Swapping From Stock Turbo To Apexi Ax53b70 (ign Timing?)

[simpletool]

I've got a reflashed ECU on my RB25DET that is running a stock turbo at about 10psi quite well, but it will ping a little at more boost. If I put on an Apexi AX53B70 and run 10psi (hopefully a touch less) should it ping?

My thoughts are that it might reduce knock due to the larger exhaust housing and more efficient turbo at that flow boost level (allow increased timing). On the counter side is the fact that it is likely to make a chunk more torque so timing will need to be retarded.

Background:

Other mods are full exhaust, fuel pump, HDi intercooler, coil packs, EBC, big radiator, etc.

I currently have an AX53B70 (P25 housing). I was going to put on the Apexi turbo these holidays when I do a big service (timing belt, etc). Then depending upon how it drives was going to get an ECU and put in injectors early next year. I just don't want to put on the turbo and find it pings it's tits off and is virtually undrivable at any boost. (I think 10psi will be about the minimum adjustment for the wastegate/diaphragm)

Any input from tuners who have an idea about timing vs turbo size?

Edited October 21, 2009 by simpletool

[SimonR32]

you need a full aftermarket computer (or a z32 ecu with nistune board)

no escaping this... not shortcuts

[simpletool]

Yeah, thanks, I know what you mean. And I will (in all likleyhood) be getting nistune after installing the turbo but....

1. But I will still be installing the turbo and driving around to check install is OK, and turbo is OK before driving 100km to get a tune.

2. The question was also to find a response to whether a larger turbo requires less timing or more timing for similar flow. Out of interest / theory.

[simpletool]

Just so you know, I ran on the Toshi remap with Apexi turbo for 3months perfectly. Car drove well, picked up some power, responsive with good fuel economy and even Brisbane - Sydney trip was great ~8l/100km.

got tuned, now have 305rwhp.

[zebra]

Bigger turbo = more airflow which means it will knock itself to pieces if it already does it with the stock turbo.

be sensible with your right foot until it is tuned properly.

[R31Nismoid]

Just so you know, I ran on the Toshi remap with Apexi turbo for 3months perfectly. \

How do you know this exactly?

You were logging engine knock and so on i take it?

I mean just the fact you can't "hear" something, does not mean it isnt occuring or is safe.

[simpletool]

Well OK, may I didn't mean "perfectly" but yeah I couldn't hear any knock - EVER. Plus monitored with SAFC2. I can't say the same about any other engine I have driven on for years - including, shitty corrolla, RB30, SR20 tuned (several times by "the best" tuners) and current tuned RB25. Plus it showed no signs of poor mixtures or erosion on the copper plugs (that lasted 20,000km). I can usually make an engine knock somehow and hear it - even when the so called expert engine tuners say it won't knock on the road. Yes, I know the RB25 doesn't like ping.

Edited July 24, 2010 by simpletool