Quote:
Originally Posted by FUNFER2
The links on page 12 is where I had problems before but now, I can get on them. Must have been on my side.
The EFI must help a great deal on mpg. I built a 428 with 10:1 compression, can is a solid flat tappet, 600 lift, 252/260 duration @ 0.50, GG- Mighty Demon carb. ect. Nothing radical. On the Mustang chassis dyno, it's 331 HP. On the Dyno Jet was something like 401 HP at the wheels. I have a 500-TKO with a 9" & 331 gears. At 60 mph the rpm is 2,000. On the Hot Rod Power Tour last year, the best I got (if I kept my foot out of it) around 16 mpg. So, with your engine having a lot more power ect., that's why it makes me think your EFI is making a vast improvement in average mpg.
I'm thinking of having Keith build me a Pond Alum. short block, his Edelbrock stage 2 heads, my Vic Jr. intake and use my 428 as a donor for the other parts. From my research in the last two months, others with the 482 have been very helpful with different combinations of cams ect. One today with a hyd. roller and about (have to look) 630 lift, 260/252, only gets 4 mpg city and 7-8 highway. That, troubles me. lol
Most of us gear heads don't give a crap about mpg but, 4 to 6 ? 
From the beginning, I was just going to buy a EFI from Dynatek. What a awesome "Webber Look" that system is, just a work of art. TWM is also a great product but, I like Dynatek's appearance. I thought the apx. $6,000 was for the FE but, not so. For the BB, the price is apx. $7,000 + parts. All said & done, I can envision the system being $8,000 or so. That's a lot for a EFI but, very cool, better running, fuel mpg. ect. But, I have decided that since I've always wanted a side oiler in the car, I'm going for the alum. 427 so. If, and that's a big if,....I ever save enough cash in my toy fund, I will but the Dynatek. The problem with that is, $20,000 for a street car engine for ME,........may be crazy, and,......... my wife would KILL ME ! 
Do you think the EFI is helping say, 10 + better mpg ?
Anyway, what a beautiful cobra you have and the engine is fantastic. And I'll be reading about your car here and on you site. The engine sounds perfect.
Speaking of the engine video, is the "whirling" sound the EFI ? It almost sounds like a turbo.
Thank you much, |
Kevin,
Thanks you for the kind words on our Cobra.
The sound that you hear on the video (when the throttle goes from open to closed) is the EFI computer closing down the Idle Air Control Motor. When the IAC is almost shut, you can hear the air whistle a little bit as it goes through the valve. The IAC is used for a number of purposes including regulating idle speed and as a "dashpot" (carb analogy) function to prevent the car from stalling when the throttle is suddenly closed.
I don't think the EFI is good for quite 10 MPG when compared to a well tuned carb motor. It probably is good for 2-4 MPG on a well tuned performance motor at cruise. The added flexibility to regulate fuel coupled with closed loop operation (amount of unburned fuel in the exhaust is used to adjust the mixture at cruise/part throttle) is probably what does the most good. The problem with a carb on a high performance motor is that its hard to get a tune that produces the best performance at WOT and still optimizes the fuel (and timing) at light loads during cruising.
If you are concerned about fuel economy and your car will be mostly street driven, you might want to consider an overdrive transmission. I've used the Tremec TKO-600 with .64 O/D on two cars that should have lousy gas mileage (a blown and Bug Catcher injected 383 ci Corvette - check my gallery for a pic) and my 482ci injected Ford in my Cobra and I have seen cruising gas mileage above 15 MPG with both. The other advantage of this approach is that you can keep the cruising RPMs way down which will save wear and tear on the motor, the car, and the driver. My cobra has 3.54 gears and it cruises at 65 MPH at just 2,000 RPM with this setup.
BTW, I've looked at the Dynatek EFI system recently (thinking about using it for a GT40 project that is in the early planning stages). I think that both systems are capable of good performance on a large engine like a 482 ci as long as the RPMs stay below about 6,500 or so. Above that, I think that the TWM would outflow the Dynatek. The EFI computer system that comes with the Dynatek is not quite as sophisicated and easy to tune as similar systems from FAST, etc. I also think that its unlikely that you'd get a really good tune on the Dynatek on a performance motor (CAM, heads, hight compression, etc) without using some sort of dyno and manually optimizing the tune. This all can be done after the motor is in the car with a good chassis dyno and a knowledgable tuner but this is something to keep in mind if you want to go that way in the future. Your might want to consider doing some things to make your car "EFI ready" when you swap in your new motor. The first thing to consider doing while you have the motor out of your car is to upgrade the fuel system to be EFI "ready". This would involve installing a return line to your tank, a regulator, and perhaps upgrading the size of your fuel feed line a step or two. This will be easiest to do with the motor out of the car and will be an essential step if you convert to EFI later. While the Dynatek system has an option that would avoid a return line, I don't think that approach would be good idea on a big block that will make the kind of power that you are looking at. EFI needs a good, stable fuel pressure in the 45-50 psi range at all loads and this would be hard to do with a returnless system given the range of fuel demands of a motor the size you are thinking about.
Another thing that you should consider doing when you swap your engine is to upgrade the eletrical system/alternator to a 100A unit. This will involve a little bit of rewiring (not difficult BTW) and you will get the another common cause of EFI gremlins (not enough current to run everything) out of the way while you are doing the engine swap.
The last thing to consider is having a bung for an O2 sensor welded in one of your pipes (passenger side is usually the best). You'll want to use an EFI system with an O2 sensor later on. Again, this will be easier while you have everything apart for the engine swap and you'll be able to use this to install an Air-Fuel Ratio meter to do a better job of tunning your carb setup when its in the car if you want to do that.
You are making a good choice by working with Keith. I'd let him pick the intake, cylinder heads, and CAM combination even if it means replacing your current intake or CAM. These three components (along with an appropriate setting of the static compression ratio) need to be properly matched (along with the exhaust) to create the best possible power, torque and broad power band. Be honest with yourself and Keith about how you will really drive your car and let him pick a combination that is best matched to what you'll be doing. I think lots of guys get carried away with what they think are "big numbers" for CAMS and intakes and create combinations that either don't work well together or product power at RPM ranges that the rest of the car (and their driving plans) are set up to use effectively. Your current CAM (630 lift, 252/260 - assume the durations are at "0.050") is a pretty big CAM for a 428 ci motor if the car is street driven. You didn't say what the LSA is on your CAM but I'd guess is probably 110 degrees or maybe less. This means that your power band is from about 3000 - 7000 RPM or so - sound about right? A cam like this would need high compression (at the limits of pump gas) and low gears and would be happiest at the strip or the track. The high overlap along with the likely rich tune on your carb that you need to get the car to idle well and perform decently below 3000 PRM is what is a likely cause of your poor gas mileage. Don't know how recently you purchased this CAM but a more up to date custom lobe profile that you'd get from Keith would give you more lift with less duration. Also, a wider LSA would be a good idea both for street performance with your carb and to better manage low RPM reversion problems that a big set of stack injectors on an EFI setup would be prone to if you go that way in the future. When you are ready to finalize things, let Keith know if you seriously want to upgrade to EFI in the future as this may change his choice in the CAM for you motor a bit.
Sorry for the long-winded post but hopefully this will help you (and others on the forum). Good luck with your project!
- Fred