Just popped the hood last night and noticed one of the injectors is leaking badly on the 951. So, it looks like it's time to replace them. Right now I have no intention of adding a bigger turbo or otherwise hopping up the engine. That said, I'd hate to decide later on that I'd like to go that route, only to have to buy bigger injectors. So the question is, do I opt for larger injectors now?

I'm fairly certain that I will only go to a larger turbo if and when the stock unit blows. But I might go for one of the Stage I or II mods on the Guru site. It appears as if the stock injectors will work with the kits, but since I'm replacing all of the injectors anyway I'm wondering if I should go to the 55lb units. Price looks to be about the same as stock injectors. So whats the catch? <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

 

There are a few things that are what you would call the "catch", probably two that are the most important in my opinion. 1.) the 55lb injectors do not match the impedance the DME prefers, 2.) the 55lb injectors won't idle too well with the stock motronic DME unless you get some type of ability to massage the signal.

There are several ways to do this but all require lots of extras. Your stock injectors will work very well up to about a 50% increase over stock hp so my suggestion would be to get yours rebuilt or find a set of used ones for low cost until you decide what you want for power and then do a upgrade to larger capacity and engine management/maf with digital signal control/ or MAP upgrade at the same time.

 

That's the reachin'st excuse I have ever seen to buy new injectors when you only need seals.
If you get the chips and the 55's, you can up the boost - but then things get out of control fast.
-J

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by special tool:
<strong>That's the reachin'st excuse I have ever seen to buy new injectors when you only need seals.
If you get the chips and the 55's, you can up the boost - but then things get out of control fast.
-J</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hey now! Ya gotta tell the wife something!

Actually, it's not the seal. The injector split so there's no bringing it back. The shop quoted me around $89 bucks a piece for the stock units, and that's pretty much what Guru Racing wants for the 55 pounders. That's what I was getting at. If the price is basically the same, why stick with stock? What additional items would I need to "redo" to run the larger injectors on an otherwise stock engine? Is there ANY advantage to going to 55 pounders over the stock units on a stock engine?

 

The minimum you would need is a set of Guru chips matched with the Guru injectors.

You will have to splice your wiring harness to intall the ballast for the injector signal and then crack the DME and KLR for the chip replacement. That is all that's required work wise.

You will enter a totally new world by then if your car truely is stock. But , you will also see noticable improvement even if you get stock properly-working injectors.

 

The minimum you would need is a set of Guru chips matched with the Guru injectors.

You will have to splice your wiring harness to intall the ballast for the injector signal and then crack the DME and KLR for the chip replacement. That is all that's required work wise.

You will enter a totally new world by then if your car truely is stock. But , you will also see noticable improvement even if you get stock properly-working injectors.

 

Oh yeah - know all about that, Gotta get myself some new volk te37's because my cup 2 's have all those structural scratches in them.
I think there is benefit to your dme driver if you turn up the boost and run new chips because it will run cooler and not be too high duty cycle. The thing is, you need chips for the injectors - now do you get the map??Boost controller?? Test pipe?? Fender stickers that say HKS???ETC, ETC.

- J

 

In reading "between the lines" I'm understanding that the larger injectors will not work on a stock engine without chip modifications. Is this correct?

Keep in mind that I'm NOT attempting to increase performance by installing the larger injectors (don't want to decrease performance either). I'm simply wondering, since I have to spend $350 for new stock injectors anyway, if the larger units Guru sells (for the same price) will work as good as the stock units do. I'm thinking that by buying larger injectors now, I would lessen the future expense of modifications that were intended to increase performance.

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by icat:
In reading "between the lines" I'm understanding that the larger injectors will not work on a stock engine without chip modifications. Is this correct? </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Yep. There's two problems with the bigger injectors:

1. They won't have the same characteristic impedance so you'll have to get some of those balance devices so as to not overwork the DME that supplies the pulses that turn them on.
2. They will pump more fuel at 'X' duty cycle (ie: time on vs. time off) than the stock ones will. This will throw your air/fuel ratio way off (to the rich side) and the engine will run poorly.

The solution to both problems is simple:

1. Balance resistors as mentioned above
2. A set of chips matched to the injectors ie: the guru ones. If your planning on upgarding later, you might as well get the chips tuned for a little more power. Of course the chips will add to the $89/injector price.
3. Some time and a couple of tips from the forum as to how to install the above.

<img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

 

I've already upgraded my injectors, and my stock ones are sitting in a box if you're interested. They work perfectly fine, car had 80K miles on it when I replaced them. If you're interested you can have them for $125US.

 

Thanks Ian,
The cost of the new ones isn't an issue, I just hate buying something that I may not be able to use later on. But thank you VERY much.

I'm looking at the Guru Stage II Kit and it appears as if 260 RWHP is possible from the stock turbo and injectors. Isn't this around 300 total HP? If so, that's about as radical as this ole boy would want to go.

The shop is flow checking the stock injectors now to see if I can get by with one or if I'll need a full set. After all of your comments I'm leaning toward a new set of stock injectors just to eliminate/lessen the chance of future failures. It appears the stock units will be fine for my needs.

 

Keith -

I have a set of stock injectors chillin on a shelf. They need to be cleaned and rebuilt, but for $25 an injector (Marren), you would have a cheap set to use until it is time to upgrade. Sell the bunch to you for nothing.

Let me know if you want them.

Oh... and guys... it a "BALLAST" resistor, not "BALANCE". Hee hee.... learn something new every day on the list!

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Perry 951:
Oh... and guys... it a "BALLAST" resistor, not "BALANCE". Hee hee.... learn something new every day on the list! </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Oops! I was thinking along the lines of impedance matching with the audio circuits I deal with at work... a "balanced" input so to speak

 

icat; are you torn? not sure if you want more performance or not? If you want more performance then buy the chips and injectors. If you do not, then purchase one new injector (or four, whatever) since they are good to around 280rwhp fairly safely. You can go higher, but I would not recommend it.

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Oops! I was thinking along the lines of impedance matching with the audio circuits I deal with at work... a "balanced" input so to speak</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">I am an audio guy too, understandable mistake. What do you do?