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Old 05-12-2012, 06:07 PM   #1
gdh
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Default MSD Atomic EFI Tech Session

I attended a tech session today with one of the designers of this system. Even though it is advertised as a no rtn system he did say it was better to run a rtn line. One obvious reason is pump life but one thing he said is an unknown is how it will run for extended periods in the heat (plus 100F) days in the south. He said that since their pump is a "pusher", placement is critical. It is an interesting system with some very cool features. For me, I am waiting to hear the reviews after a full summer season of use.

Last edited by gdh; 05-12-2012 at 06:10 PM.
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Old 05-12-2012, 10:08 PM   #2
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Flat statement from many experienced long term car guys....

MSD has a **** poor reputation for reliability....and so it has been the same with me.....

CASE CLOSED.....

check around first, you will find supporters are out numbered....

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Old 05-13-2012, 06:54 AM   #3
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I did an intensive research on a self-learning EFI systems, FAST EZ-EFI, Holley Avenger EFI, and MSD Atomic, I found the FAST system is the best system to have in terms of reliability, cost, support, and scalability, its the only system that can be upgraded to support upto 1000 HP, it uses a return-fuel system which keeps the fuel pump cool by circulating cool fuel from tank to the pump all the time, and its been used by thousands of happy users. For me, its the EZ-EFI, hands down.
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Old 05-13-2012, 07:20 AM   #4
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I do agree with your concerns and voiced them somewhat in a post in the Canucklehead Section. For me if I had to make the decision today btn MSD and FAST it would be FAST.
http://forums.corvetteforum.com/cana...day-at-pi.html

I am just doing my research to determine what route I will take when the /72 gets a frame off in a few years. There are so many things to consider, I have considered adding a c4 suspension, ls engine, 5sp, ac, 17/18" rims - then we would have a much more comfortable and better handling long distance cruiser. I plan on retiring 3 yrs this June so this will be my retirement present to myself - oh yes and to my wife (think she'll buy into that one). I have considered a C6 but I just don't really like them that much, they are a great sporting car with fantastic performance and all the creature comforts but I like the look of the C2/3's. I asked our kids and they love the 72 and have no interest in modern vettes (pretty much a consistent stmt. from the kids here which worries me about the future of the vette once us boomers are no longer buying them new).
Some will once again get ticked as I would be "butchering" a Zr-1. Well as I have said many a time, after serving many years on the track many parts were replaced, I still have the engine, heads, intake rebuilt tranny etc. but there have been so many new parts installed over the years that other than VIN numbers it no longer is a true Zr-1. I didn't buy it to restore it, 'ell I didn't even know what it was when I bought it and only paid 14.5 back in the 90/s. I will keep all of the original parts and let my son decide what to do with it all once I no longer drive it. If he wants to return it to as close to original as possible that will be his decision. Life can be both good and fun on occassion, eh!
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Old 05-13-2012, 09:07 PM   #5
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having looked at all the same stuff about the EFI i would look at how the mfg's did it. As a gm mechanic for almost 20 years, my last few gm cars had over... well over 120k in mileage and i never had fuel system issues. replaced 1 injector and filters.
Fast for me when i get the money's.
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Old 05-13-2012, 10:59 PM   #6
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The appeal of the Atomic appears to be that the computer is built into the throttle body, so less wiring and it's prettier.

Return vs. returnless has very little to do with pump life reliability. The fuel pump runs at 100% anytime the engine is running. So it's always pumping enough fuel to feed your engine at WOT and redlined. So extra fuel has to be pumped back to the tank when the engine is not using it.

Older fuel injection used a return system. The reason they stopped using this was all the warm fuel being pumped back to the tank was creating evaporative emissions. Fancy way of saying it was causing more vapors to be emitted from the gas tank.

New systems still use a fuel pressure regulator that dumps excess fuel, the difference is that it is built into the fuel pump assembly. So its still returning the fuel, but is internal to the fuel tank.

If you want to use a returnless system, you can use a LS1 covette fuel filter which has the regulator and return line built in, so the fuel return only has to be a foot or two long.

One instance that WILL cause pump damage in a returnless system is if you deadhead the pump into a fuel regulator. I.E. using a pump running 100 percent all the time pushing fuel into a regulator mounted at the throttle body. Fuel pressure may be 45 at the injectors, but line pressure will be max pump pressure all the time.
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Old 05-14-2012, 07:27 AM   #7
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Quote:
Originally Posted by Learning_Curve View Post
The appeal of the Atomic appears to be that the computer is built into the throttle body, so less wiring and it's prettier.

Return vs. returnless has very little to do with pump life reliability. The fuel pump runs at 100% anytime the engine is running. So it's always pumping enough fuel to feed your engine at WOT and redlined. So extra fuel has to be pumped back to the tank when the engine is not using it.

Older fuel injection used a return system. The reason they stopped using this was all the warm fuel being pumped back to the tank was creating evaporative emissions. Fancy way of saying it was causing more vapors to be emitted from the gas tank.

New systems still use a fuel pressure regulator that dumps excess fuel, the difference is that it is built into the fuel pump assembly. So its still returning the fuel, but is internal to the fuel tank.

If you want to use a returnless system, you can use a LS1 covette fuel filter which has the regulator and return line built in, so the fuel return only has to be a foot or two long.

One instance that WILL cause pump damage in a returnless system is if you deadhead the pump into a fuel regulator. I.E. using a pump running 100 percent all the time pushing fuel into a regulator mounted at the throttle body. Fuel pressure may be 45 at the injectors, but line pressure will be max pump pressure all the time.
With the MSD system their pump cycles on and off on a continual basis as it is a pusher type pump. That is also the reason why placement is critical so that gas can essentially flow down to it then get pushed onto the engine. The pump life was one of the points that the MSD tech. brought up a number of times and stated often that by not running a return the pump life would be shorter due to pwm (on and off to also regulate fuel). He is also concerned with how it will survive the summer heat of the south.
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Old 05-14-2012, 11:29 AM   #8
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Gotcha. I checked out the MSD site, but they were a little vague on the fuel system. I can see how pulsing the fuel pump could be harmfull. Not only for pump life, but the computer would have to have some feedback to make sure it was maintaining the proper fuel pressure. If fuel pressure varies, so will air/fuel ratio.

GM first started using pulse width to modulate fuel pump output in the supercharged Grand Prixs, and now it's on the new Camaros. However there is still a mechanical fuel pump regulator to accurately control pressure.

If it was me and I wanted a returnless system, I would run the pump at 100% and use the LS1 Corvette filter/regulator.
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Old 05-14-2012, 11:29 AM
 
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