z-ya

11.5 - 12.5 AFR range is fine.

Get your AFR right first, then give it more timing. You should be able to run 26 degrees of advance easily.

We are running around 24 degrees at 14psi. At atmospheric pressure the timing is around 33 degrees. As the boost increases, the timing is backed off in a linear fashion until it reaches 24 degrees at 14psi. Idle is around 25, and gradually increases to 33 at atmospheric.

At 25 degrees advance, and an N42 head, it might be.

Somewhere in the 8.7:1 range if the dish is the same size as stock.

PM me, and I'll send you my address.

No. PM me if you want me to.

The primary decision is EFI or carb. The difference is dramatic. I spent Saturday helping to tune a Rebello 3.2L with tripple Mikunis on a Dynpack dyno. We spent a lot of time switching main jets, and drilling out air valves, and finally got the mixture right between 4000RPM and 7000RPM. Between between 3000 and 4000RPM it goes pig rich, and there isn't much we can do about it with carbs. With EFI, we could tune that area out to get the best drivability. May get a bit more torque down low too. Below 3000RPM it is way lean. Not sure why the engine made 304HP on Rebellos engine dyno, and only 222HP on the Dynapack. I was expecting between 250 and 260WHP from the 3.2L. This engine makes it peak power around 6500RPM. I've used this Dynapack a lot in the past, and can say that it's HP numbers are very accurate. Although it does measure less than a Dynojet.

I measured the opening time on a set of DSM 450cc/min injectors. I think they are Mitsubishi OEM units. The opening time was around 0.9ms. If you have a spare injector, I can measure the opening time for you. I'd like to build a spread sheet of common injectors and their opening times.

Joe, Yes, the wider pulse widths will require more power from the injector drivers over a longer period of time. This is why the current limit % is so important. If you choose too high a number, the injectors will draw more current, causing the drivers to overheat at long opening times. 35% equates to around 1A of hold current. Any more than that, and you are just heatingup the injectors and injector drivers. Do you have a good charging system in the car?

There is no way 50mm could be added or removed from the pistons anywhere on a L28, so I think the builder meant 0.5mm (which is equal to 0.020"). 25 degrees is a lot more than 15. Try backing the timing off more with the BTM. Also, you really need to know if the pistons in there are dished or not. If they are flat tops, you are over 10:1CR, which will ping like crazy with an N42 head.

Did you verify that the total advance is 15 degrees with a timing light? Rev it up to 3500RPM in neutral and check the timing with a light. Your CR should be around 8.6:1 (I'm assuming you meant 0.5mm overbore), which should be OK. Stock dish size in the new pistons, right? Note that with a P90 head, your CR will be in the 7.6:1 range.

Glad to hear some of my work has been useful. A injector PWM time of 1.0ms is too short for the stock injectors. The opening time is around 1.25ms, but can vary depending on the injector. A safe number that should work for all Nissan injectors is 1.5ms. PWM current limit percent should be in the 35 to 40% range.

It may not be the hose that is leaking. When these injectors get old, they can start leaking from the week hold in the plastic injector body. You really should spend the $ and get them cleaned and tested. 5/16" EFI hose is close, but the metric hose you can get a tthe dealer fits properly. 5/16" has a slightly smaller inside diameter, and is hard to get on the injector barb.

I get my injectors cleaned an plow tested at Witchhunter: http://www.witchhunter.com/ Gordon does great work, and get them back to you quick. The only thing he doesn't do is install new hoses. You can do this yourself. Just pick up some new injector hose, cut to length, and dip the hose in fuel before pushing it on the injector barb.

I think you need a special machine to soda blast. There maybe someone in your area that will do it for you. I found a guy near me that will do a complete 240Z for $900.

I've heard that soda blasting is the easiest on your body panels. I know that sand blasting can deform sheet metal. My next project will be entirely soda blasted. The nice thing about baking soda is that it that it washes away with water.

If you choose to build your own, you've got this site, and msefi.com to help you along the way. I live in NH, so I can also help you out if need be.

When deciding on Megaquirt, or commercially available units, you need to decide if fixing it yourself is OK. Commercially units have a warranty, and support. The MS support community is quite good (actually better than most manufacturers), but when it breaks, you have to fix it. If you purchase a pre-built unit from one of the builders out there, they will typically fix a unit for a fee. If you start experimenting with some of the other features in MS (Extra code), you are on your own for the most part (except for sites like this). There are a number of aftermaket units out there that are great. They all have hundreds of features and capabilities. Enough to make your head spin at least a couple times. I like MS for it's simplicity. If everything is wired right, most new installs fire up right away. MT is an easy to use software package that let's you make changes in real time while the engine is running. There are still commercial units out there that can't do this. There are bugs, and untested features in MS (not that there aren't bugs in commercial units). Yea, MS doesn't do sequential fuel or ignition, but for 95% of all applications, it is not needed. Again, the decision is if you want a company backing up your investment or not.

Nice work, keep us posted on your progress.

I have the same one. Bolt it in. I suggest removing the thin harness bar behind the driver seat, and replacing it with a tubular harness bar welded across the rear most vertical tubes. Position it so that it lines up vertically with the harness slots in your seats. The way it comes from Autopower, the driver harness bar is to thin, and gets in the way of seat movement. The passenger seat doesn't have a good place for harness attachment. Do it now before you get it mounted in there. I know it is supposedly SCCA approved, but that driver harness bar is has got to go.

I use 2 or three squirts with simultaneous. It doesn't run well with 6 squirts for some reason. My point is that the injector outputs alternate even when in simultaneous mode. I've measured the injector cycle with a scope, and they are the same if in alternating or simultaneous mode. This is where I'm confused. Any insight into why this is the case (besides a bug in the extra code)?

More manifold progress.

Yes, I meant simultaneous. Simultaneous works just fine. Smooth idle, great performance. I will look into this later as I really want to understand why the MS alternates the injection cycles even in simultaneous mode. When I figure it out I will let everyone know the outcome.

I measured an OEM NA injector that is fresh from being cleaned and flow tested, and the opening time is around 1.2ms. For OEM NA injectors I would set the PWM as follows: PWM time threshold: 1.5ms PWM Current Limit: 35%