, but I have always known that racing is expensive, and eventually if you are out there long enough things will happen. Track event like this for me is a way to get it out of my system so I don't do stupid things on the public roads. It lasts about a month or two, then I have to go back and get it out of my system again. It costs $130 for the day and that includes class room time, a very experienced instructor, lunch, and drinks for the day. That’s cheaper than a speeding ticket (until you add the cost of an engine).

This car has a long history of track DE's both with and without the supercharger on it. I would say at least 12-15 events in the past 4 years along with a car control clinic at the Tire Rack headquarters (like an Autocross event with sprinklers spraying the track to get you sideways).

There was no indication prior to the engine letting go. I just finished a long sweeping right turn, the car was straight, but the weight was still sprung on the driver side. I was accelerating onto the back straight at about 4000 rpm in 3rd gear. I never let the car hit 6000 rpm, I will shift just after 5000. It happened in an instant (bang, what was that, oil hits rear wheel, spinning, recover on grass, stop in a cloud of smoke).

The oil level was full. I check a number of things before heading out to the track and before each run of the day, oil defiantly being one along with tire pressures.

I have not decided if I can just replace parts or will need a completely different engine yet ... after I pull it and do the autopsy I will make that decision based on what damage may have occurred to other parts. The engine still turns over, so there is hope.

I know one thing for sure, when the engine goes back in it will be much stronger than the one I take out (both mechanically strong and hp wise). Maybe a stroker, Intercooled, dry sump, ... so may ideas that I have admired others for doing in the past may be on the table. Keep those ideas coming guys.

I will post photos after the engine autopsy so we can all learn what to avoid in the future.

AO

Intercooled and dry sumped!

If you're serious about a stroker, there are many options. I can introduce you to Todd in Green Bay. He built Kibort's motor.

Cosmo Kramer

Aww that is a real bummer Mark. At least this makes a perfect excuse to buy more performance parts. You should be able to find another block without too much difficulty and then build it baby!

I am glad you weren't hurt and I am sure you will get your beast back out there in no time. Track days seem to do these things whether it is mechanical failures or crashes it is just par for the course. I agree though, there is nothing else like it. I used to do track days on my sportbike to try and get it out of my system instead of riding stupid on the street. Unfortunately after a track day I found myself taking exit ramps at 80 mph with my knee down with my newly found confidence!

Mike Simard

I don't know what happened with your car but cylinder/piston breaking detonation always seems to happen 5-6k in my experience. Keeping the rpms low isn't going to help if you have high dynamic compression and common issues like mixture, ignition, oil consumption etc.

littleball_s4

Doesn't seem a common rod-fatigue issue. At 4000, the forces are half what you have at 6000.

I don't think bad rings could cause that without massive blowby (noticeable).

Maybe full-pull before full-warm condition made the piston crack and then seize and sent the rod out.

Who knows. Only the autopsy will tell.

Edit. Just read you were about half way through the session. So thermal shock seem also out of the equation.