Quote:
Originally Posted by ilivas
The overboosting likely causes a lean condition and detonation. I wonder if it’s a tuning issue. Has that happened a lot? It’s hard for me to wrap my head around instant torque breaking a rod bolt. I can see a lot of factors breaking rod bolts, but it’s hard for me to see a torque curve doing it. NA motors have even more instant torque.
It’s not a huge platform, so really not many people have pushed them to their limits. You’ve been around here longer than I have so you would know better, but from what I’ve seen, only a couple people have pushed them so their may not be a ton of info on the motor. In the other platforms that I’ve dealt with, there are more bad tuners than good ones. I’m not yet sold on a lot of things till I can see a lot more tuners with a solid general consensus.
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Heat + oil starvation on corners/braking + instant torque @ ~350lbs = broken rod bolt
That's pretty much the recipe for a blown track motor on quite a few before they started building them. Then everyone redid the con rods/bolts and custom oil sump pickups to make up for this issue.
As for the overboosting, it's all from JB4. Piggybacks cannot react fast enough to save this engine from failure once that occurs. Events were almost always the same: boost to 25psi+ and cylinder blew due to a ring failure. Not saying that it will always boost but due to the lean conditions that JB4 runs the car in plus that overboost... yeah.