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Best 496 headers?

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Old 03-04-2007, 06:39 PM
  #121
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I think that too may boaters, especially here on the forum are getting to test crazy! You've got lots of tests on 496's with various manifold and header styles and brands. God knows we have done to many of them and I have the dyno bills to prove it! Let us as an industry and group never think that individual tests alone are the sole determining factor for a high performance boater to make his exhaust upgrade choice. There are so many different motor types, horsepower and model types, that what works for one will not always work for another. The boaters that are interested in changing their exhaust systems should use reliability, cost, looks, ease of installation, useful life and personal preferences in making their choices as well as how the systems really performed on their type and model of motor. No smart industry professional will guranty how a given boat is really going to perform with some addtional power added with exhaust changes. It just to much of a moving target with each boat size, weight, hull type, setup, water condtions, driver skills, etc. to sit here and say that someones boat is going to go exactly this much faster with some engine , hull or drive change! Manufacturers of header and quality manifold systems should substantiate there improvements with independant tests and correct published data. some have, most have not, therein lies another factor that potential exhaust system buyers should use to make an informed decision. If a manufacturer cannot or is not willing to prove his claims or results then "Buyer Beware" Its just that simple, game over!

Regards,

Ray @ Raylar
Well said.. Jamie / Lakeside

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Old 03-06-2007, 02:53 PM
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I think that too may boaters, especially here on the forum are getting to test crazy! You've got lots of tests on 496's with various manifold and header styles and brands.
I'm sorry to say it, but the tests I've seen are pretty much meaningless, because the manufacturers of the headers refuse to post baseline data. They also run their tests and correct them for non-standard conditions for pressure and temperatures, which inflates the horsepower readings. They often run dyno tests "on the fly", which gives higher horsepower readings than steady state, and then compare them to manufacturer tests run steady state. They put performance equipment on an engine which has already been modified, so, of course, the horsepower increases are higher than if if they were put on a stock engine. They change spark timing and fuel, but never test the same changes on the baseline engine. Consequently, people are skeptical, and they should be. The aftermarket industry as a whole has a horrible reputation for fudging data, and making outlandish horsepower increase claims. Then they wonder why people don't believe them. Personally, I believe nothing that is posted by the aftermarket as far as horsepower gains anymore, and that includes these so called performance magazines, unless I see testing done using OEM industry test procedures (which will probably be a cold day in...well, you get the idea).

Ray, I don't think we are "test crazy". We are just skeptical.

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Old 03-06-2007, 11:15 PM
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Well Michael, you have a good right to be skeptical. I can only speak for my aftermarket company and not any of the others. I can tell you we test to an SAE standard which has been adopted by most companies who want to have comparible data. We do our tests with a baseline before tests and we then test the new changes with the same dyno, same day same conditions and we also use some steady state tests as part of our tests and we also use these steady state tests for our durability testing. We don't adjust the figures with different offsets, we only correct the outputs on the dyno for fuel specific gravity, atmosheric pressure at the time of each test as well as ambient temperature and humidity. We bring the engines in our dyno tests up to nearly the exact same operating temperatures on both coolant temp and oil temp before we make the pulls. We are usually conservative on our figures and we try to error on the low side. I feel our tests are about as correct as we can reasonably make them and of course we have a lot of boats and customers demonstrating in the water that the power increases we see in testing are actually expierenced in performance gains on the water. So all I can say is that there are other aftermarket companies that use a similar level of "correctness" in their testing and obviously there are others who use the "dart board" approach or just flat massage the numbers where they want them to be. In a perfect world this would not exist and all I can say is I hope more aftermarket companies adopt an "honest" policy and procedures for their tests. Until then I guess everyone will just have to by their performance products from those who do. This is the best way to send a message to those who don't or won't!!

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Ray @ Raylar
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Old 03-08-2007, 05:12 PM
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Well said, Ray! Thank you.

Michael
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Old 03-08-2007, 08:22 PM
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Ok guys, we're on our way. Just completed all the base line testing on the test boat. We made 5 different runs with GPS. Different directions and even different drivers. We went from a slowest of 62.6 to a fastest of 63.5. All but one run was under 63. I just finished prop shaft dyno testing the engine. Again I made 3 pulls and they were within 1 HP of each other. So, what did it make at the prop you ask???? 387 HP at 5000 RPM!!! That is a solid 10% loss through the drive.

Another bit of trivia. THe boat has 2 gas tanks. One has 87 octane and the other has 93 octane. I switched to the 87 for one pull and it didn't change the HP one bit.

So, we have our baseline data. We'll get the exhaust switched in the next couple of days and dyno it again.
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Old 03-08-2007, 09:33 PM
  #126
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nice bob.....keep us posted. What exhaust sets are you going to run?
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Old 03-08-2007, 10:58 PM
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Bob:
Nice start to a great series of eye opening tests! Glad to see my statement about octane not making more power is here in black and white to close that old wives tale! Keep it com'in!

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Old 03-09-2007, 12:40 AM
  #128
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Originally Posted by Raylar View Post
Bob:
Nice start to a great series of eye opening tests! Glad to see my statement about octane not making more power is here in black and white to close that old wives tale! Keep it com'in!

Regards,
Ray @ Raylar
I agree Indeed.. Jamie
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Old 03-09-2007, 02:20 AM
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Ok guys, we're on our way. Just completed all the base line testing on the test boat. We made 5 different runs with GPS. Different directions and even different drivers. We went from a slowest of 62.6 to a fastest of 63.5. All but one run was under 63. I just finished prop shaft dyno testing the engine. Again I made 3 pulls and they were within 1 HP of each other. So, what did it make at the prop you ask???? 387 HP at 5000 RPM!!! That is a solid 10% loss through the drive.

Another bit of trivia. THe boat has 2 gas tanks. One has 87 octane and the other has 93 octane. I switched to the 87 for one pull and it didn't change the HP one bit.

So, we have our baseline data. We'll get the exhaust switched in the next couple of days and dyno it again.
This is good stuff!

What temperature and pressure are you correcting the horsepower to?

I can't wait to hear about the next set of tests. Don't forget to put it all back to stock at the end to be sure nothing changed with the powertrain during the tests.

Michael
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Old 03-09-2007, 10:45 AM
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I have an electronic weather station. We are at 800' elevation. Ambient air temp was upper 70's. However I placed the weather station right by the flame arrestor to get a more accurate inlet air temp. That temp was 88 degrees. I'm using the "standard" correction method. The final correction factor was 5%, uncorrected HP was 360.
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