I know that they create lots of backpressure and do not flow as well as other manis, but what hp can i expect with one, i made 265 with a 50 trim turbo with .48 hotside. i want to change to the .63. i seen that ef made 400+ with a huge turbo but i still want to keep my a/c and p/s. anyone know what is the average power made on the log?
People have taken tubular logs past 500whp. AFAIK nobody has actually logged backpressure between various manifolds, pun not intentional. They just come up with the theory that since 2 runners fire towards each other, it must be bad -- dispite those cylinders having the greatest seperation between firing (one fires when the other's valve is closed). They don't flow the best, but they're not going to hold you back a ton.
I'm going to guess you did 265whp at a wimpy 10psi or something? I've seen stock SOHC's come close to that with logs & equally sized turbos when they used the stock MAP. Upgrade to a 2.5/3/4 bar MAP sensor and quick pussyfooting around. Most turbos are night and day difference between 10psi and 20psi.
Eh, the individual cylinder trims on a log manifold 1.8 liter in the 400 whp range are pretty uneven. It's mostly cyls 2 and 3, as usual, because being thermally landlocked in the middle of the engine plus the pretty much equally crappy restriction to flow across the runners means that they have a much higher ratio of building heat to shedding heat. It's not the flow, per se, as it is the rate of heat buildup and the use of fuel as coolant that affects the trims. But, whatever.
thank you for an actual good reply. i made 265 at 18 psi with a log mani, 2.5in dp open with a/c and p/s. 6inch intercooler, 2in hotside piping and 2.25 in to TB. stock head and intake setup. gm 3bar precision sc50 .48/.60
Sounds par for course. I make about 300 at 18 on a 9:1 Z6 with the same turbo and a ramhorn, but I think the 2.5" charge pipe and better IM/TB means just as much as that plus it's cheaper to boot.