Trying to decide on injector size

[SE_DynamiK]

Hey everyone, I've been running obd2 injectors and shit since I did my swap and haven't had the time nor the funds to change a few things I wanted to change at the time. So naturally, things started to eff up a little and now I have a horrible misfire in cylinder 2 that I believe is due to my injector wiring getting damaged, so I figure I'll change all of that shit out one time while I have the funds available and get it all taken care of.

For summer, I plan to throw in some type-s pistons and cams, and either a tri-y header or the Bisimoto header (depending on production time), so I figured I'll upgrade everything in preparation. So far, I've ordered an MSD cap, rotor, and coil; walbro 225lph pump; high compression .0014" headgasket; Bisimoto flywheel; and custom 2.25" exhaust, along with the AEM cai and Blacktrax spacer already on the car.

All that's left now is to purchase the injectors, and I'm debating between getting a set of DSM 390cc or DSM 450cc injectors. I would like to just upgrade straight to the 450s, but I didn't know if they would be overkill. Right now I'm running the 290cc obd2 h22 injectors, so I figure going to 390cc would be good enough because its more than the 345cc obd1 injectors and less than the 450cc DSM. Either way, I will still have to get a new basemap, but the 450s would probably require some tuning to run properly and efficiently.

So my question is: would the 390s be enough for what I have planned, or should I just get the 450s?

[nine_deuce]

I think 450cc injectors would be over kill. Those are used for boosted applications. I've got DSM 360cc injectors and have had no issues. I was told by a member on this forum that the 360's would be perfect. Not too big, not too small

[Ghetto_CB7]

My Openion

If it were me, and it was just a little while ago LOL.

I would look into upgrading intake manifolds while you are doing this work.

If you do I would highly recommend getting the euro-r manifold and opt for Acura RDX injectors.


I recently did this and I am very pleased with the performance.

Besides that it really cleans up the engine bay, and keeps oem quality and reliability. Plus the RDX injectors are cheap and perform really well even on low HP engines.

[SE_DynamiK]

^ It's funny you say that because I was checking out that euro-r set up last night as well.
I think I'm just gonna go with the 390s so it will give me a little room to play with, but not too much room.

[Losiracer2]

I think the RDX's are 410cc's if you're curious about them

[Ghetto_CB7]

Yes

Yes, the RDX are 410cc Saturated Injectors.

I am running them and LOVE them. They are cheaper then most after market injectors and according to research done, they have a lot of advantages over most after market injectors.

Do not worry about them being too big! They work just fine with my setup and I am pretty much stock. I would not overlook them because of their size.

They are less then $40 a piece.

Anyway good luck with your decision.

Edit: with all you have done, you will REQUIRE tuning regardless of the injectors you choose to run.

[PirateMcFred]

For summer, I plan to throw in some type-s pistons and cams, and [a] header, so I figured I'll upgrade everything in preparation.

Awesome!

So far, I've ordered an MSD cap, rotor, and coil; walbro 225lph pump; high compression .0014" headgasket; Bisimoto flywheel; and custom 2.25" exhaust, along with the AEM cai and Blacktrax spacer already on the car.

MSD cap, rotor, and coil => unnecessary unless your OEM ones need replacement.
walbro 225lph pump => totally unnecessary for ~210whp or less
high compression .0014" headgasket => going to get adj. cam gears to compesate for the timing retard?
Bisimoto flywheel => should make it revvy
custom 2.25" exhaust => go for 2.5" it'll eliminate the top end restriction.

All that's left now is to purchase the injectors, and I'm debating between getting a set of DSM 390cc or DSM 450cc injectors. I would like to just upgrade straight to the 450s, but I didn't know if they would be overkill...

So my question is: would the 390s be enough for what I have planned, or should I just get the 450s?

390s will do just fine. I ran 375 RC peak and hold on my old H22 build and at 205whp they were at 80% duty at sea level. Going a little higher will work fine for you. If not it's easy to bump the fuel pressure and retune. Any change in injector size will necessitate a retune.

I would not recommend the RDX 410s as they are not as simple a swap as the RCs, Precisions or the DSMs. They require a different/modified fuel rail and an adapter at the other end, as well as a proprietary electrical connector:



Good luck with the build!

[Ghetto_CB7]

Intake

That is why I recommended he upgrade intake manifolds as well.

And for the horsepower he is looking for, a euro-r or comparable manifold is not a bad Idea at all.

[PirateMcFred]

Recommending a $500+ intake manifold over a larger exhaust is putting the cart before the horse IMHO. While it's a good idea, it's an option that has not been proven to consistently provide a reasonable bump in power over a reasonably portmatched H22A dual runner IM on mild builds. I didn't see where he said what power he was expecting to get from his modifications anyway. I agree it's a nice manifold there are more cost-effective mods he can pursue before upgrading the intake manifold.

Just my 2¢ :wave:

[Ghetto_CB7]

I agree to a point

The OP has mentioned exhaust already in the setup, I was recommending additional modification's that would benefit him.

I would also like to point out that although exhaust can be done relatively cheap, nice ones often are expensive, as are headers that produce power.

And I believe that internally built performance engines are only as good as the supporting bolt on modifications you couple them with.

Yes, camshafts and piston's are important upgrades, however I believe you should have high quality bolt on's before jumping into internals. I know many people that will disagree with this, but from my own personal experience that is the path I recommend.

A lot of people (not saying the OP is one of them) underestimate the cost of building an engine with different internals.

Camshafts are a perfect example, without tuning, and degreeing them in they are not very usefull and quite frankly dangerous for the motor.

I noticed that the OP does not mention tuning software on the list and would like to point out again that IT IS ABSOLUTELY NECESSARY. I have seen many engines with quality parts both inside and out go kaboom because of a lack of tuning.

With all that said, yes you can make good power without an aftermarket manifold, but it is a good supporting modification. My 2 cents.

[trah]

Yes, the RDX are 410cc Saturated Injectors.

I am running them and LOVE them. They are cheaper then most after market injectors and according to research done, they have a lot of advantages over most after market injectors.

Do not worry about them being too big! They work just fine with my setup and I am pretty much stock. I would not overlook them because of their size.

They are less then $40 a piece.

Anyway good luck with your decision.

Edit: with all you have done, you will REQUIRE tuning regardless of the injectors you choose to run.

Uhh if your using the rdx 410's then its overkill if your stock. I use them but I have supporting mods. What's your fuel pressure @? The injectors should be around 47-54 psi with the hose disconnected.

[Ghetto_CB7]

I am internally stock (now)

I am currently internally stock, however I will not be in the near future.

I am running the stock fuel pressure regulator, with no adjustments and running fine. I should not need to adjust my fuel pressure at all when running the injectors, they work fine at low psi.

I do not have the money to build the motor all at onece, but when I upgrade I do it for my build plan.

Thank you for worrying about my overkill, but there are many factors that could lead someone with an internally stock motor to want these injectors.

[PirateMcFred]

The OP has mentioned exhaust already in the setup, I was recommending additional modification's that would benefit him.

<snip>

With all that said, yes you can make good power without an aftermarket manifold, but it is a good supporting modification. My 2 cents.

You're right, I'm a n00b. I defer to your expertise.

[Ghetto_CB7]

Uhhh, no

First off, thanks for the sarcasm.

I have seen your build thread, and am very aware that you know more about engine building then me.

Second, all I did was reccomend a manifold / injector combination. I was unaware that recommending quality parts would upset people.

No hard feelings, I hate therads that end with people getting upset at others over stupid things. Good luck with the build, I'm sure it will put down some nice numbers.

Either way, this thread is way off topic now.