What's a safer combo: low boost more timing, more boost less timing?

[ANGREY]

I'll frame the question with some parameters so it doesn't turn into a "what's better money or love" type debate.

1) Assume you were building a high compression (12:1) modern motor with VCT, and a full build capable of handling way more power theoretically than you were wanting to run.

2) Assume plenty of fuel and injector capability to set the A/F as safe or moderate and hold it there under any conditions and you're running E-85 as fuel.

Let's say you built the motor and all the component parts to handle 1500 hp (huge intake and TB, more than capable fuel system, long tubes, upgraded valve train, rock solid drive train, etc), but you really over-engineered it so that it could safely run 1000 hp with plenty of spare safety.

Would it be "safer" or less risky to run large amounts of boost and conservative/safe timing (keep in mind it's 12:1 compression, but also E-85)

OR would it be preferable to keep the boost moderate and advance the timing further out?

Basically, if you have room to spare and desire a lesser hp/tq level than the motor is capable of handling (and high compression and E-85) is it better to run 18 psi and very safe timing or run 15 psi and bigger timing?

Does it make more sense to run a smaller pulley with less timing or a larger pulley with typical 20-22 degrees of max timing?

 

[01yellercobra]

There are quite a few ways to answer this for both sides of the arguement. Especially if you start getting into blower efficiency range.

My opinion is it's better to run a little less boost and make up with the timing. The reason being in most setups timing can be controlled easier. Either through air temp or knock sensing. I know nowadays boost can be electronically controlled, but there's still some mechanical stuff that has to happen before boost is dumped. Timing changes happen pretty quick with a computer.

Plus if you're not spinning the blower as hard it makes less heat in the first place.

 

[ANGREY]

There are quite a few ways to answer this for both sides of the arguement. Especially if you start getting into blower efficiency range.

My opinion is it's better to run a little less boost and make up with the timing. The reason being in most setups timing can be controlled easier. Either through air temp or knock sensing. I know nowadays boost can be electronically controlled, but there's still some mechanical stuff that has to happen before boost is dumped. Timing changes happen pretty quick with a computer.

Plus if you're not spinning the blower as hard it makes less heat in the first place.

Interesting, or let me frame it another way:

Car one runs 18 psi but only 19 degrees of timing to reach 1000 hp, and has higher IAT2s

Car two runs 15 psi but 22 or 23 degrees of timing to reach 1000 hp, has lower IAT2s but is on the edge of what the knock sensors will allow.

Which car is "safer" in terms of abnormally hot conditions or less than optimal fuel?

I guess I'm leaning toward your answer because the ECU can pull timing back in the second example but there's no changing the boost production in either example.

It's just an interesting question for shorting the setup. Or to demonstrate more extreme,

Would you rather run naturally aspirated but at MAX timing to make 500 rwhp OR
Run the same motor with 4 or 5 psi and dial the timing back?

I guess it really depends on the efficiency of the intercooler, which is probably sized to start presenting heat issues once it gets past it's optimal heat exchange range.

 

[biminiLX]

We are currently having this same debate with both my car and a friends WHipple Coyote.
The right answer is which combo makes the car faster.
I’m leaning towards less boost and more timing but it’s easier to control timing, so running medium to high boost and ramping in the timing has been working for us.
I personally think that I think the seat of pants is better with less boost and more timing but I’m planning to make the decision on which is faster on track. TBD.
-J

 

[01yellercobra]

Interesting, or let me frame it another way:

Car one runs 18 psi but only 19 degrees of timing to reach 1000 hp, and has higher IAT2s

Car two runs 15 psi but 22 or 23 degrees of timing to reach 1000 hp, has lower IAT2s but is on the edge of what the knock sensors will allow.

Which car is "safer" in terms of abnormally hot conditions or less than optimal fuel?

I guess I'm leaning toward your answer because the ECU can pull timing back in the second example but there's no changing the boost production in either example.

It's just an interesting question for shorting the setup. Or to demonstrate more extreme,

Would you rather run naturally aspirated but at MAX timing to make 500 rwhp OR
Run the same motor with 4 or 5 psi and dial the timing back?

I guess it really depends on the efficiency of the intercooler, which is probably sized to start presenting heat issues once it gets past it's optimal heat exchange range.

I would run the second combo myself. Someone on here made over 700hp with a standard inlet Whipple 2.9 at 18psi. I'm running that same blower/boost on 91 and am making 620hp. Once I'm ready for E85 more than likely I'll leave the boost and ramp the timing up.

For the N/A vs boost the simple answer for me is boost. I know it's a broad question, but having dealt with N/A 4.6's I'll go boost everytime. Don't need to go as extreme with the parts to make the same power as you can with boost.

 

[ANGREY]

We are currently having this same debate with both my car and a friends WHipple Coyote.
The right answer is which combo makes the car faster.
I’m leaning towards less boost and more timing but it’s easier to control timing, so running medium to high boost and ramping in the timing has been working for us.
I personally think that I think the seat of pants is better with less boost and more timing but I’m planning to make the decision on which is faster on track. TBD.
-J

I'm just trying to figure out how to sandbag the motor and make it safer. I could run a bigger pulley and tune it properly/optimally and reach 1000 rwhp or I could run a smaller pulley and dial back timing and fatten it up and make 1000 rwhp. I'm just wondering which is "safer" or more resistant to outlier conditions (bit of bad E, hot intake temps or a string of rips where it's very heat soaked).

In either case, it'll be stupid power that the chassis can't handle and more for a fun street setup. It'll be on roller skates either way. If I get to where that's no fun, I'll pulley way up and dial it back to something that can actually grip somewhat