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Old 04-25-2023, 10:35 AM
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Default MSD Atomic EFI limitations

I'm working on a customers 1970 RS Z28 originally a 4 sp which now has a Blueprint Engines 600 Hp 496 ci BBC, Tremec 6 speed with an Atomic system on it. The system doesn't have a lot of tuneability and it's hard to get the IAC count dialed in. Is this system capable of handling 600 Hp? Don't have any experience with these systems.

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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
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Old 04-25-2023, 12:14 PM
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I don't know much about the software on those things, but depending on the model number it may be undersized. The 2900 basic kit is rated up to 525hp while the 2910 kit is rated up to 620 hp.

It's my understanding that the original 1.0 atomic kits have no ability to tune beyond its handheld, while the newer 2.0 version likely uses the same tuning software provided on the Sniper.

In either case, if the 496 in question is a true 600hp, you've maxed out the 2900 kit and your very close with no room to go any further with the 2910 kit. I'd be looking at either swapping out the injectors, or going to a different fuel delivery option.

Of the TBI type systems, I would go with one of the FiTech units here. If you are not running timing control and have no plan to do so, I'd opt for the MeanStreet. It is 800 hp capable and designed specifically for engines like this at a slightly lower price point without the need to control timing. If you do want to run timing control I'd opt for the 1200PA.

For this engine I like the FiTech units specifically because of the price point on the MeanStreet, or with the 1200PA, it's off-idle tunability compared to the big Sniper Stealth units. The 1200PA uses 8 injectors to reach 1200hp capability, but in cruise and low throttle applications, it shuts down 4 of the injectors, which gives you much better manners on the street.

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Old 04-25-2023, 03:15 PM
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It is the 2910 kit. I have to replace the intake and fix an overheating issue before I can drive it around so it can self-tune. The current intake is an early Torquer that rotates the carb off-center slightly and is definitely not the right one to run. I'll use a Torker II, thanks for the response.

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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
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Old 04-25-2023, 03:29 PM
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Not a ton of error margin in there. I believe that system would use an 80 lb/hr injector. Once you get it up and running I would want to monitor fuel flow rate at WOT. If you're 90% or higher to the total fuel flow of the injectors, you may want to think about alternatives.

I think however that the 620 hp figure is probably slightly conservative. Most of these units will be okay up to 630ish, to 640 hp at the very upper limit.

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Old 05-04-2023, 10:16 AM
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Two things to note about the Atomic: 1) I've heard of a lot of issues with out of the box parts being bad, i.e. IAC motor needing replaced, MAP sensor being bad, etc. A lot of the parts are actually interchangeable with early GM TBI units so swapping out for diag isn't too cost prohibitive; 2) They are super sensitive to minor adjustment and/or mis-tuning, so timing being off by a couple degrees, ported vs. unported vacuum, can make a major difference in driveability. Some of it you have to check out manually, some of it you just have play around with the settings in the tuner.

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Old 05-27-2023, 04:06 PM
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I am replacing the old Torquer race intake from the '70s to another because the intake is the wrong one to use and an air cleaner won't fit. I wanted to use a Torker II but they don't make one for rectangular port heads so my options are a Victor Jr or RPM dual plane. Is there any downside to using a dual plane with the MSD FI?

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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
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Old 05-27-2023, 06:11 PM
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No, use the intake you would typically use for a carbureted application.

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Old 05-28-2023, 09:46 AM
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Quote:
Originally Posted by AG View Post
Is there any downside to using a dual plane with the MSD FI?

My motor is pretty mild, But I tested 5 intakes on a chassis dyno - 2 dual planes and 3 single planes. Overall average power, the dual planes were best.

I'm running the FAST XFI Sportsman, which uses the throttle body from an EZ 2.0 system. FYI, at around 315rwhp, that system was around 46% duty cycle on the injectors.

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Old 05-30-2023, 10:00 AM
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The motor is a BBC Blueprint Engines 496 ci that makes 600 Hp. I highly doubt the owner will ever rev it high enough to be making the 600 Hp, but if he does, it will probably be high on the injector duty cycle since the EFI system is good to 620 Hp. I will go with the RPM Air Gap intake.

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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule.
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