Boost for Mountain car?

[BAYoung]

There's over 10,000 feet of elevation difference in Wyoming alone. So you're still going to have sizeable variability in the motor output just tooling around your local region. That means you'll be forced to either leave money on the table and set it up for max boost at lower elevation (and suffer when you go higher) OR you'll set it up for max boost at highest point (with a small pulley) and then run more detonation and preignition risk if you go lower. We haven't even begun to talk about the DA changes from temperature.

Hey it's your car. Knock it out. I have a PD blower setup. If I was going to live in the mountains I'd definitely want either a turbo setup or a centri setup with a valve to keep things as constant as possible.

I like the down low torque of PD superchargers too much. And the sound.

Sponsored

 

[Angrey]

On the gen 3 coyote, if the tune is set up a certain way, a PD can make more or less the same boost no matter the elevation (within reason).

There are load (air mass) limiters which simply limit the throttle opening if the air mass is too high. So you can put a pulley on that’ll make 10-11psi at 8000 feet, then set a load limit at whatever air load value that is. Then when you drive back down closer to sea level it’ll just limit max throttle blade opening to maintain the max air load limit.

@engineermike has written about this (and other aspects) but it seems none of the "usual" tuners are either capable or willing to limit based upon air load and throttle opening. Which is why they demand certain pulley sizing base upon fuel.

MOST (if not all) of the typical tuning shops are not going to want you to run smaller than a certain size pulley on pump 93. (even though as you point out, it shouldn't matter, they can limit the output based upon air load).

If I were on E85 and using a PD blower, I'd be much more apt to just allow it to flex based upon DA. But as I said earlier, assuming the tune is typical (not managed by air load, but actually maximized to the pulley/charge output of the blower and rpm limit) and you experience huge swings in DA, then you have huge swings in torque/power production.

That leaves two choices. Tune it short anticipating better DA conditions down the road (leaving power off the table). OR, tune it optimized and then hope and pray you don't smoke the motor when the DA is 3K feet better on today's run than when it was tuned. Neither of those is preferable to just setting up a mechanically controlled overboost setup with a control valve or a wastegate.

Or, if you know a tuner who's using the OE PCM that's willing to tune based upon air load and throttle blade angle (by gear) then point them out.

If that were the case, tuners wouldn't care what pulley you run, because they'd just work it out in the tune. As it is, tuners ABSOLUTELY care about what pulley you have on the blower, especially if you're on pump gas.

 

[Angrey]

I like the down low torque of PD superchargers too much. And the sound.

If you were going E85, I'd say no worries.

E85 is a much better fuel and much more accommodating to wide swings in ambient conditions. Combined with the adjustment of the tune and wideband, you can tune it pretty healthy and still be okay if the DA improves the incoming air by 10 or 20%.

On pump 93, because it's not making as much steam to start, most guys are going to want to set it at optimally what the car can make.

And as I already pointed out, that leaves two real options. Tune it for bad DA at altitude and Summer temps and set the pulley up to make appropriate boost, then hope and pray when you go lower and/or the temp drops significantly that you don't smoke the motor or overwhelm what little adjustment is available. OR, you neuter the tune and make it accommodating to a wider range of conditions. That's exactly what the OEM's (who have to warrant your motor) do. That's why the OE tunes are always more conservative. They know the vehicle will live longer if the tune is safe and conservative and can adjust when it gets more/better air, or perhaps the fuel isn't so great or both.

With the overboost solution, you get the best of both worlds. You set the car to run a certain boost level and that's it. When it's high up and temps are hot, it's close to it's max output. When it's low and temps are down, it's bleeding off a bunch of boost. Samey same output all the time.

 

[BAYoung]

If you were going E85, I'd say no worries.

E85 is a much better fuel and much more accommodating to wide swings in ambient conditions. Combined with the adjustment of the tune and wideband, you can tune it pretty healthy and still be okay if the DA improves the incoming air by 10 or 20%.

On pump 93, because it's not making as much steam to start, most guys are going to want to set it at optimally what the car can make.

And as I already pointed out, that leaves two real options. Tune it for bad DA at altitude and Summer temps and set the pulley up to make appropriate boost, then hope and pray when you go lower and/or the temp drops significantly that you don't smoke the motor or overwhelm what little adjustment is available. OR, you neuter the tune and make it accommodating to a wider range of conditions. That's exactly what the OEM's (who have to warrant your motor) do. That's why the OE tunes are always more conservative. They know the vehicle will live longer if the tune is safe and conservative and can adjust when it gets more/better air, or perhaps the fuel isn't so great or both.

With the overboost solution, you get the best of both worlds. You set the car to run a certain boost level and that's it. When it's high up and temps are hot, it's close to it's max output. When it's low and temps are down, it's bleeding off a bunch of boost. Samey same output all the time.

Plan is to run sunoco e85-R. It's a summer car anyway, and i make enough to justify the cost.

 

[HKusp]

Then where should i look for a fuel system? Thanks for letting me know!

https://arcanep2.com/fuel-systems
Start there. They have a really nice fuel pump set-up with a fuel bucket that has one way valves to keep the pumps immersed in fuel. The system re-uses the stock fuel level sender as well.

 

[SheepDog]

https://arcanep2.com/fuel-systems
Start there. They have a really nice fuel pump set-up with a fuel bucket that has one way valves to keep the pumps immersed in fuel. The system re-uses the stock fuel level sender as well.

Im considering switching out my Division X pump hanger for this Radium Unit. Return Style

 

[BAYoung]

https://arcanep2.com/fuel-systems
Start there. They have a really nice fuel pump set-up with a fuel bucket that has one way valves to keep the pumps immersed in fuel. The system re-uses the stock fuel level sender as well.

Thank you! Will do

 

[engineermike]

FYI, setting up a load limit is super easy. You could basically pulley the car to make the target absolute pressure (e.g. 25 psia) at elevation and then set a load limit just above that so it will cut throttle at lower elevations. Something like the below would function like that, with an added low rpm boost limit and a soft rev limiter at 7500 rpm:

This takes about 45 seconds to add to a tune....

 

[engineermike]

What will really tick you off is learning that the Gen3 PCM actually has the ability to float the load (~boost) limit up and down with learned ethanol (and octane, lambda, et. al.) if you have flex logic turned on and calibrated. How cool is it that you can pulley for 20 psi when it learns you're on E85 but limit it to 12 psi on gasoline? The ecoboost actually uses this same logic to float boost up and down with learned octane.

The LSPI limits are load limits as a function of the Blending modifier and charge temp.

 

[illtal]

What will really tick you off is learning that the Gen3 PCM actually has the ability to float the load (~boost) limit up and down with learned ethanol (and octane, lambda, et. al.) if you have flex logic turned on and calibrated. How cool is it that you can pulley for 20 psi when it learns you're on E85 but limit it to 12 psi on gasoline? The ecoboost actually uses this same logic to float boost up and down with learned octane.

The LSPI limits are load limits as a function of the Blending modifier and charge temp.

So is this like similar to hitting a brake torque limit based on airflow? If it is like this the Ford PCM is nearly as powerful as a standalone.

 

[engineermike]

So is this like similar to hitting a brake torque limit based on airflow? If it is like this the Ford PCM is nearly as powerful as a standalone.

In the stock pcm you can set torque limits, load limits, rpm limits, timing limits, AFR limits, cam timing limits, knock retard or advance limits, lambda limits, etc…. And you can set most of them as a function of other things like rpm, charge temp, lambda, gear, etc.

 

[HKusp]

So is this like similar to hitting a brake torque limit based on airflow? If it is like this the Ford PCM is nearly as powerful as a standalone.

The Coyote PCM is by far the most complex of the big three. The GM and Mopar versions are not nearly as "capable" as the Ford.

Sponsored