Dual 90mm DBW on e38 tuning
12-17-2019, 10:03 AM
#1
Teching In
Thread Starter
Dual 90mm DBW on e38 tuning Hello all, I am in the process of getting my blower onto the 6.0l using the e38 PCM. I will be running dual 90mm LS3, using the TorqueRush X2 controller. It will essentially a mirror box...matches the other based on commanded position. This is a 2 bar SD OS, with a 2bar MAP sensor, 850cc injectors, e85, air-to-water intercooler.
To this point, it has been without the blower installed, just NA for break in and keeping some use while working out the rest of the details on the blower. I have it running now through about 3k rpm, but never touched PE or large throttle positions...just intended to make it safe to get to the tuner when the time comes.
My question relates to tuning for the extra throttle body and area, especially at idle. ETC scaller is set now in the 5600-ish range (stock), with a max available of 8100-ish. So I cant just double it. I am thinking it best to max it out, then using the pedel vs thottle position table to allow for more fidelity at light throttles and cruise.
Anything else i should be concerned with...just trying to get it to the tuner locally so they can work it out properly. Course VE table will need to be adjusted.
To this point, it has been without the blower installed, just NA for break in and keeping some use while working out the rest of the details on the blower. I have it running now through about 3k rpm, but never touched PE or large throttle positions...just intended to make it safe to get to the tuner when the time comes.
My question relates to tuning for the extra throttle body and area, especially at idle. ETC scaller is set now in the 5600-ish range (stock), with a max available of 8100-ish. So I cant just double it. I am thinking it best to max it out, then using the pedel vs thottle position table to allow for more fidelity at light throttles and cruise.
Anything else i should be concerned with...just trying to get it to the tuner locally so they can work it out properly. Course VE table will need to be adjusted.
12-19-2019, 03:16 AM
#2
Since the only possible reason for dual 90mm TB's would be looks or extra airflow while maintaining single TB idle characteristics, it would be useless to mirror the throttle bodies. You should use one for idle, and bring in the other as airflow increases. It would not even require electronics. With an SD tune, it would require no extra tuning to do something as simple with the second TB as a vacuum secondary carb setup for opening it. This would leave you idle tuning a single 90mm, with the looks and extra airflow potential of 2 of them.
12-19-2019, 07:22 AM
#3
Teching In
Thread Starter
gametech,
Very valid point and something I had not thought about prior to your comment. Thank you. Looking deeper into the X2 software, it looks like it will allow exactly what you describe...different ramp rates and opening positions based on commanded throttle position for each throttle. This would achieve the same as a mechanical secondary on a 4150 carb, and hopefully the same end effect as a MAP/vacuum based secondary.
I had originally pursued the idea of a DBW throttle, with an extended d-shaft to place a cable lever arm on and attach it to a second mechanical throttle, but that proved to be too much for the DBW internal motor. So decided to go this route using electronics. I hadnt thought about using a vacuum actuator for the second throttle. How would you go about doing such?
and yes, the only reasons for this is airflow and additionally the location of the extra air...these 6-71 blowers arnt well known for their even distribution.
Very valid point and something I had not thought about prior to your comment. Thank you. Looking deeper into the X2 software, it looks like it will allow exactly what you describe...different ramp rates and opening positions based on commanded throttle position for each throttle. This would achieve the same as a mechanical secondary on a 4150 carb, and hopefully the same end effect as a MAP/vacuum based secondary.
I had originally pursued the idea of a DBW throttle, with an extended d-shaft to place a cable lever arm on and attach it to a second mechanical throttle, but that proved to be too much for the DBW internal motor. So decided to go this route using electronics. I hadnt thought about using a vacuum actuator for the second throttle. How would you go about doing such?
and yes, the only reasons for this is airflow and additionally the location of the extra air...these 6-71 blowers arnt well known for their even distribution.
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NSFW (12-19-2019)
12-20-2019, 12:45 AM
#4
If your software allows different ramp rates and opening positions for each TB, then disregard my vacuum idea, as it would be a needless mechanical complication. I am unfamiliar with the controller you are using, and I thought from your first post that it did not have that capability.
12-20-2019, 06:53 AM
#5
Teching In
Thread Starter
copy, i wasnt aware of this capability until contacting them either. Here is the link for reference as well. http://www.torquerush.com/x2.html