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Horsepower Loss do to Wet Exghaust

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Old 05-31-2010, 04:42 PM
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One reason this thread is close to me is that I have to dyno a new build this thursday- dry

- because the crew doesnt want wet headers in the dyno room.

Im kind of living with this in real time at the moment.

Uncle Dave
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Old 06-02-2010, 01:18 AM
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Wink Fact is better than speculation everyday!

You guys would be surprised what wet headers versus dry headers produce for horsepower difference on a calibrated SAE dyno test. You confirm this with Bob at Full Throttle in his testing also, but we have seen about a 20-25 HP loss on a 500-600HP 496 on the dyno when a wet marine header is run with full wet tips.

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Ray @ Raylar
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Old 06-02-2010, 09:09 AM
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Originally Posted by Raylar View Post
You guys would be surprised what wet headers versus dry headers produce for horsepower difference on a calibrated SAE dyno test. You confirm this with Bob at Full Throttle in his testing also, but we have seen about a 20-25 HP loss on a 500-600HP 496 on the dyno when a wet marine header is run with full wet tips.

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Ray @ Raylar
Ray,
Do you know if the torque numbers suffered the same amount as well?
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Old 06-02-2010, 04:47 PM
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Low end torque will not suffer as much from wet exhaust. As the rpm increases, so does the amount of water and the restriction it creates. Therefore the loss will become greater as airflow increases, whether it's from increased RPM or power increases. Another impact is on the A/F ratio. Tuning without water, especially if they use dyno headers can be significantly different.

Bob
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Old 06-07-2010, 09:22 AM
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Great info guys!

Thanks.

Bill
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Old 06-11-2010, 09:13 AM
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Thats a nice manifold. Very popular these days.

When you say heavily - how heavily?

I would bet as you pass the 600HP mark the headers begin to payoff.


UD
HP3 race engine valve train (except CC 929 valve springs and stock lifters) , heads additionally ported and bigger valves by J Valako, bored & stroked to 521ci all forged and balanced, cylinders bore knotched, HP3 Gen 2 cam and set up, HP3 timing, Raylar intake, throttle body bored by RV Morse Machine & blended by J Valako, HV oil pump, Dana Flow Torque exhaust with #5 risers, 3x18 oil cooler, PCM555 custom ECU recal by Dustin Whipple. When I saw Bob Lloyd's Full Throttle Marine wet exhaust dyno test (posted on the FTM web site) of the Dana Flow Torque exhaust with #4 risers on a stock 496 versus the CMI headers showed essentially the same performance increase over stock manifolds I was sold.

The design goal was max NA hp on 87 octane.

Last edited by Rage; 06-11-2010 at 09:19 AM.
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Old 06-11-2010, 11:10 AM
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HP3 race engine valve train (except CC 929 valve springs and stock lifters) , heads additionally ported and bigger valves by J Valako, bored & stroked to 521ci all forged and balanced, cylinders bore knotched, HP3 Gen 2 cam and set up, HP3 timing, Raylar intake, throttle body bored by RV Morse Machine & blended by J Valako, HV oil pump, Dana Flow Torque exhaust with #5 risers, 3x18 oil cooler, PCM555 custom ECU recal by Dustin Whipple. When I saw Bob Lloyd's Full Throttle Marine wet exhaust dyno test (posted on the FTM web site) of the Dana Flow Torque exhaust with #4 risers on a stock 496 versus the CMI headers showed essentially the same performance increase over stock manifolds I was sold.

The design goal was max NA hp on 87 octane.

Sweet.
Valako's got a great rep, and Ray & Larry build great stuff.
What do you think its making?

UD
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Old 06-12-2010, 11:57 AM
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Sweet.
Valako's got a great rep, and Ray & Larry build great stuff.
What do you think its making?

UD
~600CSHP dry exhaust now but the cylinder to cylinder high rpm AFR spread needs to be tightened up a lot which is in the works and could provide significant further improvement.

I owe a huge amount of thanks for the guidance provided by Bob Lloyd of Full Throttle Marine, Dave Gilbreth, Innovation Marine, Jim Valako and on and on and the good parts available in the industry.

Last edited by Rage; 06-12-2010 at 12:12 PM.
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