rods, pistons, headstuds, maybe some sleeves...

all depends how you make that 450 whp... if you are running an fp green/red/black at the ragged edge (35+ psi) you'll need a stout motor. on the other hand, a higher flowing turbo can make that at much less boost pressure (say, 27 psi) and be a lot nicer on your engine.

I grenaded my engine on the stock turbo at 35 psi (just a guess... stock MAP only registers 33.5 psi)

 

Good point, I always get a chuckle when people say you'll blow your engine running a big turbo without building your engine. If you tune them to about the same peak HP, the larger turbo will be easier on your engine as it will require less boost to reach similar HP numbers at the cost of less response and shifting your power band to the right.

 

i dunno about that.... apart from incorrect (read bad) tunes its the torque that kills engines...

torque is torque, doesn't matter how you get it, 15psi or 25psi...

 

x2

The two posters above Tephra don't really seem to understand the relationship between boost, engine output, and stress on internals. Remember, boost pressure is just a number.

 

Well yeah, your engine can die from excessive torque regardless of the tune due to internals unable to cope with the stresses. They can also die from a really bad tune much earlier than expected, that's not rocket science.

I was talking more about the quality of the boost and how it would make the tuning more risky and difficult. For example a smaller turbo at 35 psi is pushing much hotter air than a larger turbo pushing 25 psi even if they might have the same peak HP.

When I talk about horsepower it can be assumed without spelling out every time that horsepower is torque over time, and that the sudden shock of torque when boost hits is typically when the trouble happens. Be it too much torque for the rated capacity of the internals being exceeded, or a really bad tune.

Hope that clears it up a bit.

 

oh, I understand, and torque definitely is a big part of the picture, I am speaking strictly in terms of cylinder pressure, which while related, is not always directly proportional to torque at the wheels.

you can be running 35psi boost on the stock pea-shooter turbo, resulting in a higher cylinder pressure than a turbo that does not need to work as hard to keep up, yet still be making less torque.... what is so difficult to grasp about this?

edit: I just realized I pretty much copied Hiboost's above post... however I do resent the fact that I'm dismissed as being told that I have no idea what I'm talking about :-/