Injector Guru's Wanted

[the_tonkau]

Opinions on injector upgrades needed!

-Engine rb30det VCT HEAD around 300-350rwkw

Just picked up the long motor from the engine builders and before slinging it back in I need to sort out my fuel delivery issues.

To get around the expensive side feed problem I have had a fuel rail built to suit the more popular top feed injectors but am struggling to find out what injectors will do the job cheaply. I have worked out that they will need to be around 550cc to flow enough for the power output but I'm having issues with compatabilty with the Apexi PFC. It likes high impedence Jap brands and the common Bosch 363(low impedence) apparently don't work to well with the PFC. I have heard RX7 S6 secondary injectors work OK but they are proving expensive and hard to get secondhand. Anyone have a proven setup that will suit this setup?

[Guilt-Toy]

go to the SARD 700CC bolt in injectors - sell your rail.

[the_tonkau]

go to the SARD 700CC bolt in injectors - sell your rail.

The rail is costing me nothing and sard product is very expensive. My intake manifold doesn't know if the fuel is coming from a $50 injector or a $200 injector and I would rather spend my budget on upgrading my rods to race items and ceramic coating my forgies......but...... sards would be nice and easy if I had the bucks...

Anyone else have a proven solution?

[Sydneykid]

Simple, use low impedance, top feed injectors and put a resistor in series with them to bring them up to high impedance. I am using the usual S5RX7T, which are rated at 550 cc's, but actually flow around 565 to 570 cc's at 36 psi base rail pressure and 625 cc's at 45 psi.

[the_tonkau]

Aha , the Kid is in the house. As always, cheers for the input. My Tuner (ex apexi japan trained) tells me that he has had probs making low imp units work nicely with the PFC (specifically Bosch 363's which can be bought cheap/flow around 550cc and are a common performance upgrade). Within the PFC you can tell it what injector setup you have, what have you told it when you use those s5 rx7 units? are they primary or secondary units? shit it's frustrating not knowing....

ta

[Sydneykid]

Aha , the Kid is in the house. As always, cheers for the input. My Tuner (ex apexi japan trained) tells me that he has had probs making low imp units work nicely with the PFC (specifically Bosch 363's which can be bought cheap/flow around 550cc and are a common performance upgrade). Within the PFC you can tell it what injector setup you have, what have you told it when you use those s5 rx7 units? are they primary or secondary units? shit it's frustrating not knowing....

ta

I am not a rotary expert, but I think the S5RX7T had 4 X 550 cc injectors. I got mine off a well know rotary race engine builder a couple of years ago, we went though 8 to get 6 good ones.

I believe you would have problems with just low impedance injectors. but the resistors should fix that. As for settings, I didn't tell the Power FC anything, I just tuned the maps. The default injector lag is 0.528 milliseconds at 14volts.

I believe that Rochester make high impedance top feed injectors, so maybe try them. The Electromotive ECU (popular in US racing) runs peak and hold which likes low impedance, so they should be cheap and popular over there. With no import duty (free trade agreement, good on you Johnny) they are even more economical.

Hope that helps:cheers:

[R31Nismoid]

why are you cutting corners for a big power motor?

i'd be using the normal rail with nismo 700cc injectors and then you know 100% they will work without any problems at all as they are tried and proven.

im not even using an adj reg and ive got no problems

[Gradenko]

go to the SARD 700CC bolt in injectors - sell your rail.

So, in spite of Sard injectors known for being hard to fit (not a drop in, even with collars!), hard to tune (non-standard injector lag) and as side feed injectors, generally a pain in the ass to remove and install (pintle caps off of the shelf are they?), you recommend them do you? They are the cheapest of the jap side feeds and it shows. If you *had* to go side feeds, the nismos or hks are a far better choice.

Rails cost nothing and theres a far greater range of top feeds. I don't blame the_tonkau for going this route.

[the_tonkau]

Thanks for the imput guys! Spending big bucks doesn't always mean the best solution as many tuners of modded cars know all to well. Lets say I find a cheaper way around the touch your toes/bend over cost of expensive side feed injectors, I'm sure alot of the people on this forum would be able take advantage of this cheap solution. Isn't that the idea of this forum? to share idea's and solve problems economically?

Keep the idea's coming team!

Cheers

[geordie]

Another idea is to get a company like AVO to high flow stock injectors also. Apparently you can get stock rb25 370cc jobs up to 500cc........

[Sydneykid]

Another idea is to get a company like AVO to high flow stock injectors also. Apparently you can get stock rb25 370cc jobs up to 500cc........

Yep, but they charge more than I can buy new 550cc Rochester injectors for:cheers:

[R31Nismoid]

Another idea is to get a company like AVO to high flow stock injectors also. Apparently you can get stock rb25 370cc jobs up to 500cc........

Yeah, but then the spray pattern becomes and issue i beleive

[black_tx5]

The series 4 rx7 injectors are rated at 550cc and are high impedance. Model number is 195500-1370.

[the_tonkau]

Well guys, in the end I went down the route of reco S5 RX7 injectors (high impedence 550cc top feed) for $300 and had a mate from Mullins Engineering in Bayswater make me up a new fuel rail. Looks great and from the research completed, should work great. Next issue is trying to make the rb25det plenum fit under the bonnet (r33 S1 gtst) after the rb30det went in! wish me luck lads!

cheers

stevo

[ricknismo]

So 195500-1370 are definetely high impedence and no good for a gtr?

[lukevl]

The standard RB25 inlet manifold needs to be modified to use 363s.

[geordie]

So how do you change from side feed to top feed? How much does it cost to fabricate a fuel rail and can you use the rail of an R32 RB25 (as this top feed)

[Cubes]

The default injector lag is 0.528 milliseconds at 14volts.

Is this for the RX7 550cc injectors or RB25det injectors?

[Sydneykid]

Is this for the RX7 550cc injectors or RB25det injectors?

That's the Apexi Power FC default, so it is for standard RB25DET injectors.