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Some carb / intake info

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Old 10-07-2016, 04:59 PM
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I was talked into going with the 4150s by the original engine builder because of the improved driveability. In retrospect I should have gone with the 4500s and matching intake from the beginning. Peak horsepower with the first cams and 4150s was 56-5700. The final 4500 and cam combo peaked at 5600 with 1in spacer and 5700 with the 2 in
With that small of a head you really want the largest intake you can get your hands on.

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Old 10-07-2016, 05:09 PM
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With that small of a head you really want the largest intake you can get your heads on...
I'd tend to agree, but like I said I couldn't buy just to test with and I wanted to know without a doubt I would gain power before I spent $. I considered going larger with the entire induction setup including heads but it was a huge expense. I wanted a money back guarantee on the power I was promised and I wanted the power under 6k rpm, not over. Of course no one would make a promise like that so I went with what was free and then purchased what I could.
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Old 10-07-2016, 06:34 PM
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Just an FYI cause I know your using a solid lifter cam. The bushing type rollers will nock 25hp right out of the motor.
50/50.
Where do you draw the line... with open spring pressures? Good and bad with both needle and bushing.
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Old 10-07-2016, 06:54 PM
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50/50.
Where do you draw the line... with open spring pressures? Good and bad with both needle and bushing.
I don't draw the line as far as spring pressure. I've ran up to 1250# open with titanium valves. Really depends on the entire valve train package...
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Old 10-07-2016, 08:52 PM
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Now, those original builds with the smaller cams / 4150s walked all over the dominator combo at lower rpms. They were even at 4600 and then the dominator combo pulled away from 4600 to the end at 5800. I really wish someone had the skills or program to overlay all these graphs.
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Old 10-07-2016, 09:10 PM
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Here's the graph of the 2 4150 pulls. One with spacer and one without. You can see the spacer improved everything. Also this combo with the smaller cam / 4150 easily outperformed the dominator combo up to 4600 then the Dom combo pulled ahead till the end at 5800. Notice this graph has torque on the right on a different scale than hp.
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Old 10-07-2016, 09:15 PM
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Here is the Dom with 1 in. spacer graph.
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Old 10-07-2016, 09:21 PM
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Now, those original builds with the smaller cams / 4150s walked all over the dominator combo at lower rpms. They were even at 4600 and then the dominator combo pulled away from 4600 to the end at 5800. I really wish someone had the skills or program to overlay all these graphs.
That comes at no surprise. Combo/application. Twins vs single... Sacrifices will always be made to achieve maximum hp but not necessarily always ideal for every application. I think you ended up extremely well. Sure more time and more money might have gotten you a few more ponies but give you credit for doing what you did. Going to dyno to jet and look for leaks and go home is not worthy in my opinion.
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Old 10-07-2016, 09:22 PM
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Here is the Dom with 1 in. spacer graph.
Nice
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Old 10-07-2016, 09:28 PM
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The boat tended to like to cruise @ 45-4600. I didn't spend much time below that so it was a decent trade off for the top end. Even with all that low end torque with the original combo the boat just didn't seem to like cruising at 3500
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