OEM Sidefeed to Topfeed TGV Conversion (05/06 to 07+ Conversion)

[Enlight]

8 hours ago, Tehnation said:

ah wtf, any writeups on how to setup a topfeed conversion? 200 bucks and some plumbing isn't bad actually, probably need like 100-200 in hoses, adapters, etc., depending if you use rubber or braided steel lines.  Or did some company make our lives easy and has a fueling kit that we can just by with everything we need? 

I came across this video which you might find helpful:

35 minutes ago, m sprank said:

The center holes not fitting is the norm. On a metal manifold you can port the inner holes and have just enough meat left to securely mount. With the plastic manifold you have the brass inserts giving support to the mount holes. In order to port the inserts must go. Then it is my understanding that you do not have enough meat left to mount.

With that information, it seems like filling the TGV center holes and re-tapping them would result in a cleaner install, the manifolds themselves would remain untouched. I don't love the idea of using JB Weld to fill the holes, but if I can tap a straight hole I think there will be enough cast aluminum to hold the bolt to its proper torque value. Drilling straight will be the hardest as I don't have a drill press and I don't want to spend machine shop money.

[m sprank]

I would tig weld, not jb weld. But, I doubt many members have access or know how.  Too much vibration to trust jb weld.  Its basically epoxy. 

It is an option, I suppose.  

[KZJonny]

There are some "no weld" aluminium welding products out there. Could be a good middle ground between JB weld epoxy and proper Tig welding to fill in the holes in prep for re-drilling and tapping. It would probably be worth investigating the heat required for them tho, to make sure you weren't likely to distort anything.

I would also think that given the relatively  low torque these fasteners are under that with good surface prep, filling them in with ali wire from a Mig spool gun would be sufficient for the task. Probably more people out in the world with a Mig + spool gun than Tig in their garage?

Not nearly as nice looking of a final product, usually, but with a little filing at the end, you should be able to make it a nice flat surface for mating up.

[Tehnation]

2 hours ago, Enlight said:

I came across this video which you might find helpful:

With that information, it seems like filling the TGV center holes and re-tapping them would result in a cleaner install, the manifolds themselves would remain untouched. I don't love the idea of using JB Weld to fill the holes, but if I can tap a straight hole I think there will be enough cast aluminum to hold the bolt to its proper torque value. Drilling straight will be the hardest as I don't have a drill press and I don't want to spend machine shop money.

Isnt that a plastic manifold in that video? Is that the same as ours or is it made to line up with those tgvs? Maybe the holes on that manifold are different? Might be easier and cheaper to just swap to that manifold as well. 

[Enlight]

I believe those are different from ours, but I just shared the video to show how he got fuel lines from another model.

[Tehnation]

That manifold seems like it could work, couldn't be to different. Video said its from a 11 wrx, which might be the same as the later 4th gens. Maybe we can get some of the 07-09 guys to measure those inside holes and we can do some math? 

[Enlight]

Another good discovery, I don't know if I'm just late to the game and/or stupid. I just mounted the stock '05 LGT motor and sensors to the '05 WRX TGV housings and they plugged right in - no problem. This means if you held on to your stock TGV motor+sensors, you just need the WRX TGV housing and not the motor/sensors, since those are becoming very hard to find.

This has been a bumbling  journey for me since I bought my car pre-modified. At first, I thought "side-feed" meant the orientation of the injectors to the housing, not how the fuel rails attached to the injectors. This is compounded by me being sold the wrong TGV's (Facebook marketplace is a real crap shoot).

[Tehnation]

wait a minute..... those tgvs in that video are a 3pin not 5pin? Am I missing something? Why couldnt we just buy all of what that dude bought and stick it on our heads? 

At 5:18, I only see 3 pins. 

[rhino6303]

9 minutes ago, Tehnation said:

wait a minute..... those tgvs in that video are a 3pin not 5pin? Am I missing something? Why couldnt we just buy all of what that dude bought and stick it on our heads? 

At 5:18, I only see 3 pins. 

2 are hidden in the frame. They are above the 3 like shown below.

 - -

- - -

[Tehnation]

k, thought I was going crazy. 

A used intake manifold is like 50-100 bucks. 

Cause the 08-09 topfeed intake manifold is different from the 05 06, same part number as the 11 wrx, but everything else is the same, the vacuum system, throttle body. So it might be able to mount to tgvs that we need. 

The 05 intake manifold is about 1.25" from center to center for those center bolts. Enlight, are the threaded holes closer or further together? Could you measure the tgv center to center? 

Anyone with an 08-09 and has a ruler or caliper?  

I'm thinking rather than fill and drill, just buy a 75 manifold from the junkyard and call it a day.

[Tehnation]

If I recall correctly the reason I butchered the top feed fuel rails was to get it to work with our side feed intake manifold, the bridge between the cylinders that strip with the 2 bolts we are talking about has to be in a different orientation to get the topfeed fuel rails to fit over that bridge, so that can be the reason behind the holes not lining up. So a top feed intake manifold might actually work with a top feed tgv. The years now are the issue, who knows if they changed the design but it seems top feed and side feed manifolds should work cause all the sidefeed manifolds work with eachother, so i'm hoping its the same for top feeds. 

[rhino6303]

2 minutes ago, Tehnation said:

If I recall correctly the reason I butchered the top feed fuel rails was to get it to work with our side feed intake manifold, the bridge between the cylinders that strip with the 2 bolts we are talking about has to be in a different orientation to get the topfeed fuel rails to fit over that bridge, so that can be the reason behind the holes not lining up. So a top feed intake manifold might actually work with a top feed tgv. The years now are the issue, who knows if they changed the design but it seems top feed and side feed manifolds should work cause all the sidefeed manifolds work with eachother, so i'm hoping its the same for top feeds. 

I have oem top feed tgvs and rails with my sidefeed intake manifold.

[m sprank]

The manifolds should be the same for mounting. The difference is the mount for the fuel lines and the FPR.  The change to top feed moved the FPR to the manifold and the fuel lines obviously changed too. 

 

Some are overthinking this. I have done sooo many top feed conversions.  The difference is the electronics were deleted and now they need to be left intact.  The housings and mounts are all well known and documented.  The electronics is the new piece.  If you can't tune past it, and must have top feed with "working motors and sensors" you will need to build an electronic device like Rick has described. 

Edited February 18, 2023 by m sprank

[Tehnation]

And I strike out again.... looks like i'm gonna have to do this the hard way.... sidefeed conversion though.. ugh.. cause getting some topfeed tgvs is going to be a task as well. 

[Tehnation]

So let me ask again cause this is confusing, the electrical stuff I mean, the reason we can't use the 5 pin is cause the signal sent to the ecu is not in the right range cause the polarity is switched. I don't know much about electrical stuff cause I hate it but is there some kind of electrical fuckery that we can put on that signal line to the ecu that reverses the polarity or whatever to reverse what the voltage read by the ecu? This has got to be a thing in the electrical world, no?

Can the signal be swapped by changing something in the ecu map, like tell it to read it differently? If so i'm wondering why cobb wouldn't at least throw us a bone and allow people some options, cause this seems like a parameter that can be adjusted with a tune, which would help out a lot. Maybe it can't but seems like something feasible within their new restricted realm.  

I need to get my car tuned, i'm running on crap boost and 11mpg... funny thing is the car is still fun to drive with this shit base tune. But now that things are different, I can't expect a dyno tune until I get all this in order, and I wanna go to the meet , but I'm not driving 100's of miles on this tune while getting 11 mpg lol. 

[subisubisu]

I don't have nearly the expertise of some other members here, but I think I know these answers, at least to a point:

1) I think the electrical signals can absolutely be processed to reverse the 5-pin signal to provide the 3-pin ECU connection with a response it will be happy with.  I started looking at this myself, but I am currently between short block and long block and it will be a while before I can connect up electrics, so don't wait on me.

2) I think that if you understand what is happening in the ECU and have the ability to overwrite it, you can absolutely make changes that accomplish the same thing.

3) From what I am hearing, here and elsewhere, the big tuners and many of the medium ones have had the fear of god put into them and no way, no how will they be observed to take any action to modify the emission system that god and the OEM created.

[Tehnation]

OMG! Am I going crazy or did all of underdogs posts get deleted, or was that a different thread???? I was trying to find the information he posted on the signals etc. 

I wanted to confirm if the signal needs to be changed going to the tgv or to the ecu. I have no idea how the tgv works, I'm assuming the sensor either gets a signal from the ecu to tell the motor to move or the sensor sends a signal to the ecu to move the motor. 

 

[gkstar]

Photos to support evidence of figment mismatches. I have not tried the 07+LGT plastic manifold and probably at this point a little to far it to make the exploratory purchase. Unless someone has one super cheap
 

02-05 Top feed TGV two firmest issues with stock lines pic 1&2

1. as mentioned plastic manifold does not match up on inner. Approx 4mm off center. Two items to adjust fill and retap, remove brass inserts and potentially add brace on top of plastic then tighten

2. Tabs on intake hit lines. Possibly dremel tabs off

on side feed from metal manifold. Purchased just the reducer pieces from Radium and bolt kit from IAG. Stock top feed fuel line attachment holes are narrower then side feed. Attempt was to “make” a conversion kit without doing new lines too. Could notch one of the brackets and add washers on bolt top and bottom to sandwich the piece but that is a little shady.

 

[Tehnation]

So the fuel rail main bolts don't even line up, or they can't cause of those tabs? 

I just checked mine, I had to cut off the front tab to get the passenger fuel rail to fit. 

[Tehnation]

12 minutes ago, Tehnation said:

So us 4th gen 05-06 lgt owners who modified to topfeed via deletes are in need of some electrical wisdom due to the new CARB laws making tuners run for the hills. The 05-06 has 2 seperate devices a sensor and motor to control the tgvs via 2 pin and 3 pin connections, the newer 07-09 topfeed lgts have a single 5 pin connector for both, but the sensor has reversed polarity so this: 

05-06: 3.8-4.9V (Closed), 0.2-0.9V (Open)

07-09: 0.4-1.2V (Closed), 2.8-4.6V (Open)

 What we want is something more like this 

05-06: 3.8-4.9V (Closed), 0.2-0.9V (Open)

07-09: 2.8-4.6V (Closed), 0.4-1.2V (Open)

Is there any kind of electrical thing a ma jiggy we could splice in somewhere to make this happen? Something simple and cheap to reverse the polarity of the sensor signal or something along those lines? 

I made a new post. Hopefully someone might have an answer. 

[gkstar]

16 minutes ago, Tehnation said:

So the fuel rail main bolts don't even line up, or they can't cause of those tabs? 

I just checked mine, I had to cut off the front tab to get the passenger fuel rail to fit. 

Correct, the stock Wrx/sti top feed fuel rail bolt holes do not line up with side feed TGV  bolt holes. 

[m sprank]

More forum f&ckery.  Ricks posts are gone.  This is like the forum upgraded again.  I lost over 12k posts and tons of pix in the last upgrade.  Where are Ricks informative posts?  I think other members posts are gone too.  There was a lot of discussion about what electronics were needed and who could possibly make them.  Did the Govt/EPA get to the forum too?

[rhino6303]

I think this might work. This circuit takes a constant 12V and then you feed TGV voltage and invert it. It uses a TLV171 opamp. I found this and built the simulation to test that it gives intended voltages.

0.5V outputs 4.5V and vice-versa.

Edited February 22, 2023 by rhino6303

[Tehnation]

So how would I make that? And how big of a unit would it be do you think? Would need to make it long and slender so we could put a big shrink around it or something to keep it safe from elements. 

[Tehnation]

What do I need to buy to make that?