Originally Posted by Full Force (Post 4524812)

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

Originally Posted by Full Force (Post 4524761)

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..

Originally Posted by MILD THUNDER (Post 4524827)

Not necessarily. Its just pipe.. If you extend them, and for some weird, strange, unneccessary reason, you decided you want to go back to shorter wet risers, its nothing a chop saw can't fix.

Originally Posted by adk61 (Post 4524837)

just for ****z and giggles, here are the numbers of my 317s as of 6pm this evening, for further info see my facebook page AK Racing

Alan Kranczoch

Intake .200 = 155cfm, .300 = 228, .400 = 289, .500 = 336, .600 = 368, .700 = 388 .800 = 392 exh .200 = 117, .300 = 158, .400 = 205, .500 = 228, .600 = 258 (w pipe 277) .700 = 260, (280) .800 = 261 (283)... so this is the preliminary flow test done after minor bowl work and marine valve job...

just sayin!! can't wait for my CNCs to be ready!! Giddythefukup!!!!

Originally Posted by MILD THUNDER (Post 4524770)

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.