What's better, more timing&lower boost or high boost&lower timing?

[mikyrc]

What's best guys?

Is it better to run for example 17psi and pretty advanced timing or to run like 20psi and not so advanced timing?

Both cases the timing should be advanced 'till it starts to count knock, but the low boost will allow to advance it more.

Which case should give more power?
And wich one should be safer?

Thanks guys.

 

[andymoraitis]

Miguel,

On pump gas where the knock threshold is lower, it's boost over timing. While each motor is different the same general principles apply. I would rather run 25 psi at 12 degrees of timing than 20 psi at 16 degrees of timing. It all depends on what you can get away with in terms of knock since cooling efficiency of the air charge is a huge factor on pump gas. On race, throw timing and boost at it since the knock suppression capabilities are so much higher.

Adios,

Andy

 

[mikyrc]

Hi Andy, i was writting a PM to you but i saw your answer.

I wanted to tell you on the PM but i'll do it here. I finally got another ECU from Jeff (dsmchips) He's a good guy. That one is working perfect.
He also added a more agressive timing maps to it, but i'm getting knock above 4k rpms at more than 17psi of boost.

So he'll have to send me another eprom image. I asked him to burn me a custom timing maps between the stock ones and those he sent me last time. So hope the car will run perfect now.

Altough the car at 15psi is a lot faster than with the stock timing maps and at 18psi.

That's why i was wondering what should i do, if run higher boost or higher timing advance.

But now i understand that is better to run higher boost first and then give it some advance if possible.

What boost will you run in my case? I'm using 98 RON that we think is something like your 93.

Thanks man.

 

[andymoraitis]

Miguel,

On 93 octane with a 16G I would shoot for stock timing maps at an 11:1 A/F ratio. I'm not sure how much boost you'll be able to get away with, but I ran 22-24 on mine on the same A/F and timing map with a large sidemount. Just make sure that Jeff caps the timing advance at 16 degrees to give you more room on pump gas. Try it and see what the knock does and then let us know.

On a related note, I knew Jeff would take care of you if there was an ECU problem. He really is a great guy.

Stay well,

Andy

 

[mikyrc]

But Andy, i was running the stock timing maps on the old eprom chip and i felt the car very slow compared with the '97 stock ecu and SAFc set at -20%.

Now the power comes very strong even at low boost (14psi) and pulls very well, but at 18psi it knocks most of the time. I'm running 11.1:1 or so.

Don't you think that the best setting could be leaving that agressive timing from iddle to 4k and after that point to soften it a bit? Something between the stock and the agressive?

Or is not possible?

 

[andymoraitis]

What I would tell Jeff is to keep your timing map aggressive until it hits 4K and then make sure it only rises to a peak of 16 degrees. You can try that instead. Just remember that while these are all 4G63's sometimes they behave like they're all different motors.

 

[mikyrc]

Andy, do you think that bypassing the throttle body coolant lines will help controlling knock?
And blocking the EGR?

What's the boost i should run on my setup?

Those are my mods:

Aftermarket air filter, cone type
cold air intake plate
2,5" intake Pipping
HKS SSQV BOV
SUPRA SMIC
ARPs on stock head gasket
NGK wires
NGK BR7ES plugs
2,5"/3" exhaust, no cat
16G turbo ported
Regrinded DKS 264/272 cams
550cc injectors
3000Gt fuel pump rewired
FullThrottleSpeed AFPR
Joe-P MBC
'95 GSX ECU+keydiver stage 3 chip
5 knob style SAFC
PLX M-300 wideband

93 gas

 

[andymoraitis]

Blocking the FIAV will do nothing for knock and blocking the EGR may actually increase it. When the EGR adds NOX to the intake charge it actually cools the combustion temperatures slightly. I'd leave that stuff alone unless you want to do a vacuum removal.

As far as how much boost you can run, every motor is different. I can't pull a number out of the air and say that this is what you can run. Monitor it for knock and when you see 5 counts on the first bar of your stock boost gauge, back it down until it goes away. That's the only way to find the safe limits on your setup.

 

[mikyrc]

ok, so the limiting factor is the knock, not that i can blow the head gasket or turbo, right?

I thought that eliminating those coolant lines from the TB you allow it to be cooler, helping maintaining intake temps lower so knock chances are less probable.
But by your answer i guess those coolant lines effect is insignificant.

 

[nightspeed87]

Blocking the FIAV will do nothing for knock and blocking the EGR may actually increase it. When the EGR adds NOX to the intake charge it actually cools the combustion temperatures slightly. I'd leave that stuff alone unless you want to do a vacuum removal.

Huh? What is a vacuum removal? Also, So your saying that blocking the EGR increases knock chances? Not that im knocking your knowledgeable opinion Andy, but just curious if any one else can confirm this, because why would it be listed in the free mod sections then, because I was about to block my egr and block the FIAV next weekend. ( I still am going to block the FIAV though even if it doesnt do anything. )

 

[nightspeed87]

Andy, do you think that bypassing the throttle body coolant lines will help controlling knock?
And blocking the EGR?

What's the boost i should run on my setup?

Those are my mods:

Aftermarket air filter, cone type
cold air intake plate
2,5" intake Pipping
HKS SSQV BOV
SUPRA SMIC
ARPs on stock head gasket
NGK wires
NGK BR7ES plugs
2,5"/3" exhaust, no cat
16G turbo ported
Regrinded DKS 264/272 cams
550cc injectors
3000Gt fuel pump rewired
FullThrottleSpeed AFPR
Joe-P MBC
'95 GSX ECU+keydiver stage 3 chip
5 knob style SAFC
PLX M-300 wideband

93 gas

Maybe a front mount would help you out a little more with your knock problem.

 

[andymoraitis]

Huh? What is a vacuum removal? Also, So your saying that blocking the EGR increases knock chances? Not that im knocking your knowledgeable opinion Andy, but just curious if any one else can confirm this, because why would it be listed in the free mod sections then, because I was about to block my egr and block the FIAV next weekend. ( I still am going to block the FIAV though even if it doesnt do anything. )

Re-read post number eight above. I mention why blocking the EGR may increase combustion temps. Vacuum line removal is basically yanked off everything not needed to run the motor. I have one vacuum line to the intake manifold which handles the AFPR and boost gauge, one for the BOV and one more that goes to the brake booster. Getting rid of emissions related paraphenalia eliminates a ton of vacuum lines.

 

[mikyrc]

Andy 20psi is a good boost setting if it doesn't knock? WIll not be harmful for the 16G or Head gasket?
Or even i could run more boost without breaking anything if the knock is under control?

I'm afraid as i already blow a head gastet by running to much boost. But that was before i put the ARPs and using a cheap brand aftermarket HG.

What about puting a lower temp thermostat and a higher pressure coolant filler cap? Will it help on knock?

Do you think that disabling the PCV valve will do anything?
I mean cap off the intake nipple but run a hose with a "T" to the other cranckase ventilation nipple on the side of the Valve cover and vent them to the atmosphere with some kind of filter.

Thanks for your help.

 

[andymoraitis]

Changing the PCV setup should have no effect. I check mine periodically to make sure it's still sealing properly, but I still run the stock PCV arrangement without a problem.

As far as the headgasket, I ran 26 psi on mine with the Big 16G and I also had stock head studs on the motor. When the motor was rebuilt, the headgasket looked perfect. Even the new motor uses an OEM composite gasket (this time with ARP's). If the tune is correct, you won't compromise the gasket. What does that more than anything else is out of control knock from running a piggyback and skewing the timing maps. Too lean is too lean no matter how much boost you're running.

For the thermostat, I run a 180. Using a cooler one may limit your ability to see full timing if the ECU doesn't see the engine up to correct operating temp ranges. If they go too high it does the same thing.

You're just going to have to play with it a bit and see what you get away with. Increase the boost in small increments (2-3 psi) and look for knock. When you see knock, back the boost down until it's gone and you'll keep everything safe.

 

[nightspeed87]

For the thermostat, I run a 180. Using a cooler one may limit your ability to see full timing if the ECU doesn't see the engine up to correct operating temp ranges. If they go too high it does the same thing.

Ive heard of this, so until the cars fully heated up in operating temp range you have less power because of changed timing maps ? Isnt operating temp 190, and if so therefore a 180 would be to cold right? I thought about getting a 180 a while back and someone told me bout what your saying.

 

[mikyrc]

Thanks man.
Yeah i also heard that about the ecu pulling timing if the water is not at the desired temp.
So how did you solve that?

 

[olmytsi]

Here you go:

The ECU will not update long term fuel trim values under at least the following conditions:

2G: coolant < 179F, intake >= 133F, baro < 22.9 inHg, baro > 31.6 inHg

The ECU will force open loop mode under a zillion different conditions, including the following.

2G: coolant < 51F, coolant > 228F

So as long as the ecu sees at least 179 degrees, it will switch out of learn mode. I'm pretty sure a 180 degree thermostat allow the coolant temps to go above 179.

 

[andymoraitis]

Here you go:

The ECU will not update long term fuel trim values under at least the following conditions:

2G: coolant < 179F, intake >= 133F, baro < 22.9 inHg, baro > 31.6 inHg

The ECU will force open loop mode under a zillion different conditions, including the following.

2G: coolant < 51F, coolant > 228F

So as long as the ecu sees at least 179 degrees, it will switch out of learn mode. I'm pretty sure a 180 degree thermostat allow the coolant temps to go above 179.

Nicely said and thank you for posting the technical figures for future reference. And yes, the coolant temps will rise above 180 with a 180 thermostat. Running a 140 or a 160 may be a different matter however.

 

[slipstream808]

Timing is affected as follows:

Enter ECU Learn Mode :: 170F (77C)
Coolant Fan ON :: 200F (93C)
Pull 1 degree timing :: 206F (97C)
Pull 2 degree timing :: 224F (107C) *
Enter Open Loop Mode :: 228F (109C)
Default Coolant CEL :: 235F (113C)
A/C Override :: 240F (115C)

Intake temperature will also cause a reduction in ignition advance. The tables are laid out like so, with interpolation occuring between the points.

2G intake air temp ignition advance adjustment:

185F = -3°
132F = -2°
100F = -1°
73F = 0
48F = 0
20F = -1°
-23F = -2°

 

[nightspeed87]

Timing is affected as follows:

Enter ECU Learn Mode :: 170F (77C)
Coolant Fan ON :: 200F (93C)
Pull 1 degree timing :: 206F (97C)
Pull 2 degree timing :: 224F (107C) *
Enter Open Loop Mode :: 228F (109C)
Default Coolant CEL :: 235F (113C)
A/C Override :: 240F (115C)

Intake temperature will also cause a reduction in ignition advance. The tables are laid out like so, with interpolation occuring between the points.

2G intake air temp ignition advance adjustment:

185F = -3°
132F = -2°
100F = -1°
73F = 0
48F = 0
20F = -1°
-23F = -2°

oh really... I have my cooling and a/c fans hooked up to constantly stay on whenever the ignition is on. Will that effect anything the ecu see's as far as changing timing?

 

[mikyrc]

2G intake air temp ignition advance adjustment:

185F = -3°
132F = -2°
100F = -1°
73F = 0
48F = 0
20F = -1°
-23F = -2°

Those temps are measured at the MAS right?
Nothing to do with temps entering the intake manifold right?

So if you manage to run fresh air from the car outside to the air filter you shouldn't see any timing pulled i guess.

 

[slipstream808]

Yes, those are the temps as seen by the MAS. There isn't any manifold intake temperature sensor.

If you use a DSMLink, it locks the IAT and baro sensor to 'non detrimental values'.

 

[slipstream808]

oh really... I have my cooling and a/c fans hooked up to constantly stay on whenever the ignition is on. Will that effect anything the ecu see's as far as changing timing?

Nope.