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Old 04-05-2013, 09:23 AM   #1
jthatch12
Scooby Specialist
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Member#: 321715
Join Date: May 2012
Chapter/Region: Tri-State
Location: Philly/SJ
Vehicle:
03 Big 16G WRX
PSM

Default $150 660cc Injectors (yes they work)

WARNING - SOME MODIFICATION TO INJECTOR HOUSING NEEDED

Vehicle: 2003 WRX

Product Title: Venom Performance 660cc Injectors

Product Description: Uncapped, Modified Denso Injectors (Vendor Provided Flowtest report included)

Cost: $150

Hey everyone, this is one of my first real reviews. Yesterday my brother in law and I just got done installing 660cc injectors purchased from TLFPerformanceParts for $150... yes thats 4 injectors for $150! The injectors are modified by Venom Performance and came with a flowtest sheet (will upload this later, currently away from home).

Though some modification to the injector housing was needed for installation, these injectors very affordable and are performing well with no other changes to the tune besides the obvious Scaling, Latency, Tip-in parameters. Car feels and drives exactly like it did before with the stock injectors (less some additional tweaking needed to optimize latency & tip-in enrichment, more to come on that).

Sounds too good to be true for 150 bucks doesn't it?

The only catch is that you have to modify the plastic injector housing to remove some material to clear the TGV port so the injector can seat properly aganist the rubber grommet at the base of the nozzle. We found this out the hard way as the intereference was not apparent until the install was completed and MASSIVE vacuum leaks presented themselves at start-up.

The picture below shows a stock injector (blue/gray) next to the Venom 660cc injector (organge). Notice the silver-ish ring about the OD of the orange housin of the Venom injector. This impression was caused by intereference with the TGV port hole during the first installation.




Looking at the injectors side by side you can see how much thicker the new injector is in comparison to the stockers. During the initial install the interference condition was not obvious. We were able to install all injectors and torque down the rails to spec without any issue. The additional injector height that was created by the interference condition was absorbed by "smushing" the C-section grommet at the top of each injector when the rail was bolted down. As you can imagine we ran into some pretty big issues with vacuum leaks at the first start-up.

The thicker injector housing riding on the top of the TGV port was preventing the flange around the base of the nozzle from sealing against the grommet Thus creating a manifold leak at each injector (no fuel leaks were observed).




The solution was to carefully grind away some of the plastic injector housing to achieve a similiar Outer Diameter as a stock injector in order to clear the TGV port (Kudos to my Brother in law Scott!). In the picture below, you can see a faint impression on the stock injector that denotes how deep into the TGV the injector sits. We had thrown around the idea of countersinking / counterboring the the TGV ports but shuddered at the risks involved with performing that kind of modificaiton with TGV's still installed on the vehicle. However, had the TGV's been off vehicle (delete mod, etc.) we would have likely pursued this route as there appears to be a large amount of excess material present on the TGV's around the injector port.

Side by side comparison between : Unmodified, Modified, and Stock








First we tried the injector housing modifications on the drivers side only and noticed a improvement. Immediate Fuel Correction was still pegged @ +25, but the AFR had droped from 19-22 @ idle to 15-17. Long story short we gave the passenger side injectors the same treatment and everything returned to normal. It was a night and day difference. With an injector scaler of 660 and stock latency values the Immediate correction was dancing around -3. There is a little more tuning we have to take care of regarding tip-in enrichment and latency, but for now the car is running like a champ!

In conclusion, there was some risk involved with shaving down the injector housings but I felt that at a price point of 150 bucks it was worth the risk. Boy was I glad we went ahead with it!

I will upload more supporting data when I get a chance. Feel free to ask any questions!

Tuning for the injectors:


Update 5/2/13, latency values dialed in as well as tip-in. All corrections are now within 3%


More pictures from the install are available here on dropbox:
https://www.dropbox.com/sh/s8vbefe5duwfexz/oOycH_OaxL


TLF Performance Parts Website:
http://www.tlfperformanceparts.com/

VENOM Performance:
http://www.venom-performance.com/

*for clarification, as stated Venom Performance is the company that modifies the injectors, TLF simply flow tests them and sells them
* Registered users of the site do not see these ads.

Last edited by jthatch12; 05-02-2013 at 05:50 PM.
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