The Next Big Change
The Next Big Change
There’s a whole lot coming up for the 2010 race season. Not the least of which is the “new” motor pictured above, as well as an “uber motor” as I refer to it, which will probably be 2011’s big change.
You may be wondering why a new motor.. Well it turns out, those N/A rods that were in the motor last year just weren’t meant to make more than 300whp.. heh.. Ya know that saying, you’re not going fast enough if you’re not breaking things? This is what I love about turbo’s.. Dial up the boost until it explodes, and turn it back a notch. hahaha..
What happend.. Well I got tired of my manual boost controller not working properly, I confirmed it was the MBC by unhooking the boost reference hose from the wastegate. Suddenly I could get to 18psi as fast as I could press the throttle down. So I installed the boost control circuit in my MS, along with a fancy new PWM frequency multiplier board.. I figured the higher the frequency, the better.. So I set it to the max multiplier of 256, along with MS’s 11khz frequency, I think I ended up something over 2.8MHz.. Needless to say, it turned out the valve didn’t work at that frequency. I dialed up the duty cycle 1% at a time, and kept making pulls. I finally went from 3psi to 18. My overboost protection was kicking in and the car was bucking a bit. I stayed in the throttle hoping it was a boost spike and my boost control would do it’s thing. 2 seconds later I heard a sound that’ll make a grown man cry. It sounded like I was spinning my tires in gravel and the gravel was being flung against my floorboards. It was my engine block. Drat.
I’ve torn the motor apart and done some extensive examination. It was NOT detonation, there was zero sign of that on the pistons, the spark plugs came out looking gorgeous (and actually went into my van at one point where they continue to work great). It simply was a case of too much power, and possibly the overboost shutdown at those power levels being too harsh.. The rods buckled, folded, and in general were torn to shreds. All in the span of about 2 seconds, at that point I pushed in the clutch and coasted with the engine off.
If you remember my dyno plot.. I was making 265whp at 8psi of boost.. So if you figure 7hp per psi, that’s 335whp at 18psi, over 350hp at the crank, and who knows how much torque, 400ft lbs? The N/A rods were intended to make 150hp, and close to 150ft/lbs of torque.. Needless to say, the destruction was epic.. And I have pictures...
Thursday, March 11, 2010
One thing I noted in the autopsy was that I didn’t lose any rod bolts. They’re all still in tact on the half of the rod that’s still on the crank. Even the bearings still spun freely on the crank. I lost 2 rods, cylinders 2 and 4. The shattered piston above was cylinder 4, I was able to reach in and remove it by hand once I removed the head. About the head, all the valves survived, the head lives on with no damage. The piston ring in one of the pictures above is very telling, when the rod buckled and snapped, it came back up and punched through the piston, shattering it, and leaving that nice tell tale shape in the ring.
So anyways, The engine in the first picture in this post is a ’03 PT block, with actual SRT4 rods/pistons in it. That will be going in this season. The motor I had hoped to have done this season is just too good to rush, so I’ll work on it after I have the car up and running again and can take a leisurely pace with it. I’ll cover that motor more later on.
I also have a few other tricks in mind for this season.. Such as an electronic 4 speed automatic, controlled by a MegaSquirt derivative called “MegaShift”.. I’ll probably start a new blog for that. I’ll link to it here when I do. For now, enjoy the epic carnage pictures. :)
