New STI Looking For More Torque and Drivability

[bbrock171]

Hey guys, just got my '13 STI and loving it, especially running an intake, TBE and protune. The only thing that bothers me is coming from an '11 WRX it seems like I have to get much higher in the RPMs to see any power. I know it's to be expected with a bigger turbo. But this is troubling because a lot of my driving is stop and go city driving, and with my SPT exhaust it just draws a LOT of attention when I have to rev above 4000 to get any power. I liked that the WRX had plenty of power in the low end (after I went stg 2), and was expecting the same with the STI but I'm just not seeing it. Would be nice to not have to downshift two gears to get the car off it's a$$ and moving, ya know?

I've done a lot of reading the last few weeks and it seems a lot of the info out there on this issue is grossly outdated, so I was hoping to start a new drivabiity thread to share new ideas and experiences with the recent (08-13) model years.

The one thing I've read a million times is "Get rid of your catted uppipe!" Well, I don't have a catted uppipe so that's not very helpful. Is there still any noticeable change in spool for the non-catted years? I'd bet it's far less dramatic.

Would headers help noticeably? I don't want to spend the $1000 if I'm not even going to notice the difference.

A shortblock, turbo, etc are not out of the question if you have any insights on those, but they won't be happening any time soon...and I like power, so I don't want to downgrade to a smaller turbo. Maybe one with faster spool that can still handle high boost efficiently, if that even exists.

I've also thought about e85, but heard from a few people that with those torque levels the OEM clutch goes pretty quick. Anyone have any experience with running e85 on the later model STIs? While I wouldn't mind the additional power, I'm more concerned with shifting the power band to the left a little or leveling it out a bit than I am with just getting higher peak numbers.

Looking for more area under the curve. Thanks.

[MainFrame]

The turbo in the 09+ WRX is the same size as the turbo in the STi..


Headers would shift your power further to the right (less bottom end, more top end), which is not what you're wanting. A tune is about the best you can do (aside from spending thousands on a stroker). e85 would probably help out, and if you're worried about the clutch just don't tune for that much peak torque. You could also upgrade your boost control system..

If it were me I would get a good turboback exhaust, a 3-port EBCS, and a good MBC. Then take it to a tuner and tell them what you're looking for in the tune. If that's not enough then think about EWG or e85.. or both.

[bbrock171]

The turbo in the 09+ WRX is the same size as the turbo in the STi..


Headers would shift your power further to the right (less bottom end, more top end), which is not what you're wanting. A tune is about the best you can do (aside from spending thousands on a stroker). e85 would probably help out, and if you're worried about the clutch just don't tune for that much peak torque. You could also upgrade your boost control system..

If it were me I would get a good turboback exhaust, a 3-port EBCS, and a good MBC. Then take it to a tuner and tell them what you're looking for in the tune. If that's not enough then think about EWG or e85.. or both.

Interesting, it definitely seems to spool about 500rpm later. Wonder why that is.

Thanks for the header info. It just made sense to me that EL headers would cause the turbo to spool faster. I definitely do not want to shift power to the right any further!

EWGs are loud as hell, aren't they? Not really looking for that either, but I'll keep it in mind. Sounds like e85 and a good protune would be a good solution. But yeah, I'll deliberately have to keep the peak torque numbers limited until I'm ready to upgrade the clutch.

[MainFrame]

EWG is silent until you hit target boost. Mine rarely opens unless I floor it.. and even then, you can always re-route it back into the exhaust. One advantage to doing that would be that you could run a catless downpipe without having to worry about boost creep. And catless will out spool catted every time.

[bbrock171]

Good to know. I bet it sounds pretty mean when it does open up though, haha.

I'm running the Invidia catless DP, and have had zero issues with boost creep so far. I'm tuned for it though, not just running a Cobb map.

[MainFrame]

Yeah, not every car experiences problems with boost creep.. if you're already catless and not having issues it's probably not worth the trouble and expense of installing an EWG and recirculating it

[Sinister]

Any modification that makes the car more efficient will make it have more lower end power.

I had more torque at 3200 RPM than the stock WRX had peak torque.

[bbrock171]

Any modification that makes the car more efficient will make it have more lower end power.

I had more torque at 3200 RPM than the stock WRX had peak torque.

Care to elaborate?

[Sinister]

Some engine modifications are supporting mods for bigger power, some are big power modifications, some enhance the engine efficiency. Usually porting and polishing certain components, heat wrapping, and removing emissions components all increase engine efficiency. Have you thought about TGV deletes, and porting and polishing your turbo? Also a boost control solenoid can help spool.

[Sinister]

Also... who tuned your car? and is there a dyno plot we can see?

[MainFrame]

Yeah.. there are a lot of things you could do engine wise (higher compression, port and polish heads, rally cams, etc). But I wouldn't suggest cracking the engine open unless you have to.


Things like TGV deletes, port and polish intake manifold, and port and polish throttle body will help to some extent. A good intake and turbo inlet could also help out a little. I wouldn't expect a huge difference from any one of those mods, but all together it would be a noticable difference.




I'm still kicking around on a base map, but I recently noticed I'm hitting 15psi @ 3000rpm in 4th gear.

[bbrock171]

Some engine modifications are supporting mods for bigger power, some are big power modifications, some enhance the engine efficiency. Usually porting and polishing certain components, heat wrapping, and removing emissions components all increase engine efficiency. Have you thought about TGV deletes, and porting and polishing your turbo? Also a boost control solenoid can help spool.

I've given all of those a thought actually. I've seen a couple different ways to do the TGV delete - do you have any experience with doing this yourself? I'm a DIYer with not a lot of experience and no alternate means of transportation, so I can't afford to hit a snag and not have an operational car for a couple of days. Given the TGV's function, would that hurt me on my emmissions inspection? I can handle swapping out the downpipe once a year, but the TGV sounds like a lot more work. Wouldn't want to do that if it's going to give me problems.

Porting and polishing sounds like a good idea as well. I might do that if I get some free time.

I've read the a BCS on later model STIs don't do a whole lot of good, and in some cases aren't even as good as the stocker. But again, I'll look into it further.

Also... who tuned your car? and is there a dyno plot we can see?

Sadly no dyno plot Cobb's imaginary, er, simulated dyno reads ~ 365hp and 410ft/lbs pretty consistently. I was/am being etuned by Eric at TP. The butt dyno is very happy compared to my old WRX; I just would like more low since I spend so much time putting around town and can't get on the highway all that much to enjoy the top end.

Yeah.. there are a lot of things you could do engine wise (higher compression, port and polish heads, rally cams, etc). But I wouldn't suggest cracking the engine open unless you have to.

Things like TGV deletes, port and polish intake manifold, and port and polish throttle body will help to some extent. A good intake and turbo inlet could also help out a little. I wouldn't expect a huge difference from any one of those mods, but all together it would be a noticable difference.

I'm still kicking around on a base map, but I recently noticed I'm hitting 15psi @ 3000rpm in 4th gear.

Confirmed my fears - PnP, TGV, BCS, turbo inlet, etc etc all just to see a noticeable difference in spool. Was really just hoping for a silver bullet with a $5 price tag...you let me down

Thanks for all the advice guys. I'll just take it one step at a time, I guess. I plan to have this car for quite a while.

[Donkey]

Light weight crank pulley is a good "bang for the buck" mod that is easy to install yourself and you can feel a little better acceleration. You can get a used one for around $50-$75. Next would be a turbo blanket and maybe some ported/polished exhaust manifolds. The manifolds are pretty easy to install and should reduce spool time.

[EndlessSea]

and I like power, so I don't want to downgrade to a smaller turbo. Maybe one with faster spool that can still handle high boost efficiently, if that even exists.

yes it does exist, its called a twin scroll turbo. but im not sure if there are any kits out there for the wrx/sti, or if it would even work given the header/uppipe configuration. maybe someone else can chime in on that

[Donkey]

yes it does exist, its called a twin scroll turbo. but im not sure if there are any kits out there for the wrx/sti, or if it would even work given the header/uppipe configuration. maybe someone else can chime in on that

Some of the JDM STI Subies had them from the factory. Or you just go rotated. People been using both methods for over a decade. Unfortunately both cost $$$$$. Easier than twin scroll is buy a bolt on turbo with a ball bearing CHRA.