why are stock injectors ok for 160+ whp NA applications where it is not recommended for 150+whp forced induction?

 

because you're not forcing more air into your engine, more air = more fuel...right?

 

i figured if you are making 150 hp NA or turbo, you are consuming the same amount of air and gas. maybe the extra air compensates for slower air flow, and lower compression ratios?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by duh blacksheep &raquo;</TD></TR><TR><TD CLASS="quote">i figured if you are making 150 hp NA or turbo, you are consuming the same amount of air and gas. maybe the extra air compensates for slower air flow, and lower compression ratios?</TD></TR></TABLE>

I would think the same thing. Just because the air gets pushed in there instead of pulled shouldn't mean you need more fuel.

 

first, just as a note, many NA engines use larger injectors. lots of times 180hp+ NA engines also use larger injectors.

second, you can up the fuel pressure on stock injectors, but they may become unreliable and stop working. BOOM goes engine for instant lean-out.

now, for the reason an NA 150whp engine uses stock injectors and a 150whp turbo engine doesn't:
NA engines are more efficient at making power than turbo ones. that is to say, that an NA engine producing 200hp will use less fuel to make that 200hp than a turbo engine would need to make 200hp, everything else being even. this is called the Brake Specific Fuel Consumption. it's a measure of how efficient an engine is at making power, not how efficient it is a going around town. NA engines just require less fuel per HP, plain and simple. this is on average, BTW. not ALL turbo engines take more fuel than a given NA engine to make each HP, but generally speaking, this is true.

satisfied? understand?

 

ok, i think i got it now thanks!

another guestion off topic:

turbo cars tune their a/f ratios at 12.5:1 more or less, what about NA cars? is it the same?

 

no.

since Honda did not design their engines for turbo, and because gasoline engines in general do not cope well with detonation, turbo cars are sometimes tuned for a rich a/f ratio to prevent any conditions where they would lean out and cause detonation, possibly destroying the engine. detonation is far worse for a boosted engine than a NA engine, though, and many NA cars are tuned for a leaner ratio, like 13.5:1 or so in order to make more power. running rich takes a away power, but adds a little safety. for an NA engine, this little power is a high price, but turbo engines make so much that a few HP is well worth some safety, as turbos are only reliable when tuned well. still, in the hands of a good tuner, a boosted engine can run 13.5:1 as well, but more care must be taken that under no circumstances will the a/f lean out. the dyno isn't the same operation conditions the car will run under on the street, so the tuner must be careful about how lean to tune it.

"leaner is meaner" is the saying; leaner (up to a point) makes more power, but also cause the combustion to be much hotter, which can damage an engine over time. usually, an import engine with at least 90% volumetric efficiency, which includes most fuel-injected Hondas for the last 15 years or so, can successfully make more power by leaning out until about 13.8-14:1 or so. this is the leanest it can get before losing power, although often a richer mixture will make more power even on NA engines. i usually tune mine for 13.2-13.5:1 after 5k rpm. before that, i let it go between 13-14:1 depending on what works best (and what i have time for).

 

interesting.

so factory tuned cars are stoic 14.7 when cruising cause they're not mashed on the gas, and when they are floored, it is probbaly a little richer than stoic?

thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by duh blacksheep &raquo;</TD></TR><TR><TD CLASS="quote">so factory tuned cars are stoic 14.7 when cruising cause they're not mashed on the gas, and when they are floored, it is probbaly a little richer than stoic?thanks</TD></TR></TABLE>
false. all EFI cars fluctuate between rich and lean very quickly. the engine's sensors tell it how much more fuel it needs or how much less it needs, and it corrects, and it's constantly correcting, thus the fluctuation. when in open loop mode, which is when you have it floored, it will not fluctuate. rather, it will run on a preset map of how much gas to give it. it will run a bit richer than would be stoichiometric if gasoline were 100% tri-methyl pentane. this is why when you put aftermarket parts on your car, it won't run right and make power to its full potential until it has been tuned. even a car with just a header and exhaust will make more power with some tuning.

any more questions which have answers much more in-depth than you thought? i'm here all week! haha. seriously, you have good questions.

 

the more you write, the more i understand. thanks for you time.

yeah, these kind of things i never really quite got, so i want it squared away.

the reason i ask is that my turbo timer (apexi) has a built in o2 sensor volt reading i never really cared to look at. It shows .7V-.85V when im floored at 2krpm but start to drop to .5 for 4krpm to 5.5krpm, and then starts to drops off even more down to .37V by the time i hit redline. Ive had the greddy kit for over 2 years and driven 45kmiles. It kind of worries me, so im in the process of changing over to uberdata. I dont plan on boosting more, i just dont like how the a/f is leaning out.

 

You have to remember Hondas are economy cars and are built for 10 year durability. They weren't built for boost so every thing is designed for good gas, mileage injectors included.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fred 150 &raquo;</TD></TR><TR><TD CLASS="quote">You have to remember Hondas are economy cars and are built for 10 year durability. They weren't built for boost so every thing is designed for good gas, mileage injectors included. </TD></TR></TABLE>
^crap

don't worry about your greddy kit. the reason it includes larger injectors is exactly like i said. larger injectors means less fuel pressure which means not worrying about injector failure. you're all good, man, and enjoy it. greddy makes a great kit, done the right way.

 

mine doesnt come with injectors, intercooler or FMU, just the blue box. =/
but its a cheap kit, so im not complaining, still a good foundation to build on i suppose.

 

get the injectors, intercooler is a good idea, and use the FMU. i think the Greddy kit is very sound if you don't have many other mods. if you have cams or pistons or something, you'll need it retuned, but if you just have cam gears and exhaust you might be able to get away without retuning.