stock or aftermarket injectors

[NeMiZiS]

When I installed my throttle body, I noticed a huge difference in the higher RPM range.

 

[-dsm4life-]

o ok well ill keep the 55 mm tb on my parts list its 7 mm bigger than the stock one so i should notice a difference to

 

[bullettdsm]

So no matter you do to a 420A as long as your not adding a turbo, or nitrous etc.
There will never be a need to install larger injectors?.

Pretty close to a true statement,

I'm really not trying to argue, it just seems like at some point you would want bigger injectors.

When you go over 200whp.

I understand that you are asking the question, not questioning the answers.

At around 175whp I was at the point of going (at the highest point) to around 87% duty cycle on stockers. I know many people go into the 90's and higher, but for the sake of accuracy and heat, I don't like going over the low 80's. So at that point I decided to go with the 450's. With those, I am now in the 50% duty cycle of the injector.

As far as size of injectors, I believe somewhere they are listed as 190's but I know for a fact that a couple of us have had them tested at 225 to 230 (depending on who tested what. Mine were tested at 230, as I recollect).

To the OP, stick with the stockers,

MB

 

[-dsm4life-]

what would be the min sized injectors i would need for my set up then because im sure i will makeat least 175whp when ever im done with my build up

 

[VelocitàPaola]

what would be the min sized injectors i would need for my set up then because im sure i will makeat least 175whp when ever im done with my build up

You're sure of that? Don't confuse hp at the wheels with hp at the crank.

 

[-dsm4life-]

well the 420a comes with 140 stock and you should beable to get about 175 180 at the crank with just simple bolts ons (exhaust cold air intake) so i figured with a high compression rebuild and other supporting mods to keep it n/a 230-250 at the crank shoud be achieved so thatwould be about 200-210 at the wheels

 

[adammethner05]

well the 420a comes with 140 stock and you should beable to get about 175 180 at the crank with just simple bolts ons (exhaust cold air intake) so i figured with a high compression rebuild and other supporting mods to keep it n/a 230-250 at the crank shoud be achieved so thatwould be about 200-210 at the wheels

If you haven't noticed, Mark's car dyno'd at 204.1whp/169.0 lb-ft, and has taken A LOT of work to get to that point. If you're really dead set on breaking 200whp I'm sure you could do it, but not cheaply. It's much, much more difficult than just saying "with these mods I'll be at 200-210whp..."

 

[-dsm4life-]

i know i have priced most everything i will need at 3000 and im sure that ill need at least another 1000 in parts

 

[adammethner05]

Not sure if you answered this already or not, but is there a reason you're keeping it NA? With the money you plan on spending, you could put together a decent turbo kit and make significantly more power than building it up and keeping it naturally aspirated.

 

[-dsm4life-]

im wanting a beefy n/a and i will get me a turbo when i get my n/a project done. im kinda new to the dsm world i have a 93 talon with the 1.8 and a 97 eclipse with a stock 420a so i want to build me a beefy n/a so i can get my feet wet then i can jump into a turbo proect with the know how already in me head. no what i mean ?

 

[adammethner05]

Yeah I know what you mean. Even with 10.5 comp pistons you can achieve a lot of power with forced induction with the right tuning, so there's nothing wrong with starting out with an NA build first.

 

[Locke]

Pretty close to a true statement,



When you go over 200whp.

I understand that you are asking the question, not questioning the answers.

At around 175whp I was at the point of going (at the highest point) to around 87% duty cycle on stockers. I know many people go into the 90's and higher, but for the sake of accuracy and heat, I don't like going over the low 80's. So at that point I decided to go with the 450's. With those, I am now in the 50% duty cycle of the injector.

As far as size of injectors, I believe somewhere they are listed as 190's but I know for a fact that a couple of us have had them tested at 225 to 230 (depending on who tested what. Mine were tested at 230, as I recollect).

To the OP, stick with the stockers,

MB

Ahhhh

I was just going down the posts in this thread hitting the multi-quote button, until I got to this post.

 

[bullettdsm]

Ahhhh

I was just going down the posts in this thread hitting the multi-quote button, until I got to this post.

What are you saying? That I finally beat you to a post ?

MB

 

[DSMTriad]

Even thought I have a stock 4g63 my injectors are the 240cc. Well I got the 3" GM MAF and MAF-T and upgraded to the 275cc(4G64) injectors. Well I have to get the car on the dyno to see if it did any good.

 

[bullettdsm]

Let's see if I can explain, kinda simple like, about injectors sizes etc.

First off, injectors by themselves give you no more horsepower. What a larger size injector allows you to do is put more fuel into your system (IF you can use it/need it). There are lots of other things that come into play, but lets just stay on injectors.

So (with fuel pressure staying the same) the amount of time an injector stays open, regulates the amount of fuel that goes in the engine (open longer, more fuel can go through). The amount of time open is called the "duty cycle" (the time the injector is doing its duty, ). So if its open 90% of the time, then you would get more fuel through, than at say 50% "duty cycle" (for the same injector).

So now, with different size injectors we would have different size openings. Lets take a hypothetical 200cc injector (it has a nozzle set-up that allows 200cc of fuel per minute) and compare it to a 400cc injector (double the size capability at 400cc per minute). So, in theory, the 400cc injector at 50% duty cycle would give double the fuel than the 200cc injector (approx guys, I don't want to discuss opening and closing ramps and dead times etc. ). Therefore you could get a lot more fuel being dumped into your engine if you upgraded to bigger injectors because your ECU is expecting the injectors to still be the smaller size and it is making adjustments under that assumption.

With our cars specifically, we generally run rich as it is. Adding fuel with bigger injectors and no modifications or tuner adjustments (ie MSnS) will only waste fuel and could actually lose power.

Now in DSMTriad's case, he has added adjustability to his equation so he may get something out of his upgrade.

The question becomes, what is your car going to do with that extra fuel? With our cars and the stock ECU; not a helluva lot.

IDK, I just re-read this. I hope this makes it a little easier to understand

MB

 

[DSMTriad]

Let's see if I can explain, kinda simple like, about injectors sizes etc.

First off, injectors by themselves give you no more horsepower. What a larger size injector allows you to do is put more fuel into your system (IF you can use it/need it). There are lots of other things that come into play, but lets just stay on injectors.

So (with fuel pressure staying the same) the amount of time an injector stays open, regulates the amount of fuel that goes in the engine (open longer, more fuel can go through). The amount of time open is called the "duty cycle" (the time the injector is doing its duty, ). So if its open 90% of the time, then you would get more fuel through, than at say 50% "duty cycle" (for the same injector).

So now, with different size injectors we would have different size openings. Lets take a hypothetical 200cc injector (it has a nozzle set-up that allows 200cc of fuel per minute) and compare it to a 400cc injector (double the size capability at 400cc per minute). So, in theory, the 400cc injector at 50% duty cycle would give double the fuel than the 200cc injector (approx guys, I don't want to discuss opening and closing ramps and dead times etc. ). Therefore you could get a lot more fuel being dumped into your engine if you upgraded to bigger injectors because your ECU is expecting the injectors to still be the smaller size and it is making adjustments under that assumption.

With our cars specifically, we generally run rich as it is. Adding fuel with bigger injectors and no modifications or tuner adjustments (ie MSnS) will only waste fuel and could actually lose power.

Now in DSMTriad's case, he has added adjustability to his equation so he may get something out of his upgrade.

The question becomes, what is your car going to do with that extra fuel? With our cars and the stock ECU; not a helluva lot.

IDK, I just re-read this. I hope this makes it a little easier to understand

MB

Well now that you put it that way, seems like I need more air. The 275cc has the same dual spray pattern as the 2G 450s. I'm not even sure if 35cc more will help or hurt but without test, tune and a dyno I won't know.

 

[-dsm4life-]

Engine Management Piggyback for the Mitsubishi 2G Eclipse-Talon from HorsepowerFreaks

i need some opinions on this would it work for the 420a for the build im tryin to do?

 

[DSMTriad]

I would say no, its not a tunable item. SAFC would be better adjustability.

 

[99BoostedRS]

honestly in my opinion id get bigger injectors if your eventually gonna go turbo. Almost every 420a person i know have gone turbo. Hell my car isnt even running yet and i wanna turbo it . If you get bigger injectors know you'll have one less thing to worry about in the future. But remember this what i would do. If your gonna turbo it in let's say a year don't get injectors but if your gonna turbo it in like 2-3 months then yea get bigger injector's.

 

[-dsm4life-]

i dont plan on goin turbo for a while. if i keep the stock injectors would i have any problems if i do the build im wanting to do or will i need to back off on something like getting stage one cams versus stange 2 or keep stock compression versus 10.5

 

[99BoostedRS]

Honestly man i'm the wrong person to ask about that . I'd wait for a wiseman to reply back to that sorry i couldn't help.

 

[DSMTriad]

Well if you think about it, the only way a N/T will get anymore air is by bore/stroke.

 

[bullettdsm]

i dont plan on goin turbo for a while. if i keep the stock injectors would i have any problems if i do the build im wanting to do or will i need to back off on something like getting stage one cams versus stange 2 or keep stock compression versus 10.5

The definitive answer is ....NO. NO you will not have a problem with your build and stock injectors. NO you don't need bigger injectors. NO you will not get more power with bigger injectors NA.

I was on 12.5 comp and Crower 3's on stock injectors.

That is all.

MB

Oh and DSMTriad, you've got the idea. As you add more fuel, you will need more air to go with that fuel (especially when your set-up reads air flow). But the caveat is, will your curent set-up take on more fuel and air? That is what Paul (VelocitàPaola) was trying to get at. Does your set-up have the ability to take in more air? And your answer was appropriate in that you needed to get on the dyno to find out for sure.