Quote:
Originally Posted by Gscherer78ta
What explains the vacuum in the manifold if the restriction isn't the filter. I have been also wondering about the opening size of the shaker scoops. In Bob's case I don't think that's an issue because it's open all the way around. If the only air is coming through that opening, does that choke the flow?
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Greg,
I believe I simply don't have a big enough plenum and throttle body to supply the air flow requirement of the engine. I have the highest-flowing 4150-style throttle body that I could find when I put it all together, but the engine is pulling a lot of air.
When we ran the engine on the engine dyno, we switched from the original intake I was planning to use (a ported Super Victor for the LS7) which also used the 4150 throttle body to a Mast 4500 single plane intake. No other changes. Peak HP increased by about 15HP, but the curve held on amazingly well with the Mast where the 4150 Super Victor started to roll off. The 4500-Mast could flow a lot more air into the engine. The problem is all of the 4500 throttle bodies which I have found are significantly taller than my 4150, which further complicates the problem we are already fighting...
I have to choke my engine to an extent with an even more odd-ball setup of intake to get things to fit. I'm using the LS3 version of the Victor Jr with adapters to mate to my heads. That dropped things down about an inch to get me where I am currently at. It was a painful thing to do, but I haven't found another good option yet.
One last thing... With the previous engine in the car and my previous shaker setup, removing the shaker (but leaving the air filter in place) didn't change the HP at all. I was using a 2.5" tall 14" round K&N with the K&N Extreme top in that case. So the shaker was flowing enough air to keep that fed which surprised me.