Hi, would hope to know what is the different of Higher Timing Lower Boost with Lower Timing Higher Boost?

 

In "theory", an internal combustion engine makes power by burning fuel. So, the more fuel you can burn, the more power you can make. To burn more fuel, you have to have more air, which in this case, means a higher MASS flow, not more cfm.

you can push more cfm by higher boost, but it the temp goes too high, you actually get less air (outside the efficiency range of a turbo, heats things up fast too), measured in lbs/hr, since the density goes down. (Makes intercoolers useful) Then, for a given amount of fuel/air, you adjust the timing to get the most efficient burn. You can pretty much double the horsepower by doubling the air flow, with enough boost. But doubling the timing will NOT double the horsepower. Timing has a much smaller effect on power than air flow, although too much timing can quickly break things, and bring power back to zero.

Boost will make more power compared one to one than timing.

 

Thanks +1
The reason i ask is bcos when i increase boost (1.4 to 1.5 bar) my car start to knock a little on higher loads and when i lower the boost and +1 deg timing theres no knock on the same load cell.
So, i just wonder which is better for driverbility and power out put?

 

what do your afr's look like? What mods do you have? There could be other variables besides just timing/boost.

 

Gt3076R
S2 cams
85.5mm pistons
560cc injectors
91 octane (Ron 95) pump gas
50~50% W/Meth
575x300x65mm IC
AFR on knock area is around 11.2~11.4
Timing on knock area is 8~7 Rpm4500~5000 Load194

Guru Todd is looking on my map so hope he could shed some light.

 

curious as to why you run such small injectors. what are your IDC at? Fuel pump?

 

340L Aeromotive Fp and once awhile its does hit 90% IDC.
The reason is bcos of the super rich whenever i immediate wot as im using 850cc sard injectors previously.

 

Drop the timing and up the boost. 22psi not quite the efficiency of the 30r. Better/safer to make power with boost rather than timing.

Also put the 850's back in and scale them properly. Are you using SD as well? 194 load sounds rather low.

 

Hi Ex, thanks for sharing and no im running on MAF.
Im only boosting on my WG spring rate 1.4 bar (Ebc turn off).
Really a great info for "Better/safer to make power with boost rather than timing".

Will use my ebc again and will try to boost 1.5 bar & do some boost logs.
Now ive retard -1 deg timing from my load 100 til 350 and will try retard another -1deg and up boost til 1.6 bar.

The only problem when i lower the timing on the listed load is, i encounter power drops/unsmooth while upshifting especially on 4th to 5th gear.

Hope Guru Todd will help me on my map...

 

You guys are looking at this wrong. Timing is dictated by octane of your fuel. If you were to use a high octane fuel and tune to max efficiency (ie max power and tq) You will have the happiest engine. Now if you are using lower octane fuels you can either sacrifice efficiency and run lower timing or you can lower the boost to a level that is compatible with your available fuel. I personally prefer to be most efficient and limit boost by fuel octane. Some will add boost and run low timing. This adds a lot of heat and wastes fuel. However you may make more power overall this way but that isnt my preferred methodology.

 

Omg...Hi Batty200, what do you think if i run 1.6bar of boost on 91 octane but with 50/50 W/meth will it be safe?
Will try lower -1 deg timing from load 100 til max and increase boost from 1.4 to 1.6 bar....

 

have you considered the "should be smacking you in the face option" of running more fuel in your tune to make more power? yes you want a leaner A/F ratio to make power but if you want to be in the 23-25psi range on pump you're going to be running like 10.5 - 10.7 to 1, you can keep your timing and your boost, you just dump a little more fuel, adding water meth at this point will allow you to run leaner and make more power but isn't prefered with these cars thanks to the fact that these cars are made for mid range and have a huge boost spike then taper down a lot...

E85 is usually the chosen method but if you don't have E85 stations around you then...water meth could work, just find a good tuner, I used water meth on my 3000GT VR-4 and went from 18PSI at 10.3:1 on 15G turbos(sti equivalent) up to 22PSI at 11.0:1 changing my power from about 340whp to 420whp, so water meth is a great tool but isn't a happily suggested mod for this car...

 

Simplest answer is listen to the car and give it what it whats. Reason you can run more timing at lower boost, and have to run less at higher boost is:

Heat and Cylinder Pressure. Higher boost = more heat and higher cylinder pressure, more opportunity for pre-ignition/det with aggressive timing. Lower boost = less heat and lower cylinder pressure, giving less opportunity for pre-ignition/det to occur.

You can help to regulate thermal protection through mods like water/meth injection, more efficient intercoolers, intercooler sprayers, and fuel. It also depends on what you use the car for. A road race map, drag race map, and dd map would require different approaches to keep things safe.

My car for example: I run 11.7afr, 2* timing, 23psi spike at peak torque. That tapers to 11.1afr, 19psi by 7k with 13*timing on pump 93. No problems for over 2 years, no knock either. Some would say it is dangerous for the amount of timing up top, but it's what the car likes. If I add 2* of timing it knocks, if I run any leaner than 11.4 it knocks. It's happy where it's at. No two cars are alike as to what they like, one reason off the shelf tunes are useless imo.

 

Thanks Guys....Great sharing...

 

You forgot to talk about air density. The more boost you run, the denser the air charge is. The denser the air charge is, the less timing is need, because the flame front moves faster though denser air.

Also, when on knock limited fuel (like 91oct), they usually take boost better then they take timing, making a high boost, low timing tune a better option.