What's the limit of the KA24DE 270cc injectors, 200hp?

[alkemyst]

Maybe I am wrong and yes I do know shooting for a max HP NA car is going to cost way more than most swaps and doing the KA-T.

I had a car issue where I needed to order new injectors...when I got them from Deatschwerks they had a little printout that showed the max power at .5 BFSC/max duty cycle was 198HP. So just that alone tells me I really can't expect to go much beyond that. Some have said the KA24DE's BFSC is more like .40-.45 though so that shifts the power up. I don't really know much about how that number is figured out yet.

I started putting it together and thinking why many really can't break the 200hp barrier even with hi compression and all bolt ons is due to the stock injectors topping out around 200hp. This seems to be the 'holy grail' out there for power in the 240 world while their are crazy builds making closer to 300HP (race idle / fuel).

Even if you had a BFSC of .4 the stock injectors just run out of steam around this limit.

Many do run tunes at that level, but I haven't seen many upgrade the injectors until they go turbo. Even well tuned the injectors seem to be the weak link once most bolt-ons are done.

The calculation for the people that don't know is:

((HP*BFSC)/(# injectors * duty cycle)) * 10.515 = CC needed

This equation is not written properly in many posts, when I was reading up on it it was confusing.

A the following BFSC's, the limit of HP @ 90% duty cycle at the crank and wheels should be:
(all rounded)
BFSC CHP/WHP
.50 185HP/152HP
.45 205HP/168HP
.40 230HP/188HP <--- this is really pushing it.

Maybe I am wrong though, anyone know the real dynoed limits?

[racepar1]

Why would anyone keep the stock injectors on a built KA when they can just pick up a set of SR injectors for cheap? Shit I got 5 SR injectors for $60.

[alkemyst]

idk...only thing I can think of is the extra electronics. You can't just slap in some injectors.

[S14DB]

idk...only thing I can think of is the extra electronics. You can't just slap in some injectors.

You are going to need some tuning no mater what if you deviate that far from stock.

[Dousan_PG]

exactly hahahahaha
seriously
u need some real setup

[crzycav86]

You don't need bigger injectors until you need more fuel with any setup. There are two "schools of thought" for improving horsepower. One is shoving as much air as possible, and supplement with the extra fuel to go along with it. This would be the forced induction route, where you do need to upgrade injectors.

The second method is by improving the efficiency - the NA route. What you do by improving efficiency is reduce the BSFC, so you can make more power with the same amount of fuel. This is done by higher compression, optimizing ignition advance, and reducing pumping and drivetrain losses. None of that stuff requires extra fuel(unless you start detonating), so you don't need larger injectors. Sure, cams and a header increases the air flow, but not by a significant amount - not as much as the most bunk-ass turbo setup making less hp.

[crzycav86]

Another problem with "does anyone know the dyno'd limits" is that it will be different for every engine. and you will never know your BSFC until you dyno it.

If you want an example of the lowest bsfc, talk to that one guy who made 200whp. Ask him what what size injectors he was using, and what the pulsewidth was at peak hp. You will be able to figure out BSFC for his setup.

[alkemyst]

wow this thread got derailed with jibber jabber.

[anti tyler]

I want to bring this back from the dead for a few reason;

#1 being I already had this page open and didn't feel like doing a search for a more recent topic.

#2 being I have in my 2nd s13 that I picked up last year;

A bottom end built KA-t running 7psi on an RS Enthalpy tuned board, with stock injectors.


Now attempting to keep this on track with the OP, I've read over and over again the limitations and so forth for stock injectors. That's fine and dandy, I'm not saying I'm doing this right (#1 I know very little about injectors and duty cycles, #2 remember I got the car this way)

I am running this car in its current state from when I got it. And it has always had the stock red s13 DOHC injectors in it. Maybe someone can clear it up for me why this car is making 297HP 296ft lbs torque on these stock injectors, and yet it's still running rich.