Rev,

You will not need to upgrade your fuel pump until around 400 hp - as long as you run larger injectors and an appropriate control system. I'd suggest visiting the Hondata site and looking at their fuel pump test. At 50-55 psi (about what an S2000 runs) the stock Civic Si pump will support 350 hp. The S2000 pump has more capacity. If you run an aftermarket engine control system and big injectors, you can maintain stock fuel pressure (+ boost pressure) and thus the capacity for much more power than stock w/o upgrading the pump. As proof of this concept, I'm currently making 80% more power than stock on my boosted CRX using the stock fuel pump.

Should you plan on getting near the limits of the stock pump, the Kenne Bell boost-a-pump is an inexpensive (about $150-$200) mod to increase output of the stock pump slightly by boosting voltage to the pump under boost. Keeps additional wear and tear down on the pump while eliminating the need to put in a new one.

Good luck!

UL

 

Thanks for the info. A friend of mine is telling me the calculator on RC's site is known for recommending significantly larger injectors than necessary. Would I really need 550's? I'm looking to have two setups... 6 psi for the street (91 pump gas) hopefully about 315 rwhp. And a race gas setup with 8 psi (hopefully 340-350 rwhp).

Shouldn't 440's be enough for this?

Also, does anyone know of a good cast turbo manifold for the s2000? I know top fuel makes one, but isn't it expensive and designed for a really little turbo? I want to be able to do this right, but I also want to do this on a budget.

 

What is your concern with going to the 550cc injectors, switching to Low Resistance? Cost isn't much of an issue, so I'm assuming it's not that.

 

I'm concerned about getting it to idle smoothly.

 

EMS can control the injectors...you could have 1,600cc injectors and tune them down to work with a NA S2000 (from what I've been told).

 

I've heard similar things in the past as well... but I've also heard in actual use big injectors are still a problem for idling. It's like trying to water the flowers in your yard with a fire hose... Yeah, if you can turn it on for just a split second it would be fine (except that the pressure would blow all your flowers into your neighbor's garden). With big injectors, because the flow rate is so great, it is hard for the ECU to time such a quick burst to give the tiny amount of fuel used for idling smoothly. It's just easier to idle on a smaller injector with a longer pulse duration.

But I don't know that 550's would really be a problem.

 

Seems like a good point. I know that a local tuner / my mechanic wanted me to go with 650 injectors (custom) for my car to be safe...550 was the recommended minimum.

 

Rev, I use 450 cc injectors on my SC CRX with a Zdyne. Considering this engine is 20% smaller than an S2K the relationship between the 450 and 550 cc injectors is about right. I have no problem idling (or passing emissions) with the 450cc units (mine are Mitsubishi OEM injectors).

UL

 

Oh, the problem you can often come across with the RC injectors is that they tend to use a very narrow spray pattern that doesn't seem to atomize as well as the pintle type injectors used by most OEMs. The disc type that RC uses have many advantages, but good idle characteristics may not be among them. If you could find some other OEM injector (like my Mitsus, which need resistor ballast) that fits you might be better off (and get them cheaper too). RC can often help in this area as well.

UL

 

What the hell does resistance mean?

How fast can RC Engineering make injectors for meeee??

Thanks

Chris