Plenum & Injector Housing Porting

[jss06c6]

Originally Posted by Paul Workman

The 90 injector housing is the only one that you can eliminate the primary injector boss entirely as the injector seal is @ the top of the injector. Maybe you realize that, IDK.

More later...

Paul,

The '91 is the same. The Primary injector O-Ring is at the top of the boss. The secondary injector utilizes an O-Ring on the end of the injector, so you can't remove that one, but the secondaries aren't the big choke on the airflow.. the primaries are..

Steve

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[jss06c6]

Originally Posted by XfireZ51

If u don’t punch thru, ur not trying. 🤣🤣🤣

I hear ya! I'm probably not that bold!![emoji12]

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[jss06c6]

Originally Posted by tiegsd

Just had my original injectors replaced, 4 of them are no good. Happy to donate a couple to the cause.

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Thanks! I pulled one of my primary injector to check the first runner. I've got a good visual now as to where I want the profile geometry to be. I think I'm ok at this point. I really appreciate the offer!

Steve

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[tiegsd]

Np. [emoji41]

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[jss06c6]

One done.. second one will get a little more relief around the primary injector bosses and then flip it and open up the plenum side. Interesting that the secondary ports in the injector housings are chamfered on the plenum side, but full 36.2 mm on the head side.. need to pick up some more ball nose burrs tomorrow. The Foredom flex shaft grinder is super! At 1/3 horse, you can't bog it down and the foot control is a blessing for variable speed work and shut down control..[ATTACH][ATTACH][ATTACH]

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[jss06c6]

Thought I'd share some of my experience porting the head side of the injector housings. The primary injector bosses are a significant cause of turbulence in the air stream. While crossectional area increase results in less pressure required per cubic foot of air moved per minute, putting hard angles, sharp edges where ports don't align and big lumps like injector bosses in the fluid stream are huge causes of turbulent flow. In a pipe, turbulent flow is a huge contributor to reduced volume. Smoothing out the fluid stream flow promotes laminar flow versus turbulent flow.

I take a 3/8" x 5/8" ball nose burr and, using the scribe mark to identify my target diameter, I remove material at a 90 degree angle to the face of the housing. Then I use the straight side of the burr to remove the injector boss. This is followed by an oval burr to establish a symmetric bowl and port runner... No obstructions and achieving Target crossectional area. The result is a runner port with better flow than the secondary Port since I can't remove the injector boss in that port (O-Ring is on the tip of the injector on secondaries).

I might see if I can get one of my stock housings and a ported one on a flowbench to check results.. if so, I'll post results..[ATTACH][ATTACH][ATTACH]

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[jss06c6]

Unported vs ported. Plenum side[ATTACH][ATTACH][ATTACH][ATTACH]

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[jss06c6]

Friend with a Superflo 1020 flowbench took one of my ported injector housings and a stock IH to run some flow comparisons. Stay tuned..

I placed one of my ported Injector Housings on the passenger side head (still have some cleanup to do). I'm amazed at the offset in the primary port! Can't help but believe this will add as much or more than the SW headers and 3"exhaust did. I'm amazed these engines did what they did choked off on both the intake and exhaust. Looks like I'll be adding a bunch of fuel and some advance to the tune!!

Secondaries look pretty good on the head port alignment, but off on the plenum side..[ATTACH][ATTACH]

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[XfireZ51]

Steve,

The stock LT5 was good for 500hp had it not been choked up top and at the exhaust. We’re talking 1990. Imagine the earthquake that would have caused in the automotive world.

[jss06c6]

Originally Posted by XfireZ51

Steve,

The stock LT5 was good for 500hp had it not been choked up top and at the exhaust. We’re talking 1990. Imagine the earthquake that would have caused in the automotive world.

Dominic,

I sold my 2010 ZR1 and kept my '91 ZR-1 because of the huge technological shift in a naturally aspirated engine in 1990. This engine has a ton of potential. Imagine what current techniques would yield using this platform as a base! This is just damned fun to work with!!!


Steve

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