Greetings,


I am running 13-14 lbs of boost right now.

Do I need to upgrade the fuel pump ???

Injectors duty on the PFC hit 96%.

Thanks

Serge

 

In my opinion, anything over 12 you should have an upgraded fuel SYSTEM. That means everything should be upgraded, injectors, pump, rail, the whole works.

If you are thinking 14 or anything like that, also look to upgrade the fuel itself, once you get that high you might want to start looking at some racing gas.

Here's a link to: Extreme Fuel System Upgrade:

http://66.216.67.51/product.asp?0=211&1=333&3=578

Check it out...

 

I think upgrading the whole system on just stock twins is overkill, if you want to run 13-14psi I would upgrade the fuel pump and install a rising rate FPR.. you can increase your amount of fuel by up to 20% by using rising rate. Just my 2cents

Matt

 

1300cc injectors in the secondary rail with an upgraded pump and appropriate retuning on the PFC to account for the bigger secondaries should knock inj duty cycle when running 13/14 psi back down to the low 80% range.
My 2 cents,
Crispy

 

I have the same concerns, which lead to my
upgraded fuel pump.

I am running 13-14 psi @ 96% duty cycle still,
on my PFC, and I upgraded the Fuelpump.
I think my PFC is running really rich which is
leading to my high duty cycles. Wont know
for sure until I tune on a Dyno with wideband.

I guess I gonna have to get some 1200
secondary injectors. Or should I just get a
new Fuel rail?? Not sure.. anyone have insight?

 

Click here for Wade's site and go to the Fuel section in the middle, lots of good info

 

 

I'm running 15 psi right now...850cc primary/850 cc secondary and my injector duty is around 79% to 85%. 1300cc should bring it down WAY lower than that.

 

96% injector duty

injectors depend on your FUTURE plans. 1300cc's will do best for most people's application.

 

 

The duty cycle is the percentage the pfc is throwing in. It has nothing to do with the fuel pump, etc... Its calculated from the maps. Upgrading pumps, rails, lines, injectors, etc won't change the duty cycle percentage. If you throw 1200's in and don't touch the pfc, it still is going to say 96% because that is the percentage it draws from the maps. The only way to lower the duty cycle is throw in larger injectors and set the pfc correctly.

Hope that makes sense...

-Matt
'93 Touring
'87 Turbo II

 

I have a COSMO pump that I bought not too long ago from the RX7store.net if anyone is interested. This would be a direct drop in replacement for your stock unit.

New and still in the box.

http://66.216.67.51/product.asp?0=211&1=260&3=545

http://66.216.67.51/images/products/...m/fuelpump.jpg

Just bought a HUGE A$$ HKS T51 R KAI Single turbo and this guys is just a little too small for me now.

Will sell for - $300
and I'll ship it to you within' the US of A for FREE !

PM me if you want it.

Here's the write up if you're fingers are too lazy to click the link above ...


The stock fuel pump was designed to handle the fuel requirements at near stock levels. Once you've upgraded the car to a point where more fuel is required, you'll need to address this weak link in the system. We use a special, high flow fuel pump, made by OE manufacturer NipponDenso in Japan, which exactly replaces the stock fuel pump. This unit takes less than 30 minutes to install, doesn't make any more noise, is extremely reliable, requires no cutting, welding, new lines, or anything else. It's also the highest flowing unit we've tested that doesn't make the car run rich at idle, unlike other "bolt ins".
The pump has been tested to support 500+ RWHP (at 36-40 PSI base pressure) and is a good upgrade for those with upgraded ECUs and/or those adding additional injectors.

 

I should HOPE that they would change the injector sizing on the PFC! That's like the FC guys throwing in 720cc in the secondary's and then tuning with the S-AFC! Doesn't work like that....

The way the PFC works is simple. For the some of you who don't know how it works, here's a quick class... If you look at the base map(using the datalogit equipment), you'll see a bunch of numbers. These numbers represent the amount of time the injectors open up at a given rpm vs. boost. The fuel map is what is used to fine tune the base map. You take the base map block, and the corresponding fuel map block(same rpm vs. boost) and multiply the two. This will give you the time(in ms) that the PFC opens the injector to deliver fuel. Simple right?!

 

Question: so how does simply switching the injector sizing in the PFC from 850's to 1300's account for the lower duty cycles? If what you
are saying is correct and the fuel maps indicate the amount of time the injector is "on/open" then the fuel maps would also have to be changed to account for the bigger injectors too? Or am I missing something?
Regards,
Crispy

 

It would lower your injector duty's because your injectors would only have to work at a lower percentage to obtain the same fuel delivery. Here's an example...If you took 850cc injectors and ran them at 100% injector duty, then took 1300cc injectors and ran them at 65%, you would get the same amount of fuel, but the 850's would be maxed out, while th 1300's would be in the safe zone. The 850's can ONLY add 850 cubic centimeters of fuel per second while the 1300's can add 850 + an additional 450cc. The fuel map does not have to be changed. Just the injector size and the injector timing has to be changed.

 

Yes this much I understand. The question was directed at what the PFC is directing the injectors to do. You said the fuel maps are telling the injectors how long to "open up."
Ok.
If the fuel maps are saying to the injectors stay open for 0.25secs (hypothetically), changing the injector size from 850 to 1300 will increase the amount of fuel added for the same time duration the injectors are "open." So what is the PFC doing to the fuel maps to tell the, now larger, 1300's to stay "open" for a shorter period of time to deliver the same amount of fuel as the 850's? Does simply entering the new injector sizing in the PFC shift all the fuel maps?
A piece of the puzzle is missing.
Regards
Crispy

PS. you're editing your posts faster than I can
respond
I'm still learning what all the info in the PFC means (bear with me...it woudl be appreciated) so what part of the fuel map is the "injector timing" I thought this was the fuel map as injector timing is what dictates how much fuel is added?

 

...You know...I never thought of it like that....Now I'm

 

injector timing. go to settings, and then to injector. pri and sec will have(if left stock) a 0.00ms. You have to change the primary's to .04 offset and 64.5%(this value I don't have a clue what it is).

That setting is to allow for the injectors to compensate for being bigger, meaning it takes longer for them to open/close and the PFC has to compensate for this. I'm not sure "how" this works, but that's my limited understanding of it.

 

Yes, that is correct. The injector size is used in calculating all the maps. When you change it via the PFC, it affects the entire map.

-Matt

 

Ok now this seems to making more sense. Is this offset and % change a single change or does each one of the cells need to be changed...gawd I hope not!

Crispy
PS thanks for spending the time to walk me through this. I'm in the same boat...12/13psi boost 90%+ Inj. duty cycle so 1300cc secondaries on are my "needs" list

 

Matt...excellent...The answer I was seeking!

Crispy

 

Matt,

Thanks Dude...It's almost midnight over here. Brain not working correctly, and I was starting to confuse myself

 

Wade's site covers PFC injector staging. All map boxes are based on total ms of fuel needed per shot of primaries. once the secondaries kick in, the total ms on map is reduced, based on the secondary size used and programed in.

the 64.5% noted sounds alot like the stock ratio of 550/850= 64.7%

Original poster at 96% dc, 13-14 psi. going with 1100 cc secondaries (SR), and inputing this ratio in the PFC, should allow more safe delivery of same maps, with new max dc at:

96x(550+850)/(550+1100)=81%

a check of rail pressure will let u know if pump is keeping up. current map should be dyno/lambda verified.

running higher regulator pressure with oem pump is not a good idea at 13-14 psi.

 

Kevin,
so should the new ratio programmed into the PFC (if using 1300's) be 550/1300 = 42.3% (0.42)?

'tanks
Crispy

 

"should the new ratio programmed into the PFC (if using 1300's) be 550/1300 = 42.3% (0.42)"

sounds right, but I'm not sure on the exact PFC method. I'm sure it's in the PFC section.