Less Boost More Timing?

[1BADVAN]

has anyone tried it? I mean for more/different range of power?

I have heard from some GNX guys that they would take out some boost and add timing and run faster in the quarter.

I know most likely more boost would equal more peak HP, but what about adding timing for more torque to get the car moving faster?

Any ideas, opinions, comments?

[BadAssPerformance]

That would probably depend on if the extra boost is causing unwanted heat. My old turbo mad emore power at 30psi than 35 because the T04B cover was a restriction for the HiFi wheel at the higher boost levels. The intake charge dropped ~50°F dropping that 5psi...

More timing down in lower RPM (pre-boost) will aid in quicker spool time as well.

[DodgeZ]

has anyone tried it? I mean for more/different range of power?

I have heard from some GNX guys that they would take out some boost and add timing and run faster in the quarter.

I know most likely more boost would equal more peak HP, but what about adding timing for more torque to get the car moving faster?

Any ideas, opinions, comments?

that is the way the cals are set up from the factory. It is a scale that lowers the timing as the boost goes up. On a good cal your timing it maxed out in the performance range across the board. If you lower the boost the timing should be in the "good" range already. If you need to add more timing then your tune isn't right....

With that said. I have two tunes, one for pump gas and one for race gas. You can only run so much timing with pump gas. But when you stick race gas in now you can add more timing. With the race gas allowing the extra timing you can make same power as high boost on pump gas. Example. my SRT ran 7.9@89mph on 22psi and pump gas. With race allowing my timing to be bumped up I ran the same 7.9@89mph but only running 15psi.

That is what makes e85 fuel so great. It is like 105 octane. So you can run lower boost and turn the timing up. You can't do this with normal pump gas. In order to run more timing (on a good tune anyways) you'll need something keep the spark knock away..

[1BADVAN]

Thanks i guess what i am saying is without switching fuels can i keep a lower boost and crank up the timing to get a similar power range

[DodgeZ]

Thanks i guess what i am saying is without switching fuels can i keep a lower boost and crank up the timing to get a similar power range

Sorry I wasn't clear. The answer is no.

[BadAssPerformance]

Sorry I wasn't clear. The answer is no.

+1... Unless he's already on race gas that can take the timing, LOL!

[x.Gen]

that is the way the cals are set up from the factory. It is a scale that lowers the timing as the boost goes up. On a good cal your timing it maxed out in the performance range across the board. If you lower the boost the timing should be in the "good" range already. If you need to add more timing then your tune isn't right....

With that said. I have two tunes, one for pump gas and one for race gas. You can only run so much timing with pump gas. But when you stick race gas in now you can add more timing. With the race gas allowing the extra timing you can make same power as high boost on pump gas. Example. my SRT ran 7.9@89mph on 22psi and pump gas. With race allowing my timing to be bumped up I ran the same 7.9@89mph but only running 15psi.

That is what makes e85 fuel so great. It is like 105 octane. So you can run lower boost and turn the timing up. You can't do this with normal pump gas. In order to run more timing (on a good tune anyways) you'll need something keep the spark knock away..

hmmm...share some more info, Kevin. type of race gas? running straight or blended? roughly how much timing difference could you add?

I've been happy enough with pump gas tune to avoid laying out $9/gal for Cam2, the only local high octane. the law is uptight enough around here that even just my street tune will get me in way more trouble than it's worth, but I'm curious. I'm not much on track time, personally - even if it is only an hour from me.

I'm too lazy/stubborn to upgrade for E85, but I guess if you factor in the real numbers (cost and octane) blending (Cam2) a 1/4 tank at a time is well within reason. just curious how much room you made in the timing curve with the race tune.

[DodgeZ]

93 pump gas and c16 race gas. Note the pump gas timing drops off for safety at 24psi

Pump gas timing


Race gas timing


Note, this is on an SRT 2.4 not a 2.2/2.5

[x.Gen]

awesome, thanks for sharing. figured 3-4 degrees would be reasonable on a generous blend - I'm sure I won't be able to bump as much as you up top, but interesting to see. might have to grab a few gallons on my way to wrench this weekend

[Juggy]

guys are running 35 degrees advanced on E85 tunes locally....
thats with 24 psi boost.

stock SRT with E85 fuel system and bigger IC....12.5 @ 111

[turbovanman²]

Run as much timing as you can without detonation,

Thanks for the graph's Kevin,

[zin]

An engine will make best use of the cylinder pressure (convert it to HP) if peak cylinder pressure is reached at it's "sweet spot", typically between 15-20* ATDC, to achieve this, most N/A engines (wedge combustion chamber) will need 36-38* BTDC as an ignition point.

The trick here is not to add as much timing as you can, but rather to add enough to maintain the "sweet spot"... As you add boost (or nitrous) the burn rate will go up, so less timing lead is needed to maintain the sweet spot(lighting it latter still gives the peak pressure at the same * ATDC), adding too much timing will bring peak cylinder pressure closer and closer to TDC, at which point ALL of your cylinder pressure will be trying to blow the crank out of the bottom of the block, or, if you're really lucky, run the engine backwards!

It's a balancing act like running higher compression on pump gas... You could run 12:1, but with so little timing as to negate any gains the compression gave you and most likely reduce the power you could have had, if you had a lower compression and more/correct ignition advance...

Same thing for boost, if the higher boost results in unstable combustion (say really pushing a T1 Mitsu w/no intercooler), you would make more HP with less boost and proper timing...

Clear as Mud, right?

Mike

[1BADVAN]

An engine will make best use of the cylinder pressure (convert it to HP) if peak cylinder pressure is reached at it's "sweet spot", typically between 15-20* ATDC, to achieve this, most N/A engines (wedge combustion chamber) will need 36-38* BTDC as an ignition point.

The trick here is not to add as much timing as you can, but rather to add enough to maintain the "sweet spot"... As you add boost (or nitrous) the burn rate will go up, so less timing lead is needed to maintain the sweet spot(lighting it latter still gives the peak pressure at the same * ATDC), adding too much timing will bring peak cylinder pressure closer and closer to TDC, at which point ALL of your cylinder pressure will be trying to blow the crank out of the bottom of the block, or, if you're really lucky, run the engine backwards!

It's a balancing act like running higher compression on pump gas... You could run 12:1, but with so little timing as to negate any gains the compression gave you and most likely reduce the power you could have had, if you had a lower compression and more/correct ignition advance...

Same thing for boost, if the higher boost results in unstable combustion (say really pushing a T1 Mitsu w/no intercooler), you would make more HP with less boost and proper timing...

Clear as Mud, right?

Mike

thanks probably the answer i was looking for and the one i most understood

[Speedeuphoria]

simply like others have said, no

think of NA, it what you were implying were true then NA would make near as much HP as boosted apps

agree with not adding as much timing as you can. More like adding enough timing to get in the window