Hello everyone. New to the site but have a few question from the one's who have boosted their 4B11's. The 4B11T features a semi-closed deck to help with containing boost pressure and to reduce cylinder wall flex, while the 4B11 is open deck.

I'm mainly wondering how much strength is lost here. A friend of mine is wanting to build his 4B11 with a stage two block and stage one head to get around 400 to 450 at the wheels.

Another question that we are asking is transmission and axle strength but that's another thread.

My main concern is that once boost is added unless the block is forged at some point the heat and stress from extra combustion will just blow the block up. He thinks it'll be fine since (another of our friends) has a k20z3 (completely stock) running 500hp at the crank and those engine's are also open deck. He's been running the car at 9 psi for the past 3 years and it's still running strong. I argue that the k20z3 is pretty much a purpose built race engine and that the 4B11 is an economy engine, even if the rods are forged.

What do you guys think?

 

Considering a stock sleeve 4b11t will do 600whp without issue, I would venture to say a standard 4b11 would do 400 just fine with good tuning, and a turbo setup that isn't requiring a max effot tune to make 400. Sleeving it won't hurt. $1500 for peace of mind..