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

what happens if you take emi aluminum risers and divert the water around them. In effect make them dry. It will probably ruin the riser im guessing

Yes, it will burn them up !

A dry exhaust has still water flowing around the inner tube, where a wet exhaust does not need an inner tube and has the water mixed in to the tailpipe behind the riser !!!!!!

Both systems have water around the manifold/riser and even the headers do !!!!!

A dry exhaust only means that the exhaust fumes will not mix with water at all , but are still surounded by water !

Like has been covered above, most likly you will see no real HP gain wet vs dry. Dry exhaust is needed to avioid reversion for really big cams. Most performance engines can use wet exhaust with long risers. If you used short risers with a performance cam reversion is likly to happen. Every engine is different and somone that runs a dyno may be more helpfull.

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

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.

Best Regards,
Ray @ Raylar

Ray,
Do you know if the torque numbers suffered the same amount as well?

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
Full Throttle Marine

Great info guys!

Thanks.

Bill

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.