Which injectors for 3.2 turbo conversion - NEXT ROUND OF INQUIRY

[baloo]

Working on getting the parts and plan to boost my stock '87 3.2L (no internal engine mods).

I've got two major worries based on reading (no experience -- so everything appears as a possible calamity):
1) running too lean;
2) knock.

I'm pretty sure I'll go with a J&S Safeguard for the antiknock. But, I think I better increase injector size, based on the afterthought comments from Pelicaners who boosted their 3.2's.

Here are my next round of questions:
1) Any suggestions reference injector size (max boost will be .5bar)?
2) Are used injectors (e.g. from a 944 turbo) a good option, or would they be trouble due to unreliability? I guess my question is, do injectors wear out/go bad? If so, is it rare?
3) Is there any particular source for injectors for this low budget project? I like quality, but keerist, there are some things that you can get at Walmart or China that still serve the purpose.
4) Should I even bother with upgraded injectors?

Thanks.
The amount of education that I have gotten recently by asking this type of directed questions of Pelicaners can never be replaced by just "reading everything!"

[sjf911]

Are you changing your engine management system? If not, I would imagine you would want to use a rising rate fuel pressure regulator rather than change the stock injectors unless you can remap your Motronic system.

[Tippy]

Yes, he has a Begi RRFPR. At 0.5-bar, I'm fairly sure stock injectors are fine but I'm not 100%.

[baloo]

Originally Posted by Tippy

Yes, he has a Begi RRFPR. At 0.5-bar, I'm fairly sure stock injectors are fine but I'm not 100%.

Tippy's right. Have a Begi RRFPR, stock injectors, SW chip.
I read from at least 3 previous Pelican/Rennlist posts of similar conversions that they said, after their installations, that they needed to upgrade to 55lb or so injectors.

[Tippy]

I'm pretty sure PO of my car ran 0.5-bar with stock injectors, then put in 55lb'ers for 1-bar.

[spence88mph]

I didn't upgrade my injectors but I only run .5bar, I use the protomotive RRFPR and stage 1 chip, lots of fun.

[Tippy]

There you go.

[Uncle]

Very good question. I'd be keen to know what % duty cycle the stock injectors are at with .5 of a bar boost.

[baloo]

Originally Posted by Uncle

Very good question. I'd be keen to know what % duty cycle the stock injectors are at with .5 of a bar boost.

That sounds like a very important question, except I do not know what it means -- "% of duty cycle."
I have read this several times before, but I don't know if a high % or a low % is better??

thanks -- slow but eager learner.

[spence88mph]

It just the percentage of flow the injector is running at, so a 500CC injector might be running at 80% but a 700CC will be doing the same job at 50... You don't want them running at 100%.

I put my trust in Protomotive when they said the stock injectors are fine at 7psi, even at 10psi, they recommend 944 turbo units as you increase boost. Mine was done about 4 maybe 5 years ago now, admittedly the car is very rarely driven but feels great when I do!

[baloo]

Thanks to all. I'm now at about 15% of knowledge base.
Tippy -- thanks for the details you provided in re. to how the chip, fuel regulator and timing are interrelated.

[Tippy]

Very good question. I'd be keen to know what % duty cycle the stock injectors are at with .5 of a bar boost.

Duty cycle does not change with running extra fuel pressure. They open and close the same duration as factory.

[Uncle]

Yep, That's why I was asking what % duty cycle the stock injectors are at with .5 bar of boost.
IE: As per Spence's post I'd have no prob's running a stock injector if at say 80% at say 10psi. I only plan to run 7psi. Nice safe window of operation.

[WANNA930]

Call an injector Co even if you are considering used. I used Marrin? in CT for a set from my Renault R5 Turbo 2. It ran what I felt was good before I sent them in. They found one was way off in flow. They charged almost nothing for the new core and it took the possibility of buying another bad used one out of my hands.

After they had a matched set and cleaned or did whatever they did to them I could not believe the difference. I am not sold on many services or upgrades but for 30 year old injectors on cars that are not used often you will be impressed. You will also get great advise and a base number to use if you need to adjust up or down. The first fire up idled so well I though there was a problem till I realized it was running so much smoother and quieter.


I am sure there are other places that offer similar services but I can only tell you my experience with Marrin and I hope I am spelling it right? They know their stuff. Best $200 spent.

[spence88mph]

Originally Posted by WANNA930

my Renault R5 Turbo 2.

I love them!!

[911TT33]

Stock Carrera injectors are fine up to 10psi / 0.7bar. Anything higher and you need to upgrade to 944 Turbo injectors with the Proto Chip+FPR combo (and appropriate decompression mods).

[cliyde]

Agreed, stock injectors will be fine to use as long as your Fuel pump is up to snuff and Begi RRFPR is used.

Originally Posted by 911TT33

Stock Carrera injectors are fine up to 10psi / 0.7bar. Anything higher and you need to upgrade to 944 Turbo injectors with the Proto Chip+FPR combo (and appropriate decompression mods).