addtional injector set up or air fuel convertor computer?

[gsxbmx]

i have a 96 gsx that will soon be in need of fuel the popular choice seems to be throw in a apex afc and get bigger injectors wich to me doesnt seem to be all that great for a few reasons like there goes any chance of your car passing emissions all the cars i have scene wityh this set up just dont seem to run right but no one ive scene uses addtional injectors on dsm's is there a reason?? to me it seems to make alot more sense the car maitains a stock fuel system until the fuel is needed but i dunno maybe there are some down falls im not aware of also i know that my car will hit fuel cut at 100% duty cycle if i use a add. injector set up how can i stop the duty cycle at say 90% with a f.c.d please help thanks

[Edited by gsxbmx on 06-27-2001 at 10:15 PM]

[Peter 92TSI]

Hmm....

People who run an afc and injectors and can't emissions and what not simply don't know how to correctly tune the setup they have. If you are fairly unfamiliar with automotive tuning, tuning an AFC will be no easy task. My car tuned for "reliability" mode just for average driving gets around 27 mpg, and passed emissions easily.

AFC and Injectors are a cheap and proven alternative, as people have run 10s on this type of setup.

As far as an additional injector, first off wiring the injector in would be a nightmare, as you would have to use some resistor packs or what not to give the injector the correct resitance. I am not sure how it would be done, I know a few people here have done it.. so maybe they can lead you along that path, but besides that even if you did install the injector, an additional injector would not "magically" all the sudden improve everything. You would still need an afc, or some other fuel adjustments to compensate.

Peter

[RabidDonkeyBoy]

i'm going to get my TB elbow worked on to accept 2 Saab 900 cold start injectors(either 100% on/100% off no cycling). add T to fuel line for new injectors. add . add some cockpit wiring and switch. add a custom 2 stage boostcontroller.

when it's setup when the switch is on high boost is on say +18PSI and the aditional fuel injectors start at +12PSI.

switch off is low boost say +12PSI and additional injectors are off.

i'll find a link explaining this a lot better. it's from a turbo mopar website. and talks alot about doing stuff cheaply like this.

also there are a few people on this board that run 2 sets of injectors dual sets of 450's. to do that your going to need to spend a lot of money.

[Red90TSi]

OK,there are 2 ways to do things (well there are more but for times sake we'll say 2), the RIGHT way and the CHEAP way. Very very rarley do these two situations come into being at the same time and space. For example the oh so loved Starion FMIC...it's cheap, do I have to go any further? And Bosche cold start injectors, or fuel injected anywhere before the throttle body is just plain and simple not a good idea. Trying to bandaid and hack a fuel system can turn ANY motor into a heap of scrap metal at worse, or just make for a horrid running car at best. Things like this is what gave the Mazda RX7 such a bad name, people trying to get away with doing stuff cheap, and they ended up with a blown motor, and of course it was because of flawed design not user error...but that is another ball of wax all together. The best is when someone with these parts posts and wonders why they cant seem to run as well as everyone else with the same turbo ect.

Now as far as additional injectors go, it is a valid way to increase fuel delivery. Greddy, HK$ and , Haltech among many others all make AIC's (Additional Injector Controlers) however, to do this right is not cheap nor easy. As I stated earlier injecting fuel before the throttle body is not a very good way to do this, so you are going to need to have injector bosses welded onto your manifold. The AIC itself will run you ~$300 - $600. (www.rx7.com carries the haltech and GReddy AIC last time i checked) This gets you the fuel for your setup, BUT it doesn't take care of fuel cut. To remove fuel cut you could get a 1995 EEProm ECu and have the TMO mods done to it, and that would aleviate fuel cut. The only thing you lack is the ability to lean out the area where your 16g isnt moving much air, where the car expects the T25 to be alive and kicking. This could be a very small problem, but I wouldnt worry about it.

Personally I run the S-AFC and larger injectors. It is not a perfect setup by any means, but it does allow you to change 1 input to the stock computer and by doing that alter fuel flow. It leaves alot to be desired, but on the DSM it has been proven to work time and again. For apps under 400whp I'd say the AFC should be fine. Anything more than that and I would surley look into a PMS or Haltech. You have to look at your goals for the car. I am not trying to say that the most expensive way is the only right way, there are many times when it is definatly not the case. You should research all the options availible to you. You can also go with a PMS, a TRE afcMASC, a Haltech or similar standalone. There are almost as many fuel system options as there are turbos.

[Cooter]

IMO additional injectors are a patch.... unless you are running a standalone that controls them (a standalone, some of them anyway, can turn on additional injectors so there is a seamless transition and the a/f ratios stay constant)

if you (or your friends) can't get your/their cars to run right with bigger injectors and an afc then you have no business messing with it as its SO easy to tune a maf car with a little math and some common sense.. you can at least get it close enough to get the car running and then tune on egt's...

about the idea with the saab injectors and turning them on/off... thats about the most hack idea ive ever heard... how are you going to control a/f ratios? since the computer doesn't compensate at WOT its going to be RICH AS HELL except for MAYBE 50 or so rpm's on the top end where your car MAY require all that extra fuel, most likely it'll get so rich when they turn on your car will fall out of boost and foul out the plugs.. and die...

Cooter
http://www.sound-performance.com

[gsxbmx]

ok maybe i sounded a bit dumber than i really am in my previous message but a additional injectors are far from a band aid to me it seems to be the right way i already have a system picked out a simple digital system or sds with four injectors one in each inlet of the throttle body so there is no chance of leaning it out one of my friends had this system on his mr2 turbo and it worked very well and is actuall cheaper than a afc plus big injector set up. sds system with four injectors and controller wich is activated by boost pressure and knob for fine tunnning of the injectors is about 600 bucks shipped to my door wich is aint to shabby. or my other option is a sds with a two injector set up wich is only good till about 400 horsepower wich is basically pretty close to my final goal.i kinda wanted to here from people that had actually done a addition injector setup on a dsm well as of know i think i am still going a.i.c but i am not sure wether to get a 2 injectors or 4 and were to put 2 injector i was thinking on the intake elbow but how evenly would the fuel be delivred to each cylinder

[beerglass]

I've been thinking about the additional injectors as well but haven't had the time. Here's the site with the info for installing on a Mopar. http://dodgegarage.www2.50megs.com/turbo_extrainj.html
He even states that it sounds absurd, but it works for them, so it might work o our cars.

Clitnon
1990 Talon Tsi Awd @17 psi

[Red90TSi]

A well planned out, properly installed AIC system is not a band-aid. I have a friend running one on an RX7 wth 2 additional 450cc injectors (gee wonder where he came up with those :)). He is using the HKS box, but I have heard good things about the SDS system. In fact I would see the S-AFC as more of a band-aid as you in acutallity have very little control with it, you change 1 input to the ECU, but the ECU still has the ultimate descision of what is done, and its descision is based on alot more variables than just airflow Hz, rahter with an AIC you control the fuelflow, period. Either way works, do it right and I'm sure you wont have a problem. I would go in after the throttle body no matter what, and personnally would put 1 injector on each runner of the intake manifold. You could also put them on the plenum pointing to the runner you wish each to fuel but I'm not sure if the distrobution would be disturbed. As far as I have heard you want the shortest distance possible to the combustion chamber to not allow the fuel to deposit itself various places along the way.

[Genius]

The main problem with running an additional injector at the throttle body is that our manifold is of a "dry-type"; designed for air only with the intention that the fuel is to be injected at each intake port hence "multi-port injection" or MPI. Why, 'MPI' is stamped right on the intake manifold there ;). Additional injectors work great on cars with existing throttle-body injection systems (like the Mopar 2.2L and 2.4L turbo engines) since the manifold is designed to distribute an even mixture of fuel *and* air to each intake port (wet-type). What would likely happen with an additional injector in a DSM is much of the fuel injected at the throttle-body would wind up in the 3rd and 4th cylinders leaving cylinder 1 and 2 to run lean.

I do remember some time ago that one of the main speed shops had made a custom sheet metal intake that accepted 2 injectors per intake runner for a total of 8. Only 4 were activated under normal driving/low boost. Under high boost, all 8 kicked in.

[RabidDonkeyBoy]

Originally posted by Genius
I do remember some time ago that one of the main speed shops had made a custom sheet metal intake that accepted 2 injectors per intake runner for a total of 8. Only 4 were activated under normal driving/low boost. Under high boost, all 8 kicked in.

some people here may have the money that this setup would entail, but i personally am a CHEAP BASTARD, yep i said it i am a cheap bastard.

the reason i can see for using the TB elbow is that it is the only place with enough room to actually attach 2 more injectors with out going to a sheet mental intake.

if you were to pull the Intake Manifold out and mount the extra cold start injectors so 1 is spraying between 1 & 2 and 2 is spraying between 3 & 4 and route the fuel line so that the #1 injector is inline before the #2 it would help solve the leaner condition in the #1 & #2 cylinders that would be the best.

btw how can you beat $10 for 4 cold start injectors, a little metal work, some pressure switches, switches, wiring, some fuel line, etc. and your only set back maybe $50

i know these injectors click on with 12 volt power source, do these other kits just regulate how much voltage is supplied to the injectors, so say as the voltage rises in the injector from 0-12 you go from 0-100% open so 3v 25% 6v 50% 9v 75% 12v 100%. cause i don't think it would be that hard to create in affect a pressure controlled rheostat. if so i'll save my self 4-600$ and build my own kit.

[garydonovan]

>The main problem with running an additional injector at >the throttle body is that our manifold is of a "dry-type"; >designed for air only with the intention that the fuel is >to be injected at each intake port hence "multi-port >injection" or MPI. Why, 'MPI' is stamped right on the >intake manifold there . Additional injectors work great on >cars with existing throttle-body injection systems (like >the Mopar 2.2L and 2.4L turbo engines) since the manifold >is designed to distribute an even mixture of fuel *and* >air to each intake port (wet-type).

wrong. wrong. wrong.

2.2, 2.5 and 2.4 turbo engines ALL have MPI dry flow intakes.

5th injectors work- Period! I ran 131 mph this week at 35 psi of boost in Relentless on Tuesday. Extra source of fuel was 5th injectors using a NOS fan nozzle with a .38 jet at 100 psi at 30 psi of boost, now thats a lot of fuel!

watch your EGT's and you wont have any problem, best thing to do is mount the injector 6-8 inches before the throttle body to make sure the fuel is properly mixed, I have run them behind the throttle body with no problems on 2.2's though...

Gary Donovan

[garydonovan]

Go here to see a real audio clip of the car running 131 mph (and details of the weekend)-

http://dodgegarage.www2.50megs.com/new.html

Here is a direct link but I doubt it will work.

http://dodgegarage.www2.50megs.com/video/gary_sdac.zip

Gary Donovan

[Le Talon]

Why it's not a good idea to run additional injectors on a DSM...

DSMs run very rich from the factory, especially if the MAF reading is high. With a 16G, I was goign 100% duty cycle as soon as 4500 rpms with the AFC at 0%. This gave a very rich and muggy mid range power. With an AFC, you can lean things out at those RPMs when the stock program is simply dumping fuel.

With 1 or many additional injectors, you won't be able to remove fuel and your car will run rich at mid-rpm, no matter what.

[beerglass]

You have to read all the info thats been posted. The additional injectors would only be active at certain boost levels. Not at a specifice rpm.

Clitnon
1990 Talon Tsi Awd @17 psi

[Genius]

Originally posted by garydonovan
2.2, 2.5 and 2.4 turbo engines ALL have MPI dry flow intakes.

Did some homework (http://www.allpar.com/mopar/22t.html). I know better than to make difinitive statements about particular cars I don't own :o. I once owned a '90 Dodge Shadow with the 2.2L non-turbo...it had TBI. If it had a turbo, it would have had MPI. I know that now. Ah well. ;)

If the extra injector works so well, I wonder why this hack hasn't trickled down to DSM's. Maybe on the Dodge, the turbo intake manifolds are similar enough in shape to their TBI equivlents to distribute air/fuel evenly. A wet-flow intake manifold would work fine in dry-flow applications, but not vice-versa. Couldn't say for sure though since I don't have one...I could be completly wrong. :D

[FastGSXauto]

it defenitely works, it's just more of a crude solutoin to run more boost. there's not much danger in running to righ at high rpms anyways.

[garydonovan]

Originally posted by Genius
Originally posted by garydonovan
2.2, 2.5 and 2.4 turbo engines ALL have MPI dry flow intakes.

Did some homework (http://www.allpar.com/mopar/22t.html). I know better than to make difinitive statements about particular cars I don't own :o. I once owned a '90 Dodge Shadow with the 2.2L non-turbo...it had TBI. If it had a turbo, it would have had MPI. I know that now. Ah well. ;)

If the extra injector works so well, I wonder why this hack hasn't trickled down to DSM's. Maybe on the Dodge, the turbo intake manifolds are similar enough in shape to their TBI equivlents to distribute air/fuel evenly. A wet-flow intake manifold would work fine in dry-flow applications, but not vice-versa. Couldn't say for sure though since I don't have one...I could be completly wrong. :D


Not even close- The TBI manifold is based on late 70's/early 80's carb design and it's a POS. The 84-93 Turbo stuff was all designed from scratch and the 87-93 turbos utilized specific runner lengths and plenum size for optimum tuning effect.

As for why DSM pepole have not tried it.. I know a few around here who have with excellent results.

Gary Donovan

http://dodgegarage.www2.50megs.com/index.html

[Le Talon]

Originally posted by beerglass
You have to read all the info thats been posted. The additional injectors would only be active at certain boost levels. Not at a specifice rpm.

Clitnon
1990 Talon Tsi Awd @17 psi


How do you plan to remove fuel with additional injectors? It will work, but you'll run rich at mid rpm. But hey, what do I know...

[Edited by Le Talon on 07-01-2001 at 02:34 PM]

[beerglass]

Le Talon, sorry about the mix up i guess i should have read your post better. My bad. Your right if the car is already running rich in the mid range the only thing ou can do is add the AFC. But if it's running lean at the mid to top end than running extra injectors will work.

Clinton
1990 Talon Tsi Awd @17 psi

[Le Talon]

No probs! :)

Other reasons why it's good to run an AFC...

By lowering the MAF signal, you'll retard the point where fuel cut occurs.

You might fall into a more agressive timing table if the MAF signal is lowered.

And since you have a 1G, you'll reach MAF overrun before your injectors are really maxed out... So better address that first.

[S_rangeBrew]

For you that don't know it, Gary Donovan is the God of Turbo Mopars, sort of like Buschur to DSM's. The two engines share a lot of common traits, so everyone could learn a lot.

I think the dodge engines are blessed with more displacement and lower compression, so they can run higher boost. I've never understood why 1G DSM guys switch to the higher-compression 2G pistons....?

[RabidDonkeyBoy]

Originally posted by S_rangeBrew
For you that don't know it, Gary Donovan is the God of Turbo Mopars, sort of like Buschur to DSM's. The two engines share a lot of common traits, so everyone could learn a lot.

I think the dodge engines are blessed with more displacement and lower compression, so they can run higher boost. I've never understood why 1G DSM guys switch to the higher-compression 2G pistons....?



someone correct me if i'm wrong but, i belive 2g pistons are stronger than 1g pistons, and it's cheaper than going with a aftermarket set?

yeah the mopar turbos came in 2.2L and 2.5L don't know the compression but it seems the 2.2 blocks are better.


btw i belive gary donovan runs 35psi on his reliant

hmmmm. having wet dreams about 35psi :)

[garydonovan]

Yes I run 34-35 psi and as soon as my new header and turbo is fabricated I'm heading to 40-45 psi.

Gary

[3312DC]

A friend of mine (mechanical engineer) is modding an 89 Shelby Daytona, and we both have learned much from Gary Donovan. I think the best way for the 5th injector would be to control it off of 02 voltage, and find a way to regulate the injector keeping the 02 at .91... Gary, those daytonas sound amazing and SUPER loud with that 3in straight through exhuast, cops came to my friends house. They are badass cars. oh, and the compression for the 2.2l dodge 4 is 100psi.

[Colin P]

Originally posted by garydonovan
Yes I run 34-35 psi and as soon as my new header and turbo is fabricated I'm heading to 40-45 psi.

Gary

Where did you find a turbo that can do that? Are you running an intercooler? (wink)

[gsxbmx]

man did this thread go off track

[FastGSXauto]

where the hell do you find a boost gauge that reads up to 45??

[garydonovan]

Originally posted by FastGSXauto
where the hell do you find a boost gauge that reads up to 45??

They make supercharger gauges that read up to 100 psi.

Gary

[Rdy2race]

we need to get back on track or I'll be locking it,

Just start a new post if we are going to talk about 100 PSI gauges. ( also not in this fourm )

Also Gary, telling people that your running 100 PSI of rail pressure isn't enough, you should also inform them that this can cause the injector to lock up ( Lock open or closed ) or blow out a O ring and set the car on file. The whole truth not the half truth. ( and IMHO you shoule be running a larger injector if you NEED to run 100 PSI of fuel pressure ) I'm not saying that I don't think that your correct it's just there is more info to be given and just saying one thing and not outlining the risks that are taken is a poor way to give info.

IMHO pushing a injector past 80 PSI of rail pressure under boost is getting a bit scarry for most people. For someone like you that will be able to deal with a car that has been bruned to the ground, this is fine but most of the people in here are daily driven car and do not know the limits of the parts on the car ( Let me say safe limits ). Just give all the info not just half ok. ( or I will post more like this :) )

All in all I see you have been a good help to some. Keep it going. I have seen your page, nice work, some real street terrors in there!! :D

Thanx
BM-

[garydonovan]

[QUOTE]Originally posted by Rdy2race
[B]we need to get back on track or I'll be locking it,

Just start a new post if we are going to talk about 100 PSI gauges. ( also not in this fourm )

Also Gary, telling people that your running 100 PSI of rail pressure isn't enough, you should also inform them that this can cause the injector to lock up ( Lock open or closed )

Never seen it happen.

or blow out a O ring and set the car on file.

Never seen it happen.

The whole truth not the half truth. ( and IMHO you shoule be running a larger injector if you NEED to run 100 PSI of fuel pressure )

Whats wrong with 100 psi of fuel pressure? at 30 psi of boost thats only 70 psi AT THE SEAT of the injector which is what the chrysler/bosch injector is rated for, been doing it for over 10 years now with no failures, ever.

In an ideal world yes it's better to have higher flowing injectors and lower fuel pressure but at high boost you WILL always have to have fairly high fuel pressure to overcome boost in the intake, fact of life.

I'm not saying that I don't think that your correct it's just there is more info to be given and just saying one thing and not outlining the risks that are taken is a poor way to give info.

Again, in the real world I have never seen what your talking about- what your referring to is is all theory.

IMHO pushing a injector past 80 PSI of rail pressure under boost is getting a bit scarry for most people.

really? why? at 30 psi of boost thats only 50 psi that can be used to fuel the engine.

For someone like you that will be able to deal with a car that has been bruned to the ground, this is fine but most of the people in here are daily driven car and do not know the limits of the parts on the car ( Let me say safe limits ). Just give all the info not just half ok. ( or I will post more like this :) )

I take the correct precautions when dealing with high pressure fuel systems and I would assume anyone else looking to run 11's, 10's or faster would do the same.

All in all I see you have been a good help to some. Keep it going. I have seen your page, nice work, some real street terrors in there!! :D

Thanx
BM-


Thanks! I try.

Gary