BOOST numbers with fixed pulleys
#1
Member
Thread Starter
BOOST numbers with fixed pulleys
Who has numbers based on pulley size?
I have a fixed 74 now getting 16/17 psi
I have the new VRP 70mm and wanted to know what boost it makes
THanks
also reading based on obd2 port blue scan
I have a fixed 74 now getting 16/17 psi
I have the new VRP 70mm and wanted to know what boost it makes
THanks
also reading based on obd2 port blue scan
#4
Member
Thread Starter
mods include:
Rebuilt SC
Rebuilt Motor
Rebuilt Trans
3.5" Intake
Midlength headers
74mm fixed pulley
tune from race IQ
DRLs
Euroteck diffuser carbon
Carbon Side splitters
E63 Bumper Carbon Spoiler
carbon mirror covers
Custom headlights HID Kit
Secondary HE Superflo pump
Trunk tank and install kitV3 HECustom
3" Exhaust
550 cc injectors
adapter harnesses
Looped rail
One step Colder Plugs
Intake Scoops
3 piece pulley set
Belt Wrap Kit and green belt
82mm TB with ported snout
TCU
Powdercoated Surge tanks
Wrap in cooper
Carbon interior
Caron steering wheel
Freenavi with data logger
Stop Tech Rotors, Pads,lines
Goodyear Eagle® F1 Asymmetric 3
#6
with headers 74 and stock 154 crank you should be around 14.5-15 psi, stock 154 crank and 70mm with headers will put you around 15.5-16psi so about a 1 psi increase
Last edited by failboat; 11-15-2018 at 10:53 AM.
#7
Member
That chart is just an estimate and not accurate. Elevation, DA, certain mods like headers, ported heads and throttle bodies change this. I had a 74 in the past and only saw 8-9psi peak boost. My buddy that lives near atco was seeing 16-17psi with just a 77 with long tubes and a 82 tb. This is why you need to datalog and not guess.
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#8
Member
no I dont. I have the raceIQ tune for it and it runs 10.5 AFR now... I assume that is a tunning issue they can fix when i go to the smaller pulley?
mods include:
Rebuilt SC
Rebuilt Motor
Rebuilt Trans
3.5" Intake
Midlength headers
74mm fixed pulley
tune from race IQ
DRLs
Euroteck diffuser carbon
Carbon Side splitters
E63 Bumper Carbon Spoiler
carbon mirror covers
Custom headlights HID Kit
Secondary HE Superflo pump
Trunk tank and install kitV3 HECustom
3" Exhaust
550 cc injectors
adapter harnesses
Looped rail
One step Colder Plugs
Intake Scoops
3 piece pulley set
Belt Wrap Kit and green belt
82mm TB with ported snout
TCU
Powdercoated Surge tanks
Wrap in cooper
Carbon interior
Caron steering wheel
Freenavi with data logger
Stop Tech Rotors, Pads,lines
mods include:
Rebuilt SC
Rebuilt Motor
Rebuilt Trans
3.5" Intake
Midlength headers
74mm fixed pulley
tune from race IQ
DRLs
Euroteck diffuser carbon
Carbon Side splitters
E63 Bumper Carbon Spoiler
carbon mirror covers
Custom headlights HID Kit
Secondary HE Superflo pump
Trunk tank and install kitV3 HECustom
3" Exhaust
550 cc injectors
adapter harnesses
Looped rail
One step Colder Plugs
Intake Scoops
3 piece pulley set
Belt Wrap Kit and green belt
82mm TB with ported snout
TCU
Powdercoated Surge tanks
Wrap in cooper
Carbon interior
Caron steering wheel
Freenavi with data logger
Stop Tech Rotors, Pads,lines
Goodyear Eagle® F1 Asymmetric 3
#9
That chart is just an estimate and not accurate. Elevation, DA, certain mods like headers, ported heads and throttle bodies change this. I had a 74 in the past and only saw 8-9psi peak boost. My buddy that lives near atco was seeing 16-17psi with just a 77 with long tubes and a 82 tb. This is why you need to datalog and not guess.
#10
That chart is just an estimate and not accurate. Elevation, DA, certain mods like headers, ported heads and throttle bodies change this. I had a 74 in the past and only saw 8-9psi peak boost. My buddy that lives near atco was seeing 16-17psi with just a 77 with long tubes and a 82 tb. This is why you need to datalog and not guess.
#11
Member
x2. If you are seeing 16-17 PSI right now with the 74mm through torque, that means your ECU is seeing it. Car goes limp mode if the MAP sensor sees right around 17.5PSI so you are already very close (all it takes is one blip split second single read of too much pressure). If you go to 70mm you will limp mode the car on WOT pulls. Unless you either get a MAP clamp or get some legit long tube headers and get a couple of PSI decrease from the mids to the LTH (I dont know how much more flow you will achieve from mids to LTHs, so still a little bit of a gamble if it doesn't drop pressure enough.)
#12
Member
Here's a video that explains it more in detail:
#14
He didn't say 18, he said 16-17 peak. In torque that little red mark (that is sitting right on 16psi in his pic) indicates the peak value seen during that session (and the indicator can be manually reset if you want to).
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newe55guy (11-24-2018)
#16
Super Member
I have a 77 SC and stock crank, gutted exhaust to muffler with the kleemann mids...I see like 13.7 actual boost, the torque app sees a spike sometimes a touch over 14 but I don't really count that I just assume its for a brief second at like gearshift or some ****.. How do you get so much more boost than me? I'm at sea level too! Pretty sure I don't have airleaks, havent smoke tested but exhausted a can of brake cleaner checking for intake leaks..
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newe55guy (11-24-2018)
#18
Member
Thread Starter
The following users liked this post:
newe55guy (11-24-2018)
#20
Junior Member
My E55 is seeing 19psi and no limp mode at all. I'm stacked 83/180 and LTH.
x2. If you are seeing 16-17 PSI right now with the 74mm through torque, that means your ECU is seeing it. Car goes limp mode if the MAP sensor sees right around 17.5PSI so you are already very close (all it takes is one blip split second single read of too much pressure). If you go to 70mm you will limp mode the car on WOT pulls. Unless you either get a MAP clamp or get some legit long tube headers and get a couple of PSI decrease from the mids to the LTH (I dont know how much more flow you will achieve from mids to LTHs, so still a little bit of a gamble if it doesn't drop pressure enough.)
#21
Junior Member
I consistently saw 17psi when I first started racing my E55 and zero limp mode ever. I'm now 83/180 stacked and seeing 19psi in the heat. I expect 20 or more when it cools down.
#22
Junior Member
#23
#24
Senior Member
How do you get that read out into the car's dash screen? I have for 4 years now, run a Race IQ tune on a 74mm fixed pulley with EC stage 2 parts, no cats. I love the jumpy throttle response you don't get with the clutched pulley. I have read the the efficiency of the blower starts reducing rapidly if you spin it faster than a 74mm pulley does.
#25
How do you get that read out into the car's dash screen? I have for 4 years now, run a Race IQ tune on a 74mm fixed pulley with EC stage 2 parts, no cats. I love the jumpy throttle response you don't get with the clutched pulley. I have read the the efficiency of the blower starts reducing rapidly if you spin it faster than a 74mm pulley does.
This is my set up: