More Boost or More Timing Advance?

[Kevin Jewer]

Tuning for knock at high boost levels even on race gas is risky practice. You'll lose power and break parts before you see knock on race gas. I've even seen this on pump gas with a well setup pump gas car.

Additionally, don't worry about what a bost curve looks like, worry about how it performs.

 

[soldave]

Was talking to a tuner friend last night and he brought up something which hasn't been mentioned here when you take back the timing and favour boost. Retarding the timing beyond about 15 degrees, while possibly yielding diminishing returns at that point in relation to boost, also will cause your EGTs to start to go up. I know the lowest timing will be as the turbo is spooling but my EGTs already run at a pretty high temp and upping that could cause more problems down the road.

Just trying to throw that out there for some discussion.

 

[Kevin Jewer]

In order to get EGTs that could be problematic (turbo/manfifold damage), you would have to have so little timing that the car would have no power at all. Having that little timing provides no real advantages. Cylinder pressure goes up exponentially with timing advance, but if you're still picking up ~10 hp per degree, you're not there yet and have nothing to worry about, keep going.

 

[soldave]

But when I'm taking timing out and going below 15*, the gains that can be had by upping the boost instead are going down.

 

[Black_Bullet]

But when I'm taking timing out and going below 15*, the gains that can be had by upping the boost instead are going down.

Obivously you wont make the best power you can make when you pull timing and add boost, but its all a balanceing act to get the most out of your tune that you can when your limited by knock. Rule of thumb is boost makes more power than timing as long as you havent reached the point of dimishing returns. Which is also basically as long as your in the turbos efficency range and you dont have any restriction or detriment to flow in the intake/exhaust tract.)

Soldave, with your setup, and your turbo, id except youd still have a large chunk of power left just in getting the boost up some, even with some sacrifice in timing...

 

[big_d]

Excellent thread guys A very good discussion from tuners with real experience. Keep it goin' *subscribed

 

[ApexVIII]

Excellent thread guys A very good discussion from tuners with real experience. Keep it goin' *subscribed

very interesting thread! thanks alot guys

on my 2g i have 650cc injectors DSMlink v2.5 rewired Evo IX fuel pump SSAC FMIC, 1g bov, and catted 3"TBE and a ported Big16G(not a E16g though)

for some reason at 20psi i knock alot at 9* timing, i am on 91 pump

so i lovered the boost to 18 and i get to pull about 9* with out any knock, i know there is room for improvement any one have some ideas?

 

[Black_Bullet]

very interesting thread! thanks alot guys

on my 2g i have 650cc injectors DSMlink v2.5 rewired Evo IX fuel pump SSAC FMIC, 1g bov, and catted 3"TBE and a ported Big16G(not a E16g though)

for some reason at 20psi i knock alot at 9* timing, i am on 91 pump

so i lovered the boost to 18 and i get to pull about 9* with out any knock, i know there is room for improvement any one have some ideas?

What is your AFR, have you checked base timing, do you have boost leaks, what compression ratio, does the motor have blow by?
Look into that stuff first...

 

[ApexVIII]

What is your AFR, have you checked base timing, do you have boost leaks, what compression ratio, does the motor have blow by?
Look into that stuff first...

the AFR is 11:1 on my LC1

base timing is 5deg, the compression was about 155 all across. i fixed most of the boost leaks so if there is they are fairly small

EDIT: i attached a dsmlink log

the only thing that might be causing phantom knock would be that on the lower intercooler piping it hits on the oil feed line going to the turbo. so maybe that making contact sounds like knock to the sensor? ima try and fix it this weekend.

but the knock is always in the same exact spots as it is showing in the log

 

[soldave]

Talked with a friend over the weekend. Should be worth noting that one reason a few of you guys can get more timing in your cars than me is that I'm running an Evo 1 with an 8.5:1 compression rate. I think the 1G compression rate is lower, which could alter things a little.

 

[Black_Bullet]

Talked with a friend over the weekend. Should be worth noting that one reason a few of you guys can get more timing in your cars than me is that I'm running an Evo 1 with an 8.5:1 compression rate. I think the 1G compression rate is lower, which could alter things a little.

Sure does. More compression, less timing you can get away with on pump, but also consider more compression could mean less timing needed period...

 

[JayRolla]

i have always ran 10.8's with both of the motors in my car. it blows black smoke under heavy boost but i know its safe. i have never felt much of a difference on my but dyno from 11.3-10.8. maybe thats just me but my car has always ran strong in that area. im wondering if the dyno tuner will lean that out and make more power when i get a chance to get it dyno tuned...

edit: when i start throwing meth at it again ill probably end up with around 23-24 degrees of timing again...

I used to run 10.9 all day and never had any black smoke, maybe a very little. Thats weird.

 

[KeelesKustome]

Sure does. More compression, less timing you can get away with on pump, but also consider more compression could mean less timing needed period...

right.



It seems everyone has forgotten 1g's have a higher timing curve due to lost power from a very low compression ratio.

The higher your compression the more effecient the engine will run at a lower timing value, also improving gas milage under normal driving.
This is not saying you couldn't saftley run more timing on a 2g curve because you can. Just keep in mind your actual compression ratios when doing so.

 

[Boosted98gsx]

Great thread. I would like to see some numbers on the dyno provideing some definite answers to this and maybe tuning our cars would be one step easier.

It's been done numerous times.

If your turbo's efficiency is in the 30psi range, and you're peaking out of timing with 22psi, then you obviously want to dump timing to be able to get to that P/R. You will gain more with more (cooler) airflow through the engine.

 

[Archer Fabrications]

very good thread, considering that i have been having timing issues hella. i have the 9.2:1 compression on 92 pump gas and an HX40 right now, and have been dipping in negative as some of you know. some say im burning my mixture in the manifold, but i think that im allowed to run lower timing (not negative though) then most people... im still trying to get everything worked out, i just had to replace a coil pack and PTU and now my #1 injector plug wires are shorting out, new plug pigtail on the way and ill post a log in here. i dip into -3 degrees and would see knock with the evo8 mod 1 map as well as the 2g map. but after i fix this injector plug im gonna reload the 2g map and take out 2 degrees to a peak of 13* and see if that makes any change. i hate knock. its the devil.

 

[EVLGSX]

I enjoyed this thread and was bummed that it ended, so six years later- lets bring it back-

Heres a crappy pull- I was going too fast when I started it but its the best representation of what I have as of now in my logs when I just looked. I cant decide if I like the lower boost higher timing or the higher boost lower timing yet. Accurate boost control is an issue for me right now too so Im sure the higher boost lower timing pulls will bet better once I get BC in check. This is a lower boost higher timing example. As you can tell , Im trying to control the spike with a delicate throttle advancement rather than just nailing it. To be restricted by pump gas is a real bummer too.

Im relatively new to ECM link as well but Ive put a ton of time into learning it these past few months.

 

[EVLGSX]

So I guess nobody is into it? Oh well.

 

[Jaymaneotis]

This is kind of stupid but timing makes power and so does upping the boost. It really depends on your willingness to push your car. A larger spread in boost will make more power then timing alone (like 15 psi with 19 degree's of timing will make more power then 16 psi with say 14 degree's). But your talking about a 5+ psi difference then boost wins, if the tune is correct.

I agree. Thanks for the info.