Drivability for radical cars works just as well with Speed Density. Holley has no "preferred" way, but the box is capable of doing it any way the tuner chooses to do so. That being Alpha-N, Speed Density or a combination of the two. We have had no issues making Speed Density tuned cars drive quite well on the street and have done so with several Drag Week cars. Now while Alpha-N might be "easier" for a novice tuner, the other method works just as well once the tune is sorted out.

Now Holley may "suggest" certain things, because they know it will make it easier for the average tuner to deal with and therefore cut down on tech calls.........but, either way works. The engineer who designed the system at Holley, just took his pump gas Drag Week motor off the dyno. It made over 900Hp and will be going in his car for this years Drag Week. It is tuned in Speed Density

Monte

Why is it that all the car companies went to the wide
LSA cams shortly after we went to injection... I am sure
there is a logical reason... if they wanted to cover up
the idle with the electronics they wouldnt have wasted all
that money going to the wide LSA cams

Comp has a whole line of cams called the XFI. When I flip thru the catalog it looks like almost every single XFI cam has an LCA of 113. I'm guessing that there is a reason for it.

Like Streetwize already said.........you don't NEED a lot of overlap with EFI because the fuel delivery system is way more efficient, heads are better, EVERYTHING is better these days. How many stock and super stock guys you see now running 102 LSA cams like used to be common. Things change, we are smarter and realize you don't have to crutch the motor with a poor cam design. So they are not trying to COVER UP anything. They are using what works BETTER for both idle quality AND power. That still doesn't change the discussion here and that is with PROPER tuning, the ECU doesn't care about the cam. You can MAKE it work

I suspect the main reason for a wide LSA for OEM is emissions related. The more overlap, the more time there is for unburned hydrocarbons to find their way into the exhaust, either thru reversion or low rpm misfire.

On my Commander 950 Pro TBI, I went A/N to 1800 RPM to get the idle to behave with an MP509 cam. Depending on the weather, closed loop it would chase the target AFR until it quit. At idle 76 deg of overlap misses a bunch. Every time it misfired, the ECM saw that as a lean condition (no fire, all the O2 in the cylinder goes in the exhaust) and just kept adding fuel until it loaded up and quit. Unless of course the cause of the misfire was a lung full of reversion exhaust which the ECM reads as pig rich (no O2) and cuts the fuel for next time. The end result is the same, the ECM chases it's tail until the engine just quits.

We could have set it to run open loop but as I recall the fuel map resolution wasn't good enough to make that work very well. If the new Holley systems have more resolution, this is likely an option but I don't see that it is much different than A/N when all is said and done.

Kevin

I understand that you can inject the fuel at the last given moment
to help correct... but the valve is still doing the same thing...
if the O2 thinks its seeing a lean condition the next cycle will
have more fuel applied.. so in reality its chasing the last cycle
but if the overlap is minimal then it wouldnt be.... JMO... I'm
still having idle problems of going fat(before I pulled the engine
the last time)... maybe I just have the idle set to low based on what
some are showing... I figured 850-900 would be a real number... but
I also have to get the temp up higher for this to learn... above
about 1300 things come around... this is on a 105 LSA installed
at the same thing
EDIT
it could be as simple as to cold of plugs.. 3923... this time
I'm going to 3924

my car now seams to be happier with a higher idle as well. I started out at 1000rpm after its good and warm it is around 1250 to 1300. it doesn't really bother me but I really am just looking for something that is just a little more street friendly.

I am really new to this EFU stuff and I really like it, I guess I will have to do more reading and chatting on tech pages. I can make it idle much better the more I learn. I somewhat understand what everyone is saying I just need to learn all the lingo.

I Apologize for my comments, I may have taken the comment incorrectly, I'm Human. just for clarity I wasn't blaming my cam for the car not doing what I want it to I was just looking for something more efi friendly. I will do my research with comp cams this fall and maybe I will do a swap if needed.

where do I want to make my AFR targets?

again thanks a million for all the discussions

Until this last post, I honestly didn't realize you had an efi setup on the car. I thought you were thinking of going efi, and planning on changing the cam to do it.
What system do you have on the car? With that info, I'm sure you can be guided to get the engine running more as you desire.(assuming the system has the capabilities) As stated previously, some systems are limited, and you may need to make a choice between changing the cam, or ecu, depending on what you have.

I too were under the impression you were looking at EFI not a user already. What system do you have? It will help narrow down what's needed.

My suggestion, as a novice tuner, would be to turn off your O2 feedback, get the car to idle, then move spark timing to get the best(lowest) map value. Then, do the same with fuel. Once both of those are done to achieve the lowest map value, look at the O2 reading. This reading is the value that the engine likes at idle. Set your a/f table to that value. After that is done put the ecu back into closed loop.
Again, we need the system and options.

Excellent advice^^^^^^^^!!!! I need to do it myself actually.

I have on the car EZ EFI 1.0. I really do like the system it may not have all the bells and whistles as the 2.0 but in the next month or so I can upgrade my software to get me closer to the 2.0 options.

So I have the EZ EI 1.0.

I have a some time to return the 1.0 if I want and upgrade to the 2.0 but I don't think I need the 2.0.

The 1.0 definitely doesn't like a weak vacuum signal. Might be a way to trick it into running better though. Also found that my car ran best with the WOT set to 11.8 when I had one of those.

I would say you need to change your cam if you're not tuning your efi with a laptop. I don't know enough about those systems to confirm this, but maybe others here have.
When you are effectively "locked out" of any part of the tuning, you will be limited to what you can achieve. Sorry.

I would like to see you go to the 2.0
If you don't then a cam change and loss of power may result.
I'm not sure what a 1.0 is capable of.

The EZ is not the greatest choice. You are locked out of the ECU and can do no personal tuning, as other similarly priced systems allow you to do.

EFI is great and I am a BIG supporter of it, but DON'T buy a system you can't tune. As stated, other systems that cost essentially the same as the EZ can be tuned with a laptop OR let the box does it's thing only, but at least you have the choice

Here's what MSD says about cams with their Atomic EFI:

"If lobe separation angle (LSA) is less than 108° you may need to go to the next larger cam profile. If cam duration is longer than 250° (@ .050" lift) the Atomic EFI will not be suitable for your application."

Okay. Last week I said I posted my last post, but finally kiddart answered the question - what EFI system do you have. I have to respond now because I support both FAST and Holley. Neither the EZ-1 or the EZ-2 is a good choice for an engine with low idle vacuum. I agree with Monte - you should have a system that at least lets you connect with a laptop if you need to. The upgrade that Kiddart is referring to is a change in the hand-held, but you still cannot link with a laptop.

A common band aid when an engine is near the edge of too low a vacuum is to advance the intial timing. Going up to 20 or 22 initial might make the difference.