MyE28.com

Sorry if you were expecting to see pictures of another awesome turbo set up.. i would love to post them as soon as i can get this car back together and done. Im posting in hopes that the knowledgeable people out there can give me a straight answer. Ive been researching this turbo buildup for almost 9 months now with more book marked pages of infor than i can even sort through. So heres a little backround infor first....

Initially i had tried to mimic the setup by Todd's S1 kit from TCD since its pretty much the shit for lack of a better word. I picked up a manifold setup with a flange for a t3/t4 that i havent speced out yet, but im confidant ill be able to pick something on my own. The setup is for a top loader style turbo pushed way up front where the wiper fluid res. would be. Heres my dilema. Im planning on a conseravitly low boost # for right now since the cars got 183K on it, and i know its been done to cars in the 200K region without a problem but this is my first turbo build and im making this set up with room in the future to expand and up the boost. I want to run something like 5-6 lbs or so, no intercooler for now, and no megasquirt. Im doing this on a really tight budget, which i know dont yell at me contradicts the purpose of a build b.c it costs $$ to play but the car isnt even worth what the motor buildup is going to cost its just a recent toy for me i just picked up.

So heres where i sum up what i need help with. Injector size selction. Ive been scouring the 'bay looking for ford 24# injectors like ive read so many ppl talk about using. I know todd's kit uses a 30# injector, and ive read that some ppl even recommend going all the way up to 42#. The thing is theres no dfinite source for this info, ive been reading it from pages spread out on about 3 sites with about 10 or 15 posts that have like 1 or two blurbs with somehting useful in them, so its hard to really know it down and i think thats what makes it really hard for some ppl to follow b,c the info is so far between. I wish i could help to make this a place to really consolidate everything into a god compound place to look up specs. Im aweare that a larger injector will raise my idle rpm, or to something of that effect but i know that too large an injector is a concern. I also know i need to run a RRFPR/FMU and i hate to beat the dead bush but i really dont have a clear reason what i should use and why. I want to go straight and simple with everything in this build, and i thought that a RRFPR would be easy enough, raise the fuel pressure above the 1:1 ratio that i need, and keep m on the safe side with what i hope is enough from a 24 or a 30lb injector. So what do i use, and why? I hoping the big guys out there who really know their shit like Todd, or maybe even Duke or someone whos gone the FI road and has real world experience in something like this... So can you guys help me out or what? I really appreciate anything anyone can provide. Thanks guys.

I have 72 # injectors and it idles just fine. I can drop the idle down as low as I want. The secret is, a stand alone ECU. I have a Electromotice TEC3 with six separate fuel injector drivers that allow the ECU to have a very short pulse width for the signal going to the injector. I can pull out fuel at idle to the point that it will lean out and stall.

So 30# injectors will not be an issue at all and can easily support your low boost desire.

Currently at 12 psi, my injectors highest duty cycle use is 52%. Needless to say, I have plenty of injector left for additional boost.

24lb injectors will be good up to about 240 hp.

30lb injectors will be good up to about 320 hp.

This is at standard fuel pressure though. The point of a rising rate fuel pressure regulator is to raise the fuel pressure when boost comes on so that you don't have to oversize your injectors. This is only effective to a certain level though. There will be a point that you need to get bigger injectors.

I have a set of 30 lb/hr inj's I'll let go for cheap, if you should choose to go with that size. I personally just decided to go with 62 lb/hr in my stage2 TCD kit. I'm not getting enough fuel above 12 psi, but I'm trying to make mine work with a piggyback computer and no rrfpr.So, don't take my word for it, it's running but not tuned in.

Thanks for the quick replies guys, and thanks duke for the info. How much are you willing to "let go" of the injectors for.

Just saw this on the bay as i was looking to find a better t3 turbo than the one i have and came accross this one,

http://cgi.ebay.com/ebaymotors/ws/eBayI ... &rd=1&rd=1

what do you think. It does have a good price for a refurbished unit.. as i believe thats what it is

How much are you willing to "let go" of the injectors for.

PM'd you.

Maddog wrote:24lb injectors will be good up to about 240 hp.

30lb injectors will be good up to about 320 hp.

This is at standard fuel pressure though. The point of a rising rate fuel pressure regulator is to raise the fuel pressure when boost comes on so that you don't have to oversize your injectors. This is only effective to a certain level though. There will be a point that you need to get bigger injectors.

Not necessarily. These figured are calculated with a certain brake specific fuel consumption. If this applied universally, the e30 325i, with 14.75 lb/hr injectors which makes 170 hp stock, would be impossible. Alpina's B3 2.7 made over 200 hp with the same 14.75 lb/hr injectors. Its all about BSFC. Most injector power potential calculators are BS because of that.

so what your saying is that even though my hp goals are extremely conservative at this point just to get it running, i shouldnt use the 24# injectors becuase they will be under rated, therefore getting closer to their 100% cycle duty which is what i dont want. Are you suggesting then that 30# is a much safer plan?

g00b86 wrote:so what your saying is that even though my hp goals are extremely conservative at this point just to get it running, i shouldnt use the 24# injectors becuase they will be under rated, therefore getting closer to their 100% cycle duty which is what i dont want. Are you suggesting then that 30# is a much safer plan?

As a rule you do not want your injectors to operate over 85% DC.

Thanks duke. Yea i was completely aware of that from one of your posts before but thanks anyway. Im just unsure if i can get these 24# ones for a great price if they will be ok for like 5-7 lbs of boost with just a BEGI FMU

g00b86 wrote:Thanks duke. Yea i was completely aware of that from one of your posts before but thanks anyway. Im just unsure if i can get these 24# ones for a great price if they will be ok for like 5-7 lbs of boost with just a BEGI FMU

I had 24# injectors operating my NA motor which made 220 RWHP (~256 Crank HP). I had a lean condition in the 5000 rpm range that I could not tune out. I suspect that the injectors were maxed out because I did have and adjustable fuel regulator and they were getiing good fuel pressure. I would go with the 30# injectors for sure.

Duke M535ti wrote:

g00b86 wrote:so what your saying is that even though my hp goals are extremely conservative at this point just to get it running, i shouldnt use the 24# injectors becuase they will be under rated, therefore getting closer to their 100% cycle duty which is what i dont want. Are you suggesting then that 30# is a much safer plan?

As a rule you do not want your injectors to operate over 85% DS.

Duty Sycle?

How do you figure 24lb'ers would be inadequate? Especially with an FMU?

turbodan wrote:

Duke M535ti wrote:

g00b86 wrote:so what your saying is that even though my hp goals are extremely conservative at this point just to get it running, i shouldnt use the 24# injectors becuase they will be under rated, therefore getting closer to their 100% cycle duty which is what i dont want. Are you suggesting then that 30# is a much safer plan?

As a rule you do not want your injectors to operate over 85% DS.

Duty Sycle?

How do you figure 24lb'ers would be inadequate? Especially with an FMU?

Oooops - fixed.

As far as 24#, see above. I can post the dyno from that run too. I show a lean condition in the upper RPM range and I had a piggback computer which I kept adding fuel and there was not any change to the AFR. So the only logical reason was that the injectors were maxed out.

That is odd. I bet they'd be fine with an RRFPR though. They should do 300RWHP with enough fuel pressure.

What RRFPR would you suggest then for ease of installation and also performance. The BEGI FMU? if not what other choices do i have

Its not recommended to run 24lb injs for 300whp. The fuel pressures are way high, and its just not good practice. Plus, the FMUs can be real tempremental somtimes.

RussC