What changes in the tune when going big turbo?

[mituc]

I was wondering what changes on a big turbo tune?
First of all all I need is to leave the shop with the car running properly and being able to boost safely to, say, 10-12PSI. depending on how much I'll be able to figure out I may or may not throw more money on a PERM tune, but for the beginning this is what I want.

So what's going to change apart from the wastegate duty cycle tables? I guess the accel/decel tables should remain the same, and assuming I'll keep the same intake (Cobb SRI) the MAF cal will most probably be the same too.
As for the timing/load/MAP relation tables those should remain as they are I think, but I may be wrong.

[Steve @ VersaTune]

BCS DC Base is the main table that will need to be changed. Accel/Decel tables may need to be touched too since the new turbo will have a different inertia and spool profile.

Make sure that the boost reference from the turbo has a restrictor in it. Many of the aftermarket turbos do not have a restrictor and achieving boost greater than the wga spring pressure becomes a problem.

[mituc]

Ok, so I contacted Lex from MSF.org already, he told me that prior to tuning a base tune should be able to handle the big turbo quite well.
I'll change the wastegate duty cycle tables anyway just to make sure I'll not be boosting to hell, and I'll keep the MBC on the lowest boost setting also.

So In March I thought I'll only be upgrading my pump internals. But the little devils in my head convinced me to go big turbo (GTX3071 with a 14PSI WG spring + a grimspeed MBC) and I could not resist. FML - and I hope I'll have an orgasm doing it!

[Steve @ VersaTune]

There is no need for a MBC with VersaTuner. You will have much less control with a manual boost controller.

GTX 3071 is a nice turbo.

[mituc]

Hm, ok, I ordered and paid for the order but it was not processed yet. I guess I can still tell them to change a few items or not to deliver some of them and get something else instead.
I thought I can keep the stock EBCS and route the boost source through the MBC. My aim was to be able to drive the car a few miles without going into boost even with the stock tune.
I'm new to this, so what do you suggest?

[Steve @ VersaTune]

Set the BCS DC Base table to all zeros, and set the Requested Load Limit Overall table to 1.2 to limit requested load to 1.2. Those changes should keep the boost down until you are comfortable opening it up.

If you floor it, It will still try to boost to the WGA spring pressure though. You will be able to feel where it starts to spool and back out of the pedal.

[mituc]

I meant what do you suggest in therms of boost control? Should I change to the grimspeed EBCS instead?

I guess I should be fine with the grimspeed and the stock tune (and I mean stock tune from mazda, versatuner not installed) just to get the car in the shop and take it out a few hundred metres and pull over on the next street to tune it. No boost and maximum 3000rpm (controller from the right foot) and I should be fine - or not?

[Steve @ VersaTune]

The Grimmspeed EBCS is a nice piece. It will help give faster boost control response since it flows more than the stock EBCS.

You will be fine with the stock tune. Just keep your right foot under control The 3071 won't insta-spool at 2500 like the K04 does.

[skiptownmcat]

I need to pull my finger out and get a turbo, every time I get the money together some unexpected random thing happens that usually takes it away.

[mituc]

Steve, should I be able to fully control how the ECU reacts with the Grimspeed EBCS with versatune?
With a big turbo I'll most probably get the IDC at and above 80% which as far as I heard it's the threshold beyond which the WG duty cycle is reduced by the ECU logic.