Another S/C'd member worried about his AFR

[Loren]

Without taking the time to read through this whole thread... some thoughts.

What does "open loop" mean? It simply means "not closed loop". Closed loop means that the ECU is using feedback from the O2 sensor to fine tune the fuel mixture and keep it at stoich (or, I suspect maybe even a tad lean on the Yaris, but that's just a guess). In open loop, the ECU is most definitely still making adjustments and still has complete control of timing and fuel, it's just ignoring the O2 input and using intake air temp (temp affects density, a critical factor), air flow, and RPM to look up the appropriate fueling and timing in a table. By design, this will always be a rich mixture, and timing will be "conservative", similar to that of a distributor with no vacuum advance.

Now, I was thinking about all of this worry about being lean on these SC cars. (because I noticed one for sale for $2500 and had a fleeting moment where I was thinking about it... until I remembered that I don't have the money) Remember, even though your car is "forced induction" with the SC kit, it's a VERY light boost. What is it? 4psi? Maybe 6psi? Guess what? The real problems with fuel and spark retard don't happen until way beyond there. You guys are applying the kind of fear that one should have with a medium-high boost turbo to a low-boost supercharger, and I really don't think it's warranted at all.

I'd rock a Blitz SC right out of the box. Run premium fuel and be happy. Life is too short for such paranoia!

[Nexus1155]

See, but thats the thing, you can get one of these out of the box be happy and be fine, but not run optimally. I think thats what everyone is looking for. And it is such a small amount of boost that supercharger is running.

What I am trying to think now is that if you do have extra injectors it might be the only feasable option to get the AFR correct for now until someone finds an interceptor for the O2 Sensors, but will it cause a rich condition and trigger a CEL as well!. Damn these cars to hell

[Loren]

Originally Posted by Nexus1155

See, but thats the thing, you can get one of these out of the box be happy and be fine, but not run optimally. I think thats what everyone is looking for. And it is such a small amount of boost that supercharger is running.

What I am trying to think now is that if you do have extra injectors it might be the only feasable option to get the AFR correct for now until someone finds an interceptor for the O2 Sensors, but will it cause a rich condition and trigger a CEL as well!. Damn these cars to hell

Okay, I'll buy that (though I don't think there's THAT much more to gain by tuning the fuel WITHOUT adding more boost). But, the topic of this thread was, I thought... "worry" about being too lean. Worrying, I assumed about possible detonation and engine damage, not about leaving a little bit of power on the table.

One last thought: Tuning to get every last HP out of an engine is an art as much as it is a science, it's hard to do. If you screw up in the process of tuning it, you can do some damage. And once you've tuned it, you're right on the ragged edge of... trouble. Unless you're running a race team with a budget to replace the engine when it breaks, it's a lot smarter to go ahead and leave a little bit of performance untapped. Leave some margin for error. Leave the tune such that if your fuel happens to be 88.5 octane one day instead of 91, the engine still won't detonate. Out of the box, the Blitz is giving you 20% more power than stock... be happy! Be RELIABLY happy! (isn't that why you bought a Toyota?)

What's left on the table with the Blitz, anyway? Another 2%. Is it really worth all of the extra money, hassle and potential reliability issues for 4-5 hp? Every wire you cut and splice, every wire you add, every piece of hardware you add is another potential point of failure on your car.

[largeorangefont]

Originally Posted by Nexus1155

See, but thats the thing, you can get one of these out of the box be happy and be fine, but not run optimally. I think thats what everyone is looking for. And it is such a small amount of boost that supercharger is running.

What I am trying to think now is that if you do have extra injectors it might be the only feasable option to get the AFR correct for now until someone finds an interceptor for the O2 Sensors, but will it cause a rich condition and trigger a CEL as well!. Damn these cars to hell

You are really overcomplicating this. If you really want adjustability, go buy a Greddy Emanage and be done with it. I know that is not the answer you want to hear, but in the end it is the simplest and cheapest.

[largeorangefont]

Originally Posted by Loren

Now, I was thinking about all of this worry about being lean on these SC cars. (because I noticed one for sale for $2500 and had a fleeting moment where I was thinking about it... until I remembered that I don't have the money) Remember, even though your car is "forced induction" with the SC kit, it's a VERY light boost. What is it? 4psi? Maybe 6psi? Guess what? The real problems with fuel and spark retard don't happen until way beyond there. You guys are applying the kind of fear that one should have with a medium-high boost turbo to a low-boost supercharger, and I really don't think it's warranted at all.

I'd rock a Blitz SC right out of the box. Run premium fuel and be happy. Life is too short for such paranoia!

This is what I said the the beginning of the thread. These guys are not going to blow their cars up, they are just not optimal. They would get better mileage and more power under the curve with more agressive timing and richer AFRs, VS. the current setup of leaner AFRs and conservative timing.

[PETERPOOP]

They are saying there is possibly 20-30hp to gain with a tune.

[Loren]

Originally Posted by PETERPOOP

They are saying there is possibly 20-30hp to gain with a tune.

I'll believe that when I see it.

Let me qualify that. The bolt-on, out-of-the box Blitz SC kit with fully tuned and optimized fuel and spark. The initial installation is only good for about 25%, or 25-30 hp. No way is optimizing the fuel and spark going to DOUBLE that. You'll find another 3-8%... maybe as much as 10% or so, just like you would by tuning the car without the SC. That's the factory's margin of safety that you're playing with.

Now, you might see something close to that with a lot of OTHER additional mods, like a complete free-flowing intake, larger TB, better flowing intake manifold, some head work, a good header and a complete free-flowing exhaust. But, that's an awful lot of other stuff that doesn't really fall into the category of "fuel and spark tuning". And, even with all of that, I still don't think you're going to DOUBLE the output of the SC without raising the level of boost.

[kurokoma-kun]

Originally Posted by Loren

I still don't think you're going to DOUBLE the output of the SC without raising the level of boost.

Ok, well I do like what Loren said about leaving sleeping superchargers lie, as I said the same thing a few pages back

BUT, since he raised the topic of added boost, and mad science also appeals to me (and we have already strayed so far from the original topic) I'd appreciate it if you'd all give opinions on my theoretical question... NST is considering developing a set of pullies for the s/c application (overdrive crank and underdrive water pump, the only configuration that will fit in the given space). Mike estimates the combination of the two could produce an additional 2 psi of boost, or up to 20 whp. The way I understand it, boost works on a geometric progression--you get more power out of those last 2 psi than the first 2 in other words--so these pullies could nearly double the hp ouput.

I expressed interest in letting my car be the guinea pig--nothing difficult about changing out some pullies--but no one can say for sure whether the fuel system can keep up, and for all the reasons mentioned I hesitate to tackle a fuel system revamp...

Based on what you have all derived from this discussion, what are your opinions? Could I at least go ahead and be the test mule without too much danger to the engine?

I think we decided the fuel injectors are max 230cc, max fuel pressure at the rail is 46.9 psi, but even with these figures I'll be damned if I can find any way to calculate the max hp for sure.

[largeorangefont]

Originally Posted by Loren

I'll believe that when I see it.

Let me qualify that. The bolt-on, out-of-the box Blitz SC kit with fully tuned and optimized fuel and spark. The initial installation is only good for about 25%, or 25-30 hp. No way is optimizing the fuel and spark going to DOUBLE that. You'll find another 3-8%... maybe as much as 10% or so, just like you would by tuning the car without the SC. That's the factory's margin of safety that you're playing with.

Now, you might see something close to that with a lot of OTHER additional mods, like a complete free-flowing intake, larger TB, better flowing intake manifold, some head work, a good header and a complete free-flowing exhaust. But, that's an awful lot of other stuff that doesn't really fall into the category of "fuel and spark tuning". And, even with all of that, I still don't think you're going to DOUBLE the output of the SC without raising the level of boost.

I'd say we could get 10% under the curve easily, probably slightly more. Peak piwer increase I would expect 8-10%. You make more power with timing than you do with boost. LtNoogie is seeing single digit ignition advance under load. If we could get that up to where is should be, and add some fue,l the gains would be there. There is a lot of potential.

[Nexus1155]

Ehhhh I don't know about factual numbers, but if you are running stoich on a supercharger you are being robbed of power.

Get the fuel to the correct AFR and increase ignition as it will be more allowable, you will be golden. But obviously at this point you know you are being robbed of precious power that you could have.

Tuning takes some skill and knowledge, but it is not a rocket science.


As Loren said as well you would need to upgrade the flowing parts of this engine. I think the real kicker is to see the results after the throttle body upgrade..

[eTiMaGo]

as far as I understand, 14.7 stoichical air fuel ratio is the sweet spot for best catalytic converter effiency, not necessarily power?

But yes, Loren does have a good point, tuning for maximum power does reduce the safety/reliability overhead that Toyota has engineered into this car. Caveat Emptor, as the saying goes

[Nexus1155]

What kind of oil does everyone use here? That seems like a lot of sludge buildup...

If the ECU is the way people say it is it will compensate for the extra fuel to bring it to 14.7 when you add more air to the system. If you are worried about the injectors duty, upgrade to TC injectors for a little extra security. But even with that little added boost, it should bring you to about where a turbo with 6psi of power has. So It has been done power wise before, and all in all you should be good to go? :)

[Loren]

Kuro, bumping the boost up to 8psi is where you start having the real FI headaches. I wouldn't recommend being the guinea pig for this unless you have the means to really monitor things AND deal with everything that's likely to come up, like needing more fuel, needing less ignition advance, and possibly even the need for intercooling or water injection to reduce the charge temperature.

Keep in mind that Blitz is a big company that did their homework, and did their R&D and testing in-house before putting a product on the market. NST is not at the same level, and they're asking you to help with their development at YOUR own risk.

As to the power question, the increase in power is going to be somewhat proportional to the increase in pressure... with 14.7 being the basis, no zero. So, if you've got 4 psi of boost, that's a 27% increase in air. You'll lose some of that due to having to compress the charge in the intake piping and manifold, etc, so you probably don't see a full 27% increase in air introduced to the cylinder. So, maybe 20-25%? Which is about what people are seeing on the dyno from the Blitz kit, right?

Bump that up by 2 psi and you're at 6psi, or 40.8% over atmospheric pressure. So, you could see as much as 40% more power, but realistically, 30-35%.

Numbers are a funny thing. Much depends on whether you want to be optimistic or pessimistic in your estimates.

There's a reason why the Blitz kit is limited in the amount of boost it delivers. If it was EASY to reliably provide more boost and more power, they'd do it!

[kurokoma-kun]

Originally Posted by Loren

There's a reason why the Blitz kit is limited in the amount of boost it delivers. If it was EASY to reliably provide more boost and more power, they'd do it!

Thanks for the analysis. Yep, the "easy" factor is why I chose the Blitz kit in the first place (well, that and the low end torque ).

When I talked with Garm about the NST pullies we were hoping they might be another bolt-on application like a compressor itself--this is pretty much the only thing customers like me are gonna want to buy.

Well, I dunno... I think it might be biting off more than I care to chew... but the idea is still out there for folks willing to overhaul the fuel and engine management systems but are looking for a way to make additional boost.

[Nexus1155]

lol your probably using regular crap oil then, I would recommend switching to Mobil 1 Synthetic, it should solve all of that gunked up problems

[LtNoogie]

Can someone recommend a good OBD II data logging software package? I was making a few freeway runs last night in 3rd gear to collect data and saw some surprising results on the ScanGauge. Not bad readings, surprising readings.

It's too hard to videotape the gauges and the ScanGauge due to the shakiness of the camera mounts I have tried.

I was monitoring Open/Closed loop state, RPM, Throttle Position, and Ignition timing. What I saw was that the car went into Open Loop during acceleration more often than expected with the S/C turned on AND when it was turned off. This is happening before hitting 50% throttle position.

[bearda]

I'm a big fan of a good ELM327 based reader (I like the ElmScan 5, but just make sure it's using a real ELM327 and not a knockoff) and PCMSCAN. Seems to work well on my Mazda and the Yaris.

[kurokoma-kun]

Well now you bastards have got me obsessing too! (not difficult)

Today I also saw one open loop status that fell outside what you all are describing as normal triggering conditions (DFCO and WOT)... it was under boost and acceleration at 32 TPS and 15 ign timing, and persisted for like 10 seconds... wtf.

Here's one random thought, though I don't know if it means anything at all. According to the wiring diagrams the s/c fuel controller does not wire into the throttle position sensor (TPS) located on the throttle body itself (ECM terminal VTA1) but rather into the accelerator pedal position sensor located on the pedal (VPA). Other than that it hooks up to RPM, ignition switch, injectors 1-4, and MAF (VG). The two other wires go to ground and activation switch.

Since the ECM uses the VTA1 data direct from the TPS to calculate everything from valve timing to long- and short-term fuel trims, I don't know what to think of that! I guess the fuel controller is altering the VPA signal sent to the TPS, and thereby manipulating the VTA1 signal then sent to the ECM?