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Originally Posted by CallMeCrazy  I really really really really REALLY wish that people would stop using words like "The ____ engine can only handle __ psi before it breaks." tuning is a HUGE part of whether or not something breaks and all turbos are NOT created equal. 6 psi on a GT12 is not the same 6 psi on a GT60. You need to think about VOLUME when you're describing or discussing turbos. That is why the flow maps are so important when you start turbocharging something that isn't normally turbocharged. Take one small T3 60 trim (largest of the Garrrett T3 before TO4B and TO4E) turbo on a 130-150 ci engine and you may see 300 hp on 18 psi at the point where the turbo is stretched thin and being overworked. Take that same engine and use a TO4B or TO4E and you may see 300 hp on 6-8psi with the turbo barely being used. Now that that same TO4B or E and put it on an engine twice the size and it's the same deal...you need engine to make boost and you need turbo to make power. A small engine isnt going to be too happy with a large turbo the same way a large engine with a small turbo is. Bottom line is that all turbos arent created equal and you CANNOT SAY that "___psi is the highest you can go on stock internals" unless you're describing WHICH TURBO AS WELL. Go back to my posts on the GM that he's thinking of using. The turbo itself maxes out at barely 440 cfm and is capable of running 20 psi but running that much boost on that small turbo will do one thing, create heat, and make it that much harder to tune. You really need to think of your HP GOAL before you think or buy your turbo.
As for what psi an engine fails at...they all fail at some point. I recently tuned a 1.6L B16 (Honda) engine that made 550+ hp on a GT35 turbo with stock internals. To some, the ignorant (still stuck on web forums being keyboard racers) are still stuck in the mindset of "The B16 can only handle 6 psi on stock internal and maybe 200 hp before the rods bend" well guess what...mine was on 26 psi. Tuning is key and knowing which turbo when you say things like ___psi. |
I understand where you're coming from on this. Personally, I don't plan to run 33.4 psi because that is not what I'm after - I want about a 400 HP street cruiser that weighs 3500 lbs and can roll with most of what's out there while still riding and
looking like a Cadillac should...with a few suspension adjustments to prevent rear-end squat and shit like that.
I don't plan on being one of those guys that has something unpractical for use, so when I say that I want 400 HP on a built engine, then I am likely looking at 7-9 psi of boost on top of an engine that has a mild cam, port and polish, Allante intake and other gadgets (I pretty much have the aforementioned items I need there at that)...
That said, the project is still taking a bit of time. House is going through quite a few changes, but I have a new 4.9 liter ($65 from junkyard half-price day!) that I am working on with a few neat surprises in store, including my device for forced induction. The transmission is also done and will likely get a run this weekend to see what needs to be done there - upgraded 3.33 FDR with an LSD, beefier internals, shift improvements, and a Superchip for this transmission combo that I actually found in a junkyard! It is from a 1992 STS with the 3.33 FDR...
Updates soon, I promise!!!