If I was to upgrade my fuel pump and get 550 or 720 cc secondary injectors and an S-AFC to control it, would I see any increase in power? I'm just not sure if I would have enough airflow with a K&N Cone to maintain a decent A/F ratio to make power out of the injectors.


Thanks,
Phr00t

 

Why not stay with the stock injectors and use the AFC to lean them out a bit? That would give you a small boost in power because N/A's by default run rich. At least, all mine have so far.

Another idea might be to get a header and exhaust setup. Racing Beat makes some good quality stuff, but you are going to pay for it. Getting a header and a good, free-flowing exhaust would probably be the best method to get some more power.

 

Thanks for the ideas. I was planning on doing the fuel upgrades first, because they cost a little bit less than a full blown exhaust setup. But I still have the question, will bigger secondaries and a fuel controller give me more top end power or will it just richen my mixture because of lack of air?

 

dude, you dont need bigger injectors, your car already has too much fuel. you COULD get an SAFC and lean it out a bit, and you will gain more top end. You start needing bigger injectors when you really lay down the mods (including a port job)

 

Thanks, that was my question

Phr00t

 

actually, he most likely still wouldnt need the injectors. you can do about every bolt on and still not need the bigger injectors. the exhaust will probably yield the most power. the stock cats are likely dead if its higher mileage. my car didn't make power above 5400rpm until i replaced the exhaust. it ran rough and sounded bad. you can get used exhaust pieces for much cheaper than new.
whats your car like now? mileage? any stock parts replaced? anything? hows it run?

 

I've never had any problems with it, it runs steady to redline, idles at 800 steady, only problem is a 1500 rpm idle until it warms up, which I think is normal anyway. Everything looks stock.

250,000 kilometers.

 

Even with my full-blown RB exhaust and cone intake, the guys at RP in Dallas told me if anything, just to get a T2 fuel pump, that anything like a walbro (or their competition pump) would be WAY too much for our n/a's.

 

As everyone says, the stock fuel pump is more then enough.

 

A properly functioning factory setup on an N/A will flow enough fuel for 220-230HP and still not exceed 80% duty cycle on the injectors. Now most of us don't have N/A's that are close to that so we are all safe. Just get your injectors cleaned and verify your getting good/constant fuel press and save your money for the AFC or exhaust.

 

I have a S4 N/A with 117k and have added a K&N.

A couple of months back I removed the cat and put in a bypass pipe. That gave me way more horsepower thru the whole power band. But it did have reprocussions. Soon after I removed the cat, I noticed that I could get a small amount of flameage. It was fun for a while. It did not take long for me to tear apart the aging mufflers with this trick.

If you, like me are looking for a street port job down the line I would look into the full racing beat T2 system. It will give you HP gains until you get the port job, but if you port your motor you might have to replace the exaust system because of the increased power.

IMHO planning ahead for stuff like that is a good idea

 

A full racing beat T2 system? I hope that was a typo. A full exhaust from RB can't handle a streetport? That's news to me.

 

Uh, where did you get these numbers? People have dyno'd their heavily modd'd na. And it totally leaned out to around 15:1 in high rpm, and i doubt they were hitting over 200 hp. From what ive read around, once you hit 190rwhp, you start running into fuel problems. If the 460cc's were fine to 230rwhp, they couldve used them on T2's because they make 200fwhp from the factory (flywheel horsepower)

 

15:1 AFR = not good even on a n/a, 13:1 is what n/a people tune for usually.


But yes I agree with you, I seriously doubt a n/a's fuel system is good for up to 230rwhp, that just doesn't sound right at all.

 

Small correction then. I never said 230rwhp. You said that. I should have said 220-230fwhp which will translate to 200+/- rwhp. Yes at 80% duty cycle your basically maxing the injectors out while still controlling them and it would be better to go with 550cc injectors at that point. As for where did I get the numbers? www.sdsefi.com has some calculations to help pick out fuel injectors based on the expected HP of the engine and the number of injectors to be used. An inadequate fuel pump can also cause a lean condition if your maxing your injectors out. Remember many of use are still using a fuel pump that could be up to 16 years old. Without knowing what the fuel pressure at those higher rpms its all speculation.

 

yes, which is why its better to fix a part thats not working correctly than cover it up with other parts (ie bigger injectors). though at one point they may actually be needed, which is another story altogether.

 

Back on topic.

Best bang for buck mods for NA:

DIY intake manifold porting
header
weight reduction
redline MTL
LSD swap
Tires (not 17" wheels)
Shielded cone filter intake (make ur own cold air box)