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Old 05-06-2024, 04:33 PM   #11 (permalink)
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Originally Posted by racprops View Post
I have read many books that say tune your engine and drive train so that your engine is at or near your engines Torque Peek for best MPG at your preferred Speed.

BUT a torque peak of 2800 RPMs mean cruse below 2500RPMs will not give good MPG…


Yes, thus my looking into EGR to cause a more open throttle to cut “pumping losses”

I have NO boost of any kind.

Small low performance heads and valves are reported better for MPG.

WHICH is why I am running a STOCK TPI, no big tubes, stock 193 Heads with stock valves, and a stock cast iron exhaust manifold into low restrtive cats and mufflers.

Yes, at full throttle and max RPMS, but will them do 35 to 50MPG???


Yes efficient in their world…


Rich

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Ok. And your point is???

If studies of the atomization and de-atomization of fuel in an intake system offends you because it was done by someone who builds race engines, well then so be it.

Agreed, peak torque RPM is something that will affect fuel mileage.

Agreed, EGR can help keep a throttle more open. But there are a lot more factors that help keep a throttle more open than just EGR. And there are a lot more factors that help fuel mileage than just keeping a throttle more open.

I never said you have boost, I was comparing differences and similarities between the goals of the racer's community and the goals of the ecomodder's community.

Yes, heads, valves, engine, etc. all should be sized according to power needs.

In no part of this did I say, "Put a 1,000hp formula race car engine in your car to get 50% efficiency." But there's no reason that a person can't consider whether the things that improve fuel efficiency in one engine could be applied to another with similar results as far as efficiency goes, even if the total power output and use case are completely different.

For an example:
  • Many air craft have twin spark plugs, but twin spark plugs can improve efficiency, espeically in engines that you can't put the spark plug right in the middle of the cylinder.
  • Many train and semi-truck engines roll along at low RPM's, part of the reason they get good efficiency. Again, lowering the RPM's can improve efficiency in an ecomodded car.
  • Likewise, race engines are about getting air and fuel in the most efficient way by engineering the flow through large valves for most power and efficiency. There's no reason you can't use similar geometry, only downsized, in order to keep the efficiency but lower the output power.

If you don't think so, then sorry for you.

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Old 05-06-2024, 04:43 PM   #12 (permalink)
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Well you did post all those things, and I feel mostly they do not apple to what I am building.

A race car is build for the best speed, and is built to run and live at high RPMs, so I feel your comparing apples to my oranges.

A race car is running most at MAX HP and thus MAX air/fuel flow, under those conditions what they show is real.

BUT did the test my Stock 193 swirl Port heads and stock TPI on a SBC 383 at 1500 RPMs??

This is like comparing a P51 to a F100 Jet....

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Old 05-06-2024, 06:07 PM   #13 (permalink)
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The original point was this, vorices, that is, making air swirl or spin, only separates fuel and air. It happens in all gasoline engines, regardless of the purpose of the engine.

But adding swirl/turbulant/vortex "technology" to intakes and heads as a way of supposedly improving fuel and air mixing and therefore efficiency is classic snake oil in my book. Mixing fuel and air is important. It's just that swirling is not what you want if you want better mixing of fuel and air.

Personally I'd even question if your swirl heads even swirl more than stock heads. And if they do swirl more, then there's very little chance that they mix fuel and air more than stock heads. I mean, sure, I'd love to see someone with a test rig that similates wet flow with florecent, gasoline-like liquid and the camera and computer setup that can track how much of that liquid is staying suspended and/or evaporating into the air and how much if it is being flung onto the cylinder wall test your swirl heads and compare them to stock heads. But starting with the word swirl, I personally don't see much reason to believe in them.

But hey! If you think they work, maybe someday you'll prove me wrong. That's what experimenting is about. Don't take some random guy's word for it just because he posts some YouTube videos on a forum on the internet.

I still think the videos above are very relevant, educational and interesting. But admittedly they are a bit long, very unrefined, and are not intended to inform an ecomodder how to get better fuel mileage. And they are very anti-swirl. So there you have it, take or leave it, and best wishes with your build.
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Old 05-06-2024, 06:49 PM   #14 (permalink)
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I've seen most of the fuel economy improvements happen (at least from GM) in the late 00's and later. Much of this seems to come from finally adopting tech like VVT, finer engine control, etc.

Many modern turbo cars now run at stoichiometric almost everywhere on the map under boost. You would never see a pre-2010 vehicle running stoich under boost under any circumstance.

Honda ditched their high flow head from the early '00 engines in favor of a head with a sharp lip before the combustion chamber, trading flow for improved atomization under some conditions.

Offset crankshafts reduced redlines but cut friction and reduced the energy lost from cylinder pressure building before the piston reaches TDC.

Mazda ditched knock sensors entirely and bumped their engines up to 14:1 compression. They use the spark plugs to measure the ionization of the gas post-combustion, along with a powerful computer, to determine what to change before the next time the fuel is injected. Ignition timing is adjusted to the nearest tenth of a degree, and there is VVT on both intake and exhaust cams, as well as variable control of EGR, direct injection timing, etc. I was able to get a 58mpg complete tank cruising at 62mph on aggressive tires in a RWD sports car. Fuelly reports the 1990-1997 models as averaging 25mpg, the 1998-2005 models as averaging 26mpg with a bigger engine and heavier car, 2006-2015 models at 27mpg with 50% more horsepower and bigger/heavier car, and now we have the most recent model year with the Atkinson cycle engine with a 48mpg highway rating, which I see as realistic, and I'm getting a real-world 40mpg city.

Mazda's next generation engine, which uses compression ignition of gasoline, is reported to be 20% more efficient on average.
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Old 05-06-2024, 09:37 PM   #15 (permalink)
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So why would GM spend all the money in developing a Swirl Port head.

It was not in their ads, nothing like our new swirl ports give you more power and MPG...and then after the years of making these extra costly head make a newer version of it. And make them for a number of years??

I think GM had a Good reason to make them and then to make them again, and it is not a sales point.

I think that at low below say 4000 the work.

I put my trust in a Multibillion Dollar Car company over a racer shop with it comes to testing how their parts work for a everyday engine.

Here is a good article by Car Craft and their chart...I like how the flat the torque curve is stock...is only 32 Ft PH from 2K to 3.5.

I have read how the peak at 2800/3000 BUT that is were the stock cam peaked as well.

The testing on a computer dyno show a great torque curve for my build.

My engine will LOVE 1500RPMs.

So by the numbers, a TPI is said to improve by 20 to 30% Torque, HP and MPG...BY themselves alone, so 14 X .20 = 2.8 14X .30 = 4.0 More MPG...so we are at 16.8 to a full 19MPG.

I have done a 16.5 A/F ratio in a 4.6 Ford and gained 4 to 5MPG, so now I am at 21.8 to 24MPG.

I had to build an engine, so I did one I feel had a best chance of making good MPG at 75/80MPH. What the hell, if it works I win, if it doesn't I still win as I will have a good drive line.

On the other hand there are a few more tricks I can add like water injection, so it might work great...either way I win.

Rich
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Old 05-06-2024, 11:17 PM   #16 (permalink)
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I think racprops has a point, in that, while some techs benefit both power and efficiency, they are just as often add odds with one another.

Faster combustion, due to clever combustion chamber design? Improves both.

Offset crankshaft? Drastically cuts max safe RPM (big loss in power) but improves BSFC. You won't see this on race engines. Likewise, you won't see a non-offset crank on an economy engine, at least in anything made in the last decade.

There are examples on both sides, of things that help both, and things that improve one at the expense of the other.
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Old 05-07-2024, 02:41 AM   #17 (permalink)
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Quote:
Originally Posted by racprops View Post
So why would GM spend all the money in developing a Swirl Port head.
Interestingly your comment that these were developed by GM got me looking into them. From what I can tell, they don't have anything to do with swirling but rather have a ramp that leads to an edge. What's the most interesting thing is that there are also similar ramps in the videos I mentioned above. Ramps with sharp edges can help launch fuel that's flowing along the intake track back into the air stream.

https://garage.grumpysperformance.co...t-heads.10579/

Quote:
Originally Posted by Ecky View Post
I think racprops has a point, in that, while some techs benefit both power and efficiency, they are just as often add odds with one another.

Faster combustion, due to clever combustion chamber design? Improves both.
So do ramps and other clever intake tract and combustion chamber designs that help atomize fuel.

Flinging fuel onto the cylinder walls where it won't burn is also bad for both.

Also distributing the fuel throughout the air as homogenously as possible with maybe a bit more richer near the spark plug and leaner away from the spark plug can also benefit both.
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Old 05-07-2024, 03:50 AM   #18 (permalink)
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Well as in a number of things about this build, I LUCKED out on a fair number of them.

Really I did NOT have the science to make a really informed derision...just a little reading between the lines.

One was magazine article about how TORQUE was really was what got a car off the line first and HP was not there until the engine started making power.

By the way I am a member of Grumpys and they were a great help...They were the ones that did this:

Note how nearly every aspect of my build, the 193s, the TPi and my custom cam and rhoads lifters were figured in.

Rich

PS I saw that the specs part was hard to read so I made a large copy alone.
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Old 05-08-2024, 03:13 AM   #19 (permalink)
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In diesels optimum AFR is related to injection quantity and engine RPM. OPtimal varies between those and is not constant. Low rpm around 1:19 is optimal and high load higher rpm can as high as 1:50

At lowest rpm and power levels the EGR would make sense in diesel engines. I have had not time to test in this in my own TDI ECO maps
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Old 05-08-2024, 03:44 PM   #20 (permalink)
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Quote:
Originally Posted by Vekke View Post
In diesels optimum AFR is related to injection quantity and engine RPM. OPtimal varies between those and is not constant. Low rpm around 1:19 is optimal and high load higher rpm can as high as 1:50

At lowest rpm and power levels the EGR would make sense in diesel engines. I have had not time to test in this in my own TDI ECO maps
Interesting, although I'm not following the logic here. How does optimum AFR relate to RPM, and how does it change so much from 1:19 to 1:50?

I've always been under the impression that diesels are most efficient at max power (max fuel injection before it goes coal-roaling rich).

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