Sponsored

Procharger pulley reduction and 91 octane

smokinzx14r

Well-Known Member
Joined
Mar 2, 2015
Threads
64
Messages
1,591
Reaction score
355
Location
ST Petersburg FL
First Name
Lee
Vehicle(s)
2015 GT A6 3.55 Gears ..
On my ho kit I went to a 3.50 from the stock 3.70 and made a big change in power ..I now have changed to a 3.40 from the 3.50 and made zero difference in my ETs and MPH at the track ..So a pulley change of that small size ( 3.50 to 3.40 ) was a total waste of time ..So really for you to feel a change in power you would need to go from a 4.75 to a 4.50 .. What most people don't get is when you pulley down your boost comes on earlier and that is great fun and helpful for drag racing ..
Sponsored

 
OP
OP

Bartly

Well-Known Member
Joined
Oct 25, 2015
Threads
94
Messages
1,528
Reaction score
220
Location
Out West
Vehicle(s)
2016 Mustang GT
If you're at the limit of 91, dropping a pulley and increasing boost will just result in less timing. So your kind of at a wash between the two.

If your 91 quality is decent dropping a pulley and maintaining the same timing will increase power. But you wont know till you try it and log it and/or get the tune adjusted if necessary.

If your flatlining around 6500-7k a manifold change will bring up your peak hp more, as others said.

As far as I know once you change pullies you void the Procharger warranty. I had mine done by a shop just in case even though I do all the rest of my work myself.

If you're looking for more midrange power pulley down and wastegate it.
Yeah, I half think I’m at my limit with the 91 I have here. Being that it took forever trying different tune revisions to get rid of the positive knock. Only thing that worked was using Torco, and that just a bit of a pain and also just don’t like the idea of running that stuff. Finally have a on SCT tune with no more positive knock. Wastegate and smaller pulley, I like that idea, but have basically no knowledge of that, but two years ago I didn’t know a thing about superchargers either, lol. Basically a pressure relief valve with a spring to set the top pressure level? I saw your build thread, not sure how I’d want to mount one. Thanks for the idea.

Take a look at the logs first see what the knock sensors are doing. You could also run torco
Knock sensors are happy. Rarely positive. Nah, I used the Torco for a while would like to avoid that just because it’s the opposite of convenient.
 
OP
OP

Bartly

Well-Known Member
Joined
Oct 25, 2015
Threads
94
Messages
1,528
Reaction score
220
Location
Out West
Vehicle(s)
2016 Mustang GT
On my ho kit I went to a 3.50 from the stock 3.70 and made a big change in power ..I now have changed to a 3.40 from the 3.50 and made zero difference in my ETs and MPH at the track ..So a pulley change of that small size ( 3.50 to 3.40 ) was a total waste of time ..So really for you to feel a change in power you would need to go from a 4.75 to a 4.50 .. What most people don't get is when you pulley down your boost comes on earlier and that is great fun and helpful for drag racing ..
Thanks for the input, coincidentally someone offered to sell me a 4.5”. Hmmm. Earlier boost would definately be nice. Thanks for commenting on that, maybe mix it up with a wastegate like mentioned up above. Wonder if I could drop two sizes to a 4.5” pulley and mount a wastegate set for 9psi. Which would put me right about at the same boost, just get to it sooner and feel it come on sooner. Man lots to think about.
 

ahl395

Well-Known Member
Joined
Dec 30, 2015
Threads
42
Messages
2,806
Reaction score
1,210
Location
NJ
First Name
Allan
Vehicle(s)
2017 Mustang GT, 2006 Infiniti G35X
Yeah, I half think I’m at my limit with the 91 I have here. Being that it took forever trying different tune revisions to get rid of the positive knock. Only thing that worked was using Torco, and that just a bit of a pain and also just don’t like the idea of running that stuff. Finally have a on SCT tune with no more positive knock. Wastegate and smaller pulley, I like that idea, but have basically no knowledge of that, but two years ago I didn’t know a thing about superchargers either, lol. Basically a pressure relief valve with a spring to set the top pressure level? I saw your build thread, not sure how I’d want to mount one. Thanks for the idea.



Knock sensors are happy. Rarely positive. Nah, I used the Torco for a while would like to avoid that just because it’s the opposite of convenient.
Most likely if you're at your timing limit you really won't gain much by adding more boost. You'll just be trading timing for boost. At a certain point too little timing can cause unwanted issues.

The SCT tune probably had less timing commanded. Do you have a log?

Wastegating: pulleying down for say 14psi, but using the wastegate to bleed off everything over your set point (say 10psi). Doing this brings boost on faster since the boost curve climbs quicker on a pulley for more overall boost. It does not gain you any more peak power, but it significantly improves your midrange. Only downsides are depending on how aggressively you pulley down your IATs will rise some.

Only bleeding off a few psi is recommended so that too much strain isnt put on the blower. Not a good idea to pulley for 20 and run 10 psi lol. On the other side of it if you pulley too close to your desired boost you probably won't feel much of an improvment. Wastegating made a huge difference in my car on the street. Best thing I ever did aside from the blower itself. Feels like there is instant boost at all times rather than waiting for the climb to start at 3500rpm. Some people run their wastegate and bov both on the hot pipe off the blower if you were looking for a more compact setup.
 
OP
OP

Bartly

Well-Known Member
Joined
Oct 25, 2015
Threads
94
Messages
1,528
Reaction score
220
Location
Out West
Vehicle(s)
2016 Mustang GT
Most likely if you're at your timing limit you really won't gain much by adding more boost. You'll just be trading timing for boost. At a certain point too little timing can cause unwanted issues.

The SCT tune probably had less timing commanded. Do you have a log?

Wastegating: pulleying down for say 14psi, but using the wastegate to bleed off everything over your set point (say 10psi). Doing this brings boost on faster since the boost curve climbs quicker on a pulley for more overall boost. It does not gain you any more peak power, but it significantly improves your midrange. Only downsides are depending on how aggressively you pulley down your IATs will rise some.

Only bleeding off a few psi is recommended so that too much strain isnt put on the blower. Not a good idea to pulley for 20 and run 10 psi lol. On the other side of it if you pulley too close to your desired boost you probably won't feel much of an improvment. Wastegating made a huge difference in my car on the street. Best thing I ever did aside from the blower itself. Feels like there is instant boost at all times rather than waiting for the climb to start at 3500rpm. Some people run their wastegate and bov both on the hot pipe off the blower if you were looking for a more compact setup.

Thanks for the info. Here is a little screenshot of Knock vs. Timing Advance from my car HP Tuners vs. SCT. The upper plots are the SCT, I didn't go as high in the RPMs on that log, but it still shows my Knock mostly at zero and only dipping into the negative. The bottom plot shows the Knock at 4+ the whole time I'm in WOT. Timing advance is pretty close, at least close enough to see there is big differences in the KR values. With the SCT tune I seem to only see positive knock when I step on the pedal to hard and jerk the car or once in a while during some throttle situations I haven't chased down.
HP vs SCT WOT log.jpg
 

ProChargerTECH

Well-Known Member
Gold Sponsor
Joined
Oct 23, 2014
Threads
105
Messages
2,408
Reaction score
1,295
Location
Boostville
Vehicle(s)
2015 Mustang(s)
Thanks for the info. Here is a little screenshot of Knock vs. Timing Advance from my car HP Tuners vs. SCT. The upper plots are the SCT, I didn't go as high in the RPMs on that log, but it still shows my Knock mostly at zero and only dipping into the negative. The bottom plot shows the Knock at 4+ the whole time I'm in WOT. Timing advance is pretty close, at least close enough to see there is big differences in the KR values. With the SCT tune I seem to only see positive knock when I step on the pedal to hard and jerk the car or once in a while during some throttle situations I haven't chased down.
If both the HP and SCT are running about the same timing (16/17 degrees)
Then really the difference can be in other areas of the tune, such as cam timing for example.

I just had a car 3 days ago on E85 only want to run 17 degrees, with literally 5 degrees of knock. (which it ran 17.5 on strait 93 pump)

The car was hitting a TQ limit while on the E85, and using the KR to pull the power back. (basically keeping it the same as the pump gas file)

Removed the limit, next pull 21.5 degrees (still very safe) and an extra 102 rwhp :)
Sponsored

 
 




Top