Hi guys ive done a lot of searching and need a little clarification. I have a 90 miata with a cartech FMU and msd retard box. T25 on 5 psi. I would like to turn it up to around 10 psi. From what Im reading I need a 190 HP fuel pump, a wideband and bigger injectors.

I know I will need to adjust my AFM, but Im having trouble finding a good write up on that. What injectors would you guys recommend?

I know I would be best to go with a better ecu but I dont plan to keep it long term, so i dont want to sink alot into it.

Any advice is appreciated, thanks

 

used mega squirt

injector size(cc/min) = (HP * BSFC * 10.5) / (#injectors * dutycycle%)

size = (190 * .6 * 10.5) / ( 4 * .8)
size = ~ 380 cc/min [or 36 lb/hr]

 

This is what you need:
Bigger Injectors
Wide Band
Proper engine management.
Proper tune.

Get rid of your MSD retarded box and cartech FMU. Sell those for whatever you can and put toward the other parts. You don't need a new fuel pump.

 

I can appreciate that a megasquirt would be better, but Im not gonna be able keep this car very long just looking to play with it for a little while and use it to sell or trade towards a new car for the wife. Just looking to upgrade for a little more power with the current setup

 

The proper answer is to get proper engine management, but 305cc injectors, FMU, 190HP, and timing management worked just fine at 10 psi on my Greddy kit. Don't forget an intercooler.

 

Thanks, pretty much the answer I was looking for, did you have to adjust the AFM for the 305s? If so could you give me a ballpark adjustment to start from? The car doesnt have an intercooler at the moment but have one sitting in the shop that will go in before I up the boost.

 

Oh yeah. Forgot to mention that I didn't have to make any adjustments to get it to idle correctly.

 

So I have a 190 hp pump, RX7 AFM and 305cc injectors on the way. Its gonna be a week or so before I can get a wideband.

 

So the computer basically just learned the bigger injectors? Did you run it at lower boost or just go straight to 10?

The fuel pump is going in tomorrow as I think im getting a little detonation due to the 150k fuel pump not keeping up, running 4 psi right now and not really boosting it much. I also have an RX7 afm on the way. I was reading and it seems it will run leaner with the afm swap but 305cc injectors would bring it back some. I dont know how much they will add and other than the fuel pump Im not changing anything until I have a wideband.

The msd box only retards the timing 6 degrees tops from what I understand. Where should I set the base timing at for 10 psi? Also what is the best A/F ratio for a daily driven street car?

 

I ran my set up that way for a year or so with the greddy back in the day, there use to be all kinds of info on here till the megasquirt bug bit everyone. People where making over 250 whp with FPR and injectors.