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L28 4bbl EFI build - help/input wanted!


michael wales

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This is in a Mallory Unilite? Oh...I thought it was an L28ET CAS. 

Yes, I sold my Unilite after one weekend with it, and have used Nissan Distributors since, with Pertronix or Luminition conversions when necessary to remove points.

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  • 1 month later...

Quick Update -

 

So after putting a few hundred miles or so on this setup I was beginning to get very worried about fuel mileage. I had to fill up twice around 3/4 empty with 125 - 150 miles or so on the OD both times. Needless to say the low teens is not where I wanted to be, that being said I was laying on the throttle pretty hard and hadn't had a drive longer than 20 minutes or 10 miles and very little highway cruising (but a lot of off and on ramps :D ). Well I decided I'd use the Z for my daily work commute which is about 30 miles of mostly 55 -60 mph HWY cruising, pretty calm. This has bumped my MPGs up to low to mid 20's which if I'm honest I don't think is bad as my self control is still lacking and 'I'm no where near hypermiling this thing. 

 

Questions I have still

 

Atomic has 3 user settings as far as AFR  Idle, Cruise, and WOT as well as Boost and Nitrous which unfortunately I have neither of at this time

 

My current settings are Idle - 14.0 Cruise - 14.0 and WOT - 12.5

 

Would you guys recommend any changes?

 

I still haven't found a solution for controlling my timing but it hasn't been an issue yet.

 

Also I've noticed that my Odometer and speedometer are way off. Probably due to the 17 inch rims and tires the rear-end and tranny are stock to my knowledge. so if it is just wheels is the solution to change the gear in the transmission that the Odo reads off? that I can change to compensate or am I completely off?

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Isn't the fuel added at the start of the runners?  The pseudo-carb?  Should be the same ratio for all, unless air is slipping by without picking up fuel then passing to individual runners unequally.  With mulitport injection, you could see a runner air flow imbalance. but equal fuel injected for all, leading to varying AFR per cylinder.

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Idle is about as lean as you want to go. If you try 14.7 it will develop bad habits. The L-Series likes 13.5-14.0 AFR at idle.

Cruise is dependent on the parameters. Using EGT on each plug I've routinely gone to 15.5~16.5:1, and some people have said they went as far as 17~18:1 with fast burn chambers and strokers that inherently have more torque and don't need the Tq or Hp at legal cruising speeds. I don't know how it's adjusted or if you can do it on the fly but on a level road or even long slight grade just start turning it back until you get bad behaviour...spark knock, bucking, or lean surge. Go back the other way half or 3/4 a point and that is as lean as you want to go with a light load.

 

Power is as low as you need to go without being able to quantify it empirically... Make a pass, change the AFR, make another pass. In three pulls on the dyno you will know.

 

One BIG thing is watch your accelerator shot function, injection volume and duration time. On Megasquirt, that function can be the difference between 17 mpg and 30 mpg! If it's shooting a little squirt of fuel every time you touch the pedal it drastically impacts the fuel mileage. If you are proper on fueling, you will not need acceleration enrichment unless making a big throttle angle movement, especially at low speeds.

 

As for comparing a modern multiport sequential injected dry manifold system to a sand cast wet manifold system and basing a conclusion on it...well...

Edited by Tony D
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thanks for all the inputs guys. I went ahead and leaned out the idle and cruise and didn't notice much loss of power just a little less of the gas smell from the exhaust. The car seems to be running well so I'm wary of making many changes but the settings I do have other then the basic ones above are pump squirt and  power valve which are set as a percentage from 0 -100% here is MSD's explanation of each

 

 

Pump Squirt - To assist in throttle transitions the Atomic EFI

 

has a feature to mimic the pump squirt of a carburetor.

 

This works by increasing fuel delivery by a prescribed

 

percentage any time there is an increase in throttle

 

position. If needed, make small changes of no more

 

than 5% increments without further testing. 25% is

 

sufficient for most engines. Almost all vehicles will use

 

between 15 and 35% pump squirt

 

Power Valve Enrich - To assist in manifold pressure

 

transitions the Atomic EFI has a power valve feature.

 

This works by adding fuel based on MAP transitions

 

while moving the throttle. Large cam vehicles with low

 

vacuum generally required a slightly smaller number

 

while stock/small camshaft vehicles with a high vacuum

 

may require more. If needed make small changes of no

 

more than 5% increments without further testing, 25%

 

is sufficient for most engines but between 15-35% is

 

normal. Typically, the higher the vacuum (more stock)

 

 

 

 

 

 

 

 

 

 

So I'm assuming these are similar to the settings you were describing Tony? I'm partially torn between just leaving it alone until I get my turbo parts all assembled since ill need to start over again I think even though MSD does have a completely separate setting for boost... either way thanks again guys, its nice to have somewhere to bounce ideas off people who have similar setups and experience beyond the MSD forum, where if its not above 5 liters they have no idea...

the higher the percentage needed.

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Continue tuning the NA Portion. It should be something totally different when under boost...you physically can't tune boost map until you actually have boost.

 

The power valve is the MAP-DOT on the old MS (like a soft squirt) that riches fuel on those little throttle changes that don't activate the pump squirt. I'd turn that down and see how slow roll ons to the throttle respond. Turn it back until is coughs on roll on, that's not enough fuel...go back a few clicks... My bet is you will need the full 35% or higher.

 

I don't know how that works on this system, but if you drop throttle you go to 28-30" vacuum...and even a slight roll on makes that go from 30 past your normal 19 at idle and then on to 15", so you could be activating the power valve when you really shouldn't.

 

Another MS fuel saver is FUEL CUT...turn the injectors OFF under that 30" of vacuum, between 3500 and 2200 rams (or similar to stock range) -- that can really save gas as well.

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  • 1 month later...

Quick update, I decided to take TonyDs advice and tune the N/A portion and after hitting a seeming wall and not feeling like i was getting everything i should, so after going over every, and i mean every last setting I noticed that my throttle position sensor was only going to 50%...I was sitting here the entire time with half throttle because in a hurry we put the throttle cable into the mid slot not the top, its still only hitting 82% throttle but the difference is amazing its actually putting my Triple Webers to shame... I really cant tell you guys how nice it has to have my Z start on the first turn of the key, idle perfectly, and now scream from drop of the clutch to the rev limiter. I still feel like an idiot for not figuring this out sooner now I just have to solve the last 18% issue. 

Edited by michael wales
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Well that's definitely good news! 
We all forget to check the basics.

On my setup it's a throttle cable and not the linkage. I had to adjust the throttle pedal down considerably to prevent it from over-pulling on the throttle quadrant. Upside was the pedal was right at brake pedal height afterwards.

If that TB has a throttle quadrant, make sure it's rotated for full throttle, and then set up your 0% by either adjusting the pedal height or cable jacket length. I just put a different TB on my Suzuki Turbo and had to add a bracket about 1" longer to get what looked identical quadrant on the newer TB to open fully with my existing cable and throttle pedal setup. Quadrants usually are set to be tangential at WOT. Usually the pedal throw on the S30 pedal is more than enough to get that pull straight off the top of the pedal, taking it off a bellcrank really reduces the amount of pull you get.

 

Mechanical Linkages are another thing entirely, and usually require one of the bellcranks being lengthened for more stroke, but sometimes you can simply shorten the pullrod on the top of the pedal to the first bellcrank to lift the pedal up off the floor more and give you more stroke.

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At least you got a really high-resolution partial throttle map done! That will pay in your drivability. Inadvertently, the blocked throttle made you tune the most used portion of the throttle range extensively...long term, that will pay off as you seem to be seeing now. Which is great!

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  • 4 weeks later...

Well the Z has been on the back burner a bit while I have been toying with a Honda CB175 my brother gave me. Other than a few fun drives on the back roads I haven't got it out or changed much since I think I'm going to have take the throttle linkage apart to fix the last little bit of issues I'm having with it. It is still running great and the fact that I'm enjoying it so much has been+ slowing my enthusiasm to put the turbo on. I will say that the air cleaner that is on it the low profile Edelbrock is killing the top-end more then i realized after a few quick runs sans air cleaner. I'm wondering if going ahead and getting the "carb hat" I'm going to need come boost time and then running some piping and a regular cone filter out to the front in the cool air might be better than what I'm running now.

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  • 4 weeks later...

So while I've been dragging my feet with the turbo setup I've also been looking at the few items I still need in addition to just my manifold/turbo to put the boost into effect. Mainly the turbo lines and associated equipment.

 

Well then I found this. http://compturbo.com/spotlights/oil-less

Anyone heard of oil-less turbos?? Seems like it would ease my install and add to the oddness. Let me know what you guys think!

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