20psi + E85 makes et drags scream!

[phat_ridegt]

if you dont know what you're talkign about, dont comment.

the function of the iat, is to add/subtract timing in colder/warmer weather. if you zero it out, you use your main spark tables only.

anyone who is doing this, certainly scans their car frequently, and knows how much timing they are running, and what the afr is

 

[The Broken Regal]

lol i can set my IAT #s to whatever I want... my car is gonna go KABOOM!

 

[esteinmaier]

Yea, I don't know what I'm talking about. I just get paid to fly around the country tuning cars and building/designing turbo systems. Nevermind that I helped develop NGC crank and cam decoders and sequential fuel injection algorithms for MS.

So if air density isn't determined by IAT, what determines it?

I don't know HPTuners or factory GM ECUs, but I can tell you what air does. And if you are tuning an without air density, expect your tune to be good at that temperature only, and as soon as it gets warmer or colder, expect it to be way off.

 

[phat_ridegt]

regardless of what you do for a living......my car only uses iat to add/subtract timing when the temp changes. how would it measure the density? its a two wire resistor sensor...?

 

[Yaj Yak]

regardless of what you do for a living......my car only uses iat to add/subtract timing when the temp changes. how would it measure the density? its a two wire resistor sensor...?

 

[esteinmaier]

Temp = density. Same reason ricers think a CAI is going to make their cars into ferraris. Colder air is denser, therefore requires more fuel to maintain a specific a/f ratio. Are your cars MAF or MAP? Because if they are MAF, it would make a lot more sense that they would not tune based on temp for air density. The calcs for PW must weigh heavily on whatever is used to determine density. Your ECU takes your air volume X air density X VE value X EGO to determine PW, and probably has a few other calcs in there as well with less weight. So whatever determines density, whether that's air temp or MAF is a requirement.

Besides both our egos colliding, why only 17 degrees of timing advance? I'm up to 29 degrees at 200kpa, more like 26 degrees where you're at. Even at 38psi of boost, I don't think I'm running that little timing. I haven't run the car that high yet, so I don't know for sure how it's going to like it though. e85 is incredible for detonation resistance, given the octane, and then you cool down the air at the port lots more, and combustion is a couple hundred degrees cooler. I would think you could make tons more power by using the combustion in the CC instead of the manifold. Are you hearing any knock through the stock sensor at all?

 

[Yaj Yak]

correct me if im wrong but....


these cars dont like that much timing... plus... he's prolly almost flirting with 500whp where hes at...

our cars are maf as well...

 

[esteinmaier]

I'm surprised. What's the static compression ratio of the motor? I'm running the same timing advance roughly at 200kpa as my car did stock at 100kpa, and my compression is still 9.2(x). Stock it's 9.3(x). I'm in the same power range myself. 2.0L at about 23psi of boost, 8600rpm, big turbo, big cams. Typically, stock F/I applications will have pretty low compression, and that makes them eat timing up pretty well.

I need to play with HPTuners a bit. Even if the stock IAT is only varying ignition timing, it's still worth using if you're tuning it to make power, as too much timing advance with hot air is also going to cause similar problems. Relying on a band-aid like a knock sensor looks great on the dyno sheets, but for long-term driving in more than season, it's not optimal. I find it hard to believe though that it doesn't also include IAT in the fuel calcs in the background. You may not be able to see on the front end what's going on, but you also don't see how coolant temp is affecting ignition timing either from the end user standpoint.

 

[phat_ridegt]

no im not getting any knock...

we use both map and maf, however the map is pointless for wot tuning because it is only a 2bar map....

most everything is adapted through the maf sensor...using forced induction with a 3800, more than 24* timing is not only asking for trouble, it doesnt make any more horsepower than 20* and a point or two leaner.

i dont know much about other platforms, but this holds true with most all late model gm gas motors...

what sorts of tuners do you use for gm if its not hptuners?

 

[phat_ridegt]

coolant temp is used more than iat, but on my car i dont use either....

my compression ratio is 9.4:1, stock is 8.5:1...i dont know what the static compression ratio is...just a plain ole pushrod motor...

 

[Yaj Yak]

L67 stock as far as I know is 8.5:1... i dunno thats the block he has in his car.

You are a 4 cylinder car correct?

As for the IAT stuff... I bet on other cars the IAT sensor is more important... as for relying on a knock sensor- I can guarantee that is not the case here... one of the biggest things that plagues these cars is the fact that they chip pistons quite easily and quickly once any knock retard begins... and my cars scans did not change at all after I started running an IAT sensor again...

 

[10sec]

I love how this guy compares two different cars to each other because he's a "tuner" I can't wait to tune my car just like everyone tunes neons, cause it's the same shit. Air is air no matter what motor it's going into.

 

[shaferz]

Sorry, but I have to agree with esteinmaier to some extent. IAT DOES affect fueling. If you do not believe it, go to youtube, search for 'shaferz' and look through my video's. There is one where I am using my timing commander to emulate IAT temps while recording video of my aeroforcetech gauges showing LTFT's and STFT's. There clearly is a change.

Fucking work blocks youtube, otherwise I would post a direct link.

 

[Yaj Yak]

http://www.youtube.com/watch?v=pae11hkkAZI

 

[Yaj Yak]

whats weird is mine didnt change at all...

 

[Yaj Yak]

main reason mine isnt in there is cuz i dont have anywhere to put it pre turbo...

 

[shaferz]

Just realized that I probably snapped that vid while doing some VE tuning. I was likely in SD mode at the time.

 

[esteinmaier]

You're actually better off placing an IAT as close to the intake manifold as possible, i.e. after the turbo and intercooler. That's where the most accurate data for the air going into the engine can be extracted.

But given the choice between not having an IAT sensor in use at all, or having it hanging in ambient air, I would choose the latter. At least it will get things ballpark and let EGO correction take care of the rest.

And yes, 10sec. Air is air no matter what car it's going into. My neon is closer in tuning characteristics to the motor in discussion than a stock GTP would be. Timing advance relative to stock timing advance will be similar or at least proportionate. If you can tune a forced induction 4-stroke motor, then you can. Whether the motor is a supercharged briggs & stratton or a quad turbo v12, it is tuned the same way. Just the actual variables themselves vary. Which is why I asked about compression.

As far as knock, I agree completely. If I were tuning it, I would put it on a dyno with a close eye on the knock sensor, and if there is a way to log with HPtuners, keep advancing timing as long as power is increasing. If knock happens earlier than power levels out, I would pull 2-3 degrees from whatever portions of the table are causing knock. If the advance ceiling is knock instead of power, I would be pretty surprised anyway because of the fuel. 93 is a whole different story though.

 

[Yaj Yak]

You're actually better off placing an IAT as close to the intake manifold as possible, i.e. after the turbo and intercooler. That's where the most accurate data for the air going into the engine can be extracted.

But given the choice between not having an IAT sensor in use at all, or having it hanging in ambient air, I would choose the latter. At least it will get things ballpark and let EGO correction take care of the rest.

And yes, 10sec. Air is air no matter what car it's going into. My neon is closer in tuning characteristics to the motor in discussion than a stock GTP would be. Timing advance relative to stock timing advance will be similar or at least proportionate. If you can tune a forced induction 4-stroke motor, then you can. Whether the motor is a supercharged briggs & stratton or a quad turbo v12, it is tuned the same way. Just the actual variables themselves vary. Which is why I asked about compression.

As far as knock, I agree completely. If I were tuning it, I would put it on a dyno with a close eye on the knock sensor, and if there is a way to log with HPtuners, keep advancing timing as long as power is increasing. If knock happens earlier than power levels out, I would pull 2-3 degrees from whatever portions of the table are causing knock. If the advance ceiling is knock instead of power, I would be pretty surprised anyway because of the fuel. 93 is a whole different story though.

Well my thought process behind that is... my outlet temps of the turbo after the i/c or even after the turbo for that matter... are lesser than that of the roots supercharger that came from the factory put out. yet... theyd still be higher than where the iat sensor was previously (before the tb/maf/everything... if i got a screw in sensor or something- and put it in the piping- who knows how hot the air would be...

so if there are such fueling changes- I would almost assume that it would be better suited for the iat sensor to be before the turbo and everything- cuz that would be the closest to where the temps were where it was stock.

 

[phat_ridegt]

As far as knock, I agree completely. If I were tuning it, I would put it on a dyno with a close eye on the knock sensor, and if there is a way to log with HPtuners, keep advancing timing as long as power is increasing. If knock happens earlier than power levels out, I would pull 2-3 degrees from whatever portions of the table are causing knock. If the advance ceiling is knock instead of power, I would be pretty surprised anyway because of the fuel. 93 is a whole different story though.

this is normal tuning in ANY car QFT

 

[esteinmaier]

Well my thought process behind that is... my outlet temps of the turbo after the i/c or even after the turbo for that matter... are lesser than that of the roots supercharger that came from the factory put out. yet... theyd still be higher than where the iat sensor was previously (before the tb/maf/everything... if i got a screw in sensor or something- and put it in the piping- who knows how hot the air would be...

so if there are such fueling changes- I would almost assume that it would be better suited for the iat sensor to be before the turbo and everything- cuz that would be the closest to where the temps were where it was stock.

So the stock IAT is actually located before the supercharger in stock applications? Wow, that's not very good engineering. From the factory, they are tuning on best guess. I guess I can't really give you shit for not tuning properly if GM doesn't either. Any change in efficiency of the supercharger would change relative temps, and then the tune would be off.

 

[Yaj Yak]

Im almost willing to bet tho... that the difference when ambient temps change- the change in outlet temps is minuscule since its a roots blower which is inefficient, and most likely the temperature of the sun.

 

[esteinmaier]

Well, it is pretty easy to calculate that if uncompressed air going into the compressor is A temperature, and the pressure on the other side is B pressure, then provided the efficiency of the compressor is C, then outlet temperature is X. But if C changes, then so will X. If tolerances change in the compressor over time, then C will change too.

 

[phat_ridegt]

Problem is an m90 blower is not a compressor. It just moves air. You need to get into a kenne belle/whipple to get into a compressor.

I agree there are scenarios that iat is important but my car isn't one of them :-8

 

[esteinmaier]

My point is just that it compresses air. Whether it's referred to as a blower or compressor, or charger, it all ends up in compressed air.

Well, I guess you and I disagree, and you're not going to do what I would do if I were in your shoes. So I guess time will tell if your tune stays true. Hopefully it does. Although let me know if you go to the dyno anytime soon. I would love to see what happens as timing is adjusted. I would be willing to bet it wakes up pretty good with more timing as compared to gasoline.