subscribed, would love to hear more.

 

The World Challenge races in St Petersburg is airing on VS right now. I got a glimpse of your Evo crossing the finish line for the first race. Hopefully you get things sorted out for the rest of the season. I'm subscribed and will be following along.

 

Hi All,
Tested at the Streets of Willow yesterday after major dyno tuning. Car was making good power. Water temps were in control thanks to a triple bypass conversion. Oil temps were still high 270, despite dual setrab coolers. Lost the Bosch Motorsports ABS first session. Next session, Motec went into limp mode. Came into the pits and pulled the plugs. Cylinder one showed that the piston had touched the plug enough to just dent the electrode. The scope showed no piston damage, and there was no detonation. Dialed back the boost a bit, replaced the plug and went back out. Same thing one lap later. Put the car in trailer and headed back to the shop. The data logs look good so I'm puzzled as to why this happened. We are headed to Long Beach this weekend to race. We are going to run a lower boost map and dial back to 7500 rpm. I also requested that the plug have an additional washer added for clearance. If you guys have any thoughts, chime in. Wish us luck at Long Beach.
Cheers,

 

pistons are hitting the plugs? either your using the wrong plugs or its time to pull the motor how much power/boost are you pushing?

 

Boost at 28psi tapering to 20. Plugs are correct length.

 

At the top of the stroke, how much clearance is the 10 supposed to have?

 

Well.... either the electrode is stretching out, or the connecting rod has stretched. Considering it happened in one lap..... are you still on the stock bottome end? It might be at the point where it's about to let go.

 

Stock bottom end. We thought about rod bolt stretch, but it was only cylinder 1 where this happened. Compression and leakdown were good. I'm hoping someone has seen this before.

 

I thought I read about the some 4B11 engine failures that might be related to your problem. Check this thread and the first picture. Looks like you guys might be heading for a similar failure. Hopefully not though.

https://www.evolutionm.net/forums/ev...-4b11-ttp.html

 

Hey Bill, great to see you on the track. As far as the issues I am watching closely since I plan to move to the X soon.

Couple things, for a piston to mechanically damage a spark plug, you have to have some pretty significant problems with that cylinder. I wouldn't think there is something mechanically wrong, but it is easy to just to rule it out. Easiest way to verify that piston travel (crank stroke & rod length) is the same is to measure it through the spark plug hole (stick a rod in the hole and turn the engine, measure bottom distance and top distance and then compare all numbers to another cylinder). That can rule out if anything is wrong with the bottom end. Then measure a distance from somewhere on the head to the top of the installed plug in bad cylinder and good cylinder. That gives you the comparable installed height of the plug. If you pick your reference points wisely, you can even come up with what the spark plug to piston top gap is on good/bad cylinders (within some tolerance of course). I guess you could possibly stretch a rod (although they are much more likely to bend). If everything checks out (as I would bet it does) --

I would guess the more likely thing is the tune on the car. You can deform the ground electrode with detonation, can also run combustion temps so high that its just starting to melt and deform that metal. Are you sure there was not detonation? What does the plug physically look like? Are these OEM plugs? How much hp more is the car making than original? How many ranges colder are the plugs than original?

Marty

 

I think the point of the "TTP Article", reffered to above, was that the mechanical problem is the compression ring end gap @ .004" is WAYYYY to small and the top compression ring does not have enough room to expand when it is heated up. So, after many heat cycles it eventually breaks the ring land off by warping out of shape looking for more room to expand. The part of the piston ring land that breaks off, and starts rattling around in the combustion chamber, eventually hits the the spark plug ground and closes the spark plug gap along with most of all the other damage, as described in the text and shown in the pictures above.

I agree with you, I would not worry about the squish clearance being to small and the piston hitting the spark plug ground. As a side note, I bet the piston would hit the head before it would hit the spark plug ground.

As far as the tune goes, in this day and age of electronic engine management the ECU would pull ignition timing out immediately if the motor started to detonate, and TTP does not mention there has been any evidence of detonation in any of these failed motors, after removing the head. So, I would rule out detonation as a cause of this type of failure in these motors that have failed.

 

Hi All,
First off, good to hear from you Marty. I have plenty of time now to sort out problems. Had a catastrophic brake failure in turn 1 at Long Beach saturday morning. I lost front brake pressure, but fortunately had enough rear pressure to slow the car from 140 mph to 90 mph before hitting the tire wall in the runoff area. Sprained my thumb and wrist, bruised ribs and broke my collar bone. Not sure until we get it back to GMG if it's a re-tub. Feeling pretty sore right now. Not sure yet what went wrong. I had a good pedal through the back side of the track, turned through the hairpin and the pedal went to the floor in turn 1. Multiple pumps, then decide how to crash. Not pointing any fingers, but I am running Motec m800, Bosch Motorsports ABS and Stoptech brakes. By the way, the double crush washers on the plugs solved the piston contact problem. Will be doing a lot of work on the car, and return to the series in August. Thanks for everyones support.
Cheers,

 

Damn, sorry to hear that Bill. Keep us in the loop on what failed and how so we can all learn from it.

 

Wow that isn't the news I was wanting to see, good luck with recovery and hopefully in the mean time the car will get sorted to where it will be safe and competitive.

I lost brake pressure in turn 10 at Summit Point last weekend driving with NASA but wasn't going fast enough to prevent me from nursing the car to an early apex and pumping the brakes during a balanced drift through the turn.

 

http://www.youtube.com/watch?v=cvQ0kp0tLbs