tuning boosted itb.

[electronic]

What strategies are you guys using?

Primary alpha n with secondary speed density fuel and speed density spark is what I am thinking.

I'd like to hear some feedback.

[elutionsdesign]

I've done a few that way, works quite well, spend a lot of time graphing PW vs. TPS and PW vs. MAP in megalogviewer. The transitions will be obvious.

[ArttuH]

Primary alpha n with secondary speed density fuel and speed density spark is what I am thinking.

That's basically what I have been using. Except I'm having the fuel tables vice versa. That doesn't make any difference for tuning but that way the Fuel Load will be MAP instead of TPS which makes some other functions more logical.

For fuel tuning I'm using alpha-n as main tuning table and SD is used only for fine tuning boost compensation, if needed. So for starters I set the SD table full of value 100 (= no effect) and start tuning with the alpha-n. Later on if I notice that correction is needed for some boost level I do that with the SD table. Usually pure alpha-n works just fine if boost / waste gate setting is fixed. For wider boost level range, like with gear based boost control, some correction is often needed.

[whittlebeast]

Tuning a turbo needs to be speed density as the primary. If you post up a big street data log, i can show you how to tell if you need a TPS based tweak.

[electronic]

I don't have any logs yet. I don't mind trying sd as main fuel and alpha n as a secondary multiplier. My question is what do I put in the secondary alpha n map? 100 in 100% tps and 0 in 0% tps and then tune the primary sd?

[whittlebeast]

I don't have any logs yet. I don't mind trying sd as main fuel and alpha n as a secondary multiplier. My question is what do I put in the secondary alpha n map? 100 in 100% tps and 0 in 0% tps and then tune the primary sd?

What I did was build a sheet density map first. On a true ITB build, that will cover most all driving below about 80 kpa or about 15 to 20 pct throttle. I did apply smoothing to that entire SD table to that entire table when I was done. I then created the multiply by Alpha-n table and put 100 everywhere. For TPS, the throttle points are like 0, 5, 10, 15, 20, 30, 40, 50, .... to 100.

The RPM points are the same on both SD and AN tables. From that point on, most tuning happened on the AN table.

Most all tuning at that point on is based on scatter plots and Histogram data gathered in MegaLogViewer HD. My motor does not run closed loop AFR at all as on track, my rpm per sec accel rates are in the 1000 range.

I will be happy to help if you want. You will not find this tuning method in the MS tuning manual.

Andy

[elutionsdesign]

I would take Andy's offer, he's one of the best I've seen.

[electronic]

That was my plan actually except for some odd reason I was going to use sd as a secondary multiply map. It's a lot easier for me to have an alpha n map and then add fuel for boost on top of it.

BTW Andy where are you at in St. Louis? And who do you use for dyno?

THank you.

[whittlebeast]

One of my best friends owns one. He really only let's friends on it. Tuning is not his day job. Racing is his addiction.

[whittlebeast]

I can not think of a motor combination that would call for AN tuning as the base.

[ArttuH]

I can not think of a motor combination that would call for AN tuning as the base.

Well, I have been using that approach several times on boosted ITB engines. Basically I first tune it as AN with lowest possible boost setting and keep the SD table filled with value 100 at that point. Once the AN table is in good shape I start upping the boost and making needed corrections to the SD table. Works very well in reality and tuning is quite straightforward IMO. As drawback there will be typical AN problems like inaccuracy at low load conditions but in practise I haven't had any noticeable trouble with that.

[electronic]

I can not think of a motor combination that would call for AN tuning as the base.

My engine prior to turbo was tuned with pure alpha n, it ran pretty good.

[red-racing]

I will also run pure alpha-N with multiplymap. should be pretty straight forward

[suberimakuri]

Yes ve1 speed density, ve2 an. Multiply map off.
Same for ignition although this could be speed density only perhaps.
Using blend afr tables with 105kpa transition or so to target lower AFR on boost. Again could be speed density only perhaps.
Seems fine.

[whittlebeast]

I always start with SD and multiply MAP turned on.

[Matt Cramer]

Another option - one of our techs here is putting together a turbo / ITB Nissan Skyline and is running it off a MAF.