Fuel injector size?? And check my combo.

Fuel Ijector size depends on a few things... are you planning on keeping the fmu or ditching it???

brewpounder said:

well i was gonna use the fmu, is a dyno tune necessary?

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Ok, you are going to get LOTS of crazy answers to that question... is a dyno tune necessary??? Prepare for a lecture from everyone who doesnt even have a blower.

Ok, ill tell you my take on the thing through my experience.

My car is completely bone stock save for headers, h-pipe, catback, and a vortech sc-trim @6psi.

I kept the stock injectors but gave em a boost with a larger fuel pump and the fmu. I have ran this set-up as my DD (only car I own) for over a year and half no with absolutely NO problems EVER and never a dyno tune.

Basically what Im saying is... NO a DYNO WAS NOT neccessary for me. However, I do not doubt a dyno could find more power in my set-up and help me run a little safer. either way, it wasn't worth the 600 extra bucks to me.

Now, if you are planning on adding anything major with that blower. I.E. a smaller pulley for more boost, or heads, or anything along that line.. Yes, you will want larger injectors than 19lbs. You can get ur FMU recaliburated for the larger injectors and hope for the best which works for some people. Id reccomend buying a wide-band 02 sensor so you know what your air/fuel ratio is at that point just to stay safe.

Here is where everything gets hazy... yea, if you are boosting big with an H/C/I you are best off with a Dyno tune in my opinion.. and even better off to splurge for large 42lb injectors and ditching the FMU. If you are willing to put that much money in your car you need to be willing to pay to keep it safe and driveable ya know?

everyone else is going to say striaght up tune it.. u'll see

brewpounder said:

getting a dyno tune is no problem, i will do it but i cant right away, are you saying the fmu will not work with larger injectors unless its reprogrammed? And the only mods im doing to this motor is what i listed, i will soon get a crate motor maybe a year or so, and use these parts on it. But i didnt think 19# would be enough for the stock engine with 6psi, i do have a 190 intank now, just wanna know what size injector will make it run best. Thanks for your info by the way i appreciate it.

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Yes, 19# injectors w/fmu and fuel pump is just fine for a bone stock motor and 5-6 psi.

A FMU is not something that is "programmable" per say.. but yet recaliburateable... A FMU is nothing more than a fancy fuel pressure regulator... as boost increases it... it increases the fuel pressure on a certain ratio.... (it uses a vac tree to determine boost and pretty much blocks the return line to some degree to increase the amount of fuel going through the injector)

so, if you were to change the fuel injectors to say 30# but kept the 19# fmu caliburation... the fmu would send far too much pressure through the 30# injectors and bassically make ur car pig pig rich.

Vortech sells caliburation kits that range between 30-60 bucks...

Id say keep the 19's for now and upgrade when you upgrade the engine/heads/etc. just DO NOT go past 6 psi on the 19's

brewpounder said:

ok thanks for the help, ill keep the 19's in there, but should i still install an afpr? also what kinda power is your car making?

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I wouldnt bother with the AFPR at all.... I really have no idea what kind of affect that would have on a car equipped with an FMU. sorry

I also dont know how much power im making... never been to a dyno

All I can tell you is that from a roll at 40mph in second gear I can gut stomp the gas and send the tires into oblivion... BFG's Traction T/A...

Edged out my buddies full exhaust and cammed LT1 94 formula by 2 cars lengths up to 120. So, it makes power... I just dont know how much.

Everything looks good except the 1.7RR's, if you do put them in you should install some new (stiffer than stock) valvesprings. 100k mile old springs have a hard time controlling even the stock cam/1.6 RR over 4000RPM. and some hardened pushrods would be a good idea too

vikingpower said:

Everything looks good except the 1.7RR's, if you do put them in you should install some new (stiffer than stock) valvesprings. 100k mile old springs have a hard time controlling even the stock cam/1.6 RR over 4000RPM. and some hardened pushrods would be a good idea too

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QFT

you should really replace the stock valve springs with those upgrades.