Safe Boost Levels For Auto Turbo...?

[suff]

PFT!

Want boost? Look at the newish VW TSI Engines..

"The maximum boost pressure of the Twincharger is approximately 2.5 bar at 1,500 rpm, with the exhaust turbocharger and the mechanical supercharger being operated with about the same pressure ratio (approx. 1.53). The compressor alone delivers a boost pressure of 1.8 bar even just above idling speed."

Thats 36PSI for those that dont dive!

[05gtwagonman]

MMM, as invited, I'll chime in -but the knowledge isn't as high as some here...

From a ezi-flash tune, my guage sits fairly flat on 16psi. I have been assured that this is no problem... Without the tune, but stock except a couple of cheap mufflers, I experienced boost spikes as high as 20 psi. As I understand any prolonged boost above 18 psi without a tune will invoke the 'fuel defender' (at least that was what it was called on the 96 wrx I had) and cut the fuel to save the engine.

Now if you tune the motor to have the correct timing and valve advancement, you should be able to set a higher boost without a serious risk to detonating the engine. But the caveat is serious risk...

What I am chasing, and I belive that you should chase too, is the earliest increase in boost presure and therefore power, particularly torque. My 05 manual came fairly close to 150kw (what I hoped for) at the treads on a dyno that is recognised as fair, to a bit hard on the output figure. I am assured that when I can get the exhaust valve timing working correctly ( a problem covered in the thread about surging through the rev range further down the page here) I should be able to pick up 10- 15 more kw in the top end. What chiptorque did was chase the early onset of torque. I gained 100nm more at 3400 rpm post tune, and this has dramatically changed the car's drivability.

Chase the early torque by getting the turbo to deliver as early as possible. You can do this by improving the intake temp and air flow, and the exhaust back pressure and flow... A turbo is a pump in the simplest terms...
If you like try a bigger top mount, this should help a little too, but to go any further, is to find the limit of the flow rate of the standard turbo. At that point you should look at a higher flow turbo, up and down pipes, and full exhaust system.

BUT: you can easily gain high RPM powah but it will be at the sacrifice of the early onset of the disease called torque

You will need to make that descision for yourself.

Much respect to the twin turbo crew and the work I hear of in relation to Kosti- but Subaru went to considerable time and energy with the (at the time) new design of the small twin scroll you have.

In short, you can get more boost, at the possible sacrifice of longevity, but you said it yourself. It's a daily, you don't need a smelly mess on the side of the road, and performance increases via boost levels comes at a potential price...

You can chase a figure on the dyno, but you would be better off looking to improve drivability, and the first don't nessisarly get you the second...

Do ya feel lucky punk? ... well do ya?

[west_minist]

The 2001-2003 Twin-Turbo is nice to 20+psi. A big intercooler helps. Nice to see Kosti is doing well.

The 2003+, 17psi is good. 16.5psi is prefect. Over that, is not much power. The intercooler is too small. A good upgrade is the VF37.

[swingn]

The 2001-2003 Twin-Turbo is nice to 20+psi. A big intercooler helps. Nice to see Kosti is doing well.

The 2003+, 17psi is good. 16.5psi is prefect. Over that, is not much power. The intercooler is too small. A good upgrade is the VF37.

Have you tested it out with the various boost levels on the different turbos?... Maybe some dyno graphs for our viewing pleasure?

I'm not overly concerned about the power percentage you gain from pushing it up higher (Say over 17PSI). I just want to make sure that it is running safe while getting the best performance / boost the turbo is capable of ... Until the new turbo arrives of course

Will be running a Greddy Profec Type S, so will realistically be running lower boost for my everyday driving.

[tangcla]

... so will realistically be running lower boost for my everyday driving.

No you won't Matt, I know you, you'll be running it on high boost every day.

[Arith]

... so will realistically be running lower boost for my everyday driving.

No you won't Matt, I know you, you'll be running it on high boost every day.

You said it Clarence! The HKS EVC has 2 settings: A Boost and B Boost

B Boost being the higher boost when the situation calls for it. My poor car has yet to see A Boost.

[05gtwagonman]

This phenomenon is what powers the bug to modify... Today my car is awesome!!!! so much poooowwaahhhhhh!!!!

Three days later, it's pretty cool.
3 weeks later your itchin' like a coke whore on the good ship abstenance, and your lookin' for the next upgrade...
Like drug addicts- are you really going to leave part of the hit in the bag?
Good luck with that!
If we had that kind of self control we'da bought NA...

[Arith]

Haha! I was just talking to Trieu about that yesterday because I teased him about always driving in I drive. I said I drive in S# mode all the time, and after putting on a new mod it feels fantastic! But then after a few weeks it feels slower. Then slower. Until eventually it feels stock again and I have to get another mod to reclaim that 'rush'. So yes, very much like a crack addiction.

But Trieu man has the answer! Always drive in I drive. Then once in a while throw it in S# mode and you'll feel like you've just done a huge upgrade!

[05gtwagonman]

Again, great idea if you have the self control...
My name is Richard. It's been 15 minutes since I last had a blat at full noise...

[west_minist]

Have you tested it out with the various boost levels on the different turbos?... Maybe some dyno graphs for our viewing pleasure?

No diff turbo's except the stock ones. one of my customer will be swapping his VF38 for the VF37. WIll let you know how it goes. I think the compression on the 2004 JDM GT is 9.5, if not and it is still 9.1, i expect between turbo response and nice spool. Not only that, it is an auto.

I'm not overly concerned about the power percentage you gain from pushing it up higher (Say over 17PSI). I just want to make sure that it is running safe while getting the best performance / boost the turbo is capable of ... Until the new turbo arrives of course

What do u mean running safe?

Will be running a Greddy Profec Type S, so will realistically be running lower boost for my everyday driving.

Boost is control by throttle. More throttle, more boost (reference to map)

[XRC15T]

Different cars and different mods will change how much.
Throw it on a dyno then dial it up.

[Evil_b4]

You wont gain more power by simply cranking up the boost guys. Thats a dangerous way of doing it.

im not familier with the stock GT fuel setup but im assuming its the same a a stock B4? 550cc injectors?

To run abit more boost at least have a bigger fuel pump and a free flowing exhaust and intake. better yet a ecu remap/tune.

Im running 18psi on standard internals and my car loves it. 650cc injectors, parallel rails, sard FPR and bigger fuel pump keeps me happy and safe

[swingn]

By safe I mean it won't blow the turbo up

I know a lot of people have up'd the boost etc to get a little more power etc, but while my car is a daily driver, I just don't want to push things to their absolute limit.

I've heard, from various sources, that 16-17PSI is a good bet.

I've already got the turbo back exhaust, larger fuel pump etc. Boost would be changed when I get the dyno tune, so everything will be running sweeet

[Gonads]

By safe I mean it won't blow the turbo up

I know a lot of people have up'd the boost etc to get a little more power etc, but while my car is a daily driver, I just don't want to push things to their absolute limit.

I've heard, from various sources, that 16-17PSI is a good bet.

I've already got the turbo back exhaust, larger fuel pump etc. Boost would be changed when I get the dyno tune, so everything will be running sweeet

The turbo is the least of your worries. Damaging the engine is far more likely when you push the boost levels up with stock turbo/intercooler and fuel system. If I'm not mistaken, the GT has got hypereutectic pistons which will not handle much detonation before you do a ring land.

I've got no idea why anyone would want ot run a lower boost pressure. If it's safe, it's safe. Maybe I could understand if it was track use where the intercooler and heads get a bit heat-soaked (more probability of detonation) but to have a setup where you run MORE boost when you feel like getting into it sounds a bit ass-about to me.

I'm pretty sure stock boost in higher gears is something like 15psi tapering back to 12-ish which makes 17 across the board a massive increase.

...Ben