Sl0wbaltSS

Is there any Power gains or able to hold boost pressure better or longer with a manual boost controller like turboXS's boost controller?

https://www.modernperformance.com/pr...st-controllers

63 Nova SS

iTrader: (3)

If you are a 08-10 Tc the control goes through the computer. Only way to hold boost higher is with a higher boost can, that I know of. But with the k04 being a small turbo it has trouble keeping up at high rpm. Shift at 6,000 and use the faster spool down low. Stock powerband is around 3,400-5,800. Luckily we have 4 acceleration gears to keep it in that rpm range.

califcarm

Have people played with the adjustable rod on the wastegate to pre-tension it more? We are not holding boost (at least not more than about 20.5-21psi at 6200 rpm) because exhaust turbine back pressure is blowing the wastegate open (I am almost certain).

I know all the general sayings that the turbo is small, or the classic "it blows nothing but hot air if you do that". But I heard the same things in another 2L turbo community for years. It was thought that 20-21 psi at redline and 320whp was the max you could ever get from that turbo (toyota factory turbo). Turns out that a "helper spring" to preload the wastegate more was all that was needed (we did not have an adjustable rod).

Suddenly holding 24-25psi to redline and 350whp were possible. Was it much harder on the turbo: sure. Were the turbo outlet temps much hotter: sure. But it was making much more power if someone wanted to push it. (especially if you had better intercooling or meth injection to cool it back down more).

So has anyone really pushed the K04 to that level on the LNF? I am guessing it has more in it if someone wanted to do that.

OP: You don't need a MBC to do that, if your tune is setup to run max WG duty cycle. It's the wastegate that's not letting it hold the higher boost until redline, and a MBC won't change that.

blueLNFftw

iTrader: (16)

You would have to mess with it more than once. Disable to overboost codes and set WGDC to 100%. Would it work, probably. Is it going to make more power, doubtful; it will make things nice and hot though.

Also, if the car is only holding 21psi no matter what, there is a mechanical issue. Stock wastegate adjustment will let you hold much more than 21psi if you make it in the tune.

09CobaltSS1

I'm sorry, but I 100% disagree. You can weld the wg flap shut on a k04 and it will hold no bearing on how much "more" boost the turbo will produce or hold beyond a certain point. This is the case with any turbo. You try to flow beyond it's capability and you will no longer be able to sustain that flow.

Boost pressure is simply a function of flow (turbo size) and the resistance to the flow being produce (pipe size and engine displacement/demand). For the turbo to fill the entire charge system and intercooler, and maintain a positive pressure it MUST increase flow as demand from the engine increases with rpm. The only way to change that is go to a smaller pipe size. Unfortunately not though, you would be significantly decreasing flow only to increase boost which is a poor trade off.

Years ago when I first started messing with the lnf, I tried testing with preloading the snot out of the wg to see if just maybe it'sa mechanical limitation within the turbo components. All it naturally did was force boost to come on much faster, however it didn't effect (help) the turbo's ability to sustain boost beyond it's capability. It's just physics. You can't defy it unfortunately.

09CobaltSS1

Simple answer.... No

Not to mention the fact that without the correct tuning, the ecm will bug out and go into an over boost condition.

Also consider the massive boost spike at low - mid rpm this will cause. No thank you!

califcarm

Sounds like you did the testing I was asking about. Did not go as well as it did on the 3sgte Toyota's I have played with before.

Most internally gated turbo's with the "stock" wastegate are limited first by pre-turbine back pressure building too high and forcing the WG door open before you actually reach the point of "choked" flow (what would be seen when welding or clamping the wastegate closed), therefore increasing preload on that WG door by rod adjustment or auxiliary spring pressure some other way ("helper" spring in my previous case since I did not have an adjustable rod) allows boost to hold at higher pre-turbine back pressures. And by boost, I mean more flow from higher psi , assuming constant engine VE at this point. Technically the most the turbo can flow through the compressor side is to put 100% of the exhaust gas through the turbine side and not allow any to go around the turbine wheel via the WG. You will find eventually choked flow on either the compressor or turbine side at that point (turbine side first seems to usually be the case). I do find it surprising that the stock WG does not blow open from exhaust backpressure like most other applications do.

Should be able to tune out the unwanted earlier boost onset you mention, but it does not matter if it could not make more power on the top end.

Psykostevo

Are you convinced that the Boost Controller on the LNF isn't functioning as designed? It works. When mechanically healthy it does what it is told to. Adding a second type of electronic controller isn't going to enhance anything and will just deceive the ECU into thinking it is producing less boost than it really is, which should already be sounding like a bad idea to most of you.

There are tables (other than the Wastegate Duty Cycle tables) that control boost levels by rpm, etc. People who obsess about the WGDC table are looking in the wrong area in regards to this particular issue. Depending on LNF application that table is already usually set at 95 or 100% already from the factory.

But, even once you have maxed out all other pressure relation tables, you are still going to be mechanically limited to how much wood a wood chuck would chuck if a wood chuck could chuck wood.