. 
Drink logic mostly.. Lol. But I stand by it.
hahaha
The surge debate.
This engine was originally built for a Bravo boat. The surge is necessary to be able to shift it. It has about a 600 to 700 RPM surge. 800 to 1500. The surge can be dialed out around 1100 to 1200, way too high for a Bravo to shift. The camshaft, cylinder head combo is not designed for a smooth 800 RPM idle.
The engine is now being installed in a 19' jet. We're turning up the power. In this video, it's 4-5 lb's boost. We are going to pump it up to 12-15. :thumbup:
So that gnarly sounding engine on high boost in a jet boat should be good for 45 or 50 mph?
hahaha
The surge debate.
This engine was originally built for a Bravo boat. The surge is necessary to be able to shift it. It has about a 600 to 700 RPM surge. 800 to 1500. The surge can be dialed out around 1100 to 1200, way too high for a Bravo to shift. The camshaft, cylinder head combo is not designed for a smooth 800 RPM idle.
The engine is now being installed in a 19' jet. We're turning up the power. In this video, it's 4-5 lb's boost. We are going to pump it up to 12-15. :thumbup:
The dynamics of what causes the "surge" is more complicated than "just tune it out". Some lower HP supercharged engines can most of the time be tuned so they don't surge. Real world applications in a marine environment (non EFI), will have some surge. Leaning the idle mixture and locking the timing will usually stabilize the idle. However, any boat with high HP will have tall gears and large propellers. When you shift one of these, the instant load will cause it to go even leaner and it will stumble and sometimes die. To idle at a shift friendly RPM it is usually already at it's absolute minimum idle RPM and usually below. Then you bang it in gear, the engine drops another 200 RPM's and you're floating into someone while fighting to get it back into neutral and get it started again....
I have barely touched on the fuel requirements in a supercharged engine. Such as a slightly rich condition at idle leaves a small amount of fuel on the intake ports that helps with the instant requirement of fuel when the throttle is opened.
So Dave, a 1000+ HP CARBURETED, supercharged engine that surges, more likely than not, does not need to be tuned.
Lean rich lean rich lean rich.. Lol. That's all I'm reading Brian.
Most likely to take care of it going lean and raising RPM.
It goes over to the engine tuner that can make it have a steady idle.
RD
I'm not an engine builder Brian why the hell you asking me?
I just don't like watching a motor chasing it's tail all over the place trying to figure out where it should idle.
The answer is in the thread.... The engine isn't trying to figure out anything. It can only do what it's programmed to do. In this case, SURGE! It has a purpose...
The answer is in the thread.... The engine isn't trying to figure out anything. It can only do what it's programmed to do. In this case, SURGE! It has a purpose...
oint
Brian,
You can tell by Dave's posts, he doesn't have a clue about engine building. Hell, he hasn't asked you once about the muffler bearings and their importance related to surge issues .
hahaha
The surge debate.
This engine was originally built for a Bravo boat. The surge is necessary to be able to shift it. It has about a 600 to 700 RPM surge. 800 to 1500. The surge can be dialed out around 1100 to 1200, way too high for a Bravo to shift. The camshaft, cylinder head combo is not designed for a smooth 800 RPM idle.
The engine is now being installed in a 19' jet. We're turning up the power. In this video, it's 4-5 lb's boost. We are going to pump it up to 12-15. :thumbup:
The dynamics of what causes the "surge" is more complicated than "just tune it out". Some lower HP supercharged engines can most of the time be tuned so they don't surge. Real world applications in a marine environment (non EFI), will have some surge. Leaning the idle mixture and locking the timing will usually stabilize the idle. However, any boat with high HP will have tall gears and large propellers. When you shift one of these, the instant load will cause it to go even leaner and it will stumble and sometimes die. To idle at a shift friendly RPM it is usually already at it's absolute minimum idle RPM and usually below. Then you bang it in gear, the engine drops another 200 RPM's and you're floating into someone while fighting to get it back into neutral and get it started again....
I have barely touched on the fuel requirements in a supercharged engine. Such as a slightly rich condition at idle leaves a small amount of fuel on the intake ports that helps with the instant requirement of fuel when the throttle is opened.
So Dave, a 1000+ HP CARBURETED, supercharged engine that surges, more likely than not, does not need to be tuned.
Is this the same Dave that has the fire breathing small block too?
Drink logic mostly.. Lol. But I stand by it.
All kidding aside Brian.....so why does it surge.....
Is this the same Dave that has the fire breathing small block too?
LOL
Nothing wrong with a small block, just had to slow ol' RD down a bit. Calling a guys blower surge gay was crossing the line
