This I can't tell you with any certainty. I would bet that you would be in 400's before this is your problem, but that is just an educated guess. 400 real horsepower ain't hay - it would be what I call a "90%er" - tuned well with matched gears, it will beat 90% of the cars out there. Although this isn't a direct comparison, lots of LS1 guys are building 800+ horsepower turbo engines off truck manifolds turned forward. I have seen multiple 400+ hp 2.3L ford turbo engines built off a stock turbo manifold as well. And Hank will undoubtedly be able to tell of 650+ hp SyTy's on stock manifolds was well.

During a conversation with the guy from Sissell's (My mind draws a blank on his name you guys know who I'm referring to - Mike?) and he recommended limiting boost to 14# on the inlines. 13# on the squirrel performance website turbo calculator would make 425hp on a 250. So for 12-13# boost and 400hp, the 292 manifold and a steel pipe elbow is simple, easy, cheap, durable, and well matched to the power output. Cheap easy and effective - that's how I like it!

Last edited by 56er; 11/29/10 02:55 PM. Reason: added stuff
"The first rule of overkill: You can never have too much overkill."
"Overkill is underrated."