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Old 02-08-2012, 03:38 PM
BogiesAnnex1 BogiesAnnex1 is offline
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Originally Posted by ChevyTruckGuy
Was looking around for new mod for my truck and came across this found it very interesting if true. The video don't by a local talk web show! attracted there attention! to see what this guy is doing watch the video! like to here input Seems this is being use quit a bit all over you tube! going to do some more research! If true this is good news for fuel

This seems to confuse throttle bodies of port and direct injection with throttle body injection and shows a few carburetors to boot.

Since the injection is electronically managed the modifications done would be automatically compensated for by the computer. The air leak would speed up the engine idle and lean out the mixture. The computer would be informed of the idle increase against the other conditions its mapped to and would command the Idle Air Control (IAC) to cut back back the throttle plate bypass air to slow the motor back down, you wouldn't even know this happened unless the change was so extreme that the IAC couldn't get control, in which case you get a code light illumination.

For leaning the mixture, if this actually occured the O2 sensors would read the lean out in response to this the computer would command the injectors "on" time to correct the mixture. Again unless the change was more radical than the system can respond to, if that were to happen you'd get the engine trouble light and a code.

The discussion about air flow past the throttle body having an effect on mixture homogenization is the same argument that was given for these type modifications and gadgets sold for carburetors. Port or direct EFI works completely different from a carburetor or Throttle Body Injection. The only thing going past the throttle body of central port, tuned port or direct cylinder injection is air. The fuel isn't added till just ahead of the intake valve on central and tuned systems, there is no manifold mixing nor is there any way of having manifold mixing. For direct cylinder injection, the fuel is added directly into the cylinder. For these the intake system from throttle body all the way through the intake valve carries nothing but air. For all these injection schemes including the CPI and TPI, fuel mixing occurs inside the cylinder.

One can argue that Throttle Body Injection suffers some of the same mixing problems with air that carburetors have. But engines using TBI since it came into widespread use in the mid 1980's all feature some sort of spin gadget somewhere along the intake tract, or in the combustion chamber adjacent to the intake valve. For Chevy it was the Swirl Port head that has a ramp just ahead of the intake valve. Ford put a similarly functioning vortex generator within the combustion chamber which causes the incoming wet flow to tumble and homogenize the fuel and air. Along with those gadgets a lot more attention was and is paid to combustion chamber design to increase burn speeds, improve burn completeness, and reduce emissions. The CPI and TPI motors pushed the head combustion chamber technology even further finding that the gadgets can be removed when the induction is only air and that the chambers can be shaped to accomplish the necessary tasks. Here you get the GM Vortec and Fastburn heads, the Ford GT40, and MoPar's Magnum to name a few.

Starting in the mid 1980s is what I call the second generation of emissions engines, you see designs that in many ways are more similar to the Muscle Car era engines than are the first generation of emissions engines of the 1970's. Basically the second generation and on has moved from reducing emissions with external add-ons and functional compromises into incorporating the function into the root design. Once that happened power and mileage began to make enormous improvements while reducing emissions.

Today we're pretty much into the 3rd or 4th generation of these emission engines, they deliver power, mileage and life expectancy far beyond that of the Muscle Car era and first generation of emissions engines. When you figure that the internal combustion engines use of the heat it makes is at best 33% while it throws 66% away in exhaust and coolant heat. One can see that there is room for a lot of improvement yet to come. This will result in a cost/mileage competitive electric car being even further away in future time. These new cars and trucks have caught governments in a financial bind as mileage has improved tax revenue has fallen while highway use, thus the need for new and repair for old highways has increased faster than revenues. Those of us living in the west are going to start paying tolls over the next few years which is going to come as a rude awakening to us who are used to going anywhere at anytime for the cost of fuel. I can't say I like it; I'm just reporting and forecasting.

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