Sir-PSychedelic

Which size of injectors do i need and from which company?

thx

Mahjik

iTrader: (1)

http://rx7.com/cgi-local/3rdgencalc.cgi

thewird

iTrader: (8)

I think those numbers are overly optimistic lol. 550/1300 at 80% gives almost 450 HP.

thewird

Mahjik

iTrader: (1)

People have done about 400 on the stock injectors in the past, so that definitely seems doable. You might take a look at this thread and check out the post where I quoted one of Wade's posts:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/what-situation-do-you-have-259912/

mono4lamar

iTrader: (32)

You can run 4 X 850's all around a be fine. I'm sure you could use the factory fuel system but at that amount of power it might be smart to pull your injectors to clean and flow match them.

zenofspeed

iTrader: (1)

For some reference. I did a pull the other day on stock injectors, stock twins at 14psi. and 304WHP. The log showed 98% duty cycle. 11.5-12.0 AFRs.

The motor is ported, so I think I should have around 330whp if it weren't for the low compression (75s and 85s)

It isn't clear if you mean just crank HP or WHP. For crank HP, I think you could do 380 on stock fuel. But HP can vary car to car. You must mean crank HP since the twins are out of breath at 380whp.

What PSI are you intending to run your stock twins at?

thewird

iTrader: (8)

Oh, its Flywheel HP, I guess that makes more sense.

thewird

Sir-PSychedelic

My plan was to get the maximum out of the twin system and i thought that would be max 380-400 HP at the crank... And i dont want to change the twins every year.

The ports are stock.

Another Problem is form which company shall i buy the injectors. Sard is nice, but very expensive 550$...

Edit: And u have to calculate, that we have 98-100 octan gas in Germany

zenofspeed

iTrader: (1)

well, I heard the octane ratings in Europe do not equate to the same ratings in the US. Like 98 would be called 92 here or something like that.. Could be wrong though.

If you want the twins to be reliable, I personally wouldn't push them over 13 psi. But you can get 295-310 WHP at 13psi on stock injectors. So around 350+ crank.

slayerx7

iTrader: (4)

I ran those #s in the calculator, and came up with 414 HP, minus 20% drivetrain loss = 331whp, as far as calculators go thats dead accurate.

I was wondering though, would 850/1600cc injectors be well suited to make the most of the BNR Stage 3 sequential set up? Im thinking so, I dont care about ideling rich, but I dont want the car to bog when the secondarys come to life either.

thewird

iTrader: (8)

Too much fuel lol. Thats for single with a LOOOT of boost.

thewird

Mahjik

iTrader: (1)

Considering healthy stock FD dyno's around 220rwhp (I've seen slightly higher, but just rounding for ease), then your 20% for driveline loss is a little too much.

Hitokiri_Gensai

iTrader: (2)

i think the FD is more like 14 or 15% loss, which is about 38 hp loss.

rollingsband1

I personally want to run 850/1200cc injectors for my setup and thats even when I go with BNR's sequentially at 17-18psi :-)

till then im just going to tune 850cc's all round.. and maybe just up the fuel pressure 5-10psi if all else just for safety margin.

zenofspeed

iTrader: (1)

Well, nothing is perfect. For all I know I only hit 13.5psi. It is hard to diagnose little things. Also, I think my peak HP was reached at 7k rpm and then the stockers wouldn't hold full boost. The shop said I would probably pull 330whp if the compression wasn't shoddy. Me thinks my housings are worn out.

That is too much injector IMO. And as far as idle and bogging, that is all in the tune. Maybe something like 750/1200 if you want to play it safe while maxing out twins. I don't know, I'm just guessing from what I've read and talked about. I won't be pushing twins that hard, I'm just going single.

slayerx7

iTrader: (4)

Yeah I ws just told to figure 20% drivetrain loss for a safe guesstimation converting BHP to WHP. And given, the issue, and what your shop had said, I was just impressed that a calculator would pin it within 1HP. But sounds like that was more of a fluke. But I sure liked the #'s entering 850/1600 running 80% duty. Ive more research to do, but for now that sounds like a little much fuel for my BNR's. Thanks for the input though!

thewird

iTrader: (8)

How much horsepower do you think 550/1300 with 16 pounds on BNR twins with a safe trackable tune will give? Or rather how much injector duty cycle will that need/use.

thewird

fendamonky

iTrader: (6)

I still have my stock injectors in. Now I don't know if it's just an incomplete tune, or what.. But I will regularly see over 90% running at .8-.9 bar (using PFC Commander to monitor) on a cold night.

My IDC seems to fluctuate fairly easily. I know that my car dyno'd 280rwhp at 86%

I'm not sure if this will help out or just confuse the issue.

I am about to completely re-vamp my fuel system when I put in my BNR's. From what I have heard an 850/850 set up is good for just about anything you will reasonably hit with a twin set up (I'm putting in an FPR and turning up the pressure just to be safe).

As far as drive train loss.. the last time my car was on a dyno my sheets pulled 338BHP and 280WHP on the peak run. I'm kinda tired right now and stupid, but I think it's right around 17% power loss.