higher boost/lower timing - how far is too far?
Oct 26, 2008, 07:22 PM
#21
If I recall correctly it lost about 60wtq peak and an insane amount of area under the curve, the horsepower almost came together way way way way way up top at 7600 (stock turbo), and that was with me adding in timing on the 19.5psi map as well.
From what I have seen on the dyno, Boost will always give you more torque then timing will on our (stock compression) motor. Same thing up top unless it's a turbo that has gone beyond it's efficiency.
Last edited by razorlab; Oct 27, 2008 at 12:22 AM.
Oct 27, 2008, 08:35 PM
#23
I ran 28psi at peak torque w/6 degrees of timing @ the 300% load cell... and 20psi at 7k with 10 degrees of timing.
on 92 octane. I made 350lb-ft/ 330awhp on a Dynojet. MIND YOU... It's October in the PNW... and its like 50 degrees outside at the warmest.
My car only runs into knock @ higher rpm's...the timing advance from the increase in RPM is very little. As you can see...there isn't much timing advance to be had. I've backed the timing off to remove all knock... the car works well.
Just a side note... race gas fixes all your problems.
on 92 octane. I made 350lb-ft/ 330awhp on a Dynojet. MIND YOU... It's October in the PNW... and its like 50 degrees outside at the warmest.
My car only runs into knock @ higher rpm's...the timing advance from the increase in RPM is very little. As you can see...there isn't much timing advance to be had. I've backed the timing off to remove all knock... the car works well.
Just a side note... race gas fixes all your problems.
Oct 27, 2008, 09:07 PM
#25
It's more turbo size then anything. If you are pushing the airflow limits of the turbo, you are probably better off backing off the boost and running a little more timing advance. You'll only give up a small amount of power, but the car will feel a lot better under power.
If you have a ton of airflow available, it's surprising how high you can get the boost and drop the timing and never have an issue. Also, higher boost pressures NEED less timing advance anyway, so even if you have to drop the timing, you might still be right where the motor wants to be almost regardless of fuel quality.
If you have a ton of airflow available, it's surprising how high you can get the boost and drop the timing and never have an issue. Also, higher boost pressures NEED less timing advance anyway, so even if you have to drop the timing, you might still be right where the motor wants to be almost regardless of fuel quality.
Oct 28, 2008, 03:50 AM
#26
So, there isn't such a thing as "dangerously low timing"? For example, if you were running 30 psi and 8 degrees up top (not what I'm doing, BTW), that wouldn't be a problem if the car ran well and made more power than lower boost/higher timing? Are there EGT issues to consider?
Speaking of low timing/high boost, did you guys catch Mellon's 10.5@138 g-tech video on pump gas/stock ECU? 35 psi...
Speaking of low timing/high boost, did you guys catch Mellon's 10.5@138 g-tech video on pump gas/stock ECU? 35 psi...
Oct 28, 2008, 07:06 AM
#27
Yes, there is a "dangerously low" timing value. Especially when modifying the valve timing (cam gears / Mivec). If you get under 3 degrees and you track the car you will melt stuff. Ask me how I know. I ran 25psi at Summit and VIR and finally at CMP it gave up on me. I melted the TURBINE BLADES. INCONEL! Now... the turbine melted only after the gasket melted (which introduced more air in the exhaust, which means I had a flamethrower) but still... too low timing increases EGT... especially if you see knock and then you get pulled down to 0 degrees or negative timing... Turbo won't last long that way. I was even running water injection. I don't go below 6 now.
