Had a chat with Holly support about choosing the right EFI

[Jammer369]

Since making the decision to go with a 427 Dart, the next choice that needed to be made was how to get the flammable stuff into the cylinders. For quite some time I have tried to understand the different EFI products from Holley. Since I am a simple minded guy and need pilot friendly instructions (pictures and chatting with a live person go a long way), I decided to give Holley a call and go over all the differences. I am sure most of you guys know all of this already but just in case there is someone like me who lost a few too many brain cells in your third decade of life, here is what I found out:

One of the biggest differences between the Sniper and Terminator lines is the ECU is contained in the Sniper Throttle Body itself whereas the Terminator ECU is a separate unit and can be placed away from any source of RFI. He did say that some guys run into an issue with RFI and need to take additional measures to shield the Sniper ECU from interference. I was more interested in the Terminator line so I didn't ask any other questions about the Sniper line.

For the Terminator line, this is where I was always confused. What's the difference between Terminator vs Terminator X, Terminator vs Terminator Stealth, etc.

The difference between the Terminator and Terminator X is the ECU. The Terminator has the HP ECU EFI Software and Firmware whereas the Terminator X has the Holley ECU Software and Firmware. The HP ECU software has quite a few more features including traction control and the ability to run Low Impedance injectors. The Terminator ECU is also waterproof and heat tolerant whereas the Terminator X needs to be protected from high heat and moisture. It is worth noting also that the Terminator X comes with a screen to monitor or program it whereas the Terminator does not and needs the purchase of a screen or use a laptop to program.

The word stealth with either system denotes that it is not a Multiport system but instead has the injector in the Throttle Body.

One of my must haves is decent low RPM drivability. Luckily I found a post by Jeff Kleiner (https://thefactoryfiveforum.com/showthread.php?41616-New-Engine-427&p=476840&highlight=air+cleaner+2181#post476840, post #6) where he talks about that very subject when referencing intake manifolds. I already had read that in general, dual plane manifolds are best for low end numbers and driveability. He recommended the Performer 2181 (RPM range of idle to 5500) which is a dual plane, non multi-port manifold. Jeff also pointed out that one of the benefits of the 2181 is that it has a pad height of 4.120" which works well with the higher deck height of the dart 427 block I will be using. This helps with hood clearance. Since this is what I am looking for, the correct Holley EFI for my build is the Holley Terminator X Stealth (550-1002)

Hope this info helps someone out.

[sread]

Just a word of caution - while its true that normally a dual plane intake is better suited for low speed driveability it's not unusual for throttle body efi systems to perform better with a single plane set up. Can't tell you why, but have heard of many instances where throttle body systems and dual plane intakes didn't play well together. If you are running a 427, low end torque is not going to be an issue unless you go really big on the cam. I am running a Terminator throttle body system on an LS1 using a single plane Holley intake and it is extremely snappy and responsive.

[Jammer369]

Just a word of caution - while its true that normally a dual plane intake is better suited for low speed driveability it's not unusual for throttle body efi systems to perform better with a single plane set up. Can't tell you why, but have heard of many instances where throttle body systems and dual plane intakes didn't play well together. If you are running a 427, low end torque is not going to be an issue unless you go really big on the cam. I am running a Terminator throttle body system on an LS1 using a single plane Holley intake and it is extremely snappy and responsive.

Thanks for the info. I had read about that and asked the Holley guy about it. He ended up downplaying it. I have also seen several threads talk about the throttle body only measuring the air on one of the two planes and thus not delivering the proper mixture based a possible difference in flow. One video had a guy machine a 1/2" channel in the divider between the two planes directly under the throttle body. Supposedly it made a difference. I would really like the RPM range for the manifold to start at idle so I don't have to keep the rpms up leaving the neighborhood.

[phileas_fogg]

I seem to recall an episode of “Engine Masters” where they compared dual vs single plane manifolds, maybe carb spacers in the same episode? At the time I remember thinking the 1/2” notch on the dual plane would probably give the best of both worlds & then maybe add a 1/2” spacer to squeeze out a little more top end power.

They’ve also compared all sorts of intakes on the same engine, so I’d look that episode up too.


John

[Jammer369]

I seem to recall an episode of “Engine Masters” where they compared dual vs single plane manifolds, maybe carb spacers in the same episode? At the time I remember thinking the 1/2” notch on the dual plane would probably give the best of both worlds & then maybe add a 1/2” spacer to squeeze out a little more top end power.

They’ve also compared all sorts of intakes on the same engine, so I’d look that episode up too.


John

Thanks! I will see if I can find that one. I just watched a short video on milling the 1/2" divider to match the RPM Air Gap manifold.

https://www.youtube.com/watch?v=yrDuXGmnqRw

[Jim1855]

Jammer,

With about 65k miles on my 427w as a guide, although with a carb, I wouldn't expect that you'll have any issues motoring through the neighborhood no matter which manifold you choose.

Now carbs are different than EFI but if using a "carb" style throttle body the fuel mixture pathways are the same. The advantage of EFI is being able, mostly, to tune out the stumbles, idle issues and air/fuel mixture. Generally, this provides a smoother power delivery, better idle and off-idle operation.

I ran a Performer RPM dual plane early on, worked well and provide great torque at the bottom end (1,000-2,000). I'm now running a Vic Jr. single plane. I am considering the Super Victor to push the torque curve up further into the RPM range, kinda like traction control, I don't need the bottom end torque. I have one ready to go on. I have friends running the Super Vic on 427 or 462 ci motors w/o problems or concerns. Any dual plane manifold will be more low end tolerant than the Super Vic.

There is no good reason to think that you won't have sufficient torque to drive the car. My motor has about 250lb/ft torque at 1,200, 300 at 2,000 and 400+ from 3,000 on. Yours should be reasonably similar. How much torque do you think you'll need to motor along at 25mph?

The only reason to think that you won't be able to cruise through the neighborhood in a civil fashion is you haven't yet figured out how to modulate your right foot.

Jim

[Jammer369]

Jammer,

With about 65k miles on my 427w as a guide, although with a carb, I wouldn't expect that you'll have any issues motoring through the neighborhood no matter which manifold you choose.

Now carbs are different than EFI but if using a "carb" style throttle body the fuel mixture pathways are the same. The advantage of EFI is being able, mostly, to tune out the stumbles, idle issues and air/fuel mixture. Generally, this provides a smoother power delivery, better idle and off-idle operation.

I ran a Performer RPM dual plane early on, worked well and provide great torque at the bottom end (1,000-2,000). I'm now running a Vic Jr. single plane. I am considering the Super Victor to push the torque curve up further into the RPM range, kinda like traction control, I don't need the bottom end torque. I have one ready to go on. I have friends running the Super Vic on 427 or 462 ci motors w/o problems or concerns. Any dual plane manifold will be more low end tolerant than the Super Vic.

There is no good reason to think that you won't have sufficient torque to drive the car. My motor has about 250lb/ft torque at 1,200, 300 at 2,000 and 400+ from 3,000 on. Yours should be reasonably similar. How much torque do you think you'll need to motor along at 25mph?

The only reason to think that you won't be able to cruise through the neighborhood in a civil fashion is you haven't yet figured out how to modulate your right foot.

Jim

Thanks for the info Jim!

All I have to go on is what I have read on the forums. I was mainly basing a lot of what I wrote about looking to go with the Edelbrock 2181 from a post Jeff Kleiner made that I posted a link to above. In that he talked about a friend of his who has a 427W with a Performer 7181. If I understand the post correctly the issue is the ability of the engine to run smoothly below 1500 RPM. His friends neighbors don't take kindly to him having to get out of the neighborhood at a higher RPM bc the engine doesn't run that smoothly close to idle. If I read it wrong it would be great to know. From Jeff's post:


I suggest that you stick to a #2181 both for fit and driveability. My customer with a very mildly cammed 427W running the #7181 complains that the car is very unhappy below 2,000 RPM (says all of his neighbors think he's being an ********* when he drives through the neighborhood with it wound up to 2,500 in first gear but he kind of has to!).The open plenum and huge ports just don't promote enough velocity to keep fuel atomized at low speed. I know you like the look of the oval air cleaner but they are very restrictive; I usually recommend a 14" round with a drop base and an Extreme top which will let it breathe.

The difference my be that I am planning on running an EFI which does atomize better than a carb.