and, I decided to go with the holley hp efi system. I think ill be the first one to use it on an ls1

Ive been playing with the software for a month now and I love how intuitive it is.

I love the 31x31 table for boost and I like the self learn feature that was in the video

I also like that it is a plug and play system for ls1

I also played with a couple other software packages but they were not as intuitive and definitely way more expensive


what I would like to see

1.analog style gauges - everyone knows that graphical gauges are easier to read than numbers

2. dwell table. sure, you can set the dwell, but it only allows one setting. I would like a table where I can have low dwell at low rpm, and high dwell at high Rpm.


I sure hope the one for ls1 works. I'll report back once I get it up and running

...what I would like to see
...
2. dwell table. sure, you can set the dwell, but it only allows one setting. I would like a table where I can have low dwell at low rpm, and high dwell at high Rpm.
Not sure where you are going with this one or what the point is?

In an EFI system dwell serves merely as a coil charge time and depends on the particular ignition coil being used. Different coils take a different amount of time to charge and once they are fully charged there is nothing more to be gained by leaving the powered up except to generate more heat. So really you want to set dwell to the minimum that fully charges the coil. Reducing it further provides less spark output energy as the coil is not fully charged.

Note that in contrast to a mechanical points system where dwell was measured in degrees and thus time varied with RPM, in an EFI system dwell is specified in milliseconds and thus constant across all engine speeds.

Here is what I mean. Take an ls1 for example.
Tests show that around 5ms of dwell is where you get the hottest spark. Increase dwell and you increase heat without increasing output. Reduce dwell and you reduce output, but heat is also reduced.

Most of the better efi systems allow a dwell table, that way, I can have say 2ms dwell at idle with greatly reduced heat, and 5ms at wow for max performance

Here is what I mean. Take an ls1 for example.
Tests show that around 5ms of dwell is where you get the hottest spark. Increase dwell and you increase heat without increasing output. Reduce dwell and you reduce output, but heat is also reduced.
I follow you up to here, presuming that we are talking about heat in the coils from electrical current flow...

You already have cooler operation at idle because of the reduced duty cycle (longer cooling time between heating ignition events). So reducing charge time for thermal benefits does not seem to be needed.

You also do not have the turbulence at the low end to ensure mixture firing from spark. So I would think you want just as much or more spark energy at idle as you do for max performance.

The system components need to be designed to support some maximum duty cycle thermally. Based on environmental and duty cycle conditions there will be a stable temperature established that must be within the tolerances of the igniter and coil components. These conditions are worst case at higher RPMs and output. So again I come up with idle being well within and under the limits so no benefit to reducing coil charge time there.

Most of the better efi systems allow a dwell table, that way, I can have say 2ms dwell at idle with greatly reduced heat, and 5ms at wow for max performance
So I get the need to be able to configure dwell once overall. I could see varying dwell based on changes in system voltage or IAT/CLT.

What is the control variable input to the table? If RPM, I still don't get why this would do anything beneficial varying dwell.

Unless you really have it backwards... if the thermal parameters were marginal you might actually rely on higher mixture turbulence and mixture enrichment to improve mixture ignition. Then you could reduce spark output energy and not lose reliable ignition. Then you could reduce dwell somewhat to compensate for the higher duty cycle heat buildup at higher RPM.

you are right too, that lower rpms mean fewer firings per time span, thus less heat. I didnt think of that . I still would like the feature though

most of the ones Ive seen are rpm based. some people increase dwell at higher rpms, some decrease dwell at higher rpms(I dont see the need to decrease in a COP system though so it might be on some distributor based systems

A distributor based system will generate a lot more heat due to it's greatly increased duty cycle. I seem to recall something about the GM HEI module tweaking dwell based on RPMs but I don't recall quite what the adjustments were.

Congrats on the purchase. You are right, the Holley software is real nice. Laid out in a very easy to u/s way. Helps non-efi folk like me learn efi a little faster. The help function alone is real nice.

Congrats on the purchase. You are right, the Holley software is real nice. Laid out in a very easy to u/s way. Helps non-efi folk like me learn efi a little faster. The help function alone is real nice.

they did a good job.

I hope there is continued development and improvement of the software.

they did a good job.

I hope there is continued development and improvement of the software.
I would be the first guy to purchase traction control if they developed that!

I would be the first guy to purchase traction control if they developed that!

doug f has said he is working on it, in a separate box, but the current box allows for some rudimentary traction control

well, I was able to fire it up last night and I must say Im very impressed so far. hookup with the ls motor was very easy. only 5 loose wires to hookup(
battery positive,
battery negative,
switched 12 volts,
ignition 12 volts and
ignition ground).
if I were having the efi control the fuel pump I would wire a 6th wire thats already relayd to the fuel pump. but I chose to control the fuel pump by myself.

I loaded a table(dont even remember which) selected all the cells, and just kept adding fuel till it would start and stay running. it only took about 4 tries so I guess I got lucky and picked a close fuel table.


I plan to use the learn feature to create the rest of my table

Seun whats the updated more final verdict on this versus Megasquirt? I'd like to spend less money on the Megasquirt, but then again I would like the least amount of hassle too, for instance I would buy the Megasquirt assembled if I went that route. Does the HP EFI self learn pretty good? The Megasquirt seems like there is alot of fiddling with the VE tables. Are you using the ignition control on the HP EFI or an MSD box? This is for an LY6, S400, LS3 intake and 63# injectors with gasoline, we dont have E85 up here unfortunately. Thanks for any ideas or advice!

Seun whats the updated more final verdict on this versus Megasquirt? I'd like to spend less money on the Megasquirt, but then again I would like the least amount of hassle too, for instance I would buy the Megasquirt assembled if I went that route. Does the HP EFI self learn pretty good? The Megasquirt seems like there is alot of fiddling with the VE tables. Are you using the ignition control on the HP EFI or an MSD box? This is for an LY6, S400, LS3 intake and 63# injectors with gasoline, we dont have E85 up here unfortunately. Thanks for any ideas or advice!


the box is not bad. It was $1500 with a O2 sensor. the megasquirt was $400 for a new MSII, $200 for O2, $300 for msd6010, and approx $100 for a homemade harness, and $150 for a relay board and connector to wire up the megasquirt, so the price difference for new vs new is really not that much

I like the holley better than the ms because it is plug and play for the LS, it has the 31x31 tables, the learn and closed loop correction are pretty good when it is working, and the connectors to the ecu are beefier

I prefer the Megasquirt datalog viewer by at least 10x. and phil tobin the designer is constantly updating it. the datalog viewer on the holley is , Frankly, pi$$ poor, it is also slow to download logs from the ecu to your laptop. like annoyingly slow. it also does not allow you to batch download so you have to download each single log at a time which means you have to basically sit there the whole time at the ecu while it downloads.

I also like the fact that the megasquirt had gauges in the software so I can buy my own touchscreen lcd to use for gauges, or just use the laptop. those can be bought for $100-150. the holley touchscreen is $600 !!! the holley dominator has like 20 outputs yet it doesnt have a single output to drive a simple analog 0-5v gauge that you can buy used for $5. they make you buy their digital gauges which are $99 each. so if you are going to do like mike beck on the yb forum and have 14 gauges, prepare to spend $1400 on gauges

the holley also has a weird issue that I never had with the megasquirt. and this might actually be that it reads the crank sensor more accurately than the megasquirt, but it would drop the crank signal for a split second even though the engine is still running. thats all well and good except that it knocks the engine out of closed loop, disables the self learn, and worst of all goes into like a startup fueling routine. so imagine that you are at 4500rpms and 8psi of boost like I was on the dyno and that crank signal blip happens. it goes into the startup fueling routine and the AFR goes DEAD LEAN under boost, at high rpms, under a load. had I been on gas, the engine would have self destroyed i think.

finally support for megasquirt is better. I called holley about an issue and they had no answer for me. you can put a problem on the megasquirt board and have an answer quickly. now, the holley doesnt seem to have as many problems as people report on the megasquirt forums so that one would be a wash.

outside of those it is a robust piece. is it the final answer for people looking for affordable efi, IMO NO! but at its price range I think it might still be the best out there. if Megasquirt would come out with a more robust ecu connector, I would more than likely switch back.

one thing about megasquirt is they now have a self learn. I have never used it so I cant comment, but it is there, and they had an after the fact learn feature in the past that worked really well so Im thinking that their real time self learn should be pretty good too.

if you a looking for an affordable system why not check into efi live or hp tuners with a factory pcm. then you have access to hundreds of tables that people have already created. the guy I use for dyno tuning literally has a tune for almost any ls combo you can imagine and then you just tweak from there. My buddy is building a 5.7 and we are planning to try efi live.

Thanks for the info, that gives me alot to think about. That is scary on the dyno. I already have a new MSD 6012 box sitting here, I'd have to sell it if I did not go with MS, but like you laid out, the HP EFI isnt much more expensive total in the end. Im really interested in the closed loop control, do the 02 sensors react fast enough to actually run down the track in closed loop? My idea was to spray alot of alcohol once it hits 6 psi or so to add alot of octane, could closed loop adjust really quickly to take this into consideration or is that just an overall bad idea? I know on my Nova I spray alot of 50/50 mix at 5-6psi and never feel any hiccup with the carb, I was planning on using even more alcohol on this setup, individual port nozzles, probably enough to drop a little over a point on AFR, really wondering how closed loop on any of these setups could handle it all at once.

Thanks again for all the details.

Thanks for the info, that gives me alot to think about. That is scary on the dyno. I already have a new MSD 6012 box sitting here, I'd have to sell it if I did not go with MS, but like you laid out, the HP EFI isnt much more expensive total in the end. Im really interested in the closed loop control, do the 02 sensors react fast enough to actually run down the track in closed loop? My idea was to spray alot of alcohol once it hits 6 psi or so to add alot of octane, could closed loop adjust really quickly to take this into consideration or is that just an overall bad idea? I know on my Nova I spray alot of 50/50 mix at 5-6psi and never feel any hiccup with the carb, I was planning on using even more alcohol on this setup, individual port nozzles, probably enough to drop a little over a point on AFR, really wondering how closed loop on any of these setups could handle it all at once.

Thanks again for all the details.


ill have to look at my datalogs to see how well the closed loop worked.I think it should be able to compensate for methanol injection but I cant be certain.

ill also look at the software again. I believe it has staged injector strategies but I cant remember right now if it has dual tables. ie, at 6psi when your methanol comes on, it could go into a second table that is a bit leaner on the fuel side. I'll have to look at that tonight


I went back and looked at my last post and it seems a bit harsh. the holley is not a bad setup at all, and it is really good for being a plug and play deal. it takes 15 minutes to hook up and you can fire the motor , so it is really quite convenient if one doesnt mind paying a bit more for gauges. the hardware and wiring is really nice. the software needs more work before I can wholeheartedly recommend it.

the megasquirt was $400 for a new MSII, $200 for O2, $300 for msd6010, and approx $100 for a homemade harness, and $150 for a relay board and connector to wire up the megasquirt, so the price difference for new vs new is really not that much

So its about $1150 if you do the MS or $1500 for the HP EFI, it really isnt enough difference to get too bent out of shape about either way. Then it is just down to which does what and if you want to do more fiddling or less. Im thinking less fiddling, I hate wiring stuff, maybe I should do the HP EFI. Does the HP EFI kit come with the coil harness or is that a seperate piece? It seems like it might be seperate.

I thought about doing a stock ECU and a tuner but I really want the open loop learning stuff, and the support from Doug would be nice too.

Thanks again

the $1500 hp efi kit comes with every thing you need.

64duece on here sells them and was unbelievably helpful when i had questions - and i didnt even buy from him. i would recommend him

i would recommend downloading the software and playing with it. i also looked at the software and it allows you to use multiple sets of injectors and the second set comes in at a set duty cycle so you cant really do the whole meth programming thing.

Thanks for the info, that gives me alot to think about. That is scary on the dyno. I already have a new MSD 6012 box sitting here, I'd have to sell it if I did not


I dont know if you already purchased a system but here is an update on the holley.

First, it is really easy to add a tach, so that is no longer a problem. just remove a pin from A1 add it to a28, and since it is already a loose wire, just splice the tach signal in. voila.

second, the rpm errors are GONE. I took it to the track and had the same issues as the dyno. I sent the log files to Doug, he said that they had found a possible issue with how the holley handled the ls 24x signal. Doug sent me a new firmware to try and I have not had a single hiccup since. I took it back to the track and the little 4.8 now revs to 7400 cleanly EVERY TIME.

third, I found how one can program failsafes into the system(fyi I think MS has failsafes built in) by programming output functions and sending them back into the 2 step revlimiter, or to activate a warning light.

fourth, the closed loop control works quite well - it does a good job of keeping the AFR close to where I want it and one can set the speed. I like a setting of 3. at first I had it at 5 and it was working too fast and over correcting for blips in the afr

after running it at the track, I would Highly recommend this system with the following reservations.

1- holley still needs to program analog style gauges into the software instead of forcing one to buy the $99 gauges

2. the datalogger still needs work

3. I would like the learn table to work faster lol

The next sw release will have gauges and logger updates (although I think it is very nice as it is, much nicer than any other EFI system)

The learn table can correct 50% above 2500 RPM in a couple dyno pulls, so there isn't much left!!

Glad it is working right for you!

Thanks for the patience.

The next sw release will have gauges and logger updates (although I think it is very nice as it is, much nicer than any other EFI system)

this is great news on the gauges and logger. that way I can buy an lcd monitor to monitor everything. the holley is looking better and better.


here are my personal suggestion for the datalogger/viewer

1. let us batch download from the CPU instead of one at a time. it will save users a lot of time

2. pause, play, 2x 4x .50x buttons on the logger so users can view at our speed.

3. real time playback of datalog files if users want to match the output to video

4. save our screen settings size settings - this way If I want to view the datalog and the fuel map at the same time I dont have to reset it everytime I close the window. gets kinda old at the racetrack, using a laptop, if you know what I mean.

5. viewer settings should save. I like black backgrounds and it would be nice to not have to set a black background everytime I reopen the windows


Glad it is working right for you!

Thanks for the patience.

no, thank you for listening to your customers. that makes an amazing difference and I can see the holley being the top dog soon. the hardware is already there, and now the software is getting there.