[biglad]

Hi all!
Looking at doing a turbo conversion to the g13bb in my jimny. I have found a manifold and turbo i want to run (small garrett t15).
My question is, seeing as though im only going to run 5psi or less with such a small turbo, will i need a fuel controller like an apexi safc and tune? Or can i get away with the standard computer tune?
Any advice would be great.
Cheers
Mitch

[Jezza86]

id ask a shop. if you lean it out too far with the extra air you wont be making much power and will be risking engine damage.
for the gains you could get turboing the G13 you might be better off with a G16 which will be as rev happy, wont lag, and will give you more power and torque compared to a untuned depressurised turbo.

[Gwagensteve]

Run a wideband lambda sensor.

Steve.

[Rhinoman]

Stock tune will fall over when you go onto boost as you will exceed the limits for barometric pressure.

[Gwagensteve]

You and I know that Rhinoman, but saying so is taboo- apparently the way to set up "cheap" turbo conversions is to reduce boost to the point all the problems with timing and fuelling are "small" enough that they don't result in catastrophic engine failure, and patching over them with some dubious fixes.

I suggested wideband lambda sensor so at least the owner would then learn for themselves how badly their car is fuelling under boost rather than believing the "it will be fine at 5psi" or "just use a rising rate reg" comments that are the normal "fixes" suggested for fuelling a cheap turbo conversion.

Steve.

[Rhinoman]

As soon as it exceeds the limits of the baro it will go into fail safe mode, at most you'll be able to run 2-3psi. A rising rate regulator won't get you out of failsafe, cheap fixes like that only work on a MAF based system, particularly one with no baro like the Swift GTI. You don't really need a wideband on a system like the one proposed, just watch the fuel trims max and wait for the bang.

[Gwagensteve]

That definitely sounds better than a $600 G16B

Steve.

[Brenno]

The g13bb doesn't go into failsafe mode once 5psi of boost is produced.
A rising rate fuel reg was put on the g13bb supercharged motor I had (and is still going after 7 years). I think the afrs were around 12.5:1 on full boost (max 5psi.). The owners after I sold it check it out on a dyno run. Produced something like 70rwkw.

[Gwagensteve]

I'd suggest a supercharged motor is easier to fuel than a turbo motor though.

[Gwagensteve]

Out of interest, and I'm not stirring shit at all Brenno, how do you know the computer isn't going into fail safe mode? As I understand it this is normally rich and retarded, so with a rising rate reg to tune full load A/F, maybe it is in fail safe under boost?
Steve.

[JrZook]

Gwagensteve wrote:

I'd suggest a supercharged motor is easier to fuel than a turbo motor though.

Wouldn't matter in the terms of what rhinoman was explaining tho. Once boost rises past the ECU limits it would go into skirt mode.

Rhinoman: In the terms of fail safe are you talking about the main processor shutting down and running off the crude limp home chip arrangement or is it a software induced fail safe on the main?

[losfer]

you certainly can run low psi safely through a stock motor and stock computer and a rising rate fpr , but will it be nice to drive , NO .

factory cars non forced induction are programmed to see a certain amount of "manifold vacuum" . generally manifold vacuum is measured in Hg (inches of mercury) . generally at idle on a standard engine you would expect 18-22 Hg , on a high performance engine with big lumpy cams you can see as low as 12 Hg at idle , at wide open throttle you will see 0 Hg for an instant then it will taper off as load decreases . A factory ecu is programmed to handle anything withing these ranges. with forced induction as boost comes on you are wandering into pressure (usually measured in bar or psi , both units of "atmospheric pressure") it has no fucking idea you are on boost , it isnt going to retard the timing , it isnt going to dump more fuel in (injector pulse width).

Ive driven forced induction cars with all sorts of methods to try and trick the ecu , remapped chips (all they do is retard the timing and dump extra fuel in at certain rpm ranges ) , regraphed distributor , fuel pressure regs and none have driven nicely , so in my opinion you cannot even come close to spending $1000 on a cheap aftermarket ecu and a $500 tune to get some decent driveability.

[Rhinoman]

JrZook wrote:

Rhinoman: In the terms of fail safe are you talking about the main processor shutting down and running off the crude limp home chip arrangement or is it a software induced fail safe on the main?

I'm talking about fail-safe rather than limp mode, it may be an advantage as it will back off the timing and enrichen the mixture but its not tunable. I went through this with a Jimny ECU, it was possible to tune the motor really well off boost but once boost started to climb you would see the Baro reading climb with it until it maxxed and then it took a dump and switched to the Alph-N map, you can tune that buts its very crude. I looked at rescaling the maps and disabling the baro but its a lot of work. Its a limitation of a MAP based system, with a MAF theres usually a fair bit of overhead and it can cope with a fair bit of extra airflow, on a MAP based system you have a bunch of maps and none of them go above atmospheric pressure.

[Brenno]

JrZook wrote:

Gwagensteve wrote:

I'd suggest a supercharged motor is easier to fuel than a turbo motor though.

Wouldn't matter in the terms of what rhinoman was explaining tho. Once boost rises past the ECU limits it would go into skirt mode.

Rhinoman: In the terms of fail safe are you talking about the main processor shutting down and running off the crude limp home chip arrangement or is it a software induced fail safe on the main?

Re: Gwagonsteve. I assumed safe mode (ie. limp mode) is the second line in JrZooks above comment. I could be wrong. All I know is, it drove, drove well, for a long long time (and still going). Not something I would probably do again as it was cheap to set up, but risky as I didn't have a wideband from the start. It may have been a once off for all we know.