Question about injectors and turbos...

Well, If I were to get an evo3 16g turbo, are the stock injectors too small? What size should I go with for running 15-16psi? I know to get dsmlink and I know I would have to get a FMIC, but I dont know about injectors...thanks

If you plan on maxing out the turbo you will need 680s or 720s to be safe. 550s will get you to the 16psi mark though(I have some that I'm willing to sell)

I wanna stick with 16psi because Ill need something reliable after a rebuild, Ill dump money into my car once Im good and set with my career in a year or 2 :), how much are you willing to sell them for?

for 16 psi I don't think you NEED to get a fmic I would say its always a good idea but not entirely necessary. I think 660's are good to max out that turbot but the extra room with bigger couldn't hurt (as long as you have link not safc). Does link show A/F ratios or do you need to get a gauge?
Can you add ur mods in your signature so we can see what your running
Oh yea and I beaat NFSMW the ending is really fun don't want to spoil it for ya

I wanna stick with 16psi because Ill need something reliable after a rebuild, Ill dump money into my car once Im good and set with my career in a year or 2 :), how much are you willing to sell them for?
Pm me with an offer, they are almost new rc's I believe but there isnt a sticker on them, I was going to use them but I diceded to go bigger.

Why would you even bother buying an evo3 turbo with the intentions of not running higher then 16psi? Thats pointless.

You'll want 660's or higher with that turbo, and most defnitly want a FMIC.

Why would you even bother buying an evo3 turbo with the intentions of not running higher then 16psi? Thats pointless.

You'll want 660's or higher with that turbo, and most defnitly want a FMIC.

So when I get my evo3, I will need to buy 660s? I don't really plan on going dsmlink, even though I should for best performance, but aren't the 660s hard to tune out on the safc2? :frown:

for 16 psi I don't think you NEED to get a fmic I would say its always a good idea but not entirely necessary. I think 660's are good to max out that turbot but the extra room with bigger couldn't hurt (as long as you have link not safc). Does link show A/F ratios or do you need to get a gauge?
Can you add ur mods in your signature so we can see what your running
Oh yea and I beaat NFSMW the ending is really fun don't want to spoil it for ya

im about to race the lancer evo 8 guy.

It took me a week to beat that game

Haha Ricer I don't know if thats a good thing or a bad thing...
Anyways safc2 can go +-50% so ur still ok with 660's link can do 60% I think but I don't have it.
edit. I just realized you have safc2 so you know all that already I guess the difference is it just lies to ur ecu where link changes it (which is just dandy till u lose power)

I have a ported evo 3 gt which is fully ported compared the evo 3 MHI. I run 17 psi with 550's, safc, and few other goodies in my sig. No front mount yet, but my car defiantly gained more power. Its not so bad to only run 16 or 17 on an evo 16g. Just support it with the fuel stuff and youll be happy.

That maft thing will still completely bollix timing though, and since I can't live with that, I still have to recomend DSMlink. :)

660s require 32% adjustment for injector compensation, 450/660-1. That leaves 18%, 14% of which is required to get to 11:1, 9.5/14-1. Which then leaves only 4% for trim adjustment, or futher leaning out on race gas, which isn't much. Either way, I don't recomend using that much of the AFC's 50% range unless you have some way to lower base timing (1g, or 2g with 1g CAS). I've gone over some of the math in the past outlining how to figure out how much air you have to flow to make a particular adjustment factor give stock or at least reasonable timing curves. Without going through it now, I would guess that a 16g is not even capable of enough flow make 660s look stock as far as timing advance goes.

I've also never been much of a fan of the "80% rule." Probably just because I have run injectors at 100% and more for years on end with no noticeable or measureable side effects. In fact I just upgraded the EVO to 950s, just because I can, but it's run the last year at 102-103% IDCs on the stock 580s. Doesn't mean it's a good idea, but I have to ask myself what is worse, running an injector at 95% IDC which seems to have no real side effects, or running 28 degrees of ignition timing on pump gas, which does have known side effects ;) This is a very tough topic to debate, since there are so many variables, most of which are in the mind/strategy/budget/risk tolerance/etc of the owner. My recomendation can even change slighty depending on the mood I'm in :D

To try to make my take on this short. If you are on an AFC or other ECU porking device, with no way to compensate for base timing (still a hack mod, since it makes changes across the whole rpm range, which is of course undesireable at idle for example) keep the injectors on the smaller side of what you can get away with. For example, 550s will support 40 lbs/min at 100% with all the usual variables accounted for. It takes a bit of work to get that from an EVO 16g on pump gas. On race gas they are good for ~42 lbs, and not many poeple will ever see over that. I get 43 on occasion, and at least one other person reported 44. But on race gas, you've got some fudge factor anyway. This will be acceptable to most poeple. To take it one step further, you would need to be flowing about 32 lbs/min at 6k rpm to keep the ECU over it's percieved 2.1 g/rev point, keeping WOT timing in control. Certainly attainable by the average guy, even at relatively low boost. Though it may take a little more than 16 psi, IIRC.

In contrast, 650s make much more sense. They can support 48 lbs/min, and with a maxed out evo3 at 43, you're looking at 89% IDC. Certainly reasonable, and at something like 35 lbs you're down at 73%. So even if your boost line falls off the WG and you completely max out the turbo, the ECU will know this, try to add fuel, and if you have enough pump, the capacity is there to save your motor. Certainly makes good sense to go this route.

But let's look at the other side of the coin now with 650s, with an AFC-like device, and no way to adjust for timing. Airflow is going to be hacked by about 46%, as described above (injector compensation and leaning to ~11:1 only, no other adjustment). You need to be flowing ~51 lbs/min at 6k rpm to stay over the 2.1 g/rev cutoff. Not going to happen ;) So timing will be increased. To try to get an idea of how much, let's use the 35 lbs/min example again since it's not hard to reach that on pump gas. At 6k rpm the ECU is going to see 1.4 g/rev. WELL below the 2.1 rev range. Unfortunately I have no good way to calculate or look up what the target timing advance will be at that point, but it will be well into the 20s. No longer very safe or reliable IMO. :)

So this becomes a difficult decision between having plenty of fuel on hand to cover the unthinkable (but inevitable) but with excessive timing advance, or pushing your luck with less fuel capacity, but having safer timing advance. It's not an easy choice, but I have to lean to the smaller injector here, which is very unlike me. And this is the reason I always seem to push DSMlink so much. Eliminates the compromise, and is good not only for making the most power you can on your setup, but for increasing safety as well!



You can also see that the more you know about this stuff, the harder it can be to make these choices. 99.9% of poeple have never even considered the numbers I went through above. And they may be pretty successful. But we really need to be fully informed. Even if it makes things a little more scary and a little tougher to decide, at least we know we are making educated decisions. So while all the jackasses say things like "Just get the 550s, so and so ran 9s on them!" I feel we should all take the time to make the right choice for the right reasons.

:D

I could go on for hours about this, so I regret having to cut it so short. Hope this helps people out anyway.

Another great write up. So your saying that with a rewired 190 and 550s that will be enough for a s16g if the injectors are running at 100% IDC?

"enough for a 16g" is a subjective question. If you lose control of boost and max out the turbo, it may not be enough. For the average person with no crazy failures, it will be enough. I usually go on about how you should size all fuel system components to the max airflow the turbo is capable of, but with all this ECU fuckery it's a little more complicated :) But to reiterate, I have seen no problems running at 100% IDC, or close to it, but that's not to say I think it's an ideal situation either ;)

The 190 rewired is juuust big enough to support an evo 16g. In the case of fuel pumps however, you can go bigger and not incur any real penalties. So it can make much more sense to go bigger. But of course, taking the next step to a 255 really does require an AFP in my humble opinion. In the max boost scenario above I think the 190 would fare better than the 550s, so it may be a worthwhile risk if the AFPR really isn't in the budget.

Again, so much of this is subjective and open to so many variables, it's hard to give straight answers. I know it sounds like I argue "yes" and "no" at the same time on this topic, but it should provide poeple with the necessary info to make the call. :) If everyone could run DSMlink, my suggestion would be 950s all day long, and the world would be much simpler...

I'm actually thinking about selling my afc and 550s and just getting dsm link(should have done it from the start)

Wow, thanks alot Kevin, you rule!

Hey kevin I understand the first calculation you did with the injector sizes/compensation but the second one about the leaning of the stoichometry you think you could elaborate on its the one with the 9.5/14 I didn't get where does that 14% come into play and is that a constant applied to any size injector?

I just want a simple anwser, 660's or low 700's, 255 pump, FPR, s-afc, evo3GT at around 14-20 PSI. Is that ok to run the car on? And not fuck anything up that I don't want it to? This is a budget racer, aka my personal roller coaster, and might not even see a track. Can the s-afc handle bigger injectors and the pump with the given range of injectors? Becuase I can't really afford dsmlink and TIT big injectors. I am so confused im going to stab my eye with a spork.

650s or above + SAFC2 = too much timing advance. It's simply lying to the computer too much. Keep saving your money and get dsmlink, or run 550's and see how much psi you can run without going lean on a dyno.

Kevin's post earlier described the timing advance issue thoroughly, so I'm not going to try and explain that anymore. Do it once, do it right.

Hey kevin I understand the first calculation you did with the injector sizes/compensation but the second one about the leaning of the stoichometry you think you could elaborate on its the one with the 9.5/14 I didn't get where does that 14% come into play and is that a constant applied to any size injector?

At over 2.1 g/rev the ECU's target AFR is 9.5:1 at any meaningful rpm. These charts available to DSMlink users FYI. So a 14.x% change will bring AFR to 11:1. And in reality, that's exactly what it takes. It's not just math, it's the way it really works when everything is in proper working order. That applies to any size injector, since the injector is already compensated for. You can also apply the same calculation to any AFR you want to target. But please note that this is just what the ECU will be shooting for, and your actual AFR may be different is something is amiss, like fuel pressure, injectors not flowing what they are rated at, boost leak, airflow meteting inaccuracy, etc. This is why knowing the difference between the calculated target AFR (DSMlink provides this as "AFratio") and measured WBO2 AFR is so valuable. It can be used to diagnose all kinds of problems. Add calculated boost and measured boost from a MAP sensor and, well you get the point... Information is power (and safety) ;)

Thank you thats what I needed to know
My only thought now is why would the ecu's target be 9.5 when 11 is a better mix?

Thank you thats what I needed to know
My only thought now is why would the ecu's target be 9.5 when 11 is a better mix?

safety first

Heres a question that I think is answerable but I don't know.. Especially don't know how to do the math so Ill just let kevin do it ( IF it is at all possible).
Ok so To my understanding with the rewired 190 and the 550's it can support 39lbs/min on the 16g (2g). Now the 16g max's around 42... Now lets say our line comes off and were running the turbo to the max. But we also have our safc set to -50%. HOW LEAN will You be running {assuming all other factors are negligible (boost leak and what not)}?

Ok, on my budget and wants from my car right now, I would do a rewired 190, 550s, and the evo3. I would like to run approx. 18-20 psi on it, but is that doable on that setup?

Also, how much boost would you have to be running to hit those airflow numbers you were talking about, Kevin?

hahah everything is the samething I just posted but just shorter, sorry kevin and crunchy =(

Ok, on my budget and wants from my car right now, I would do a rewired 190, 550s, and the evo3. I would like to run approx. 18-20 psi on it, but is that doable on that setup?




I think you'll be fine running 20 psi on that set up. I already run 17 psi(no front mount). Been running it for almost a half yr now with my current set up. You have a front mount so that fuel/turbo set up will benefit(sp) much more. I'm pretty sure the rewired 190 be fine too, but a 255 be safer most likely(fpr is your call).

Thank you thats what I needed to know
My only thought now is why would the ecu's target be 9.5 when 11 is a better mix?

Like crunchy said, it's a warranty deterant. Plus poeple do some crazy shit, and things go wrong with sensors and such, it allows for some error margin.

Heres a question that I think is answerable but I don't know.. Especially don't know how to do the math so Ill just let kevin do it ( IF it is at all possible).
Ok so To my understanding with the rewired 190 and the 550's it can support 39lbs/min on the 16g (2g). Now the 16g max's around 42... Now lets say our line comes off and were running the turbo to the max. But we also have our safc set to -50%. HOW LEAN will You be running {assuming all other factors are negligible (boost leak and what not)}?

One way to look it is what will AFR be with maxed out 550s and 42 lbs/min. By reverse engineering the math a bit I get 11.5:1 or so. On a properly set up car this won't lead to catastrophic failure, but if anything in the setup is marginal it could get ugly. For example, bad gas, or the low octane stuff poeple get stuck with in some areas.

550s would be set at -18%, with another ~14% for getting to 11:1, so about -32%. I'm not sure why you'd be at 50%. That would be shooting for nearly 14:1, which is much leaner than you would end up with targeting a more normal AFR but maxing out the 550s, as mentioned above.

Ok, on my budget and wants from my car right now, I would do a rewired 190, 550s, and the evo3. I would like to run approx. 18-20 psi on it, but is that doable on that setup?

Also, how much boost would you have to be running to hit those airflow numbers you were talking about, Kevin?

The boost figure is completely meaningless without knowing a few key points in the setup. Mainly anything that affects VE, or more specifically, displacement, and VE affecting mods like intake manifold, cams, etc. On a stock cammed car, 20 psi would be ok. It would take ~25 psi to get over 40 lbs/min on your "typical" street setup. With just the addition of cams however, you will reach 40 lbs/min at 20 psi. I get 42-43 lbs at 19-20 psi on the EVO depending on temperature. 19 psi in the cold, 20 psi with typical temps for this season, and sometimes 21 psi if it's real warm during the day. You get the idea. :)

Another interesting thing to note is that by pulling the line off my wastegate actuator and installing my BOV backwards (or run my Gus Modded 1g BOV that I just installed) I get 42 lbs/min across every single gear from start to finish. Boost will hit anything from 25 to 28 psi at the beginning of each gear, but will taper to the same 19-20 psi value at redline. The turbo maxes out based on airflow. The boost is an afterthought. Boost is left over airflow ;)


The best way to keep it safe is to know the numbers, and log airflow. On a 2g any ODB2 logger reads airflow. My pocketlogger read in lbs/min. You can convert this to g/rev with a little work. Unfortunately you can not read airflow on a 1g logger, DSMlink is the only way. DSMlink provides airflow/rev, and airflow/time, in a variety of units.

So then if you say that by your calculations the 550's at -50% can still put the a/f at 11, with the evo16g flowing at max then technically can't the 550's support that turbo?
I do realize it leaves no margin for error

So then if you say that by your calculations the 550's at -50% can still put the a/f at 11, with the evo16g flowing at max then technically can't the 550's support that turbo?
I do realize it leaves no margin for error


until you raise the boost past that calculation.

But the 16g won't be able to raise boost because it is at full boost

jus thought i would give some of my info ... my buddy has his stock 450 injectors and stock intercooler with a 16g and he is pushing 15psi without fuel cut. 16psi hits fuel cut tho.

So then if you say that by your calculations the 550's at -50% can still put the a/f at 11, with the evo16g flowing at max then technically can't the 550's support that turbo?
I do realize it leaves no margin for error

I'm pretty sure -50% on 550s would be more like 14:1.

I'm not sure why you'd be at 50%. That would be shooting for nearly 14:1

Boost has absolutely part in injector capacity.

Fuel cut also has nothing to do with fuel system capacity.

wow... That's a lot of shit, to absorb into my brain.