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Old 04-05-2011, 11:54 PM   #1
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Default how much can my injectors handle?

So Im continuing to piece together my turbo setup, and am trying to decide which turbo to go with. im looking at either a godspeed gt25 with an 8psi actuator, or a gt28 with a 14.5psi actuator. I already purchased some 460cc injectors, and my plan is to go with MS standalone, stock fuel pump. I dont want to mess with a FPR if I dont need one right away, so im wondering how much boost I can safely run with stock fuel pump and 460's and no other fuel modifications.

sorry if this has been covered, couldnt really find an answer by searching

any insight greatly appreciated
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Old 04-06-2011, 12:01 AM   #2
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Old 04-06-2011, 12:02 AM   #3
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The stock fuel pump is the kicker - it could tap out at 180whp or 240whp. You should replace it with a Walbro 190.

Walbro 190 pump and Rx7 460s are good for ~230whp on an otherwise stock fuel system.
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Old 04-06-2011, 12:11 AM   #4
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My stock 1.6 pump ran out of juice at 180whp. I haz a Walbro 255 wtih 550's at 55% duty at 290whp.
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Old 04-06-2011, 12:13 AM   #5
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so if i look at the last table, assuming my pressure will remain at 43.5, and i managed to get 200hp, and my bsfc is .65 (upper range) with this over estimation, i would only need 430cc injectors. I guess I was looking at it as the injectors need to be able to keep up with the airflow, not with a horsepower range, but i guess since the horse power is controlled in part by intake pressures, that kinda makes sense.

either way, seems 460's are good for around 200hp, and im not aiming that high yet, so maybe ill just stick with the gt25 at 8psi? im worried gt28 with 14.5psi actuator might be pushing my luck?
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Old 04-06-2011, 12:33 AM   #6
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Your injectors are useless if the pump feeding them falls on its ***.
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Old 04-06-2011, 12:44 AM   #7
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looks like ill be adding a walbro 190 to my list. main question was really to try to help me decide which turbo to go with, I mostly auto-x so I want something that will spool as quick as possible, but also give me some headroom. I didnt wanna go too big for the injectors I purchased either tho. im thinking gt25 because it should spool pretty quick, but I feel like a gt28 would still spool pretty quick and give me more headroom, the fact it comes with a 14.5psi actuator is just what scared me. I wanted to start small and work my way up, but dont want to buy two turbos in the process, i guess ill just look into a smaller actuator for the gt28 to start me out with
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Old 04-06-2011, 12:47 AM   #8
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I bought the godspeed gt28 and put an HKS 10psi wastegate actuator on it. You can find them on ebay and it needed very little modification to fit.
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Old 04-06-2011, 12:47 AM   #9
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I have a 7psi actuator shoot me an offer if you end up needing it. it should fit right on since its from a chinacharger just like youll be getting
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Old 04-06-2011, 12:57 AM   #10
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18psi, ill let you know once i finally decide. that seems like a good idea to me tho

thanks everyone
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Old 04-06-2011, 09:30 AM   #11
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Quote:
Originally Posted by Savington View Post
The stock fuel pump is the kicker - it could tap out at 180whp or 240whp. You should replace it with a Walbro 190.

Walbro 190 pump and Rx7 460s are good for ~230whp on an otherwise stock fuel system.

^this is truth.

with that being said, I'm pushing mine to almost 100% DC around 230rwhp.
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Old 04-06-2011, 06:46 PM   #12
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what do most people do, get an in tank replacement? or just add an inline booster type pump? im guessing in tank is probably alot cleaner/more reliable/just better?
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Old 04-06-2011, 06:49 PM   #13
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in tank pnp drop in. simple/cheap/easy.
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Old 04-06-2011, 07:08 PM   #14
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No extra lines needed for in tank. See my bosch 044 how-to.
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Old 04-06-2011, 07:31 PM   #15
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You assume pressure is the same as airflow. Is your goal to make intake pressure or power?
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