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Re: Cool Predator Video!!!
[Re: 2QUICK4U]
#207689
01/30/09 08:39 AM
01/30/09 08:39 AM
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Joined: Feb 2005
Posts: 232
Lansing, MI
MuscleMike
enthusiast
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enthusiast
Joined: Feb 2005
Posts: 232
Lansing, MI
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I knew this was going to come up but I hoped to have the engine finished on the dyno by not but it was not to be.
This is a 645" big compression, rasied cam w std journals, wet sump engine. Marvin from Quick Fuel asked me just before PRI if I some big HP engines about to be dynoed. I said yes and he told me he wanted to try out some of him new "Marvinator" main bodies (don't know if that is the real name, we just call them that) Quick Fuel now has their own dominator main bodies. That have some really cool features. The biggest feature is the actual length of the main venturi. Traditionally big carbs (large ventrui & throttle blades) flow excellent air and make great power but will have 2 downsides. 1) poor acceration and 2) not very responsive to air bleed changes. This is made worst by big cams and big intake manifolds. You can do things to help these issues like sheer plates, super suckers, stepped booters and tricks inside the manifold but that is only curing the symptom, not the problem. The longer venturi acts like a collector extension by creating more signal and the longer venturi allows more "creative" booster placement. The new casting also has a raised entry above the top of the main body. Marvin said that it helps "straighten " the air entering the venturi. Similar to how oine would use a radius entry on a intake port when flowing a cylinder head.
The 1150's we were testing responded very well to small internediate and high speed air bleed changes. The engine would flat line around 6700. Marvin and I agreed it is not a manifold or intake problem because the air bleed changes were helping. The issue we had was the booster venturi was moving too much fuel at higher engine speeds and we could not tune it out with air bleeds. Marvin was excited by the results and was happy the booster was working "too well". Marvin is making me a few differnt boosters to try and we will get the engine back on the dyno and hopefully finished next week. We are also going to try a set of 1250s after that!
As you can see by the graph the engine flat lines around 6700 up to when I backed out of the pull at 7300. The A/F was a steady 12.9-13.2 up until 6800 and then it would drop to 12.0 and stay there. I figure if I get the A/F right all the way thru the pull it shoudl make peak power around 7300.
Last edited by MuscleMike; 01/30/09 09:07 AM.
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I think I could get in the 7's with that.
Mike. 
