RX7freak08

Ummm I need to get a wide band but the electric is a cheap way to go. Why is because my n/a street port. I don't know if I'm going to be running rich or lean. So I need to know as a cheap way. Any ideas.

Tatakai

iTrader: (2)

realisticaly narrowband (what i assume your talking about- the cheapies you can get at autozone) are really just a light show. the range on them are basically 14:1-15:1 and so it wont tell you anything, since anytime you get on the gas it'll say your rich, anytime you let off you'll be lean. horrible possible replacement of a real wideband.

RX7freak08

I had planned to run 460cc primaries and 550cc secondaries. Then some people told me to go with 550cc primaries and 680cc to 720 secondaries. I have a FD fuel pump and new fuel filter. So tell me what I need.

Yeah that was what I was talking about.

younG_Gunner

iTrader: (2)

I don't know what your power goals are, but aren't 720's a little too excessive for an NA?

RX7freak08

well I guess people were thinking about the fact later I was going to put a stock turbo on the 6 port motor.

bennyess

i have the sabre a\f ratio guage on 89t2 and it works fine nice and responsive , you can tell when the fuel cut is about to kick in, displays rich when wot/under full boost, and lean when throttle is closed, displays optimum when cruising/part throttle, works for me motor still holding up.

Evil Aviator

Somebody who knows what he is doing can use a narrow-band O2 meter for tuning, and anybody with basic automotive knowledge can use one as a simple monitor. A wide-band O2 meter is more accurate past the stoich range, and is better for people who are not such great tuners. However, it is a bad idea to try tuning the car yourself if you don't know what you are doing. Rather than spending money on a wide-band O2 meter, I recommend that you just take the car to a good tuner and let him use his own O2 meter.

You can calculate your fuel requirements here:
http://www.rceng.com/technical.aspx

FYI all O2 meters on the market are electric.

What in the heck are "polished rotors"?

RX7freak08

The fuel rail pressure what does an rx7 have pressure wise.

Polished rotors uhh I bought them from joeylrech. They are so clean you can see yourself in them. If you dont believe me ask scrip7 he measure my seals on the rotor.

The Shaolin

iTrader: (5)

shiny=/=horsepower

Half turbo setups do not work good at all N/A. Pick one or the other. Don't install half the parts on your car now, do it all at once.

RX7freak08

what do u mean

Evil Aviator

Sorry, I guess that link is a little confusing for non-geeks, lol.

Just scroll down to the bottom of the page to the Fuel Injection Worksheet.

-Enter your estimated flywheel horsepower.
-Enter the number of injectors as 2 (I will explain later).
-BSFC is more complicated, so ask your tuner if you want to be accurate, or to just take a guess use .55 for NA or .65 for turbo. Some high-boost engines in which the owners cut corners with crappy Ebay parts and amateur tuning have been known to have a BSFC as high as .80.
-Enter a fuel rail pressure of 43.5 for Mazda injectors with the stock fuel rail pressure, or enter 39.8 for non-Mazda injectors with the stock fuel rail pressure.
-Press the button to calculate the fuel flow, and look at the cc/min number. This will show the total cc/min needed per rotor, and then you can make your own choice on how to go about getting that rate. For example, if the calculation is 2,000cc/min, then you can use 1,000cc primaries and 1,000cc secondaries, 800cc primaries and 1,200cc secondaries, 400cc primaries and 1,600cc secondaries, etc. Round up to the closest available injectors.

They were probably just cleaned well. I am not aware of any performance advantage in polishing rotors.

RX7freak08

Ok well I got. 62.23 lb/hr and 654 cc/min. That is 180hp. Then 69.15 lb/hr and 727 cc/min. That is for 200hp.
At the flywheel.

JustJeff

iTrader: (13)

Very nice post!!! This also helped me with similar questions

RX7freak08

Yeah it is.

RX7freak08

Here you go Aviator.

Evil Aviator

OK, you calculated everything correctly. What is your question?

86gxl_fc

okay, so once it calculates the cc/min etc.. is that what you need per rotor to make the horsepower its trying to accomplish per rotor?
on mine it was 1050 cc/min per rotor for 260hp, thats per rotor.
so would the final outcome be 2100 cc/min for both rotors for total of 520hp ??

scrip7

iTrader: (6)

He is using a stock ECU so there is no tuning unless he goes Rtek or the like. And a narrowband sensor is designed to read anywhere from .1 volts to around .9 volts during operation. A wideband is designed to produce anywhere from .1 volts to around 5 volts, so you can see obviously the difference in range, sensitivity and accuracy when determining a/f ratio. Also the stock narrowband has no heater element. A narrowband zirconia-type sensor such as the stock one doesn't start producing useable voltage until it reaches 600 degrees which takes a few minutes to get there. A wideband sensor with it's integrated heater starts working in about 10 seconds. With a rotary motor and experimental injector sizing, you can't afford the risk of going lean and popping your motor. An 02 sensor isn't the kind of part you want to "cheap out" on. Save your pennies.

4WDrift

iTrader: (3)

I dont know any real tuners who use a narrow band to tune theirs or a customers car. thats just dumb. if your running a turbo motor at an afr of 14.0 (where a narrow would say rich) your gonna pop that motor . I agree with Scrip7 dont try and skip on your tuning.

classicauto

iTrader: (3)

You'll never produce enough power with a streetport to warrant using anything other then the stock 460cc injectors.

BurlesonRX7

ok do I understand this correctly? if each rotor uses 2 injectors totaling the amount below your engine will make the corresponding horsepower (or something close to that)

200 hp = 725cc/min of injectors per rotor
275 hp = 1000cc/min of injectors per rotor

This was using Evil's NA settings.

classicauto

iTrader: (3)

For 250 flywheel HP, with a VERY safe 60% duty cycle - you'll need 550cc injectors.

But good luck coming anywhere near it with a streetport, especially on a stock ECU.

Given that fact alone (no EMS) I would stick with 460's as it will make every aspect of driveability better, and again, will never be pushed beyond its limits on a street port.

The wideband question has been covered well so far, so sorry for the off topic-ness

JustJeff

iTrader: (13)

Bring on the flaming of the noob....

Horsepower at the flywheel...I simply took the Mazda listed hp of..um..I believe 205. I've got a mostly stock JDM S5 swapped into my 89 convertible. Only differences from stock are a 3" RB exhaust, custom intake (4" bent pipe) with an Apexi cone filter and an FCD. Oh and I've got no air pump and a dual alternator pulley, but I doubt that adds any hp since I've kept my P/S and A/C.

Future upgrades:
1. wideband A/F gauge
2. possibly upgrading injectors and fuel pump...fuel pump is the N/A.
3. maybe a turbo timer or/and some other additional form of engine management

I'm also sorry about the offtopic question..I probably should have started a new thread.

classicauto

iTrader: (3)

Best bet is searching the FAQ, I believe its got a lot of "must have" mods for starting out.

There should be no "I'll upgrade the fuel pump eventually" if you're running a turbo car on an N/A pump. They have greatly different outputs, do it now.

Other then that it sounds fine.

RX7freak08

So basically what people are saying is. The 550cc are only good for 200 or more horses. The 460cc is still good for the street port. Now there is a tuning shop right down the street for me. Will my car be driveable to get it there for tuning. If so then 460cc are fine.