Modern injectors, new fuel rail - no heat soak problem

[Patcon]

Maybe your fuel priming circuit would help?

[HusseinHolland]

9 hours ago, Patcon said:

Maybe your fuel priming circuit would help?

Seems possible - I guess it depends where the vaporization is taking place - it would seem likely that it is more than just in the injector body, as it takes at least a minute (it feels like more) to level off & return to normal. Fiat added an injection cooling fan system to their 80's version of the Bosch L-jet - it had a shroud on the intake with a duct attached to a blower. There was a temp switch on the manifold to trigger the blower on shut down. 

I think I read some reference to something similar on here, however I've not seen any pics. I can't visualize what a mess that would like like on the L28 EFI.

[Zed Head]

4 hours ago, HusseinHolland said:

where the vaporization is taking place

It might be in this thread or one of the others but I had posted some links about Mopar's fix for a similar problem with their Jeep engines.  It was a foil heat shield for a certain injector.  Apparently keeping the injector body itself cooler helped solve the problem.  The L series engines are perfectly set up to overheat the injectors with their position right next to the bulky exhaust manifold.

[siteunseen]

They put them on some ZXs, not sure of the years. '81-'83?

[HusseinHolland]

7 hours ago, Zed Head said:

It might be in this thread or one of the others but I had posted some links about Mopar's fix for a similar problem with their Jeep engines.  It was a foil heat shield for a certain injector.  Apparently keeping the injector body itself cooler helped solve the problem.  The L series engines are perfectly set up to overheat the injectors with their position right next to the bulky exhaust manifold.

Interesting. Fiat has the same issue, since the 70's-80's EFI was also placed on a non-cross flow cylinder head. I added additional shields on mine to protect the injectors, which mounted in a similar fashion.  The X1/9 had massive vents in the engine cover though, so that made a significant difference over my 75 280Z. Presumably this was in part the reason for the hood vents on later Z's.

1 hour ago, siteunseen said:

They put them on some ZXs, not sure of the years. '81-'83?

Thank you for the pics - seems the center 4 are more prone, unless they just said **** it- blow some air in the general vicinity & hope for the best 🤪

[HusseinHolland]

Been out of town since Wednesday - before that, I had the heat soak issue even though the ambient temps were in the 40's-50's. I'm going to make a heat shield, however since I have to remove the rail again, I decided to get newer injectors & a billet rail, and just get rid of all those thin metal tube rails.

These came while I was away

ProtunerZ rail & injector seat adaptors, 19.4lb/hr Bosch injectors 0280155712 (GM, Saab application)

 

[AK260]

So buddy I recently went 4 row aluminium red and the fuel rail heat issues at idle or after a fuel stop have nearly all but gone.

Sure the temps dropped from high to low/mid 20°c when I was testing it but it made a difference like I couldn’t imagine. My carbs fuel bowls which used to get “warm” are also cool to the touch now also.

Even idling to warm up in the garage on a cooler day used to make the fuel rail too hot to touch comfortably (imagine what fuel would have been doing inside it)!

I used to think heat shielding was the main solution, but how much a decent rad can affect this has taken my by TOTAL surprise.

[HusseinHolland]

11 hours ago, AK260 said:

So buddy I recently went 4 row aluminium red and the fuel rail heat issues at idle or after a fuel stop have nearly all but gone.
Sure the temps dropped from high to low/mid 20°c when I was testing it but it made a difference like I couldn’t imagine. My carbs fuel bowls which used to get “warm” are also cool to the touch now also.
Even idling to warm up in the garage on a cooler day used to make the fuel rail too hot to touch comfortably (imagine what fuel would have been doing inside it)!
I used to think heat shielding was the main solution, but how much a decent rad can affect this has taken my by TOTAL surprise.

Not sure that a carb setup would be a direct comparison, however that is good to note. I'm not likely to be buying a new aluminum rad yet, as I will need to reverse the rad flow / hose locations when I do the VQ35DE conversion.

 

Edit - just noticed you are in Surrey. I was born & lived in Kingston-Upon-Thames until I was 10, after that we moved around various countries. Where are you?

Edited November 13, 2023 by HusseinHolland

[Captain Obvious]

13 hours ago, HusseinHolland said:

ProtunerZ rail & injector seat adaptors, 19.4lb/hr Bosch injectors 0280155712 (GM, Saab application)

How does the flowrate of those new injectors compare to the originals?

I did a very little looking around a while ago and it seems the originals are low flow compared to most of the newer stuff.

[HusseinHolland]

10 hours ago, Captain Obvious said:

How does the flowrate of those new injectors compare to the originals?

I did a very little looking around a while ago and it seems the originals are low flow compared to most of the newer stuff.

We had a conversation on this  - I had to look around to find it - it was in the FPR thread

Stock are 17.9lb/hr  - 188cc @2.5bar - which translates into around 19lb/hr @ 3bar  - so I bought 19.4lb/hr - 205cc. 

 

 

Edited November 14, 2023 by HusseinHolland

[HusseinHolland]

Test fitting the ProtunerZ rail & adaptors, made a new section of fuel feed using 6AN braided hose, and a 6AN U-bend to feed the CSV

Adaptors came with SS Allen head screws, I don't like them. So, I used coated Sems screws

Bosch 0280155712 205cc

Added a support off the stock forward head mount point

Back together & running. I'm working on a heat shield template. 

Edited November 14, 2023 by HusseinHolland

[Zed Head]

Here's a link to a table I had found a while ago.  The original web page seems down but the table exists in various forms.  028-150-105 seems to be the standard Bosch original form replacement for the Nissan analog.  In those early days they gave different part numbers based on hose length.  I think that up to -112 are the same basic injector.

It downloads a pdf file.  Those 712's are high impedance.  You'll want to remove the dropping resistors, I'd guess.  Although I ran high impedance on my engine and they worked fine either way.  Looks like you might be a hair rich with those.  Good luck.

https://alfaclubvic.org.au/forum/index.php?action=dlattach;topic=13145.0;attach=28987

and https://www.google.com/search?q=stanweiss+injector