I'm in the process of trying to put together a parts list to get around 350whp, if not closer to 400whp. Now my question is, would an aftermarket topmount such as the APS unit or something of similar size be big enough to handle that much power(boost) and not be restrictive? I was aiming towards using the VF22 turbo and doing a monster port on it. If I recall right, the VF22 was capable of handling 25psi at 7000RPM. With the supporting mods and a good tune, you think I'll be able to reach that goal? I recall reading somewhere that an individual with the VF22 ended up benefiting more from a front mount compared to the TXS topmount. Any thoughts and/or suggestions would be great. Thanks.

 

not to be a d*** or anything but i'd say go with a FMIC. i dont think a TMIC will be able to retain a low enough core temperature to avoid heat soak. IMHO a FMIC is the way to go if your looking for 350wph. O and im sure you know this but for 350 awhp you need like 475 hp to the crank so you definitely need a different drivetrain to handle 350wph (STI RA would do it).

as far as the IC is concerned, i'd say turboXs FM or Greddy FM

 

400 whp is possible with a US or JDM STi topmount. Not sure if the stock WRX topmount is big enough, but I'd lean to no. Also, the VF22 probably won't give you 350 whp, definitely not on pump gas. I'd plan on at least a 20G or GT30 or FP Green.

 

id say six speed to be safe

 

well, im definitely wanting to upgrade to a bigger top mount, most likely the APS Top Mount, but I'm still looking into others. I just wanted to make sure that it wasn't going to hold me back with a big turbo. So a 20G turbo wouldn't be too big for the APS top mount?

Cobb Tuning looks like their designing a nice top mount, however with the way things have been going with the AccessTuner, it'll probably be another year before that'll ever get released.

 

why 350whp. sometimes chasing a number doesn't acutally make you faster. 350 is a good round number, but what do you want your car to do? 1/4 mile, road, top end, dyno queen, just to talk sh*t to other people. I mean there are a lot of reasons. If you want quicker spool time, basically no lag, I'd go top mount. That means rolling beside someone, if they get on it, you wont have to wait while they pull away from you, and then play catch up, where you would need that extra hp just to make up ground, if you had a front mount. If you are going to build your car to autocross or road corse, I'd get a front mount because it wont heat soak, and you will retain power. ( i have a STI top mount and If I'm driving around getting on it for an extended period of time, my car slows down noticibly.) So in order to maintain a lap time, I'd go front mount.

The reason I like my top mount and top mounts in general, is quick spool time. The ability to have the power right when I step on the gas. there isn't a mile of piping for the boost to build up to pressure.

If you want an IHI turbo like a VF22, actually the one I'm getting. I'd stay top mount, that turbo is a JDM STI take off, made to run with a STI top mount. It's bigger then all the other IHI's used on imprezas, so the top mount will help on your lag becasue is spools the latest, but holds/ pulls harder higher in the powerband. If you just want the number "350" you will need a bigger turbo, which I would deffnatly recomend a front mound, if you are running anything bigger then a IHI, made to fit directly on a WRX. I don't think, from what I've read you could pull 350whp out of an IHI, on pump gas. Maybe off 100+ octane with a pretty agressive map, and some high boost. But you probably wouldn't want to ride around like that every day, with your car drinking 5$+ per gallon gas. So For that number I'd get a bigger turbo then a IHI as other people said, deffinatly get a front mount, and more then deffinatly get a tranny rebuild or 6speed. Have fun that's around 10g's if you do your own work and mabye around 13g's if you have someone else do it. That's for turbo, tuning, IC, and 6spd"6500$". So if you are dedicated to that number, there you go. That's basically what you have to do in perspective. That is all considering you have suporting mods, uppipe, downpipe, exhaust, Engine management, injectors, fuel pump, and around that number you may need pistons, and rods.

You may also want to consider a stroker kit. Just another option. Hope that was helpfull.

 

That was helpful and I appreciate you taking the time to write all that. I have a lot of reasons actually for why I want to get close to 350whp. In the end, as long as I am over 300whp, I'll be satisfied. I like to take a few street challenges when given the opportunity and also go to the drag strip to make some passes. That's more of why I want to be close 350whp. However, I love going to autocross events and have been doing so for the last 3 years now. I'm a member of NASA and would like to get more into the track racing. I'd like to stick with the top mount, because of the quicker spooling. As of right now, this is what my upgrades list consists of:

EcuTek reflash $650 (+$400 for tuning software)
STI Geniune hood scoop $185 (factory painted white)
APS air splitter $165
APS Topmount intercooler (includes required lower piping/parts from turbo to IC) $1050
VF22 Turbo $600
650cc injectors $650 (anything cheaper than PE?)
Upgraded fuel rail kit (Perrin) $400
Walbro fuel pump $100
EcuTek Dyno tune $???

I just threw in some rough numbers. My guess will be that it'll be around $4k for everything. I'm running the AccessPort right now, but I'm planning on unmarrying it and selling it so that I can have the car tuned with EcuTek. I'm just not sure how much the tune will cost. I'm a few hours away from Mastro Subaru and they told me $999 for a EcuTek reflash and dyno tune. Seems kinda high if you ask me.

 

It's not related totally, but I came across some stock WRX injectors that have been modified to 850cc. They claim to run them with their VF34 at 21psi and have no problems. Isn't 850cc alittle big for any of the IHI turbos? I would be using them with the VF22 turbo. Just want to make sure I wouldn't be running too rich, even after a tune.

 

They are 740cc modified. Who told you they are 850? Either way, yes, they are far bigger than needed for any IHI turbo.

 

Actually these are on ebay, not sure if either of them are yours or not. The one claiming to run the VF34:
http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

There's another set here thats alittle cheaper:
http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

I assumed that they would be too big, but they mentioned being used with the VF34 turbo and the other one was running on 400hp, which is what the VF22 is capable of. Unless they are referring to wheel horsepower, then that wouldn't be the case with the VF22. In either case, it made me look into it to find out for sure if they would be suitable for the VF22 I plan on running. If so, I'd rather spend $200 for those, rather than $650 for a set of PEs.

 

What Ban was trying to relay to you was modified stock injectorsusually flow at 740cc not 850cc. Usually all that is done to modify stock injectors is the restrictor at the tip is cut off(think circumcision[sic])

 

Personally, I'd send my injectors to Kingpin or Perrin to have them done professionally, rather than trust an eBay seller who overclaims their actual flow.

 

I sent the seller an email asking if he had any documentation of the injectors being modified and he said no, so I didn't want to risk it. That sounds like a good idea BAN SUVS. I was actually just about to start looking into that to see where I could send them off to, to get modified.

I appreciate all the helpful comments from everyone.

 

All these arguments are good but what about turbo lag. With a frontmount there is a considerable amount but with a top mount there is considerably less.

Cheers
Rush