8 injectors
 

So, I just purchased this intake manifold on ebay. I just bought a 99 head as well, so I needed an intake manifold, throttle body etc. My goal is 450whp and my 550's just aren't going to cut it. I was planning on upping the fuel pressure and maybe going with something slightly larger but I saw this manifold and said "hell, why not?" This way, I can use some ridiculously large injectors and still have my idle/cruise quality. I'm thinking about going with stock injectors for the primaries and 1000-1200cc's for the secondaries.

Anyway, the whole reason behind this thread is to discuss my options in injector sizing and megasquirt configuration/wiring. I have been looking at the differences between dual table and staged injection, and I think that staged injection is the road that I'm wanting to go down. It seems to me that it will be much simpler as there will only be one fuel map to tune. I also like the fact that you can set it to slowly switch between sets of injectors.

For the wiring, I can come out through the middle connector on my mspnp but where would I come from on the board?

Seems like a lot of trouble when the Deutchworks stuff that people are having good success with are $340... their 600's should get you to 350whp with acceptable duty cycles on a '99... and no worries about impedence or clips or double tuning.

If you really want to know about fueling a '99, PM Popstoy over at m.net.

Oh wow, i forgot that i took my specs out of my signature. It's a 95 car with a 99 head.

Well, 350 is not 450. I've talked to Deatschwerks and they dont have anything bigger than 600's

The old FM Link Piggyback ECU for the NB cars used an arrangement just like this, where the stock injectors were left connected to the stock ECU, and four additional injectors were placed in the manifold and controlled by the Link. That could very well be a manifold from an FM-equipped car in that eBay link.

That said, bear in mind that the MS only has two injector channels to begin with. It may well be a tossup insofar as idle quality is concerned in running two banks of 4 injectors vs. buying a single set of 750-850cc/min low-impedance injectors and the JBperf peak & hold driver board to run them.

What sort of transmission are you planning to run?

Very, interesting. That kind of shoots down my plans. Maybe i will modify this manifold and inject nitrous instead of fuel. Anyway, I've thrown my ideas for fueling back and forth for a while now and I guess I will stick with 1 set of big injectors. Maybe raise the pressure slightly if I need to. Either way, I needed an intake manifold/throttle body and $100 shipped was better than $425 + shipping from planet miata.

Transmission wise, I have a 6 speed and if that breaks, it will be quaife time for me.

Yeah, as much as I hate to say it, running an AFPR and a set of 550s may well be the best solution here. At 100 PSI, your current injectors should flow more than enough fuel for 450bhp.

This should be an interesting build to follow.

I have a 12:1 fpr but i'm not sure that's my best bet. I got it from magna for cheap. At 20psi+ my walbro 255 will be maxed out. Or, i could just do a big wet shot of nitrous. That will take care of my fueling/power issues :)

savington is planning on running RC750's with his ms. Maybe you should give him a shout, i think he is planning somewhere around 350whp isn't he?

I have some Deatschwerks 750cc injectors, but maybe they were a limited run.

So, I received the intake manifold today. The injectors are wired up so that they all go to one connector. So, that means that they were all activated at the same time. That got me thinking. What if i used something like the WI circuit to turn on all the injectors at the same time to 100% duty cycle. Something like a 5th injector, only with 4 of them so that the fuel is evenly distributed. Would this overheat the injectors?

You run the risk of them refusing to shut off, which can have serious rammifications.

Really, I think you're going to have a hell of a time getting a set of secondaries to come online smoothly. I would send the MS back to DIY and ask them to set it up to PROPERLY control some peak/hold injectors (no resistor packs). Then grab some peak/hold RC750s for an Rx7. Hang onto your Bosch 255, and if you run out consider doing a Bosch 044 inline. If you max the 750s, bump the fuel pressure until it's no longer an issue. That will get you the idle quality you want, as well as the power.