injectors and fuelrail

[shift00]

I would like to know what kind of injectors and fuel rail size/style I should purchase for my z. I've read on this forum all kinds of different set-up people run, but for a beginner like me its hard to understand what I should run for good fuel economy and performance. Not to mention every thread i've looked up in relation with this subject, most have turbos and mine does not. If you guy's can give me any avdise other than the "SEARCH" response that would be great. I've done enough searching and all it gets me is confusion. Thank you for you help.

 

1977 280Z na

N42 block and head

aftermarket exhaust, cold airintake and headers( if it matters)

I rebuilt the motor completely stock with bored 20 over piston.

[shift00]

anybody have a clue?

[Calgary280ZT]

Well, no one's chiming in, so I'll give it a whirl. The mods you mention won't increase the hp by much, if at all. You're going to be making about 150 at the wheels, give or take. The rule of thumb is 1 hp per injector cc. I think the NA injectors flow 168 cc...good to 168 hp approximately. Therefore, your stock injectors should be fine.

 

Just to give you an idea...the stock turbo injectors flow 268 cc. My mostly stock set up probably puts out around 225, maybe 240 hp. So I was fine. In a couple of weeks I'm installing a high flowing Rebello head, T3/T4 turbo etc. I hope to make 350 hp. Now i need bigger injectors, so I'm going with the 440 cc Supra injectors.

 

Hope this helps. This is the third or fourth thread in the past couple of weeks where guys want to increase injector size on NA motors without doing anything other mods. Is it something in the water?

[alexdeprat]

Well it truly depends what you’re seeking i.e. cleaner engine bay, maintain the stock setup/look, etc… to be honest you can get great performance with the stock set up, few people just get bigger injectors (more cc’s). Most people choose the 14mm Oring GM style injectors and aftermarket fuel rail since you can get then everywhere; there are also 11mm Oring injectors with the same style, your choice.

Moreover, Rx7’s and some Supra’s N/A injectors have a “screw in style” that in order to be use with ours L6 intakes, they have to be machine for the fitment, in difference with the other mentioned which in term, are more or less (few mods)Plug n’ Play.

 

 

Alex

[Daeron]

I guess it isn't really a point that is spelled out that often, but to be honest this *is* the sort of question likely to fall by the wayside here.

 

The answer is, if all you have done thus far is mild modifications to the exhaust and a cold air intake, the stock EFI still sees it as essentially the same motor. Some would say that installing the aftermarket exhaust, the 60mm throttle body and the stock NA 300ZX injectors (which were slightly larger, i think about 15cc or so) is the simplest way to feel like you did something, but others would argue that even those simple changes would be so un noticeable without significant (not MAJOR but significant) work to the intake manifold, and the intake and exhaust ports. The thing to remember is that this EFI system is very simple, very antiquated, and built to run at stock performance levels.

 

There are a handful of old school "tweaks" that can be used to "fool" different aspects of the computer, but really without a wideband O2 sensor and the ability to constantly pay attention to your a/f ratios while operating the engine, you won't really see significant change.

 

That is not to say that by installing an aftermarket fuel rail and new injectors of a similar or slightly larger flow rating would necessarily be a bad thing. The fuel rail can be used for later endeavors in the Quest For Vroom and still be perfectly suitable to stock running. Also, replacing old factory original injectors is likely a sound idea at this point in time; you never know what performance hidden faulty parts could be "robbing" you of.

 

However, in the end, you have to keep in mind that a slight overbore, headers and exhaust, and a cold air intake alone do not make a performance package, and throwing big dollars at injectors now, with stock EFI, is going to start hurting engine performance if you go too big. If you DO plan on going larger later, then you could get a rising rate fuel pressure regulator, and use other "stalling" steps before you are at a point where larger injectors are NEEDED.. this would avoid buying an intermediate set of "stockish" injectors before you are too far upon the Quest.

[shift00]

Okay guys i think the moral of the story is... run the stock set-up. I guess i just read somewhere on here, that the stock injector are junk and so i was looking to replace them. Thanks guys so much for your answers. it really helped me out. I would be far behind if it weren't for this forum.

[woldson]

Yea the injectors are fine as long as you don't go turbo. Basicly if you seach abit you will find that they will only flow so much fuel thus limiting the amount of hp you can achieve.

[shift00]

what year of 300zx injectors should i get? Also if there a good fuel rail that you guys would recommend?

[jc052685]

Stock non turbo injectors are good for aprox 190whp. Turbo injectors aprox 270whp.

 

The purpose of changing injectors is to increase the amount of fuel you are supplying to the engine. If you do not have a need for the extra fuel you dont need to change injectors.

 

 

 

Cliff notes: Your injectors are fine.

[z-ya]

With the changes you have made, the stock injectors and fuel rail are more than adequate (unless you want bling). What you really need to decide is if you want to keep it reasonable stock (keep the stock ECU) or not. If you want to keep the stock ECU, then changing injectors is really a waste of time and money. If you are interested in switching to an aftermarket ECU, this will get you the most performance out of what you have already done. If after tuning the aftermarket ECU your engine "needs" more fuel, then I would look into new injectors at that point. I would suggest 280ZX turbo injectors as they will work with your stock fuel rail. The stock fuel rail (although not all that pretty), is a good design, and is good for well over 300WHP.

 

Pete