z31p_Timbo 021: Forum archive import (z31performance)

2026-05-15T05:11:08Z

Forum archive import (z31performance)

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{{ForumImport
|op_user=Timbo_021
|op_date=2016-10-26 10:28:01
|post_count=5
|archive_url=/Z31performance_archive/forum/z31-performance-upgrade-forums/engine-management/533025-pencil-stream-injectors.html
}}

'''Timbo_021:''' (2016-10-26 10:28:01)

Anyone ever used them and have any comments? I have just purchased a set of 870cc, low Z Siemens units. Figure they should work seeing as how the injector port aims on the back of the intake valves but original injectors are a 15 degree cone. Any tuning or driveability issues?

Cheers

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'''88sinZ:''' (2016-10-29 03:04:31)

Since no one has responded here's my take

From what i've read in ''Street Turbocharging: Design, Fabrication, Installation and Tuning by Mark Warner'' pencil stream will work but is not ideal for properly atomizing of the fuel. i.e. a more stable AFR. The book is a great read and well worth buying.

870's are some serious injectors, like low E85 range or serious boost on pump gas.

Preferably i'd suggest a multiport disc style similar to this

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'''Timbo_021:''' (2016-10-29 09:18:13)

Cheers for the reply,

Yeah, they'd be ideal. I couldn't find anything locally with low impedance which really sucks now that I think about it.. Just wondering if I should run these or spend a bit more time to look for something else. That book sounds amazing, i'll look into it after i finish my reply! I might run them with 60psi base pressure and see how they go, my engine is coming out for rebuild in a few months anyway so i'll take one for the team. But yeah, I'm thinking about running race fuel because its easier to get and cheaper in my situation so yeah, will be a bit of boost.

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'''260DET:''' (2016-11-05 07:21:41)

If OE are 15 degrees then I'd stick with that, also I'd go with the latest version of what's available because injector design is constantly evolving and the latest injectors invariably will perform and atomise best. Which is particularly important when choosing hi flow injectors. And I'd be preferring recognised brands like Bosch and their US equivalents, not some tricked out ebay specials.

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'''Timbo_021:''' (2016-12-26 06:10:41)

Siemens aren't tricked out ebay specials dude, you would have heard of that brand before. I got it running and with a rough tune it idles and drives better than it did with the rx7 550's at 40psi base fuel pressure. Cold is not so good yet but I'll see if I can iron it out a bit. It's also nice having aluminium rails now that don't leak [archived image: biggrin.png].

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z31p_Timbo 021: Forum archive import (z31performance)