Fuel Injectors

[Memph]

I understand the disadvantages in having injectors that are too small.

But so far the only negative towards bigger injectors is cost. and as stated previously the difference between 550cc and 740cc injectors is only around 50 bucks.

Which brings me to the question. Can i have injectors that are too big? advantages/disadvantages.

Cheers guys.

[R31Nismoid]

Fuel economy decreases generally speaking the larger you go.

Being it is hard to get larger injectors to behave like smaller ones on idle etc.

i've moved back to 550's with my RB26... so we'll see if there is a larger difference.

That said, with 740's i still managed around 350km to a tank

For me, that was pretty good

[Memph]

so assuming both cars in question have (say) 250rwkw

though one has 740's and the other has 550's

both are tuned fine.

Would economy be similar for the two?

[rs73]

For a mild street tune has anyone tried upgrading stock R33 injectors with a JDM spec S15 injectors rated at 480cc/min? Will those injectors fit straight away without any mods?

The problem is most package are sold in set of 4, so either you buy 1 set and then hunt the remaining 2 or buy 2 sets and try to sell the spare 2.

[Sydneykid]

I understand the disadvantages in having injectors that are too small.

But so far the only negative towards bigger injectors is cost. and as stated previously the difference between 550cc and 740cc injectors is only around 50 bucks.

Which brings me to the question. Can i have injectors that are too big? advantages/disadvantages.

Cheers guys.

Let me start of by stating that I am not the world’s best tuner, far from it. With that out of the way, I always find it harder (more time consuming) to tune a car with larger than necessary injectors. That means slightly higher tuning costs, if I was doing it (not that you would want that) .

Secondly, all injectors are not the same flow rate, commonly you will find 1.5% to 3% variation in their individual flow rates. I find larger injectors are at the higher end of the scale. So 3% of 740 cc’s is a lot more than 1.5% of 550 cc’s. You have to tune for this larger variation between cylinders. That’s a little more time on dyno.

All together, the above may not amount to much extra $cost. But it is worth keeping in mind.

cheers

PS; I have seen a standard Power FC handle 1100 cc injectors easily. After you shoot the guy that told you otherwise, hang him just to make sure he can’t spread that crap any more..

[Sydneykid]

For a mild street tune has anyone tried upgrading stock R33 injectors with a JDM spec S15 injectors rated at 480cc/min? Will those injectors fit straight away without any mods?

The problem is most package are sold in set of 4, so either you buy 1 set and then hunt the remaining 2 or buy 2 sets and try to sell the spare 2.

Yep they work just fine, last time I did it I bought 3 sets (of 4) and did 2 cars.

Keep in mind that it is only the JDM S15 manuals that have the 480 cc injectors. Not all S15’s.

Cheers

[rs73]

Yep they work just fine, last time I did it I bought 3 sets (of 4) and did 2 cars.

Keep in mind that it is only the JDM S15 manuals that have the 480 cc injectors. Not all S15’s.

Cheers

Is there a way to quickly differentiate these 480cc injectors from the non-JDM local ones? e.g. colours?

[Evasion]

^^^^^^^

And how much power do they support or how much extra could you push after changing stocko's to them.

Thanks

[Shaneo]

my calcs put 480cc at around 250kw at the flywheel

[Sydneykid]

480 cc = 480 bhp (in a 6 cylinder)

480 bhp / 1.34 = 358 kw

358 kw - 65 rwkw losses = 293 rwkw.

We have actualy snuck 315 rwkw, but with slightly higher than standard fuel pressure.

cheers

[rs73]

With that quick calculation does it mean that a std 370cc RB25 injectors will support up to 370BHP or 276kw at flywheel or about 211rwkw?

I've got my stock AFM maxing out a bit early at 206rwkw, and without upgrading any injectors except a Z32 AFM, I'd probably only get another 5kw or so for my $400?

[r33_racer]

Yeh those figures add up right. However, if you wanted to cheat as SK has said before you can raise the fuel pressure and squeeze more out of them after you change the afm, most ive heard out of std injectors is about 230rwkw...but i would say give or take 10rwkws for dyno differences. As some people have said more (upto 240rwkw) and some have said a little less (220 odd).

[rs73]

Thanks... I think the FPR one is a cheaper way to get more power. I'll see how it goes after it's tuned tomorrow.

If not, then forking out a little bit extra on the S15 ones seems like the best path for my small HKS2535, as with its power rating of I feel getting a Nismo 555cc injectors are way overkill.

[Munna1]

Is there a way to quickly differentiate these 480cc injectors from the non-JDM local ones? e.g. colours?

maroon = 480cc, purple = 370cc.

http://www.nissansilvia.biz/sr20_types.htm

[Topaz]

I have purple top Nismo injectors and wondering what they actually are?

They arent 370's are they? because I ordered 600's.....

[rs73]

Those are aftermarkets, they have of course different colour coding than the OEM factory ones. For Nismo brand, 555cc is yellow, 600cc is purple, and 740cc is red.

[Topaz]

Those are aftermarkets, they have of course different colour coding than the OEM factory ones. For Nismo brand, 555cc is yellow, 600cc is purple, and 740cc is red.

Ok good, I havent been able to find any Nismo colour meaning, thanks

[mickr33]

Hi people. What about some other brand apart from Nismo, Sard etc. Was wondering if

Bosch do a replacement injector. Does anyone know if Bosch do and if so are they heaps

cheaper, about the same, good or shite.