Sale pending, my first project (should be a good one)

[L_RAO]

So I will be making arrangements to but tmbromley's silver NSX this week.

Upon delivery my first project will be to attempt to retrofit the RDX injector onto the NSX.

Overview:
1. The RDX injector is a 410 cc injector, which will support the most powerful of N/A cars. I do not intend to go F/I.
2. It has a better spray pattern, which was necessary due to the RDX being turbocharged. RC Engineering confirmed the better spray pattern, as well as the 410 cc flow rate.
3. K-series enthusiasts have been retrofitting the injectors and making 4 whp across the entire RPM range.

If successful, this should prove to be one of the best bang-for-buck mods out there. Injectors + clips should cost me no more than $400. Plus, it's all OEM Honda.

My biggest issues will be the fitment of the injector, as to how far in the boss will the RDX injector tip stick out vs. OEM.

There are several companies that offer the injectors with retrofit kits for the K, and non-K series. For the non-K, which is what I think the C motor will most resemble, a small metal adapter is necessary in order to have the RDX injector sit better in the OEM fuel rail. All kits come with the clips for a plug-n-play situation.

The other issue is whether the ProSpeed ECU has a function to up the duty cycle to 410 ccs.

I know the AEM EMS has one, but that's a lot of money for a N/A ECU upgrade.

 

[shawn110975]

wow does Tim know your gonna tear his car up?

I would not sell mine knowing whats going to happen to it.

retrofit some injectors from another car to gain what???

a better spray pattern? your not gonna gain any HP from this and does 4hp really mean the difference.

they sell injectors that are made for the NSX. go that route since for some reason Tim's Mint NSX has issues with its injectors. which i doubt

but its going to be your car so do what you want.

save your invoice cuz when you go back to stock injectors your gonna want to return them. LOL

 

[L_RAO]

Shawn,

I respectfully have to disagree...I am not "tearing his car up".

It's an OEM part.

It's been heavily tested in other Honda-to-Honda applications.

What makes the RC Engineering "better" than the RDX? Just because it's RC Engineering?

They are both saturated.

RC offers a 440 cc injector. The RDX is 410 cc.

The RC injector is $100 an injector. The RDX is $40.

 

[Daedalus]

The other issue is whether the ProSpeed ECU has a function to up the duty cycle to 410 ccs.

1) Why would you want to "up the duty cycle"?
2) What %O2 is in the exhaust gas now?
3) Don't think you'll need clips since the NSX doesn't have any, but maybe different seals and spacers.

 

[L_RAO]

My understanding is that all ECUs need to be informed when the injector size is changed.

I'm not upping it just to up it.

 

[scorp965]

There's nothing wrong with retrofitting injectors; the Gruppe M NSX supercharger comes with OEM Prelude SiR injectors, and HKS and SARD sell rebranded OEM injectors for Supras.

The concern is going to be the clip (whether or not a pigtail is required), and the seat with the fuel rail, which you already know. If you need a pigtail, you can use the ones from the K-series conversion, if you need to machine a base, that's straight forward as well.

You should also search here for the "Fuel Pump Resistor Bypass"; the pump in the nsx is supplied different voltages depending on RPM, by shorting the resistor clip it receives higher pressure all of the time, and it's easily reversible. A tuned EPROM, like the ones produced by Prospeed, would probably fully optimize this type of modification.

I am curious to see the gains, try to dyno the car before and after the swap.

 

[Daedalus]

My understanding is that all ECUs need to be informed when the injector size is changed.

I'm not upping it just to up it.

So you're going to install injectors that spit out 64% more fuel per hour than stock, and you're also going to UP the amount of time the injector is open during the combustion cycle? Or should duty cycle be decreased instead?

I would recommend you think this through logically before spending any money. The limiting factor is not fuel. It's air. The engine needs to breathe a lot better before the fuel needs to be messed with. Intakes, headers, ITBs, even porting can do that, thus gains can sometimes be found in them. The stock fuel system is sufficient until forced induction is used.

The ONLY time these small improvements matter is when you have the pedal to the floor. During WOT the car is running safely rich to protect the engine. All the O2 is easily consumed. A better injector spray pattern will not help if there is no more O2. Do a WOT test on a dyno and record O2. I would bet even money it reads 0.0% at peak HP. In fact, chips increase HP by REDUCING some of this richness (and safety), because excess fuel absorbs heat that would otherwise increase combustion pressure.

 

[ncdogdoc]

So you're going to install injectors that spit out 64% more fuel per hour than stock, and you're also going to UP the amount of time the injector is open during the combustion cycle? Or should duty cycle be decreased instead?

I would recommend you think this through logically before spending any money. The limiting factor is not fuel. It's air. The engine needs to breathe a lot better before the fuel needs to be messed with. Intakes, headers, ITBs, even porting can do that, thus gains can sometimes be found in them. The stock fuel system is sufficient until forced induction is used.

The ONLY time these small improvements matter is when you have the pedal to the floor. During WOT the car is running safely rich to protect the engine. All the O2 is easily consumed. A better injector spray pattern will not help if there is no more O2. Do a WOT test on a dyno and record O2. I would bet even money it reads 0.0% at peak HP. In fact, chips increase HP by REDUCING some of this richness (and safety), because excess fuel absorbs heat that would otherwise increase combustion pressure.

The stock 3.0l NSX runs out of injector, long known proven fact. Now the real question is whether you can really make use of the bigger injector without aftermarket ECU and successful tuning.

Personally, I would just get an RC injector that is plug and play (That is what I did). The $240 saved by the Acura injector is pennies compared to what you will spend on all the other supporting mods to go along with your quest. But none of us would be where we are now if we had not tried something new

 

[Daedalus]

The stock 3.0l NSX runs out of injector, long known proven fact.

Then prove it to me. Show me a dyno run that shows excess O2 @ peak HP (and no HC left either, for that matter). Then explain how the engine isn't already destroyed by detonation. Don't base your conclusions off duty cycle, since that doesn't say anything about combustion stoichiometrics. You know those guys at Honda probably didn't all skip the same day of Engine Design 101. I'll say it again: The way to get more power is to figure out how to add more air first, THEN, if needed, to add more fuel.

 

[scorp965]

A better injector spray pattern will not help if there is no more O2.

Spray pattern affects the efficiency of fuel atomization, which provides a benefit to the entire combustion process; sort of like people claiming iridium spark plugs provide a benefit to the way their engine runs.

This isn't voodoo, I can't believe people are spending their time criticizing the concept, when it could easily result in cost-effective power gains.

 

[L_RAO]

Wow. I'm amazed at the range of responses here.

First, I am waiting to hear from ProSpeed as to whether their ECU program can accommodate the fuel injector increase.

Second, this both RC Engineering and American Honda have confirmed the better spray pattern. In fact, in that same e-mail RC talks about their own injector being better suited for an ITB-type application due to the spray pattern. American Honda mentions the NEED for a better injector in the RDX in the RDX press release.

Finally, as we have seen with Comptech's N/A efforts, as well as the guy who's currently wondering as to why his ITBs only gained him 20 whp, power in the C30 engine is hard to come by in N/A form. If I can safely refit the RDX injectors onto the C30, and get some real (dyno-tested) power across the entire power band, this could be one of the best bang-for-buck mods.

 

[Daedalus]

Spray pattern affects the efficiency of fuel atomization, which provides a benefit to the entire combustion process; sort of like people claiming iridium spark plugs provide a benefit to the way their engine runs.

This isn't voodoo, I can't believe people are spending their time criticizing the concept, when it could easily result in cost-effective power gains.

So now we're abandoning the increased fuel flow argument and jumping on the improved atomization train. Are you suggesting in a stock engine at WOT the fuel is not already completely vaporized by the time it enters the combustion chamber? I've been taught otherwise, but maybe I should get a refund on those auto tech textbooks sitting on my shelf and the tuition that went with them? Mixing is where the variable is, why the burn may only be 98% rather than 100.0% complete, and that is a function of combustion chamber design.

Did you know that spray pattern is considered when the plenum and intake runners are designed, and vice-versa?

Would you admit that people spend an inordinate amount of money on crap items that have no measurable benefit because they're willing to sip the koolaid and want to believe what the marketers (or other eager, wide-eyed enthusiasts) tell them? Fuel line magnets and the "Vornado" come to mind.

Let's see some proof guys. That's all I'm asking. A 4HP difference between 2 dyno runs is not proof--that small a difference will often be seen on back to back runs without changing anything. A pre-cat gas analyzer is required for this, so let's see gas numbers from a car with test pipes before and after.

Last point--cost effectiveness. NA1 headers come in around $50/hp. An Angus turbo kit is around there too, maybe a little higher. You think this mod will give ~8HP? I'm sticking to 0 HP gain (if not negative). What say you?

 

[scorp965]

First, calm your scary ass down.

Second, you're in a thread where a guy is talking about his potential modification - he's not selling you anything, he doesn't owe you anything, and he's not even soliciting your opinion.

So now we're abandoning the increased fuel flow argument and jumping on the improved atomization train. Are you suggesting in a stock engine at WOT the fuel is not already completely vaporized by the time it enters the combustion chamber? I've been taught otherwise, but maybe I should get a refund on those auto tech textbooks sitting on my shelf and the tuition that went with them? Mixing is where the variable is, why the burn may only be 98% rather than 100.0% complete, and that is a function of combustion chamber design.

Did you know that spray pattern is considered when the plenum and intake runners are designed, and vice-versa?

Would you admit that people spend an inordinate amount of money on crap items that have no measurable benefit because they're willing to sip the koolaid and want to believe what the marketers (or other eager, wide-eyed enthusiasts) tell them? Fuel line magnets and the "Vornado" come to mind.

Let's see some proof guys. That's all I'm asking. A 4HP difference between 2 dyno runs is not proof--that small a difference will often be seen on back to back runs without changing anything. A pre-cat gas analyzer is required for this, so let's see gas numbers from a car with test pipes before and after.

Last point--cost effectiveness. NA1 headers come in around $50/hp. An Angus turbo kit is around there too, maybe a little higher. You think this mod will give ~8HP? I'm sticking to 0 HP gain (if not negative). What say you?

 

[ncdogdoc]

Then prove it to me. Show me a dyno run that shows excess O2 @ peak HP (and no HC left either, for that matter). Then explain how the engine isn't already destroyed by detonation. Don't base your conclusions off duty cycle, since that doesn't say anything about combustion stoichiometrics. You know those guys at Honda probably didn't all skip the same day of Engine Design 101. I'll say it again: The way to get more power is to figure out how to add more air first, THEN, if needed, to add more fuel.

Why doesn't duty cycle have anything to do with it?

If the injectors cannot get enough fuel into the cylinders, then you don't get as much energy out. DAL proved this with their Grand AM cars and that was based on work done by RealTime first.

I changed nothing about my intake except VVIS delete. I went with Comptech cams on stock valves and cheap as shit plugs. No work to the heads, as there is not really anything that could be gained without using the 3.2 valvetrain. Just cams, injectors and a killer tune netted me 300rwhp on a pure 3.0l engine with stock compression, stock pistons and stock internals. My '95 (not a direct comparison of course but typical of the 3.0l) ran 239rwhp on the same dyno. My tuner was able to get over 15rwhp from just tweaking the tune from the first run.

I am not disagreeing with you about the O2 sats and the fact that increased air is indeed beneficial, but increased fuel with standard air does work. I drive one.

 

[usafdarkhorse]

I think the OP is going for a more efficient spray pattern than the OEM NSX injectors in hopes of efficiency/atomization freeing up a few HP - which is where Daedalus is saying the NSX injectors are probably quite adequate, maybe even more than required, for the amount of air being ingested by the engine.

I don't think you'll see much gain without retuning. It is possible, seeing as how most automakers will aim for peak efficiency/lowest emissions, to see a gain, but that will be if the engine has more oxygen to spare to match with increased fuel and not on the OEM ECU.

The key will be in a tune.

And if you do have cams and VVIS delete, ncdogdoc, that will most likely result in more than standard air.

 

[Daedalus]

First, calm your scary ass down.

Second, you're in a thread where a guy is talking about his potential modification - he's not selling you anything, he doesn't owe you anything, and he's not even soliciting your opinion.

What are you scared of? Facts?

I'm suggesting that the OP think for himself and not waste his money unnecessarily. I assumed that he posted here looking for feedback and advice, but if I'm wrong, it's OK. As you so very astutely pointed out, no one owes me anything. I swear on my mother's grave and on my first-born's soul I will not be offended if my advice is ignored. I'm not above being amused by the results though.

Why doesn't duty cycle have anything to do with it?

If the injectors cannot get enough fuel into the cylinders, then you don't get as much energy out. DAL proved this with their Grand AM cars and that was based on work done by RealTime first.

I changed nothing about my intake except VVIS delete. I went with Comptech cams on stock valves and cheap as shit plugs. No work to the heads, as there is not really anything that could be gained without using the 3.2 valvetrain. Just cams, injectors and a killer tune netted me 300rwhp on a pure 3.0l engine with stock compression, stock pistons and stock internals. My '95 (not a direct comparison of course but typical of the 3.0l) ran 239rwhp on the same dyno. My tuner was able to get over 15rwhp from just tweaking the tune from the first run.

I am not disagreeing with you about the O2 sats and the fact that increased air is indeed beneficial, but increased fuel with standard air does work. I drive one.

Duty cycle will tell you how maxed out the injector is, but it doesn't say how rich or lean the combustion is. A duty cycle of 90% @ redline is pretty maxed out, but if the AF is 8 the powerband will benefit from less fuel, not more. As I stated, cars simply HAVE to run rich @ WOT for safety.

Did you compare powerband curves before and after? I'm not surprised you saw good peak HP gains with cams, but I would be surprised if you didn't lose some torque elsewhere. Like a lot of things, cams are a factory-decided compromise. The tune is too.

The low boost CTSC keeps the stock fuel system except pressure is bumped up. But going from, say, 43 to 60 PSI has a surprisingly small effect on volumetric flow. Someone on here posted fuel flow vs. pressure, and I don't think they saw much more than 10cc/min increase at the highest pressure tested. I'd have to search to find it though.

I think the OP is going for a more efficient spray pattern than the OEM NSX injectors in hopes of efficiency/atomization freeing up a few HP - which is where Daedalus is saying the NSX injectors are probably quite adequate, maybe even more than required, for the amount of air being ingested by the engine.

I don't think you'll see much gain without retuning. It is possible, seeing as how most automakers will aim for peak efficiency/lowest emissions, to see a gain, but that will be if the engine has more oxygen to spare to match with increased fuel and not on the OEM ECU.

The key will be in a tune.

And if you do have cams and VVIS delete, ncdogdoc, that will most likely result in more than standard air.

A tune is a proven power adder. Most typically, a tune advances timing and leans out the mix just a TAD. Whereas Honda might have six sigma confidence that only a single engine would fail while being floored through Death Valley @ high noon during August, a slightly more aggressive tune might pick up 10 or 15 hp while eating into some of this confidence and safety.

 

[ENT]

I agree with Daedalus. My guess is that you might actually lose some HP after all is said and done.

Cheers,
Ian

 

[shawn110975]

did you know that 60% of power loss is due to heat?

if you wanna see real gains, find a way to pump ice water thru the engine,

I say easy power gains with triple digits on a stock.


TIM dont do it LOL

 

[Mac Attack]

Your project sounds interesting.

May I suggest a DIY direct injection mod next please :biggrin:

Dave

 

[brandonsan]

I understand why you want to do this but it will not work on a NA application without a stand alone or piggy back that has independent injector control.

 

[shawn110975]

its his car LOL

be on the look out for the new thread called
" my car wont start help "

 

[L_RAO]

So instead of the ProSpeed ECU mod I would have to jump directly to the AEM EMS?

(Still waiting on ProSpeed to get back to me).

 

[kookoo4nsx]

This is a joke right? All this for 4 hp? You won't even feel it. Just remove the spare and tool kit if you want a little more speed. Save your $400 for a rainy day.

 

[TANTO]

L_RAO - Don't let the arrogance of others who have bolted on a kit and done 6 dyno runs and now know everything about everything tell you anything. Sooner or later most of them will be blown up on the side of the road when you fly by them. If the K guys are getting this as you said it's worth trying. It's the spray pattern. Combustion chamber results come from trial and error, not analytical thinking. I'm not well versed on injectors at all, but i suspect the actual fuel use for 4 hp will be almost inconsequential as it's the EFFICIENCY of the combustion you are trying to tweek. We still don't burn anywhere near all of the fuels potential. I also can't believe the negativety. Quite a lesson about how little folks respect their fellow X'rs on this list.

 

[L_RAO]

Well, it has the been the trials & errors of the many who spent $$$ on "cold-air" intake systems & bored-out throttle bodies to let me (and others) know that there isn't a whole lot to be gained from paying money on that end of the spectrum.

And, to those people, thank you.

To me this is just another form of hot-rodding. Whether it's a sub-10 second bracket racer or a 600 hp daily-driver Supra, aren't we all looking for ways to make our cars just a little more enjoyable?