I thin k Stainless with the longer dry tails will do better then Gils, that's one reason we wanna do a few different ways is to see same dyno, same day, same conditions..

I don't see why they would be much different. Pretty similar from a design standpoint.

Nice thing about dyno'ing, is you can really see what the engine likes. I mean, if you plan on simply locking the timing at 34*, and tuning for a specific air fuel ratio, then yes, dyno'ing isn't gonna do much.

But, if you take the time to see what the engine actually likes, fuel and timing wise, you can get a really nice tune. I have always been an advocate of 02 sensors in the boat, but I don't think they are the end all. Its really nice to be able to see which cylinders are running the hottest with EGT probes, or, eight 02 sensors, to see how the fuel mixture is being distributed.

On that 1000hp 522ci build, we got to use the Daytona ignitions for the first time. Prior to that, we always ran locked timing. I pulled out 9 degrees of timing in the midrange, and we saw an INCREASE in torque output. To me, that told me that we simply were firing the plug much too early in the midrange, and it simply wasn't doing anything for the engine, except, possibly going to induce preignition, or run the plug much hotter than it needs to be. I don't see how you can really re-create that scenerio, in the boat.

You can view brake specifics, fuel consumption, CFM consumption, and a bunch of stuff. Last year, I went to a local shop, for some balancing work I needed done. It was a new shop I had never been to or even heard of, even though the guys been there for 40 years. Anyhow, he gave me a tour of their shop. They do some intense work there. He showed me his dyno cell, and he had an engine strapped on the dyno. I noticed, that he had two oxygen sensors on each side. One was mounted in the collector, the other was a bit further downstream. I asked him if he see's a different reading from them, and he said "absolutely".

These portable widebands we use nowdays, are great tools, but they certainly aren't as accurate as stuff that they have at really high end places, or general motors, ford moco, chrysler, etc. I still think there is validity in tuning an engine on the dyno, and observe what its telling you it likes, or doesn't like. When we dynoed Icdedppl's blower motors, they simply made their best power at around 11.5 afr on the dyno's meter. Leaner, it lost power. Timing and fuel mixture definitely play against or for each other. A lean fuel mix, might not like the higher spark advance, where a richer mixture will. And vice versa. Too little timing, you melt exhaust valves and lose power. Too much, you detonate, and lose power. From what I've learned, you'll see a drop in peak HP on the dyno, before you actually get to detonation/preigniton from too much timing. If the engine likes 36* at 6000rpm, try 38*. If it gains 10hp, it likes it. If it gains zero, leave it at 36.

I've heard the storys about not running anymore than 30 or 32* in a bbc blower motor, or you'll melt it down. I was just reviewing my data logs last night, 35.4 timing at 6200RPM, with 9lbs of boost and IRON heads. Plugs look great after that run. So much for that theory.

All the GIL I seen mix very close to riser exit, mine at transom, I figured that's 1 ft or so less restriction , I may be wrong in that thought, as you know of moneynis there in April I will find exhaust if not I make minedry or run mine for now, thats the last thing I'm gonna worry about joe because without pushrods, gaskets, oil temp stats and the other stuff I gotta buy yet, the headers does no good lol

Gil made fully dry jacketed tails as well. They all did . Stainless marine, GIL, IMCO, etc. Just depended on the application.

See you learn something new every day I've never seen them so I didn't think they made them that way , oops!

Mine are dry to the tip.

Busted out some old Catalogs and scanned them for you.

Seems to be alot of confusion lately between exhaust systems. Especially the Stainless Marine and Stainless Marine GEN III / Dominator III manifolds. The GEN III stuff, is completely different, than the regular Stainless Marine manifolds.

As you can see in the first picture, that is a completely DRY tailpipe. The water is dumped overboard, via the bungs towards the ends of the pipes, right on the INSIDE of the transom. You hook water lines to those bungs, and route them to an overboard thru hull fitting.

Fully "jacketed" pipes, dump water at the very tip of the exhaust, AFTER, or OUTSIDE, the transom. The water on either system, never gets introduced, into the actual tube/pipe, that the exhaust gas flows thru.

"Wet" exhaust, has the water mixing into the gas tube, at some point in the system. This is where you get into reversion issues, as well as a possible HP loss, becuase the water, is now taking up valuable real estate, inside the gas tube, and can act as a slight restriction.

I need to decide if I want to modify my pipes, once I do they are like that for good.