Well ...I've certainly 'been there done that' . Which is why I now advise anyone that will listen to start with a good insert and port both outer exhaust ports and leave the Siamese alone. In so doing the pulse strength is made less on the middle insert and there is more pulse on the outer ports to spool the turbo.

 

Summer is here yet again and the oem knock control went crazy. I had to add more IAT based ignition retard than estimated initially. I am now down 5 degrees at 50C, 8 degrees at 60C, and 10 degrees beyond that. I've also had to taper boost even more, from 75kpa down to 60 kpa beyond 50C. This is no fun, and the car literally feels slow compared to my memories of last winter. But again I can't f/// tell if it's really knock or not, maybe I should get some other system in place...

 

50C from my understanding is extremely warm for charge temp and is certainly getting into pre-ignition territory, let alone 60C. For reference on a decently warm 22-25C ambient day, my car was completely heat soaked, I started it after sitting for a few minutes and charge temp was around 48C, once I started driving and the intercooler became effective again my charge temps dropped substantially to 35C on a multi gear pull then back down to 26C during cruise. Maybe my ambients have not been as warm as you are seeing but under boost I have yet to see more than 35C charge temp under boost.

edit: Am i seeing this right, you are seeing a 45C charge temp on a 16.5C ambient day?

 

16c is my ac... when it's 35c out and 40c at road level.

 

Perfect candidate tor Water injections in aim of reducing IAT..
Or just spraying the IC with water to increase the efficiency of its energy dissipation

 

Updated pictures of your intercooler, IC piping, bumper, ducting? What fuel are you currently running and what ethanol percentage? It does seem like there could be some minor issues you are experiencing with cooling the air in your system, I'm trying to make sense of exactly everything you are presenting and factoring in the weather conditions but something just seems off or maybe I'm missing something. Your air temperatures just seem quite high

 

20°C above ambient is in deed very high for post cooling. Its not that mich boost that would "**** it"..

At 10psi / 0.7bar of boost the temp from compression is only ((273+40)*1.7^0.286)-273)=91°C
Where
273 - converting °C in to K and than back to °C
40 - ambient temp in °C
1.7 is pressure ratio for 0.7 bar boost
^0.286 - adiabatic compression of air

Having a delta T of 50°C on intercooler should give it enough capacity to work..

 

Those figures I'm complaining of happen during city driving. Essentially when it's boiling outside you can't drive within the city. Stop and go traffic, heatsoak, no airflow at all = charge temps in the 40-50C range. Obvs. the setup works when above 60-70kmh but not in a city.

 

I cant imagine charge temps that high for the climate you reside in. Again see my previous post. Even in city driving stop and go traffic, on a 41°C day (yes ambient, road temps are higher), but i still wont see temps at my IAT higher than 46°C. Once i get moving more, temps come back down to 1-2° over ambient. Something isn't adding up unfortunately. The items i mentioned might help troubleshoot.

 

For him its charge air temp not iat before turbo.

 

So is mine, i have a GM IAT sensor just before the throttle body. I undid the two wires going to the OEM MAF that are for the integrated temperature sensor, put a pigtail for a GM sensor and ran that to a GM sensor welded into a pipe in my wheel.

Im looking at my temps post-intercooler before the air goes through the throttle body and get an accurate read on temperature. Yes my IAT map has also been scaled correctly to match the GM sensor and read accurately.

 

A bone stock car gets the same IATs so you deff didn't scale that sensor right. Scaling an NTC isn't straightforward as applying a fixed % across the OEM NTC map. You need to compute each data point so that interpolation doesn't do much harm.
In stop and go traffic you're breathing the exhaust of the one in front of you, everyone has their AC on, so it literally is hell for engines. Do this for 20-30 mins straight, not covering more than 500-1000m in this time, and there you go: 20C above ambient is the mere result of this. 2-3c above ambient you get maybe in the winter... on the highway.

 

100% agree with ciprian here, probably wrong scaling. No way you get 1-2°C, not even in winter.. its a great achievement if you get that at the maf with 0 heating from the compression/turbo/heat soaked IC ect . 1-2°C delta T is close to no heat energy exchange... (No cooling capacity)...

 

This is what it gets if it has airflow, at least 30kmh average speed. Think that's pretty good... 32C out, no boost though.



I've decided to start tapering boost as soon as charge air hits 30C, by 40C it only does spring pressure(30kpa by redline) and past 45C I am also opening the BOV to keep boost below 20kpa.

Summers here regularly get to 37-40C so I've set that level accordingly. Even at such low boost levels you can still feel some torque, though it's more like teasing you instead of feeling good.

Knock control remains a mystery.

 

Get a microphone type knock sensor and listen by ears ....
I just cant believe oem noise floor / frequency isn't changed significantly enough to completely make it useless..
Also knock is (should be) listened to only in certain window of timing, ie between ignition and TDC...

I just can't believe charge temp of 40° makes it on the knock limit.. Brett is also in hot region, and is pushing way more boost. I cant see him having less than 40°C charge temps..

 

Don't forget that I have always run higher octane fuel than what Ciprian uses. These days I'm running w/m with some success but still nervous with it. I think a setup that used IAT as a safety would be great and have been putting some thought into implementing something lately.
I regularly see IAT 2-3 degrees C above ambient (post IC) when cruising out of boost on my setup as well. Dunno why you find that so hard to believe?

FWIW , I scale the GM IAT sensor using the OEM ambient sensor as a guide. IE do it when engine hasn't run for 12hrs minimum at 2-3 different ambient temps, so there is some interpolation to do. Maybe that method is flawed - do you have a better way?

 

From @Ricky SE3P i understood it as that was on boost, like Ciprian gave. Not low load like you wrote..

If knock is actually happening, retarding the ignition might be a much better solution than reducing the boost. If the ignition is later, there wont be any further compression (and heating) of the volume in same time the temp (and pressure) raises from combustion

 

No, my comments were not under boost. Under boost my numbers change a bit, but not drastically so.

I am hopeful to drive my 8 this coming weekend, and I will be making a trip to go refuel. Peak forecasted temp this weekend is 40C coincidentally, I can try to grab a few screenshots and maybe a log of what my car is experiencing in driving conditions both highway and stop/go.

 

7 tanks in, so far so good.

But I miss the power it had at 85kpa. I'm thinking of making a momentary overboost function that allows a boost target of 85kpa only under perfect conditions and for only 7-8 seconds straight, followed by a 1 minute cooldown period. This will be a nightmare to code, test and debug, but I think it will be worth it.

 

Push to pass!

 

void manage_hyperboost()
{
unsigned long now = systime();
// --------------------------------------------------------------------------
// GEAR CHANGE DETECTION
// --------------------------------------------------------------------------
// Detect gear changes by monitoring sudden RPM drops
// If RPM drops more than hyperboost_MIN_RPM_DROP, consider it a gear change
if ((last_rpm - engine_speed) > hyperboost_MIN_RPM_DROP)
{
last_gear_change_time = now;
}
last_rpm = engine_speed;
// --------------------------------------------------------------------------
// MAP AVERAGE CALCULATION (20-second rolling window)
// --------------------------------------------------------------------------
// Reset the MAP average calculation every hyperboost_AVG_WINDOW window
if (now - map1_avg_reset >= hyperboost_AVG_WINDOW)
{
map1_avg_sum = 0;
map1_avg_samples = 0;
map1_avg_reset = now;
}
// Add current MAP reading to the running sum
map1_avg_sum += map1_press;
map1_avg_samples++; // Increment sample count
// Calculate current average MAP pressure:
// - Use actual average if we have samples
// - Fall back to current MAP reading if no samples yet
float current_avg;
if (map1_avg_samples > 0) current_avg = map1_avg_sum / map1_avg_samples; // Actual average when we have samples
else current_avg = map1_press; // Default to map1_press if no samples yet
// --------------------------------------------------------------------------
// hyperboost ACTIVATION LOGIC
// --------------------------------------------------------------------------
// Activate hyperboost when ALL these conditions are met:
// 1. Hyperboost not already active
// 2. In high-performance fuel mode (octane_boost_setting == 2)
// 3. Either:
// a) Target boost is above threshold OR
// b) We're within gear change grace period
// 4. 20-second MAP average is below safety limit
// 5. Hyperboost cooldown period has expired
if (!hyperboost_active &&
octane_boost_setting == 2 &&
(target_boost >= hyperboost_MIN_TARGET || (now - last_gear_change_time < hyperboost_GEAR_CHANGE_GRACE)) &&
current_avg < hyperboost_MAP_AVG_LIMIT &&
(now - hyperboost_last_deactivate >= hyperboost_COOLDOWN))
{
hyperboost_active = true;
hyperboost_start = now;
}
// --------------------------------------------------------------------------
// hyperboost DEACTIVATION LOGIC
// --------------------------------------------------------------------------
// Deactivate hyperboost when ANY of these conditions occur:
// 1. Maximum duration (7s) reached OR
// 2. Target boost drops below threshold (outside gear change grace period) OR
// 3. Fuel mode changes from high-performance setting
if (hyperboost_active)
{
bool gear_change_active = (now - last_gear_change_time < hyperboost_GEAR_CHANGE_GRACE);

if (
(now - hyperboost_start >= hyperboost_MAX_TIME) || // Timeout
(!gear_change_active && target_boost < hyperboost_MIN_TARGET) || // NOT during gear change, and too low target boost
(octane_boost_setting != 2)) // not in high boost mode
{
hyperboost_active = false;
hyperboost_last_deactivate = now;
}
}
// --------------------------------------------------------------------------
// hyperboost APPLICATION
// --------------------------------------------------------------------------
// When active, add boost pressure offset while respecting absolute limits
if (hyperboost_active)
{
target_boost += hyperboost_KPA_EXTRA; // Apply additional boost pressure (10kPa)
map_overboost_threshold += hyperboost_KPA_EXTRA; // raise overboost ceiling
}
}
That was fun. Now lets hope it does what i think it does.

 

Over the past few months I've been building numerous software patches to get rid of OBD2 queries entirely and have quite everything I'd ever wanted just broadcasted there on CAN for everyone to hear. The advantage is that the update rate goes up from maybe 3 parameter updates / second to each parameter gets 10 updates a second. If 3 years ago I was even querying for coolant temp... now I even have measured AFR, injector pulse width(s) - for each pair, ignition coil dwell time...and still have 2-3 spots I can fill if I find any use case.

Each yellow cell is a CAN bus byte within a message that I've hacked into and gave it a new purpose in life:


It's curious that even mazda left so many parameters in there that I am sure no other module in the car needs - like which other CAN node would care about leading timing, fuel trims, fuel system status? Well I certainly care and I am glad to find these messages there already made for me, and to even find some literal holes in them that I can literaly patch more stuff in. Other messages just look like they say - stay out of this - don't touch a thing or the car blows up or randomly locks up your brakes while driving.

Those of you that aren't at their first rodeo would also know that as RPMs go up, the ECU refuses to reply to all OBD2 queries because, wouldn't you guess, it literally has better things to do. During logging this is seen as data points getting spread out... losing resolution. With obd2 queries now out of the picture, that is no longer an issue.