Ok so I have a 99 civic SI and have read a couple of thread about fmu's and I realize that they are not 100% reliable. I need to get my car running so Im gonna run a 12:1 FMU Untill I can get money for a tune.

Specs

jdm b16a
Greddy kit
walbro 255
12:1 fmu
8 psi
Stock OBD2 ecu

My questions are.

What should I set my timing at? Should I leave it at the stock 16 degrees or should I retard it?

Do I need missing link? (Only 8 psi)

Anything else I need? I just need the car running again. please help

 

As long as you're not using larger injectors with your FMU, you're not using the blue box that came in the kit, you should be fine. I remember using those on my Deltagate Mark II Drag kit on one of my first hondas back in 99

 

Yeah I dont have the blue box. I bought the kit used. I do have large injectors but im not gonna use them untill I get it tuned

 

Dont boost before tune, really.

 

You will need to use a missing link or some other form of check vale to prevent the factory map sensor from reading boost with your FMU setup. Also, 12:1 is on the higher side as far as FMU's go. You might be better off with a 10:1. However there is no real way to tell unless you had a wideband to check out your fuel ratios.

Also when using an FMU, I would recommend adding an inline fuel pump along with your 255HP walbro. (12:1 FMU @ 8psi) 12x8=96 + 40 (base FP) = 136 PSI of fuel. That's more then the walbro can really support...

Personally I would recommended doing it right the first time and not using and FMU at all. If you can't afford it, then wait.

 

I have to agree. If it can wait then do so. Back in the day i ran a lil 50 trim on 4psi with a 8:1 FMU for a few months so i know its viable. But 12:1 on 8psi. ur askin for trouble man. If you can get an intake and a header cheap just roll NA till u get a tune.

 

So thanks for all the input so far.

Anybody know about timing?

Im not planning on racing the car so I think ill be alright. Im saving up for hondata s300 so I should be able to get it by Feb or March. I just really need to be able to drive to work and maybe a little bit on the weekends. My other ride is not doing so well... so im not planning on it being a dd just need it as a back up.

 

Do not adjust your physical timing in any way. If you had advanced your timing previously by adjusting the distributor, move it back to the factory spec. You will not mess with the timing until you get a full on engine management system.

 

If he is dead set on running it with the FMU, he is better off setting it to about 10* base timing, I know this isn't the right way, but if he is going to do it, its better than nothing. As everyone said, just drive it N/A, or don't hit boost (this won't happen) until you can get it tuned right.

 

Hmm.. we ran 12:1 FMU all DAY for years on the stock engine for up to about 10psi. Not saying as though that this is what the OP should do NOW.. just stating that it was common to use the 12:1 FMU , Missing link, and stock injector. But it also had an intercooler and all the other items.

as for timing, we typically took only base timing down to about 12 or 13 degrees at the distributor for safety. After that, it was time to get real management and tune the damn car.

 

Well hey guys thanks for the advice. If anyone has anything else to add im open ears. I ordered the FMU and missing link. I will keep you guys updated on how this turnsout. Hopefully the parts get here before friday and I can get this thing on the road.

 

What would happen if I ran 440 injectors and an fmu? Is that to much fuel?

 

Way to much fuel. What you should do is stay out of boost till you have the money to get properly tuned. I never understand why people go boost without enough money. Don't go turbo if you can't afford it. How bout if the motor blows? Obviously you have no extra cash. If if you're building a boosted car. Have money to do it all right at once and some extra cash in case of anything.

 

Well first off im only asking because I have the injectors already...

Second I did try doing it right... I put it all together took it to a plays to tune it and **** detonated my motor and cracked my sleeve! I had no re emburstment of any kind. Guy is a thief!

Now...

I bought a jdm b16a and just want to get the car back on the road Ive only owned this car for 7 months and its not been parked for 3 months...

And I am doing things right... put a new water pump timing belt. I also swapped the oil pumps for the crank sensor and since the motor was out I also bought a Competition clutch Stg4 and Flywheel stg2

 

I just pulled the bov off.. zip tied a big piece of foam over the hole.. so if you have to floor it.. it'll be one big *** boost leak.. problem solved til tune.

 

So you have injectors already too, and presumably an ECU and conversion harness, since you said you were tuned before. So for about the cost of the missing link and FMU, you could have paid for someone in your area to do a quick decent street tune. So for around the same price, you could have it street tuned probably pretty decent and reliable, instead you are risking it and wasting time and money on and FMU when you will have to pay for a tune later anyways?? Doesn't make sense to me.....

 

^^ At that rate you might as well have left the BOV on, disconnected the I/C pipe at the throttle body and called it a day, as opposed to risking sucking in pieces of foam into the engine

 

Understood, but there are even 4.0 litre jeeps driving turbo w/ simply an FMU and a missing link on a bone stock setup with a fuel return system. It's been done, and will continue to be done w/ some decent results...if staying in low boost moderation.

What do you think we did back in 96 when DRAG first came out? Get a MoTec? There are better solutions now, true, that are gods way more affordable now than 13 years ago, but what we did wasn't terrible. There's even 2 former clients I have with the same setup 8 years and 150K miles later.

No, I don't recommend it, but it wasn't the worst thing in the world.

 

I agree, that is why in my post earlier, i explained what he should do if he really had to run an FMU. I also have run an FMU before when engine management choices weren't quite so easy.

That post was just pointing out that for around the same amount of money he could have a lot better setup, and at that point the FMU does not make sense. He already has everything he needs, so if he spent the money on tuning instead of an FMU/ML, he would be much better off.

 

I completely understand what you are saying... but the closest tune shop around here is no longer an option so im choosing to save for hondata and also go to a shop that wont blow my motor up... and is why im probably going to need a thousand dollars to finish it.

 

You advocate running the leaner ratio on an untuned and untunable setup? Really?



Since the FMU is placed behind the FPR, that is not how it works.

While the FPR is the primary regulator, the pressure between it and the FMU is less than rail pressure until there is enough pressure referrence going to the FMU to make it's target pressure eclipse the FPR's, thus raising the rail pressure. A hydraulic system is only as good as it's smallest orifice and the FMU is not the smallest orifice until

The fuel pressure in a Honda/12:1 FMU system doesn't operate off the FMU until ~3.75 psi, and peak system pressure at a 6 psi referrence (boost) pressure is 72 psi. Keeping in mind the differential pressure with regards to the IM is only 66 psi, this nets a 25% increase in flow and, ASSuming traditional bsfc and a 12:1 AFR, clears us for a hair over 200 whp at 12:1 AFR. Oddly enough, the last 6 psi JRSC FMU setup I dynoed was a 12:1 ratio and ran a credible 12-12.3:1 AFR pretty flat across the powerband, made 190 whp. Figure that bsfc varies with efficiency across the rpm band and the math is empirically proven correct.




To the OP: don't put the kit on your car until you are ready to do something that doesn't involve an FMU. There is a reason why nobody uses FMUs anymore. While some people got lucky it was commonly known back then that a stock B-series could handle at most 8 psi of boost, and a D16 at most 6 psi of boost, and anything more would pop them quickly.

 

Is that what I said?

 

Technically yes, but i think you were implying that 12:1 was probably too much fuel so 10:1 might be more appropriate, no one exactly knows for each setup, so it will depend, but i would err on the rich side.

 

I distinctly recall running through the math behind FMUs. You very much can dictate desired AFR @ target pressure with the caveats of any other pressure is skewed rich/lean and higher pressures than 7 psi will result in the sort of fuel pressure that forces the stock injectors shut, exceeds the pumps ability to flow, etc. There is even an ability to trim AFRs at target pressure with an adjustable FPR.



Sorry to take a hard line here, guys, but this is merely an application of basic concepts. I've been a long time fan of not answering a question unless you could prove it, which is a standard all should aspire to. Magazine and forum knowledge is often wrong, or dumbed down to the point of being wrong, and as such a disservice.

 

I understand and can also do the math to figure that out, im not sure why you quoted me with that, i never said you couldn't. It really isn't too hard to accomplish the desired AFR at a target pressue, but you would need to know (fairly precisely) the airflow of the engine at your target pressure, which we don't know on this setup.