I have a FD with cleaned up stock ports a BB 62-1 and other misc bs.

Now I currently have stock injectors with supra fuel pump.

On my haltech I'm projected to run about 12ms on secondaries @ 16psi and about 10ms on primaries.

I haven't put in my 1 bar spring (14.7psi) and just run 10psi

using this link
http://www.stealth316.com/2-calc-idc.htm

and a 8000rpm redline a 12ms equates to about 80 percent duty.

80 is the number i do not want to go over for saftey reasons.

Now on a rotary the injector has to fire 3 times per revolution. But the rotors rotate 1/3 rate of flywheel. So I believe this will still work fine on duty cycles on rotary.

now I'm sitting about 11.2 afr at 10psi with 7.5ms primaries and 10ms secondaries.

Now assuming i'm not in the efficiency of the turbo and will have to up my primaries to 12ms @ 16psi.

based off this site
http://www.rx7.com/cgi-local/3rdgencalc.cgi

I should be maxing my fuel at 338hp.

That's flywheel hp or about 83 hp more than stock >.>

Most ppl get larger enjectors when they go single turbo. I do not plan on going over 1 bar ever (mostly street car).

Based off this information i'm lead to believe stock injectors will be fine.

I believe this is partly due to the fact that stock was abouty 60 percent duty cycle.

Today I will throw the 1 bar sping in and do some tuning and see if I can keep fuel up but I think i should be able to unless this turbo really gets happy.

I think alot of ppl underestimate the stock fuel system.

just posting to see if i get any comment/concerns or if i missed anything.

 

I think it is very unlikely that the stock injectors @ 80% duty cycle will be adequate for a 62-1 at 15 psi. I'm fairly certain you will run out of injector.

-Max

 

You need to put this in the correct forum, like the Haltech sub forum.

 

The new turbo is capable of pumping a lot more volume of air at 10 psi than the twins.

 

Listen to Max on this one. He's been around the block a few times.

Why stop at 80%? You can go higher as long as your injectors are clean and up to spec. On paper, 95%-100% IDC you should have enough fuel (with increased fuel pressure) for what you are looking for. Personally, I would feel much safer running my injectors at 100% as opposed to "trying" it at 80%.

 

100 percent means they are are open all the time and that is not idea for many reason.

 

wtf this is injector duty cycle subject not a haltech. Perhaps i should as a boost related question and make it a 3rd gen question?

 

100%? wtf?

 

Think about a light switch:

Is the switch more likely to fail from staying on all the time or from switching on/off many times a second?

 

I would have agreeded with you based off of what i have read prior to doing my single but now i'm not so sure while tunning and doing calculations.

I'm just curious if anyone have ever actually attempted to figure out if they need injectors as opposed to just upgrading and following others.

I only cleaned up the ports when i rebuilt the motor.

Yes i am aware of the 62-1's potential and based off what I have read should max the injectors out easily by now. I guess i'm not seeing it.

btw it is making good power all though not dyno'd it's plenty more than stock.

 

............................... your injectors are firing when you intake is close....

you have no head room either

100 percent is very bad

thus why stock is about 60 percent

 

Yes, you have no room for growth if you are at 100%. However, if you have a good A/F and you are at 100%, then there is no problem.

https://www.rx7club.com/showpost.php...43&postcount=7

 

I 100 percent disagree with you as do most scources (haltech included)

The tables and graph below show the point at which the injectors will reach 100% duty cycle.

It is not common for this to happen but the potential for damage under these circumstances is strong so care should be taken to check this factor.

Maximum Injection Time (in milliseconds[ms]) =
(120,000 x IgnDivideBy)
(Rpm x No. Cylinders)

Refer to Appendix D for details on how to increase fuel supply. As a
general rule of thumb, injectors should not run beyond 85% duty cycle.

 

Explain this "damage".

 

blow motor

you injector will get too hot and fail being constantly held open.

all bad things will happen........

intake temps drop 10 degrees lower..... you need more fuel... you go to 12's afr under load......... you blow b/c you can't go 110 percent.

 

You should read Wade's post in the link I provided. However, I have yet to see someone's injectors fail from running over 80% duty cycle.

 

If your a/f's get lean @100% duty you can turn up the fuel pressure.

Also, we never have seen an "overheated" injector from being run static.

The turbo Buick guys run static all the time drag racing, no injector damage either.

Joe Geiman

Gasoline Alley Fuel Injection
Indianapolis, In

www.lindertech.com

 

I read a bit of that link

"Safely" is a relative term, safety doesn't have as much to do with the duty cycle of your injectors as it does everything else like charge temp, a:f ratio, timing. PFS is right on this one, think of PFS whatever you want (good or bad, I couldn't care less) but an FD can certainly make 400 rwhp with the stock injectors, it has been done.

I doubt I'll make over 400rwhp @ 1bar. I just wanted to say that the stock injectors from what I have seen are good for a good chunck of power if properly used. I still would not go over 80 percent duty and i think 400ish is around 80-85 from my projections.

 

Absolutely, but people don't talk about that around here.

 

http://www.rpmoutlet.com/03stacker.htm

It's unrealistic to establish the fuel flow to the engine based on an injector operating pulse time of 100% (wide open all the time). This formula uses an injector operating cycle based on 80%. Some full race engine management systems may operate at 85-95% duty cycle, but doing so for some time increases the likelihood of overheating the injectors which may cause irregular fuel rates or a decrease in low rpm operation.

It happens- I'll say not often but I would rather not take that chance

 

Buicks are not as sensitive to afr's as rotary.

I haven't got caught speeding lately......... guess it can't happen tho...

yes turning up pressure will fix that but I feel that is a band aid fix imo.

 

I feel dimished atomization will accour with greater preassure and more strain on the pump. Of coure it will vary with amout raised.

That is a whole different debate............

 

Your injectors are the devices that meter fuel into the engine. Once the injector goes to a 100% duty cycle it is no longer metering fuel, it's merely open the entire time and the amount of fuel delivered is then solely based on fuel pressure. Fuel systems are not designed to meter fuel in this way. If they were you wouldn't need injectors in the first place.

I wouldn't worry about 100% duty cycles harming the injectors, I'd worry about them causing fuel to no longer be metered accurately.

If everyone else jumped off a bridge would you do that too?

 

You are proving Wade's point.

 

my point exactly.

I only added the over heated injectors as an additional concern. Obviously insufficient fuel would be a greater concern.