Quote:
Originally Posted by Don
DV:
Have you had any personal experience with FI systems ? If so, when making a product/make selection, what are the considerations ?
.........thanks
Don
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Don,
There are alot of good choices for EFI systems these days. It really depends upon what you want to do. EFI has several advantages over carburated setups. These include:
1) A good EFI system can be tuned to match an engine's requirements much better that a carb can. With a carb, you make pretty gross adjustments of the fuel curve when you change jets, etc. With an aftermarket EFI system, you can change fuel delivery or ignition timing at one specific RPM and load point and not effect anything else (I'm assuming what's called a speed density system here). This is particularly useful with more radical engine setups (Big CAMS, forced induction, stack injection, etc) which tend to have "quirks" at certain load and RPM areas in their fuel and timing curves.
2) A complete EFI system can adapt to changing conditions and engine wear better than a carb. Modern systems can adjust for altitude at startup and use Wide-band O2 sensors to measure the efficiency of the engine's fuel consumption and make corrections while you are driving.
3) Idle and part throttle fuel delivery can be much more precisely tailored with an EFI system. With the addition of Idle Air Control and the level of transient throttle and load adjustability in aftermarket EFI systems, street drivability can be optimized to the point of making most any engine "drive like a stocker".
All of this comes with some costs though. These include:
1) Expense - a good EFI system will be more expensive to install than a carb. It somewhat makes up for this by requiring little or not maintenance after installation.
2) Complexity of initial installation and tuning - this is the one that gets most people. An EFI system involves electrical and fuel delivery modifications to the vehicle which turn some folks away. I've done EFI setups on two cars now and have not found these changes to be particularly difficult but they do take some time. If you are careful, the modification can be pretty well hidden (I've done these addtions on my Cobra as well as a 1963 Vette - in both cases, most of the electrical additions are well hidden). The initial tuning needs to be done on a chassis or engine dyno of the proper type and you'd be best to work with a professional EFI tuner to do this if you are not experienced with EFI. You'll find that once you've worked with a properly tuned system, it is much easier to understand than a carb in terms of making changes.
There is a really good thread that discusses the pros and cons of many of the available systems on this forum. Check out:
Stacked EFI- advise/thoughts and poll.
I am using a TWM stack injection setup for my cobra. The associated motor is a 482 ci FE built by Keith Craft. The computer is a FAST XFI system with Electronic Traction control. ETC is an example of something that an EFI system can do as a result of using a computer to control the engine. In this setup, the EFI computer is connected to a driveshaft speed sensor which allows the computer to detect when the rear wheels are slipping. It then retards the engine's ignition timing to reduce power output and control the spin.
Here's a picture of the 482 FE going into my Cobra:
This particular motor made 650+ hp on Keith's dyno.
Prior to the cobra project, I built a blown and injected small block using EFI. As you can see, this is a pretty radical setup for street use. The EFI system in this car is a BigStuff Gen 3 with a BDS injector hat and supercharger. This motor starts and runs great even in cold weather and produces 625 hp.
I hope that this helps you. If you're interested in more information on these two motor's, the associated EFI systems, and the cars they are in; check out our website at:
http://www.anitafred.net/HotRod.htm
I hope you decide to try an EFI system. Having done this twice now, I don't think I'd build another performance street motor with a carb.
- Fred