Its not the outlet size, it is the size of the diffuser.I've seen dyno sheets of Supras making 1,198rwhp using a S cover with a 74mm compressor wheel.
Would they have gained anything by going with a 3"? I wish they would have had the opportunity to try it and see.
I think the real question should be more geared towards orifice theory flow, and how much air can a 2.5" outlet flow at the average operating temperatures of the turbo?
Yes, you are right. My bad.Its not the outlet size, it is the size of the diffuser.
You need to understand that is a whole different animal from a 109 with a different rpm range.turbos that make power on high revving imports struggle on buick motors and rarely make the same power.I've seen dyno sheets of Supras making 1,198rwhp using a S cover with a 74mm compressor wheel.
You need to understand that is a whole different animal from a 109 with a different rpm range.turbos that make power on high revving imports struggle on buick motors and rarely make the same power.
That's exactly what he is asking which is why he asked the question in regards of combos at or above 700rwhp.he is talking about a buick.instead of "On a Buick, do these two covers make any difference in power on the same turbo?" (
We are talking about a buick 109 700 rwhp or better with a turbo.We are talking about what the turbo itself can produce, not the engine that it is pushing air into.
That's exactly what he is asking which is why he asked the question in regards of combos at or above 700rwhp.he is talking about a buick.
I agree, thats like me going to the Honda form and asking a question about my cummins..
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I have swapped and pushed a lot of turbos on these 109s and every time I go to the bigger cover when the car is turned up it doesn't fall off the boost cliff.now this is not for the guy that runs 20psi of boost with no timing in the motor or running 10sec passes .for most guys the smaller cover will work really good especially in the fitament area.i believe bison has tested quite a bit on the covers and I remember seeing some threads on them.Fair enough.
I know a 2.5" outlet has supported 1000rwhp on a Buick.
Too bad we can't send some turbos to a shop to do some back to back testing on an engine.
Without any real back to back testing, how could we answer his question?
or like asking if a shop keeps custom made-to-order parts right on their shelves?
I am no expert and will share my thoughts:Has anyone done any testing on hp differences between a S cover vs a H ? What is the larger H cover worth over a S cover on say a 700 rwhp combo.
S cover = 4 inch inlet 2.5 inch outlet
H cover = 4 inch inlet 3 inch outlet