Fmu?

[QUICKFLOW240]

I'm building aturbo kit at the moment and the guy who's helping me out with it thinks that rather than putting 370's I could get away with and FMU and my stand alone. Is he correct in thinking this? I will not be boosting much because I'm not buiding the motor but i still don't think it will be enough.

[WDRacing]

WHat type of standalone are you running, how much boost do you want to run? I would suggest a rising rate FPR(FMU) and a set of injectors.

WD

[bruinbear714]

If you have a standalone, can't you program it to account for bigger injectors?

If you can, then I don't see why you wouldn't want to go that route.

[maxpsi]

actually you can run up to 6 psi safely with just an FMU using stock injectors and stock fuel system. However, the fuel pump may have weakness', so i would at least replace that. i ran that setup for a long time when i first started out. A Vortech FMU w/ 12:1 rising rate should be plenty enough for up to 5-6 psi which should put you about 200-215hp at the flywheel. You dont have to use a stand alone or injectors for just 5-6 psi. The FMU is a good starting point. Eventually you wont even need the FMU if you decide to use JWt or some stand alones. I use mine still because i need that much extra fuel with such small injectors i have for that much boost and power.

[QUICKFLOW240]

well how much could I get a set of injectors capable of handling the max boost on a stock bottom end? and what would be that max boost?

[Turbo_Nismo_EC]

Now here is my question...sort of on the same subject. Even though I have decided to sell my truck, I am going to install the turbo before I sell it. Now, I WAS going to use the JWT set-up, but I think that just to get it on the truck, I was thinking of using an FMU. Now, my fuel injectors have 153,000 miles on them and I am kind of worried about raising the fuel pressure and having one of them seize because of old age. Are there any replacement injectors that I can purchase to run with my stock ECU? I am only going to run 5 psi with this set-up and am planning on running an 8:1 FMU(the n-sport is 7:1 so this should be good). I just don't want to blow the motor because of an injector. I did a search and found about the 370cc ones, but those would cause my truck to run rich, and I am looking at getting the stock 270(??)cc ones. The dealership wants 400 bucks them, do you know of any aftermarket ones?

Ok that was a little much and I probably should have created a new thread..sorry....please bear with me

Thanks

[maxpsi]

well how much could I get a set of injectors capable of handling the max boost on a stock bottom end? and what would be that max boost?

Different sizes of injectors cost different prices. Alot of times you will see bigger injectors cheaper than smaller ones. Summit is a prime example. I would go through Summit to get injectors since they seem to be the best price and will work with you on it and the price. Boost levels depend on the fuel supply. Thats really kind of a vague question you asked.

[maxpsi]

Now here is my question...sort of on the same subject. Even though I have decided to sell my truck, I am going to install the turbo before I sell it. Now, I WAS going to use the JWT set-up, but I think that just to get it on the truck, I was thinking of using an FMU. Now, my fuel injectors have 153,000 miles on them and I am kind of worried about raising the fuel pressure and having one of them seize because of old age. Are there any replacement injectors that I can purchase to run with my stock ECU? I am only going to run 5 psi with this set-up and am planning on running an 8:1 FMU(the n-sport is 7:1 so this should be good). I just don't want to blow the motor because of an injector. I did a search and found about the 370cc ones, but those would cause my truck to run rich, and I am looking at getting the stock 270(??)cc ones. The dealership wants 400 bucks them, do you know of any aftermarket ones?

Ok that was a little much and I probably should have created a new thread..sorry....please bear with me

Thanks

8:1 FMU with just an FMU and stock injectors for 5 psi is running a little on the lean side but shouldnt do amy damage unless you are constantly at high rpm. I would recomend upgrading the fuel pump so it would at least be consistant. If you are wanting good condition low mileage stock replacement injectors, i have several. $20 each.

[C-Kwik]

I would agree the pump is the biggest limitation to using an FMU. Though mine worked fine up to 6.5 psi. 7+ started to give me detonation. And as far an 8:1 being lean at 5 psi, mine actually ran rich at 6.5. Though it was rich right when the injectors failed open, then leaned out as RPM's increased. Id's say right around 4000 RPM or so. My stocks were hitting 80% duration at about 3900 RPM. Though the signal didn't max out until 5000 RPM.

[NateDogg]

How is a good way to mathematically calculate the FMU ratio for a certain amount of boost?

[Turbo_Nismo_EC]

Thanks for the replies guys!!

Well I guess I accidentally left the part out that I was planning on running the Walboro fuel pump that I always hear about on here. Now when I said that I was planning on running the 8:1 FMU that is exactly what it means...planning(that wasn't meant to sound sarcastic). I actually have a couple of the re-calibration disks that I an going to take with me when I take my truck to have it put on a dyno. But I appreciate the info on the running lean part, I figured it would not be too lean, since n-sport uses a 7:1. I think that I'll try the 10:1 first, and THEN maybe the 8:1 if it is running a little rich. My main thing is the fuel injectors. I don't want to over stress them, and that is my main concern. That is the reason I was only going to run 5 psi, cause I know for a fact that my engine can handle well beyond that, boost wise, but not too sure about the injectors. It would really suck to lose my $4500+ investment over a faulty injector.

I am interested in the injectors you have for sale though. Could you give me a little more info on them like how you came about them and how low mileage are they?(uuh that sounds bad, but you get the idea)

Thanks again for the replies.

Jason

[Turbo_Nismo_EC]

By the way...do all FMU set-ups run really injector high duty cycles like C-Kwik is talking about? Even if the injectors are new, won't that cause an injector failure running that high of a duty-cycle? Man, I am nervous running an FMU. On top of really high fuel pressures, now I get to worry about high injector duty cycles. This is exactly why I only want to run only 5 psi.

[QUICKFLOW240]

Thanks for the replies guys!!

Are you tryin to steel my thread:fight

J/K :icesangel

[maxpsi]

Thanks for the replies guys!!

I am interested in the injectors you have for sale though. Could you give me a little more info on them like how you came about them and how low mileage are they?(uuh that sounds bad, but you get the idea)

Thanks again for the replies.

10:1 is best. Its better to run a bit rich than lean.

I have several injectors. Many are pulled form extra motors i have bought, some are from junk yards, some from running cars, and the ones i was going to sell to you came from the current running 96 that was replaced with 370s and only has 29k miles on them.

One more thing, you need and FMU if you arent going to do the JWT ecu upgrade. You wont get enough fuel without the FMU. Its an absolute must or you better plan on buying another motor. I have made this mistake before on my very first KA-T project.

[C-Kwik]

By the way...do all FMU set-ups run really injector high duty cycles like C-Kwik is talking about? Even if the injectors are new, won't that cause an injector failure running that high of a duty-cycle? Man, I am nervous running an FMU. On top of really high fuel pressures, now I get to worry about high injector duty cycles. This is exactly why I only want to run only 5 psi.

The reason why the injectors max out so quickly is that the ECU has no idea the FMU is there. The ECU just accounts for the additional airflow reading by increasing the pulsewidth. At some point, the ECU will just keep the signal open knowing the mtor is getting so much air. I ran 6.5 psi for about a year on a 8:1 FMU with no problems(except my deltagate wastegate started to crap out on me and spike). I am running a stock pump and chances are, I probably maxed out flow before I actually hit 6.5 psi which is why I was probably getting detonation during boost spikes above 6.5 psi.

I wouldn't be too worried, especially if you're keeping the boost relatively low. The girl who owned my turbo kit before me ran a FMU for at least a couple of years with no problems.

[Turbo_Nismo_EC]

MAXPSI....I am interested in those injectors. I will e-mail you in a minute. Also, I was planning on running an FMU. I know the stock ECU cannot adjust for the boost.

C-KWIK.....Thanks again for the info. I feel a little better now.

QUICKFLOW240....Sorry, I wasn't trying to steal your thread. I juat had a question that I didn't think it was worth openenig a new thread.:bonghit

[Turbo_Nismo_EC]

OK..MAXPSI.."Sorry! That user has specified that they do not wish to receive emails through this board.". UUHHMM, I guess you can e-mail me at [email protected]. I am interested in your low-mileage injectors. However, even though I think they will fit, please note that I have a 95 KA24E (HardBody P/U). But I'm pretty sure they willm I'm going to call Nissan Motorsports when I get home to ask.

[Movingviolation240]

but still, with an FMU your pushing almost 100psi of rail pressure! Talk about a rig. You can expect all sorts of prolbems with injectors stalling out, and fuel leaks.

IMHO an FMU is a total waste of time, I've seen way too many KAT's be rebuilt because sombody was too cheep to shell out $75 for a set of SR injectors on Ebay and thought they'd do somthing easier.

If you havn't noticed I have a deep routed hatered towards those horrible devices. Please stay away.

PaulOrlando, FL

[Turbo_Nismo_EC]

Yeah I don't exactly trust them. As a matter of fact I am nervous using one. I'm open to suggestions. However I am basically throwing on a "kit" type set-up so I can sell the truck. 5 psi shouldn't hurt anything if it is set-up correctly.......or atleast I wouldn't think so.

[sil80drifter]

Well, having read all this, and some negative responses about FMUs on stock injectors, I was wondering whether it'd be a good compromise to use BOTH and FMU and larger injectors. Also, I have heard that the stock 2nd gen RX-7 injectors (I believe they run either 440s or 550s, prolly 440s) are a direct fit for the stock KA-E engine. Because they are both top feed style. Which kinda bumms out the DE owners, but...top feed is better anyway So they could get a new fuel rail, it's cheap if u make ur own from pre-fabbed aluminum rail (It's like 20 bucks/foot and u need 1 1/2 feet at most).

sil80

p.s.: Can someone confirm the injector compatibility with the 2nd gen RX-7?

[Movingviolation240]

depends on the year, but yes some work

[C-Kwik]

but still, with an FMU your pushing almost 100psi of rail pressure! Talk about a rig. You can expect all sorts of prolbems with injectors stalling out, and fuel leaks.

IMHO an FMU is a total waste of time, I've seen way too many KAT's be rebuilt because sombody was too cheep to shell out $75 for a set of SR injectors on Ebay and thought they'd do somthing easier.

If you havn't noticed I have a deep routed hatered towards those horrible devices. Please stay away.

PaulOrlando, FL

The problem is the ones that blew their motors probably ran too much boost or had a weak fuel pump or there was some unrelated cause. I doubt my stock pump could keep up with the full 8:1 increase at 6.5 psi. But it was still enough fuel. For the cost, it's quite effective. For a low psi system, there should be no problems with it.

[sil80drifter]

Anyone have experience with this setup? What years of FC work? What else is required to use them with the KA-E?

sil80

[Turbo_Nismo_EC]

UUHHHMMM.....I have a 1995 H-Body and I don't know about the prior years but mine has the same side-feed injectors as the 240sx. I have no idea about the RX-7 thing though.

[Wolf240SX]

I have been running a 7.1 FMU with upgraded fuel pump and stock injectors at 7psi sometimes on cold nights spiking to 8.5 psi. I have never had a problem with detonation or anything. I am currently putting down 250whp.