mark928gt

I know this has probably been hashed through a number of times. I have my injectors out being cleaned and rebuilt. I got a message from the shop today that three of the injectors are bad. I'll speak with them tomorrow to find out the details.

Here is my question. If I have to buy some new injectors it seems there are a few choices.

1. New Bosch ($240)
2. Used Bosch ($40)
3. New (I forget the brand on RockAuto) ($50)
4. New Airtex ($190)

Wondering what people would recommend if I really need to buy some replacement injectors.

SMTCapeCod

With injectors, I think "new" is optimal.

The question often becomes- is 198X "new", actually the best available?

I'd suggest 1) forget Rock; 2) GIve a call to Five-O motorsports as they have a bit of track record providing updated injectors that flow properly for 928s.

Speedtoys

" flow properly for 928s. "

You mean, any other set of used but cleaned and balanced set of 19lb injectors scattered across Ebay.

Lets not get too pushy on phrasology...its just a 19lb injector...nothing 928 about it.

Bill Ball

Other than the lower o-ring.

davek9

if you are going for any performance mods, I went with Bosch 4 hole,Roger at 928s R US sourced them for me.

Martin's928

Another vote for Five-o.

928S MN

From Five-O got the Gen III, 4 hole, correct lower O-ring balanced flow set.

mark928gt

After reading a great thread about GenII and GenIII injectors it seems I will probably go with GenIII. I also spoke with Roger at 92sRUS and he was a great help.

On the thread I was reading it was mentioned that the stock 19lb injector is tapped out at high revs for a GT. My engine is completely stock but was wondering if I should go with a 24lb injector instead. If I do go with a 24lb injector does the engine need to be tuned for it?

I did read that at the high revs the injector is only fired every other revolution. I imagine you could change this with the 24lb injector but not sure it is necessary.

davek9

Yes you would need to Shark Tune to condensate for the larger injectors, else run rich.

Rob Edwards

Yes. I would stick with the 19 lb injector Roger suggests.

jcorenman

Mark, don't try to mix new and old-style injectors, their flow characteristics won't match. If you have three bad injectors, then the simplest/cheapest option is to pick up some used stock injectors and get them to the shop for cleaning/testing. 928 Int's has them for $50, and many of us have a box of used 19# injectors in the bottom drawer that can be had for cheap.

The stock injectors work fine with stock motors, anyone who suggests otherwise is just being silly. That said, newer-design injectors do a better job at atomizing fuel, but whether that is actually measurable is questionable-- no one, as far as I know, has ever dyno'ed newer-tyle 19# injectors on a completely stock motor.

It is true that 19# injectors get close to max'ed out on a stock engine (S4 or GT), and it is also true that the stock fuel maps are overly rich at high loads-- which makes this a non-issue. When tuned (e.g. with a Sharktuner) with a more reasonable mixture at WOT, the stock injectors have plenty of headroom.

Changing to 24# injectors has some advantages for modified engines putting our more hp, but definitely requires re-tuning. The extra flow also allows the half-cycling at higher RPMs to be disabled (this is a Sharktuner parameter), but again I am not sure that is a measurable change.

My advice is this:
1) If you have a stock engine and are happy with that, then keep it stock. Find some stock injectors, get them cleaned and tested by the same outfit, and be happy.

2) If you want to start down the modified-engine path, then start with an x-pipe and freer-flowing cats. The next step is to fit a WBO2 gauge and find out what your fuel mixtures are doing, then either get a Sharktuner and start learning about engine performance, or get a set of Ken's chips and go that route. Doing either requires that you know what is happening with the fueling.

Beyond that, the GT already has nice cams so headers/exhaust would be the next step, then bigger cams and the slope gets steeper and more slippery.

Speedtoys

And still nothing '928' about the injector itself.


Roger sells the Orings FOR the 928.

Speedtoys

Why would they bother, its still a 19lb injector. It wont dyno higher.

It will idle differently, perhaps.

mark928gt

Thanks for the information everyone. I was not thinking of mixing old and new generation injectors. That does not seem to make sense. I was thinking of purchasing a new complete set of GenIII injectors.

I will stick with the 19lb injectors since my motor is stock and I plan on leaving it that way. I did call 928Intl yesterday about their used GenI injectors. They do not have any in stock and did not know when they would get any in.

Watching the videos of the different injectors I think the spray pattern of the newer generation injectors seems to make sense for better atomization. I also worry about which of my other 27 year old injectors are about to give up the ghost. I have the same worries about any used ones I might put in.

For these reasons I think I will go with a new set of GenIII 19lb injectors. It looks like they are used on a number of Volvos and are reasonably priced.

Imo000

Save your $$ and get a new set of original type 19lb injectors. The 5.0L Mustangs of the late 80's early 90's had them and they are available everywhere. The 19lb units are adequate for your car so stick with them.