Hi Everybody,

I've been looking around for the right kind of forced induction for my little black Fit (2008 Sport M/T) and I've decided on getting Kraftwerks base supercharger kit : ). I'm looking at getting Kraftwerks Intercooler kit and possibly their Fuel Injector upgrade. I'm wondering if anyone has any knowledge of the benefits/gains of installing the fuel injectors. As well as some suggestions as to what else I could do to increase the performance of my Fit. Your guys' help will be greatly apprectiated.

P.S. I'd prefer to keep it in compliance with CARB standards, but if you have any upgrades that could be in a gray area or an easy fix I'm all ears ; )

 

to be honest, i wouldnt put FI on any car without upgrading injectors. i guess krafterwerks foudn it safe enough with their base kit, but i wouldnt want to be running my injectors at a constant 100% (or close to it) duty cycle.

so there is not really a "benefit" from larger injectors, its just somthing the engine needs...more fuel.
if you get the kraftwerks kit...injectors, header and full exhaust will help gains. theres not much else to do besides that.

 

Thanks for the info NIGHTHAWKSI, the fuel injector kit from kraftwerks has 195cc injectors, would that be a sufficient upgrade for the kit?

 

You don't really need the fuel injector kit unless you're going to remove your cat. The base kit was tuned in mind of a header and or exhaust. I do recommend getting the spark plugs they sale.

 

The colder heat range plug should be mandatory considering our compression with the addition forced induction... and why would the catalytic converter be a concern with new injectors?

I would get the injectors just for the margin of safety with IDCs. 185cc/min is not a lot of fuel.

 

[quote=DiamondStarMonsters;924443]why would the catalytic converter be a concern with new injectors?
quote]

By removing the cat and putting in a test pipe, it leans the AFR, so to compensate, larger injectors are needed.

When I had the base kit, I had stock injectors and stock plugs and it ran fine. And when I went to get it dyno'd, the dyno operator noted that it was running a bit rich. Later on, I talked to Oscar Jackson about it, and he said he tuned that way so if a customer has a header and/or exhaust, the AFR would still be safe. But of course every car acts a little different, so here are my 2 suggestions:

1. Ask the guys at Kraftwerks, and you'll get the answers straight from their mouths.
2. Do a before and after dyno (it's always nice to see the gains with the supercharger), and look at the AFR, and see if you need the injectors or not.

 

[quote=Wytt;924452]
Our ECU adjusts the fuel trims (STFT, LTFT & CombinedFT) to compensate for that extra flow (less restriction) automatically. It is going lean because they are simply running out of injector (IDCs >90%).. You however were running rich because you were still within the range of flow (due to the restrictions like a stock cat) where the ECU still had enough injector to use extra fuel for combustion chamber and charge cooling.

With the extra couple lbs/min an I/H/E would allow at a given psi/cfm it apparently pushes us past what the ECU can reel in on the OE fuel system.

Not because of something involving the cat operation, which tells me that merely going from the 12-13lbs/min we see NA to 17-18lbs/min with the S/C that the margins we are operating with on the 185cc/min injectors with only 5psi on that compressor are very tight.


That suggests that you can potentially run out of injector on a very cold day with the OE Cat on and the 5psi pulley on the base kit compressor.


You can also buy a larger diameter/free flow catalytic converter to keep airflow up and stay compliant @ >2500 rpm but idle emissions will suffer and they take longer to heat up unless you are intentionally burning hot. Better than nothing I guess.

So even the base guys would be better off going bigger. The upgrade injector is still so small they aren't going to be much different from OE in terms of dead time or voltage sensitivity, even under boost.

Though you can help your IDCs on any injector by running a fatter ground strap and power line (10ga.) on a seperate relay to the fuel pump and use the stock trigger wire, especially for the 10psi guys. Our stock pump probably doesn't keep flow up too well under boost even 5psi, when base pressure is going to be atleast 3bar (43.5psi) and the last thing you want is WOT voltage drop, making the pump fall off flow and consequently your IDCs go through the roof >100%.

Ask me how I know The theory is pretty straight forward, but I can give you a personal learning experience on why bigger than "necessary" injectors are almost if not always a wise investment. Just get Flow Bench Paired injectors!

I melted two exhaust valves on the stock 450cc/min units in my old Talon after an accidental spike to >20psi when the factory wastegate actuator rod got snagged on an aftermarket heatshield and pegged the 30-0-20 gauge I had at the time and ~34.xlb/min airflow...

When I looked at the datalog trying to figure out WTF happened afterward I saw my logged voltage drop to the mid 11v range and my IDCs were in the >110% range.

A pump rewire, bigger battery and a slight bump in base fuel pressure (from 43.5psi to 45psi) and I was maxing out in the high 70% IDCs at 17-18psi boost even on cold dry winter nights pushing 32-33lbs/min daily till it was time to upgrade again.

So long story short, when affordable, the bigger injectors would be a good insurance plan.

EDIT: To try and illustrate why a margin of error is important.. here is a graph from the "small" Walbro 190lph in-tank pump that feeds my "big" 420lph in-line bosch pump.



For comparison the Talon's factory pump was originally rated for 90lph @ 12v with base fuel pressure at 43.5psi and designed to see as much as 60psi under boost on the stock turbo (FPR has to be 1:1 for forced induction applications) This was on a car rated for 215hp/205lb-ft stock. Or double what we make

I would venture so far as to suggest our stock pump is probably equal or less than 70lph capacity and likely not designed with boost in mind and similarly voltage sensitive as many pumps tend to be, and coupled with OE injectors that are close to the limit already that is a risk I wouldn't take on my $16,000 car and $3,600 S/C kit.

Other easy solutions to causes of high IDCs are replacing small stock fuel lines, fittings, and restrictive filters, which can be easy to fix with some adapters for the tank and rail, a couple -AN fittings and braided PTFE lines. Then if you go bigger in the future you can then easily install a bigger in series pump to help with supporting higher boost and greater airflow.

 

lol. very techincal there.

didnt even read it all, but mentioend earlier the krafterks kit comes with 195cc.
IMO, thats hardly an upgrade from the 185cc stock. i would want 270cc or better.

 

Let me just say this, the Kraftwerks base kit is a complete kit and not a "you tune" kit, if bigger injectors were needed, they would have put it in. Now they have it as an option for those who removed their cat. When the kit first came out, they recommended the injectors for any exhaust modification, but after several customers reported problem with them, they stopped selling to reevaluate them. At the end, it seemed the ones that needed it, were the ones with a test pipe.

Again, as a former base kit owner, I didn't experience any issues with kit on stock injectors. As the name says, it's a base kit. It's not outputting massive power, it's giving the Fit a little more "umph". Making it not feel underpowered but making it feel just right (a power level that Honda should have made stock).

 

I am aware you cannot tune the KW kit.

All I am expressing above is that if the margin for error is so tight that removing your Cat frees up enough airflow that you can max your injectors to the point you are running lean and the ECU cannot correct for that, then it would be a nice insurance policy to have the extra flow available.

I don't know what the climate is like where you live, but a drastic change in air temp can allow as much or more air in as a simple Cat removal (because the charge is now denser) which should only amount to another 1-2lbs/min. Which is not a whole lot.

Around Chicago and the suburbs -5F or -10F is not unheard of. Besides most tuners and injector manufacturers will tell you >80% IDCs is asking for trouble.

For the OP, whos profile says he lives in Yuma, where it can see ~25* F at night in the winter, it wouldn't be a bad idea. Especially if he has any intent on any additional I/H/E work in the future.

 

The 195cc injector kit is for cat delete Fits. Anything larger than a 195cc on a stock ECU will throw a CEL. You will see not see a benefit with 195cc injectors on a stock exhaust/stock cat car.

-Oscar Jr.

 

Injectors alone do not increase performance obviously. But you do have the benefit of your fuel system no having to work as hard. Is there any discernable difference in deadtime/voltage sensitivity with the 195cc/min units?

What are the actual IDCs and target AFRs for the 185cc/min injectors on the 5psi pulley for the Fit compressor? What are the largest injectors the Hondata/SuperCard unit will allow or adjust for on the 10psi pulley?

Is there a fuel or spark cut to contend with beyond a certain air mass threshold?

 

Hi,

I've got another question for all of you gear heads out there: would it be beneficial to get a header with a stock Fit or would I really only see benefits once it has been supercharged? Thanks

 

Depending on how the header tubes are designed it could shift your torque peak and the bulk of the area under the curve to the right (towards the higher end of the rev range) and create less "streetable" power (torque), like part-throttle and low rpm situations, but more peak HP.

The supercharger will help a lot with that though anyways. I would also definitely spend the extra couple hundred bucks on the bigger injectors if you are going to do more than just bolt the 5psi kit on.

But if you spend lots of time at WOT then go for it, a free flowing exhaust helps all forced induction systems, but there is no lag to worry about with an S/C, so the results will not be as dramatic compared to a turbo (quicker spool = more torque sooner)

 

RDX injectors is the way to go IMHO. Cheap and I guess they have a good spray pattern. $.02 worth