High Flowed Turbo Running Standard Boost

[Dose Pipe Sutututu]

Yes you are correct, however as the AFM voltages the ECU will go "dafuq" and just cut timing (not arguing what you said above, agree 100%)

Just to tickle your brain a litte more a larger turbo will decrease cylinder pressure, i.e. decreasing the chances of knock. Hence with larger rear housing you're able to dial in more timing. Say if the timing is still the same for x load at y rpm with z fuel & ignition you actually yield less cylinder pressure.

[GTSBoy]

There's no such thing as "pushing past" R&R. The top right hand corner of the fuel map is over 100% duty cycle. The top right hand corner of the ignition map is down to single digit advance. With a highflow at maybe 10 psi it would be possible to register a higher TP than the max of the ignition map (which is TP=208) and then the ECU will extrapolate from the last column, giving more single digit advance. It is even easier to overrun the end of the fuel map (TP=160) and the ECU will just keep commanding the injectors to stay wide open. The only way for it to become dangerous would be to shove more air in than the injectors can provide fuel for and thus get a lean condition. That would have to be somewhat more than 370 flywheel horsepower though (which is about the nominal rating of the stock injectors).

On that basis, if you had a highflow on stock boost, you'd be very hard pressed to get into any trouble at all. You'd definetly need to wind the boost up to 10-11psi on a typical highflow to shove enough air into it to even think about getting into trouble. Remember, these highflows are generally only making >250rwkW worth of flow when the boost is wound up into the uper teens. At 10 psi they're not smashing out huge amounts of air.

[GTScotT]

I have argued before that the ECU is only accessing the map based on a set formula of all the available variables. Variables that are not aligned with their intended cells when you change the turbo.

Bear in mind the Hypergear highflow has a CHRA the size of a small trim 3076, there is a lot of flow to be had and no way to know what part of the map it is accessing.

In my own personal experience 3 degrees of timing and a safe AFR had the ability to kill my SR in no time flat. In fact, it was because the tune was so "R&R" that made it so dangerous. Furthermore, a friend of mine did exactly what this thread is about on a 33 GTST (against my advice) and suffered the (described) consequences. But what does factual experience matter on a forum...

won't argue this point forever in a day -.-........ If people want to believe doing this is safe, thats fine.. If you want to further enforce to them that it is, its your conscience.

John the above probably quite well explains my position on your question.. While the bigger turbo lowers combustion temps, its still forcing the ECU to pick mixtures at random which could be dead on a no go zone for the given load point. I just wouldn't condone it to anyone....

[GTSBoy]

It's hardly random. X amount of air flow measured at the AFM is the same amount of air being put in the cylinders regardless of whether it happens at 14 psi with a smaller, restrictive turbine or at 10 psi with a bigger, more open turbine. Once the valves are shut it's the same amount of air trapped in there. And unless it is simply too much air for the injectors, it's just going to be in R&R territory.

I never said there was no risk, but I refuse to believe that a highflow at stock boost level (5 or 7 psi) is going to be able to punch right past the fuelling capacity of the standard injectors.

[GTScotT]

I don't think it will go past the fueling capacity of the injectors, I just don't think the AFM's reading is a true representation of flow. You can always scale the thing differently and have it max out somewhere else... The AFM is only interpreting vibrations across the element into a voltage reading. Knowing that flow and pressure are not relative, it would also be fair to say what happens before and after the compressor would also be different across varying compressors.

So in my mind the AFM could read a certain voltage, but with two different turbos you could be talking a different mass of air. That mass ends up in the cylinder and might be just that little bit different in the wrong way and push it towards knock. Knock is actually easy to encounter, and as I have learnt its even easier with lower timing values..

This isn't even taking into consideration how a given turbo would plot against its compressor map at such low PR, and how hot it may be blowing when revving out at 5psi. All little variables that just don't inspire confidence in my mind when talking about a motor that loves to smash itself to bits.

Truth be told, I am nowhere near this pedantic about CA or SR turbo swaps... You can easily get away with a T28 on an S13 (of whichever sort) and have no issues. Nissan clearly did a better job of their ECU's than they did the 33+

[GTSBoy]

I don't think it will go past the fueling capacity of the injectors, I just don't think the AFM's reading is a true representation of flow. You can always scale the thing differently and have it max out somewhere else... The AFM is only interpreting vibrations across the element into a voltage reading. Knowing that flow and pressure are not relative, it would also be fair to say what happens before and after the compressor would also be different across varying compressors.

So in my mind the AFM could read a certain voltage, but with two different turbos you could be talking a different mass of air. That mass ends up in the cylinder and might be just that little bit different in the wrong way and push it towards knock. Knock is actually easy to encounter, and as I have learnt its even easier with lower timing values..

This isn't even taking into consideration how a given turbo would plot against its compressor map at such low PR, and how hot it may be blowing when revving out at 5psi. All little variables that just don't inspire confidence in my mind when talking about a motor that loves to smash itself to bits.

Truth be told, I am nowhere near this pedantic about CA or SR turbo swaps... You can easily get away with a T28 on an S13 (of whichever sort) and have no issues. Nissan clearly did a better job of their ECU's than they did the 33+

Wrong about the AFM. It is a hot wire anemometer. The controller in the AFM measures the current required to keep the wire at a constant temperature. The air flowing over the wire cools the wire. The current required to keep it hot has a very strong relationship with mass flow of air over the wire.

Now, hotwires are a little fragile, and they are susceptible to fouling with oil/muck etc. But the reality is that they do last in automotive applications for many years, so they are robust enough for the task. And also, if you have an AFM on a car, and you just swap to a highflow, then the air flow reading behaviour of the AFM will be no different after the turbo swap than it was before. So if the AFM is "faulty" in way that would put the engine at risk, then it would be so regardless of which turbo was on there.

Given that we're talking about the same AFM and ECU in this OP's question, and that the ECU is famously over R&R at the top end, I don't think you can point to a wobbly AFM load signal as a potential cause for engine failure that would be triggered by fitting a highflow and running it at stockish boost.

Sure, it's not a great idea because it is a huge waste of time and there is certainly some risk that the boost would get wound up and the engine lunched etc etc.....but not from the original terms of inquiry.

And of course, your second paragraph is rebutted by my above verbal spray also. Air flow over a hot wire is airflow. Temperature and pressure of the air over the wire don't matter (bar a very small influence). The AFm actually has a separate temp sensor of its own upstream of the hot wire so that it knows what the air temp is as part of it's own calibration calcs.

The amount of heat into the compressed air at 5psi, even on a relatively low efficiency part of the map won't be heaps. The compressed air temp will certainly be low enough for even the stock intercooler to deal with. The adiabatic temperature rise of 5 psi is only about 25°C and so even if the compressor efficiency was only 50%, you'd still only rise about 40°C.

[GTScotT]

I wasn't aware the skyline was using a hot wire AFM, I always thought these were vibration (rubbish) type.

Not that it actually changes my stance, I still don't think its safe. Yet in light of your comments its probably not as dire as I am saying it is.

I'll need to look into it more, but still safer for me to advise against it than condone it. My friends 33 GTST was a total slap in the face.. I gave up on that argument and regretted doing so (as a good friend would).

Anyhow, I'm happy to admit when I am out of answers.

[Plattsy]

right now this prick has finished.

yes it does work. you can run 10psi.

however it will lag and be slower.

i lasted a month before i tuned it.

ps. i dont eat dicks scott. just your mothers ass.

[Dose Pipe Sutututu]

For a second I thought it was 1x person replying to this thread at different times haha.. then I realised it wasn't.. man one of you guys need a avatar (or both)..

anyways, back to the OP's post..

Yes get it, yes run as little boost as you can, and don't drive it hard until you get an aftermarket ECU.

and from experience, when I started peeling back my old R33, I drove around with a HKS2535 at 0.7bar all day for a while and nothing went pop with the stock ECU, stock AFM, stock injectors. However still had a wideband attached to the car, the stock ECU just dumped in loads of fuel at times < 10:1 (Innovate LC-1, doesn't read anything lower than 10)

[GTScotT]

ps. i dont eat dicks scott. just your mothers ass.

She's a disease ridden whore. Good luck with whatever you caught off her, scat eating mother f**ker.

[Plattsy]

She's a disease ridden whore. Good luck with whatever you caught off her, scat eating mother f**ker.

cheers mate!

genuine internet lulz.

[GTScotT]

Agreed.

Had a good lol' and publicly uncovered your love of scat porn. Winning!

[Plattsy]

it was never covered mate. how do you think i made my millions? rent boy like yourself?

scat mate. shit everywhere.

[picklesRs4]

well that escalated quckly

[Dose Pipe Sutututu]

not sure what's going on

[ARTZ]

What is with all the Muppets telling him to buy junk on the first page...

Hyoergear will sell you a BRAND NEW highflow and ecu for about 2k...as long as you have a good fuel pump,intercooler and clutch you have everything you need for a solid 400hp car..all it needs is a tune from a competent tuner and it will fly...

get bigger injectors it will make 450hp...

why waste time with emanage or second hand pfc when u can buy brand new shit with warranties...and NEVER need to upgrade afms or buy boost controllers or any of that shit...

Do yourself a favout kid and ignore the first page of this thread...Im afraid to even read the second...

[ARTZ]

Ok it seems our resident geniuses came to play on page 2..read what they say as it's interesting and you could learn a little,but ignore it...if you can't pay to play just get a secondhand turbo for now and start saving coin for the real thing.. Because a half baked skyline, isn't really a skyline at all

[StevenCJR31]

I wasn't aware the skyline was using a hot wire AFM, I always thought these were vibration (rubbish) type.

Not that it actually changes my stance, I still don't think its safe. Yet in light of your comments its probably not as dire as I am saying it is.

I'll need to look into it more, but still safer for me to advise against it than condone it. My friends 33 GTST was a total slap in the face.. I gave up on that argument and regretted doing so (as a good friend would).

Anyhow, I'm happy to admit when I am out of answers.

[StevenCJR31]

nissan have been using the hot wire afms since (at least) the r31s

a lot better than the restrictive "trapdoor" afms they used in the e15ets and L series of the same era

[ARTZ]

afms suck...map ftw