I had forced air technologies remove my air tumblers and all I can say is wow :eek:. My car now pulls hard all the way to redline. I can chirp the tires into second. and in first gear it scrambles for traction. also the car sounds a lot different probably cause now instead of hesitation the turbo spools and its off i go. I would recommend this to everybody the value of this mod for the $ cant be beat. without a doubt the best power increase you can get for the price

Any other mods? Running EM?

Lots of anecdotal evidence about the benefits of tgv delete, but few hard facts and even less in the way of dyno plots. If it did produce 15whp as has been claimed in other threads it may be worth the time.

How much did they charge you?

I have a turbo back exhaust & air filter I unfortunatly wont be able to tell you dyno numbers because my car wasnt dynoed before but the butt dyno notices quite a jump I will be getting a fuel pump and Ecu tek to complement the mods. I would like to see about 400hp at the crank after those mods

how is this mod done? I have heard a little bit about it before but I don't know how to do it myself

The mod:
http://www.scoobymods.com/forums/showthread.php?t=4371
Pictures don't seem to work on that thread, but there are some here:
http://www.scoobymods.com/forums/showthread.php?t=4748

Wow. Cool man. Have fun!

I still don't see how it adds power. The turbo is not sucking in more air. The same amount of air that was going in the motor is still going in, no more, no less. I bet it may be more responsive. That I am pretty sure of but I am suprised you can feel it. I don't believe this is a power mod. Ehhh, what do I know though. Been wrong before I just can't see where the extra power/air comes from.

I would like to see about 400hp at the crank after those mods On the stock turbo STi, in Arizona, on 91 not a chance, not even in the dead winter. 280whp or 385 crank on 93 perhaps.

yeah 91 octane sucks I think they are a major hinderance of airflow and that is why I can feel the power up top now especially

The mod:
http://www.scoobymods.com/forums/showthread.php?t=4371
Pictures don't seem to work on that thread, but there are some here:
http://www.scoobymods.com/forums/showthread.php?t=4748

I believe robert does tehm differently, I trust the way he does it.

I still don't see how it adds power. The turbo is not sucking in more air. The same amount of air that was going in the motor is still going in, no more, no less. I bet it may be more responsive. That I am pretty sure of but I am suprised you can feel it. I don't believe this is a power mod. Ehhh, what do I know though. Been wrong before I just can't see where the extra power/air comes from.

really? you don't see what big choke valves that take up 90% of the intake runner can restrict power?

You're assuming that tehy function and open appropriately and accordingly for power. That's not the case, they were engineered so taht the car would meet emissions standards.

even if they did open appropriately, they wouldn't open all the way at WOT. they would open accordingly to vacuum (like vacuum secondaries on a carb). That way you wern't loading the motor with the throttle plate open more than the amount of air coming in (like being in 5th gear at 40mph and flooring it). They would still create turbulence in the intake runner at anything other than "open all the way".


Another thing is that on a modified engine with more boost, the force of the boost is enough to overcome the dinky springs in the valves and actually force them closed, hence teh boost spiking that occurs.

I have the JDM ver8 manifold with no risers at all. So my TGV knowlege is limited admittidly. I never realized that at WOT they were that restrictive, 90% as you say. I assumed a butterfly opened and the restriction was minimal. I assumed that at part throtle, the butterflys were closed a good bit choking the motor. I assujed that the delete mod would make the car more responsive. My understandinf is that they help idle emisions and not WOT emisions. When the butterfly is opend there is not such a big restriction.

I am sure the car feels alot better. Still, butt dyno is notoriously unreliable. Response can me interprested as more power. I mean if the turbo is cramming air in that is being blocked 90% the compressor would surge? I don't know. You would know more than me on this as I do not even have TGV risers.

I would really like to see before and after on a dyno myself. Till then, in my mind it is a r4esponse mod not a 15whp mod. I could be completly wrong here I know that but I am just no seeing it being that bid a deal. 5whp, maybe but that is not enough to feel really. Not like is being described. You know what is enough to feel like that? Response. Alot of it and quickly.

Hey, I am not dogging the mod, I think it is great. One of the reasons I got the Ver8 was the better intake design including complete lack of TGV housings. Great mod cost effective and I a have no doubt the car feels much better with them deleted.

I've talked to Robert about getting this done on my STi, and he said that the springs that hold the TGVs open are not strong enough and the pressure can actually shut them closed. From what is sounded like, these are basically the prdoct of GM's 20% hold in Subaru. Consider these resrtictors. For me, the question in not weather or not to get it done, but weather to go FATech or APS.

As far as the debates of it being considered a power mod. Although I am inexperienced in this...even if it does not increase peak numbers, it may allow for quicker spool and cleaner flow allowing for a broader curve on a dyno-plot...not neccessarily higher power, just able to use the power longer and more efficiently.

I know robert has done many many many hours of dyno testing on the TGV's, I'm going by what he said and my personal knowledge of "how things work".

I think taht WOT they may open all the way, but only after the proper vacuum/rpm and conditions are reached. In other words not a direct relationship to throttle postion, or else they wouldn't do anything for emissions.


throw in our crappy gas and our high heat, the butterflys might never open all the way, jsut as secondaries on a carb. which is fine IF they were the main restriction for air flow, but again, they were designed to reduce emssions. And when it comes to emissions, we can assume that anything that reduces emssions (on the motor, as high flow cats will do both) at the same time reduces power.

on a JDM motor you have no TGV's so if you let out the cltuch at 1500rpms and floor it, the motor obviously isn't ingesting as much air as it will once the RPM's increase, so the ecu has to adjust to the larger opening of the throttle plate. This usually creates more emissions.

The TGV's act as a second throttle to open at a progressive rate so that teh motor spends less time "under load", in order to do that the tgvs have to open slower than jsut stomping the gas, this explains the ability of the subarus t oaccel quick when easing the throttle to WOT and why the WRX is such a dog of the line.

Now the newer Subarus use throttle by wire (cept WRX), which allows the ecu to reduce the rate at which the throttle opens, versus suddenly opening with a cable throttle.

theroretically the TGV's could open faster if teh ecu can modualte how fast the throttle opens, that way you can put the motor under less load, but teh drawback is that the engine rev's slower.

On WRX's it will get rid of that horrible lack of torque that every other subaru owner in teh world doesn't have to deal with,

liek you said it might not be a top end power nuimber adder, but it adds power over the whole powerband which is more important. IF it gave a higher peak number, it would coem alot form the fact that the engine revs faster, allowing it to get to the higher rpm's faster carrying more acceleration momentum at higer R's.

Yes that is my thought. Now that you mention that, it may infact fatten the power under the curve. I could see that, sure. Make more power at lower rpm's. I'll buy that, sure. More power. Ok power mod.

The peak number is the one I doubt moves as all. I was thinking that not under the curve. So, indeed, fatter torque curve below peak and better response. Win win.

you might get some peak jsut on the fact that the butterflies might not open all the way based on "not perfect conditions". Where if there isn't enough boost, from heatsoak or whatever. But this is more making the car more consistent and letting the engine run at it's potential rather than increasing it's power.

The difference is gonna be seen driving around, rather than on the dyno, because dyno is a more controlled situation then driving around on the street, plus it helps more in any other conditions other tahn WOT, accelerating at partial throttle and such.

So I wouldn't call it a power mod either, jsut a restricter removal.

Great mod ether way. Can't see why one would not do it. Especially on a USDM 2.0.

yeah definitely, I've always shyed away from a WRX because of it's insane lack of torque, but after finding out about the TGV's and the uppipe cat, I picked one up whne I caame across one.

I believe robert does tehm differently, I trust the way he does it.

I didn't even know there were multiple types of deletes - I thought the end result was the same - the valves being gone! Does the TGV delete have any impact on idleing or on fuel economy that you have been able to tell?

Just curious how they were able to determine that high boost closes them up - can you monitor tgv position or something? (it would make sense that you could - just curious how they determined that)

The peak number is the one I doubt moves as all. I was thinking that not under the curve. So, indeed, fatter torque curve below peak and better response. Win win.

Eric,

Peak is increased anywhere from 15 to 20hp depending on mods. We have proven it on the dyno. The vains do a good job of creating turbulance as designed even when wide open. If not why did subaru choose not to include them on your v8?

Joe

I didn't even know there were multiple types of deletes - I thought the end result was the same - the valves being gone! Does the TGV delete have any impact on idleing or on fuel economy that you have been able to tell?

Just curious how they were able to determine that high boost closes them up - can you monitor tgv position or something? (it would make sense that you could - just curious how they determined that)

scratch that, basically he does it that way, but I think he takes extra steps to make sure you don't have any probs. Every time I ask him about it, he tells me it takes him all day to do.

you'd probably get a little bit less mileage under heavy acceleration (you'rea also making more power under heavy accel), becasue you could load teh motor more. But if you didn't drive like a jackace, then their shouldn't be any reason why you couldn't get teh same or even better.

I dunno, I could be wrong, but I know every other impreza in the world doesn't have them and they run, hell, even every other car of every type doesn't have them.


edit: as far as monitoring, I'm sue you can hook up a voltmeter to the wire and read the resistence or voltage, the same way you'd read a throttle position sensor.

Eric,

Peak is increased anywhere from 15 to 20hp depending on mods. We have proven it on the dyno. The vains do a good job of creating turbulance as designed even when wide open. If not why did subaru choose not to include them on your v8?

Joe
that's crazy

Dyno proof! I stand correcte4d. Wow, it is a great mod then. I guess it partly explains the stupid levels of power the JDM ver8 makes. Thanks Joe!

ok... newb post alert.....



whats a TGV?

.......dont hurt me..

Unsure about how he monitors it. He is a cool guy, I'm sure he'd be willing to explain it if you went in to the shop.

Ok those of you who have done it or even for Joe...how much $$$$ are we talking about here to get the TGV removed?

whats a TGV? Between the intake manifold and the block. Emisions control device basicly. Search in the 2.0 and 2.5 forum for pics.

Is it easier and better to just source some JDM Ver7 RA risers. The are COMPLETLY hollow. Basicly a tube with flanges for the block and intake. Or, source a JDM Ver8 manifold and sell the STi manifold to WRX guys?

No risers at all, just aluminum casting to the block.
http://www.iaperformance.com/specialsImages/full_Copy%20of%20DCP_2820.JPG

This thread (http://forums.nasioc.com/forums/showthread.php?t=546767&highlight=air+tumblers) is your friend for all you want to know about TGV delete mod.

Joe, do you have any plots you can post that show before and after increase for only the TGV mod? Lots of folks say it makes more power, but they've done testing only after making other changes as well.

I thought this throws a cel that you can't clear or something to that effect?
:confused:

Dave

disclaimer: I may just be retarded or read too much on this site and gotten mis-information.

If the rod is 100% removed or the sensors are unhooked = CEL

If even a portion of the rod remains attached to the sensors and installed correctly = No CEL

Thats my understanding.

Nice, so most likely if you go the Ver8 route you're going to throw a cel because there's no rod to begin with but if you have them removed you can "fix" it.

Dave

I believe ECU-Tek can clear it. Not sure though but it clears most other codes like no cats etc...

Robert charges $225 I think to do the mod

I think a "Scanmaster" will clear teh CEL also.

Nice definitly something to add to the list