STi swap write up....best ever?

[maxx189]

When you do this with a 2007 STi intake manifold on a 2007 Spec.B, do you need all the other parts connected with the manifold from the STi or only the manifold itself?

[Grothe08LGT]

Have been looking for a while, and hate to bump a really old thread, but what throttle body was used with this STI intake manifold swap? Thanks, and sorry if I didn't find the obvious while searching.

[finse]

Have been looking for a while, and hate to bump a really old thread, but what throttle body was used with this STI intake manifold swap? Thanks, and sorry if I didn't find the obvious while searching.

 

I am using the throttle-body from my original manifold. You could use an STi one, but it will require you make modification to your wiring harness.

[Grothe08LGT]

All I needed to know! Thank you so much finse!

[fahr_side]

While you're on the line finse, could you tell me if the LGT plastic coolant tank has the same mounting points to the STi manifold? IE, does the LGT one bolt straight up or are the mounting holes off?

[finse]

While you're on the line finse, could you tell me if the LGT plastic coolant tank has the same mounting points to the STi manifold? IE, does the LGT one bolt straight up or are the mounting holes off?

 

It's close, but does not line up. When I first did my swap, I used the LGT tank with a custom bracket. I've since switched to an STi/WRX style coolant tank. It's the better way to go IMHO.

[fahr_side]

Thanks for the info.

 

How about the LGT fuel rails, do the mounting tabs bolt to the underside of the manifold? It doesn't look like they line up, and I'd be concerned about the pulsing in the lines from the injectors opening and closing making the hard pipes vibrate. Oh, and what year STi is your manifold from? I'm guessing it's a GDB, maybe an '07?

[finse]

Thanks for the info.

 

How about the LGT fuel rails, do the mounting tabs bolt to the underside of the manifold? It doesn't look like they line up, and I'd be concerned about the pulsing in the lines from the injectors opening and closing making the hard pipes vibrate. Oh, and what year STi is your manifold from? I'm guessing it's a GDB, maybe an '07?

 

Fuel rails mount to the TGV's. I re-used my TGV's, after porting and polishing them. Again, I think I made a custom bracket to deal with the offset of that one bolt that mounts to the underside of the manifold. I don't recall, as I upgraded to id1000's and custom fuel rails a couple years ago.

 

I think it's off an 08. No drilling required to mate to my 06 TGV's.

 

My dremel tool got a lot of use during my swap

[fahr_side]

Thanks. I doubt the manifold is from an '08. I've fitted '06 TGV housings (they were already deleted / ported) to an '08 GRB and we had to slot the two holes in the center of the manifold in order to match the TGV housings. The big nipple for the brake booster is not on the end of the runner like that on the GRB, and they moved the boost reference for the FPR to the same location as on the plastic fantastic also.

 

Appreciate your help. No-one thinks to write about the nitty-gritty.

[Underdog]

Problem with nitty gritty is that every swap is slightly different and it gets complicated fast. I swapped an entire '12 STI TGV/im/TB/TMIC setup onto my b25 heads, new custom wiring harness, all correct factory plumbing etc.

 

FPR reference is best from plenum, not #4 runner, as recently found by Cobb. I tapped into the STI BPV signal hose for my defi boost sensor, and was able to add a wye with ~2" of hose to give signal to FPR.

[finse]

I've fitted '06 TGV housings.

 

Wait, the 06 had side feed injectors, and you have top feed (based on your profile, you have an 08). Please don't tell me you are converting to side feeds?

[fahr_side]

Problem with nitty gritty is that every swap is slightly different and it gets complicated fast. I swapped an entire '12 STI TGV/im/TB/TMIC setup onto my b25 heads, new custom wiring harness, all correct factory plumbing etc.

 

FPR reference is best from plenum, not #4 runner, as recently found by Cobb. I tapped into the STI BPV signal hose for my defi boost sensor, and was able to add a wye with ~2" of hose to give signal to FPR.

 

 

I meant there are a lot of other 'walkthroughs' that are like:

 

1. Remove stock part.

2. Install new part.

3. Open beer.

 

I don't think the boost reference being at cyl #4 is in and of itself the cause of the GRB stumble. The 4th gen LGT and GH8 both use this location and have no issues. We have different FPRs and pulse dampers, in locations closer to the injectors. Use the GH8 type rails and FPR and you should have no problem tapping anywhere you like for boost reference.

 

Wait, the 06 had side feed injectors, and you have top feed (based on your profile, you have an 08). Please don't tell me you are converting to side feeds?

 

 

No no. No way. The TGV's were from an '06 WRX or FXT, top-feed, and went on to an '08 GRB that belongs to a customer. I'm also in an '08 but it's a GH8.

 

 

Sent from some electronic device.

[fahr_side]

Where did you install the control valve 11810AA060*? That's the check valve that screws into the plenum via a steel plate on the plastic manifold and I'm sure feeds vacuum to the brake booster. On the STi there's a check valve in the hose itself and the fitting on the manifold (on the runner for #4) is just a plain fitting.

 

* The valve is part #11 here.

[Underdog]

Not sure about the OP but I used the STI booster hose w/ integrated check valve. Can you remove the LGT valve from the plate and compare threads to the booster vac source port on the STI manifold?

[fahr_side]

Thanks UD. I have a GRB hose with integrated check valve I can use. The valve off the plastic fantastic fits in the port below the TB just fine. I haven't checked the location on #4 runner. I may switch to the STi type PCV and hoses as it leaves more room for the turbo it seems.

 

 

Sent from a device using some software.

[fahr_side]

Well, I ended up with a lot of GRB parts in my recipe because (1) they were available and (2) in most cases it was easier than kludging the original parts to work.

 

Intake manifold14001AB960  GRB

IM gasket14075AA161  GH8 is same asGRB

Control valve11810AA060  GH8 item connected to brake booster, GRB use as PCV

Coolant header tank 21132AA140GRB only, GH8 item doesn't fit well

Coolant hose bracket 24245AA050GRB only

Coolant hose to rad top 45162FG010  Samco hose for GRB only

Coolant hose to rad cap 45162FG000  Samco hose for GRB only

Coolant hose to turbo 99078AA710Samco hose for GRB only

BCS bracket 14874AA470  GRB only

evap solenoid valve 1 16102AA391 Same as GDB and SG9. Mount to BCS cover plate

BPV return hose 99081AA081GRB same as GDB and SG9.

PCV hose assy 11815AB450GRB same as GDB and SG9.

PCV hose bracket 11843AA011  GRB same as GDB and SG9.

PCV hose connector 3-way 11821AA460GRB same as GC8.

PCV hose 99071AB103GRB same as GDB and SG9.

PCV hose 11815AB301GRB same as GDB and SG9.

PCV hose 11815AC260GRB only

Purge valve 42084FE010  GRB same as GDB and SG9

Purge valve hose assy22310AC241  GRB same as GDB and SG9

Coolant and PCV hard pipe 21141AA131  GRB same as GDB and SG9

Cast top coolant pipe 14053AA550GRB same as GDB and SG9

Vacuum hose intake pipe to metal pipe 99071AB420GRB same as GDB and SG9

Vacuum hose 99081AA060 GRB same as GDB and SG9

Vacuum hose 99071AB352 GRB same as GDB and SG9

Metal breather pipe 11852AA150GRB only

BPV 14471AA143GRB same as GDB and SG9

TMIC driver side bracket 21885AA163  GRB same as GDB and SG9

TMIC pass side bracket 21885AA293  GRB same as GDB and SG9. Extend to meet wider IC mounting point. Ideally use bracket 21885AA330 (GRB only).

Intercooler, complete21820AA380  GRB only

TMIC Y-pipe 21830AA100  GRB might be same as GDB STI

Turbo soft 90* 14462AA354  GRB might be same as GDB STI. Not long enough for aftermarket turbos

Throttle body stock GH8. Note 16112AA270 GRB only (MAP sensor different from GDB/SG9). Use GH8/LGT is easy.

TB gasket 16175AA243GRB same as GDB and SG9. Use GH8/LGT

TB warmer hose top GRB

TB warmer hose bottom GRB

MAP sensor 22627AA440 (if using GRB TB, 3bar)

TGV 14011AB940 GRB same as GH8, mounting holes differ on GDB/SG9

GBOD pass side 14047AA681GRB same as GDB STI and SG9

GBOD driver side14047AA651  GRB same as GDB STI and SG9

Splitter 90817FG010  GRB

 

 

 

Bigger issues are:

 

 

 

The metal pipe under the manifold, for turbo cooling water and breathers, puts the hoses in the way on the passenger side. We tried cutting up my GH8 item for it's water pipe and made a hybrid with that and a GDB breather pipe. Didn't work. GRB metal pipe set does not fit with the GH8 alloy top water manifold, so we used a GRB item there too.

 

 

 

There's no elegant solution to mounting the stock GH8 / LGT upper coolant tank. Only one bolt hole on the manifold could be used, which then puts the tank so much higher up the lower bolt doesn't meet the Green Bracket of Death. Make a short bracket for that if you like but then the second hole on the manifold is too close to create a bracket for.

 

 

 

You can use later GDB fuel rails, or GRB ones, they both bolt up properly. But, the GRB fuel rails are infamous for causing the notorious STi stumble at part load. I elected to chop up and re-weld the brackets on my GH8 / LGT fuel rails to match the mounting points on the GRB manifold, and keep my GH8 FPR and damper setup.

 

 

 

Other stuff:

 

 

 

GH8 / LGT models have a one-way breather valve that mounts on a metal plate below the TB, which connects to the PCV 3-way connector. On the GRB this is installed under the TB also, though the one it comes with may only be a connector, not a one-way valve. On the GRB the vacuum for the brake booster is on the runner for cylinder #4 and the hose has a check valve inserted into it.

 

 

 

GRB water pipes from the upper coolant tank to radiator are not the same as the GDB items, which fit like socks on a rooster.

 

 

 

You can use a GH8 / LGT style turbo inlet pipe (I have a Perrin) but things get a little tight behind the PS pump. It would be easier to use an STi-specific inlet.

 

 

 

The rear-most breather pipes from the heads from the GH8 / LGT will not make it to the metal crossover pipe on the GRB intercooler. Need to adapt / lengthen these or source GRB items.

 

 

 

The engine main harness doesn't need to be extended and works quite well if you mount your evap solenoids, BCS and MAP sensor all on the gold plate on the passenger side.

 

 

 

The small bracket 21885AA330 extends the passenger-side TMIC bracket and connects it to both the turbo heat shield bracket and the GBOD. It's a GRB-only part and I couldn't source one. It's easy to extend the large passenger-side bracket (which is common with the GDB) instead.

 

 

 

Remember the throttle body is sealed with a paper gasket on the metal manifolds where the plastic fantastic uses an o-ring. The manifold to TGV also has a gasket on metal manifolds where the plastics use an o-ring. Prepare in advance.

 

In tuning I found it helped a lot to use the STi per-injector IPW compensation tables. Despite the name the tables compensate for the different air flow through the manifold runners, which is more evenly distributed than on the stock plastic item.

I also found I had to use quite a bit more tip-in enrichment on this manifold, with a maximum of an extra 1.5ms vs. the 0.5ms that was sufficient on the stock manifold.