Author Topic: Injector selection (Read 5081 times)

kowalski · « **on:** March 25, 2009, 04:15:09 PM »

So, I'm just getting the left over needed pieces for my build, and I've got a question about injector sizing.

I'm going to be running a 2.1L with a turbo @ 10.5psi to start. No idea what kind of power I'll be making but I think it will be around 250-300 I hope. There is a few extra little things i'll be doing on the internals to the motor to bump it up a little bit, however I was wondering what size injectors your guys are running and what power your making.

http://www.injector.com/injectorselection.php

that size says i'd need 40lb/hr injectors for 250hp, and 47lb/hr for 300hp, that seems pretty crazy and I'm wondering if that's accurate, and if so I should probably be looking at running a double row of injectors or something.

rob_e30 · « **Reply #1 on:** March 25, 2009, 05:28:00 PM »

It's a function of fuel pressure too. I'm not sure you'll get to those HP numbers at those boost levels. I can tell you that we run significantly higher flow rates on low impedence injectors and built the motor to run between 15-23psi.

I used the RC Engineering website and some books to arrive at the final injector.

kowalski · « **Reply #2 on:** March 27, 2009, 01:34:27 AM »

I duno, I think I should be at least at 250.

2.1L stroker balanced and blueprinted
lightweight valve train
1mm larger intake and exhuast valves
JE pistons
standalone management
and a couple of other things.

I hope I'll be up at 250ish.... 10.5 psi is just the starting boost while all the kinks get worked out, and its a daily driver so it doesn't need to be too extreme... yet

thanks for your help though. where did you pick up your injectors from?

Boosted E30 · « **Reply #3 on:** March 27, 2009, 06:24:35 PM »

You will definatly be up around 250hp on 10.5psi. my car makes 230whp on 10.5 and i didnt change anything other then pistons head gskt and head studs and standalone. im using the bosch green top injectors 42lbs they are getting close to the max though i think they will be good for 280whp maybe a bit more so i would definatly go for bigger then 42lbers if you want over 300whp.

kowalski · « **Reply #4 on:** April 01, 2009, 03:12:49 PM »

where did you get your bosch green tops from? part number?
Thanks, for the info

I'd be happy with the >300 for now, its a street car.

Plus, i need something cheap to upgrade once i feel like i need more power:)

Boosted E30 · « **Reply #5 on:** April 01, 2009, 05:46:07 PM »

I got mine from a shop in town i think the set was $350canadian. here is a link to a site selling them though. http://www.intengineering.com/Bosch-42LB-440cc-Green-p4945249.html

kowalski · « **Reply #6 on:** April 06, 2009, 12:37:23 PM »

thanks, however I read a lot of bad things about the green top injectors...

however, i read a lot of good things about these
http://www.racetronix.com/621031FM.html
delphi 440 cc injectors. any input?

JoeDellio · « **Reply #7 on:** April 07, 2009, 07:34:54 PM »

Quote from: Boosted E30;69043

You will definatly be up around 250hp on 10.5psi. my car makes 230whp on 10.5 and i didnt change anything other then pistons head gskt and head studs and standalone. im using the bosch green top injectors 42lbs they are getting close to the max though i think they will be good for 280whp maybe a bit more so i would definatly go for bigger then 42lbers if you want over 300whp.

What turbo are you using to make that power, a 50 or 60 trim? When I did my math I found that 42lb injectors like you are using would be good with a base FP of 43.5

Boosted E30 · « **Reply #8 on:** April 08, 2009, 11:14:19 PM »

Turbos .48ar with .60 trim i have no problems with my injectors they work just fine, just when i went out tunning last time it was around -8deg C out so im pretty sure it was running way richer then it would have if it was warmer which would be part of the reason why they were at 95% on 10.5psi. I was told by the place i bought them from that they should be good for over 320hp and they do alot of vw and audi turbo builds.

kowalski · « **Reply #9 on:** April 09, 2009, 03:32:09 AM »

Apparently they're a single pintle design where as the delphi ones are 3 pintles, leading for better fuel atomization.... i guess thats the only difference

ClubSport · « **Reply #10 on:** April 09, 2009, 10:28:33 AM »

I'm running stock 1.8L displacement and a DASC at 9psi. My injectors are Lucas 36 lb/hr and they are too big. My injector duty cycle at redline WOT are only about 65%, which I can read on the power commander III. I think I could go down to 32 lb/hr.

Also stock FPR. 43psi idle, 50psi WOT.

JoeDellio · « **Reply #11 on:** April 09, 2009, 10:38:14 AM »

Quote from: ClubSport;69770

I'm running stock 1.8L displacement and a DASC at 9psi. My injectors are Lucas 36 lb/hr and they are too big. My injector duty cycle at redline WOT are only about 65%, which I can read on the power commander III. I think I could go down to 32 lb/hr.

Also stock FPR. 43psi idle, 50psi WOT.

Or you could get a smaller pulley and net more boost

Boosted E30 · « **Reply #12 on:** April 09, 2009, 06:37:23 PM »

Quote from: kowalski;69754

Apparently they're a single pintle design where as the delphi ones are 3 pintles, leading for better fuel atomization.... i guess thats the only difference

If thats the only difference then its up to you to choose what you would like better the bosch ones work just fine for me im sure the difference between the 2 brands is pretty minimal if you were to try one set then the other i doubt that there would be a noticable difference in power or anything like that.

kowalski · « **Reply #13 on:** April 11, 2009, 04:00:18 AM »

yeah I kinda figured that. I red a couple posts of people on the vw forums having problems with them, but i bet its all just hear say. that being said i'll probably get the delphi ones because they're about the same price.