[Lukhard]

I need some advice on whether to purchase a Blouch 18GXT-R (the ball bearing one, as well as fuel pump and injectors) or just get a pro tune with the stock turbo for my 2006 WRX which is currently running a Cobb stage 2 OTS map. Before anyone asks, I've been researching forum posts, dyno plots, etc for a while now trying to make my decision. I'm basically looking for anyone that's been in my situation to offer some advice. My main concern is spool RPM with the aftermarket turbo. Right now I make full boost before 3k rpm, and I love it. I don't want to increase my lag at all, but I want more torque. Basically, I'm asking how much my lag will be increased with an 18g on my 2.5 block. I've read numerous quotes and dyno plots that are all over the place. One says it'll be close to stock spool and the next says more like 3800 rpm. I know a bigger turbo inherently adds lag by design. My goal is low end torque for daily driving fun. I rarely rev over 3500 rpm. My engine mods over the "recommended" Cobb OTS mods are a Borla header, STi intercooler, Cobb EBCS and I'm catless. I've also got coilovers, wheels/tires etc so the only thing left to mod is more power. Money isn't an issue at all. Any advice is welcomed. My instagram is luckywrxx if you want to see my car. I posted this on NASIOC but didn't have any luck.

Thanks!
Mike

 

[WRX-maniac]

So a few things first...... You have an 06 wrx with a catless downpipe, borla manifold, sti intercooler, ebcs, AND you are running a cobb OTS stage 2 map? If money isn't an issue, then why isn't your car properly tuned for your mods?

Have you ever read the map notes for cobb's stage 2? Recommended catted downpipe, catback, and an intake approved by one of their ots maps. Your car....... I don't know how it is even running right with a 3 port ebcs, as that part requires a tune for it immediately after installation. If money isn't an issue, then I would do the following, take the car to a protuning shop, tell them what you have done, have them do a compression/leak down test to make sure the engine still healthy after running it with a tune not efficient for your modifications. And if you luck out and your engine is ok and all checks out, have them protune it. I would absolutely do nothing else performance wise to your car until you are properly tuned and sure your engine is still reliable.

 

[Lukhard]

So a few things first...... You have an 06 wrx with a catless downpipe, borla manifold, sti intercooler, ebcs, AND you are running a cobb OTS stage 2 map? If money isn't an issue, then why isn't your car properly tuned for your mods?

Have you ever read the map notes for cobb's stage 2? Recommended catted downpipe, catback, and an intake approved by one of their ots maps. Your car....... I don't know how it is even running right with a 3 port ebcs, as that part requires a tune for it immediately after installation. If money isn't an issue, then I would do the following, take the car to a protuning shop, tell them what you have done, have them do a compression/leak down test to make sure the engine still healthy after running it with a tune not efficient for your modifications. And if you luck out and your engine is ok and all checks out, have them protune it. I would absolutely do nothing else performance wise to your car until you are properly tuned and sure your engine is still reliable.

I appreciate the concern, but I am running a Cobb EBCS map. The other modifications I've done have not affected the calibration at all. I've monitored all the necessary parameters to be sure if this. I'm a calibration engineer by trade, however I work on naturally aspirated V8s and don't have access to an all wheel drive dyno. I simply started this post to gain insight on the spool of the 18g vs stock TD04. Please don't assume that I'm an idiot.

 

[WRX-maniac]

Wasn't assuming anything. Just going off how your OP read. Never once wrote you off as an idiot. Now, with your second post, things make a little more sense as there is more info given than before. Too many people come on here that don't know what they are doing and do some crazy mods with no tune or wrong tunes.

The 18g would be a good upgrade for your car. The TD04 will inherently still spool up slightly faster than the 18G will. But having the ebcs and a good tune will help spool times decrease a few hundred rpms. The problem with the TD04 is that although it spools up quickly and hits full boost pretty early on in the rpm range, it looses pretty much all of its power in the higher rpms. It is actually a pretty inadequate turbo for the EJ255. Hence why Subaru upgraded to the larger and better vf52 in 2009.

The 18G will have a little more lag to it when compared to the TD04. Even the stock vf52 on the 09-14 wrx's has more lag than the older TD04. But I think if you have a good tuner you will be very happy with the performance of the 18G. It will probably spool up like 300-600rpms later than your TD04 (guesstimate) but will hold power much further up in the rpm/power band. I would suggest going with ID1000 injectors and the AEM320lph pump.

 

[Lukhard]

I completely understand how my original post may have sounded, sorry for the lack of info. I appreciably your response and apologize for coming off a bit defensive. The 300-600 rpm difference in spool time is making me lean more towards the 18g. I was worried it would be more like 1k more rpm later. When I poured over the 18g 06'-07' WRX builds on the "proven power" section of NASIOC, most of them looked like they'd be at least 100-150 lbft lower at 3k rpm than the TD04. Like I said, I don't spend much time above 4k rpm and just want the most low end torque possible. I've gotten used to my car and want to make a significant change without selling it and buying something new.


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