fratzog lover
Well-Known Member
Here is a good video.
A video explains alot. A picture being worth 1000 words.
Here is a good video.
Very interesting nonetheless. Was quite cool to "see through" what would normally be an aluminum intake.Then again....the video illustrates how fuel can separate from (or perhaps more accurately never join) the air. The question becomes 'how much does it matter?'.
That's a great video. I hate to say it....but it only reinforces the shortcomings of the carburetor. That's not to say EFI doesn't suffer from faults, also. My lowly Mazda 3 uses direct cylinder injection...maybe that's the answer.
DI has many issues. It’s main attribute is fuel economy, which after 50k miles or something that starts going away because the DI stuff comes the valves when they retard the cam timing and the rest of the BS that CAFE standards cause.
Then again....the video illustrates how fuel can separate from (or perhaps more accurately never join) the air. The question becomes 'how much does it matter?'.
It’s a big deal.
In a fuel economy race, I think it could be pretty detrimental. Same for a HP-per-pound of fuel race. But does that fuel have a net effect on HP? Not sure. The cylinders only care about the mixture they see, and how well they can burn it. The fuel stuck to the sides of the intake becomes a non-participant, to an extent.
Fuel absolutely has a big effect on HP, and beyond that it doesn’t always show up on the dyno. If you have 2 engines making 500 HP at the same RPM and everything being equal, the engine with the lower BSFC will always be quicker and faster.
In other words, if the air/fuel mixture that does make it to the cylinder is 'good' then the engine is gonna be happy. We see that in the impressive power and (generally) clean combustion.
What happens to the fuel that isn’t mixed well with the air??? You can’t have impressive power and clean combustion running raw fuel into the chamber.
It's safe to assume that fuel stuck to the intake walls eventually gets pulled back into the air, molecule by molecule, and into the cylinder. Is it well homogenized or not? The amount of turbulence we see would suggest that the fuel at least has a chance to be shaken and not stirred before it goes into the cylinder.
It’s not safe to assume that fuel running down the walls eventually gets pulled back into the air. Once wet fuel is on a surface, it’s hard to get it back into the air. That’s why the burr finish has been on my mind for years. If you can get the rough finish to cause the fuel to break up into smaller sizes, you have a much better chance of getting the fuel back into the air and making the fuel useable to make power.
Warren Johnson said there is no such thing as a “dry” intake manifold and Darin Morgan said a rough surface finish from 3 inches above the injector to the valve so Morgan is saying essentially the same thing as WJ is.
I agree on the epoxy comment above...no way would I use epoxy unless my back was against the wall.
The fuel must be getting pulled back into the air. If not, it would accumulate and the intake would eventually fill up with raw gas. The fuel has to be making its way into the chamber....and if it were running into the chamber in a purely liquid state, we wouldn't see clean spark plugs and good power. I think that if you are showing a decent A/F ratio on the exhaust side, the engine is fairly content. The compensation for the fuel puddling? The carb would be jetted leaner until the A/F ratio came into range. I'll bet that Kaase engine, despite the fuel puddling we see, is showing some decent BSFC numbers. I wish he told us.
This might help: MegaSquirt-II X-Tau
I quickly read that, so I need to read it again, but I’m not so sure how the article assumes all the fuel from wall flow gets back to homogeneous. It may at steady state, but in transient situations I can’t see how thats even close to possible.
Any intake manifold/port is subject to the physics that occur regards of how the fuel gets there.
As MAP drops, the fuel that is atomized becomes liquid. That’s why you need an accelerator pump shot or the Xtau correction. How all that fuel becomes homogeneous again is escaping me. It may be burnable, but that occurs so late in the cycle that it doesn’t produce any power, or very little.
I need to read that again though. Slower this time.
In other words, if the air/fuel mixture that does make it to the cylinder is 'good' then the engine is gonna be happy. We see that in the impressive power and (generally) clean combustion.
What happens to the fuel that isn’t mixed well with the air??? You can’t have impressive power and clean combustion running raw fuel into the chamber.
If that's true, then 99% of the hot rod engines out there aren't making impressive power/clean combustion...because we can see from the Kaase engine that even a high-end race engine has serious fuel separation issues. I bet that engine is making serious power despite the fuel issue. If the engine isn't running well...then Kaase is pulling our leg by showing what an unhealthy engine looks like. I don't think he's doing that.
It's safe to assume that fuel stuck to the intake walls eventually gets pulled back into the air, molecule by molecule, and into the cylinder. Is it well homogenized or not? The amount of turbulence we see would suggest that the fuel at least has a chance to be shaken and not stirred before it goes into the cylinder.
It’s not safe to assume that fuel running down the walls eventually gets pulled back into the air. Once wet fuel is on a surface, it’s hard to get it back into the air. That’s why the burr finish has been on my mind for years. If you can get the rough finish to cause the fuel to break up into smaller sizes, you have a much better chance of getting the fuel back into the air and making the fuel useable to make power.
The fuel must be getting pulled back into the air. If not, it would accumulate and the intake would eventually fill up with raw gas. The fuel has to be making its way into the chamber....and if it were running into the chamber in a purely liquid state, we wouldn't see clean spark plugs and good power. I think that if you are showing a decent A/F ratio on the exhaust side, the engine is fairly content. The compensation for the fuel puddling? The carb would be jetted leaner until the A/F ratio came into range. I'll bet that Kaase engine, despite the fuel puddling we see, is showing some decent BSFC numbers. I wish he told us.
That demonstration didn't tell me anything other than the magnitude of the forces going on. It explains and reinforces to me why I won't use crappy Moroso A/B epoxy in the intake tract because it always fails. Sorry to derail. J.Rob
A video explains alot. A picture being worth 1000 words.
I would think the HC levels on a smog report and 02 sensor would give you a good idea on what is burning and what is not. Still a fan of port fuel injection close to the valve for 95% of us, not DI as the intake valves coat without the constant flow of atomized fuel across them.
Anyone willing to bet that the clear box window style intake probably had something to do with how much liquid fuel there was? It's not exactly a great 'manifold' shape.
It’s not, but I know other people hove put cameras in intakes and when they talk, they all say it’s like a hurricane in there. Burn alcohol and it’s at least twice as bad.
Damn, those look good! Can’t wait to slap those bad boys on...About ready to send these...
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