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3.2 Conversion Fuel Injectors

I pulled my intake today to replace all my seals in prep for my conversion. I noticed a leaking injector and have decided to pull them all and have them cleaned and tested.
Should I look into replacing them for my low boost application(.5bar-.7)?
I see that many have had good results from WitchHunter..any input?
thanks,
Ben
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Old 10-13-2009, 05:46 PM
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OFF THE BOOST PIPE NOW...
 
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Do a search. There are a few names that pop up for clean/balancing them, although I think your limited to what can be doen since they are mechanical injectors.

What is the cost of new ones vs. cleaning? I know the Turbo injectors add up fast.
Old 10-13-2009, 06:58 PM
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cleaning only runs about $20 each. Replacing is expensive..$60-120 each.
Any input on putting in larger injectors for my application?
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Old 10-13-2009, 07:56 PM
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Most just use a fuel pressure reg that bumps pressure with increases in boost as this increases the flow capacity of the injectors up to 485hp.

See: Protomotive Turbosystems Description - 911
Old 10-16-2009, 06:31 PM
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stock injectors will work fine in when good condition at your power levels, you can also upgrade to 944 turbo units. There is also a cheaper Bosch unit you can use in all 3.2s with the same flow rate etc, check on rennlist, someone posted info about them a bit ago, much cheaper...
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Old 10-17-2009, 12:02 AM
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If you are going for re-programmable EFI, there are lot's of other injectors that will work and can be had cheaply.

For example: We had lot's of SAAB's on junkyards. Turbocharged ones have Bosch 0 280 150 431 injectors which are 349cc pieces. I picked up 12 of them for 10$ a pop. They will support 400HP on 6-cylinder application and are "standard" Bosch size. Check if there are junked cars with suitable injector sizes (you might want to look for turbocharged cars) and buy a bunch.

You can use hi-impedance injectors instead of low-impedance injectors but not the other way around.
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Old 10-17-2009, 03:16 AM
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Should have given a little more info. Protomotive chip, Begi RRFPR, K27 turbo, .5bar wastegate spring, no intercooler but planning on using a water/meth/alcohol injection system. I will have a full time AFR guage with logging to watch the mixture.
I was just wondering if I had to replace some of the injectors, would it be wise to go up in size or simply not necessary.
thanks,
Ben
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Last edited by ben parrish; 10-17-2009 at 12:59 PM..
Old 10-17-2009, 03:58 AM
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Originally Posted by ben parrish View Post
i wa just wondering if I had to replace some of the injectors, would it be wise to go up in size or simply not necessary.
thanks,
Ben
I would recommend that you sell your used 3.2 injectors and purchase a used set of higher capacity injectors. As Goran mentioned, there are lower cost, higher capacity injectors out there that will provide the fuel delivery you need. There are only two variables with any injectors; duty cycle and fuel pressure. I not aware where the duty cycle of the sits on the 3.2, but it's probably near 85%. You can raise the fuel pressure on boost( ~10% ), but going above factory rated injector pressure may give you unpredictable reliability, spray-pattern results.

How much horsepower do you seek in percentages? 10, 20, 30%?
If you are seeking a .5BAR maximum, use the rule of thumb of 10BHP gain for every .1BAR increase....my vote goes to bigger injectors.
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Old 10-17-2009, 04:54 AM
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I advise against raising system pressure. Most EFI Bosch injectors are rated for 3 bar fuel pressure and it's there they have optimal spray pattern.

Also, fuel volume DOES NOT increase linearly with fuel pressure. If you double fuel pressure your flow rate raises with 41%. Add boost on the top on it and it's obvious why fiddling with FPR is not worth considering. Thus, your pump would need to supply fuel at 7 bar (!) pressure in order to provide 41% more fuel than stock (on turbocharged engine boosting 1 bar).

Keep the stock 3-bar FPR and change injectors so you have approx 80% duty cycle on highest load.
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Last edited by beepbeep; 10-17-2009 at 06:06 PM..
Old 10-17-2009, 06:18 AM
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Goran, I have read many of your past post and value your opinion based on your experience. I do, however, have to ask you why you don't recommend using a RRFPR but many people that have done these conversions say it's a must? Even Protomotive has this as standard equipment on their conversions.
thanks,
Ben
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Old 10-17-2009, 01:22 PM
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I like what Goran is saying and that would probably be a better approach.

However, there are not chips that I know of that would support doing this. It would require enlisting someone to develop a proper chip to do this or a piggy back computer. This would require a fair investment.

One of the advantages to the Protomotove approach is that the RRFRP is not only is there proven chips available but it is somewhat self adjusting for different levels of boost. If boost increases, more fuel. If it decreases, less fuel.

If one wanted to they could do a MAF conversion and possibly tune around new injectors using the MAF to AFM adopter box to fine tune AFR's. Would still need some help with a chip on the timing side and some on the fuel side.

Even more interesting would be to attempt a MAP conversion. There is a cool box that with the adaption of a TPS might work. Some one on the 944T board seemed to have success doing so. See:FULL THROTTLE SPEED - MAF Translator PRO

Again, the Promotive approach is proven up to almost 500hp so it would take a lot less development time.
Old 10-17-2009, 02:32 PM
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I don't want to reinvent the process here. I think I will stick with what protomotive does for now. If I decide to search for more power(he, he) I will look into bigger injectors and a different controller. Perhaps megasquirt.
Seeing how I have had this conversion planned and collected parts for over five years, I may very well never get to the next level......??????
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Old 10-17-2009, 04:35 PM
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Quote:
Originally Posted by ben parrish View Post
Goran, I have read many of your past post and value your opinion based on your experience. I do, however, have to ask you why you don't recommend using a RRFPR but many people that have done these conversions say it's a must? Even Protomotive has this as standard equipment on their conversions.
thanks,
Ben
I a bit against RRFPR because it strains fuel pump and is non-linear device where boost enrichment is governed by a spring and is superimposed over actual fuel MAP. I'm even more against adjustable FPR as they allow you to make complete EFI map obsolete with one turn of the pressure-adjusting screw.

I'm not aware how different companies engineer their conversions. But 3.2 engine is already EFI and you could do the conversion "the right way" with 400$ worth of MegaSquirt II and bigger injectors while keeping predictable stock 3 bar FPR in place. I understand that you can do light-boost conversion relatively simple and cheap with RRFPR's and such but I still believe that proper turbo conversion should use 3 bar stock FPR, properly sized injectors and WBO2-verified fuel map.
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Old 10-17-2009, 06:04 PM
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I also agree with Goran to a point but I have run the protomotive system for 2 years now and it's held up well, it is literally plug and play, there are no adjustments to be made, FPR and chip, add some boost and 360hp with AFRs that are pretty much spot on, all can be done in an afternoon. I know of someone running the same system just with 944 turbo injectors and 1 bar (3.3 pistons and cylinders) and it's a daily driver, a very fast one too!
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Old 10-20-2009, 03:09 PM
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Originally Posted by beepbeep View Post
I a bit against RRFPR because it strains fuel pump and is non-linear device where boost enrichment is governed by a spring and is superimposed over actual fuel MAP. I'm even more against adjustable FPR as they allow you to make complete EFI map obsolete with one turn of the pressure-adjusting screw.
I won't use one because of the chance (ok, maybe a small one, but...) the internal workings of the RRFPR fails - and it will fail on full boost and would lean out mixture and burn your motor. The way I see it, why screw with yet another variable - it's just not worth it for me.

Marren Fuel Injectors shared with me, measurements on injector pulses within the fuel rail on WOT, using only 60 lb injectors. It was amazing how much each injector upset fuel flow through the stock 3.2 fuel rail. The reason I add this comment is that for proper tuning and reliability, the fuel system needs to be simple, consistent and dependable - otherwise you'll be chasing your tail trying to tune properly.
Old 10-20-2009, 06:57 PM
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