Max boost?
Moderators: Helpinators, Moderators
Max boost?
Ok. I have been dieing to know this for some time now.
How much boost can the stock motor take before it lets go? And when i mean stock i mean you did nothing to the bottem end, nothing to the valve train, you didnt swap the cams and heads. I mean nothing! All you did was a intercooler, injector, turbo swap, ecu. How much could you run with a setup like that before melt down?
Thanks!
PS. I have hurd 20psi but not sure about that. Anyone to back me up??
How much boost can the stock motor take before it lets go? And when i mean stock i mean you did nothing to the bottem end, nothing to the valve train, you didnt swap the cams and heads. I mean nothing! All you did was a intercooler, injector, turbo swap, ecu. How much could you run with a setup like that before melt down?
Thanks!
PS. I have hurd 20psi but not sure about that. Anyone to back me up??
93 Legacy Turbo AT Sliver Stock, Ultra Rotty Body
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
The cummins turbo may take a while to spool up, but when it does WOW!
More to the point, your question is how much boost? I think a more appropriate question would be "how long"..
More to the point, your question is how much boost? I think a more appropriate question would be "how long"..
84 GL Wagon - sold
84 DL Wagon - sold
92 L Wagon - sold
96 LS Wagon
93 SS daily driver
1946 BC-12D Taylorcraft restoration (airplane)
Me - retired engineer and pilot / flight instructor
84 DL Wagon - sold
92 L Wagon - sold
96 LS Wagon
93 SS daily driver
1946 BC-12D Taylorcraft restoration (airplane)
Me - retired engineer and pilot / flight instructor
-
- First Gear
- Posts: 164
- Joined: Mon Sep 24, 2007 6:21 am
- Location: Winnipeg, Manitoba, Canada
with a properly tuned setup its not the boost pressure that will kill the motor, it's hp.
if stock honda motors make upwards of 400hp on stock bottom ends i wouldnt be surprised to see stock 5-600hp subie on a good tune..but what do i know!
if stock honda motors make upwards of 400hp on stock bottom ends i wouldnt be surprised to see stock 5-600hp subie on a good tune..but what do i know!
Summer Fun = 1991 Civic Si Turbo
Winter Fun = 1991 Legacy Sport Sedan
Winter Fun = 1991 Legacy Sport Sedan
Hmmm. So its more about having a good tune than anything else. Makes sense to me! So what are some of your guy running for boost?
93 Legacy Turbo AT Sliver Stock, Ultra Rotty Body
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
-
- Third Gear
- Posts: 851
- Joined: Mon May 12, 2008 4:19 am
Do some searching about a guy named Xypher, he was running around 28psi on a stock block - albeit he bought a brand new block from Subaru to run. He ran 28psi on his daily for a long time. I think he has since upgraded to a EJ257 block nowadays.
The man also knew his stuff and had it set up right.
The man also knew his stuff and had it set up right.
Lee
93' SS, 5mt swapped, 182k, not stock...
96' N/A OBW 5sp, 212k, Couple mods... RIP
99' N/A OBW, 4eat, mostly stock.
93' SS, 5mt swapped, 182k, not stock...
96' N/A OBW 5sp, 212k, Couple mods... RIP
99' N/A OBW, 4eat, mostly stock.
-
- First Gear
- Posts: 240
- Joined: Thu Aug 07, 2008 6:29 am
- Location: St. Louis, MO & Carbondale, IL
- Contact:
Wedge over on RS25 ran a EJ22T shortblock for years at 22lbs before it let go. I'm 90% sure his internals were stock EJ22T. I know the con rods were because thats what went when it finally did pop. Put a rod through the top/side of the engine. From what I understand the EJ22T rods are the weakest part of the internals but they will still take some abuse. I've got '22T rods and crankshaft in my EJ25 hybrid engine and I just started running 11lbs (up from 8lbs).
-'97 Outback - EJ25 block/pistons/HLA heads, EJ22T crank/rods/ECU, EJ20G intake manifold/fuel rails/440cc injectors, VF8 @ 11psi. . . . Fuel cut > me
Ok cool! So i can run a fair bit of boost without killin it.
I just want around 20ish. So nothing like 28! Thats nutty.
Sweet
I just want around 20ish. So nothing like 28! Thats nutty.
Sweet
93 Legacy Turbo AT Sliver Stock, Ultra Rotty Body
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
He had Wiseco pistons & stock rods on that car.impreza_GC8 wrote:Wedge over on RS25 ran a EJ22T shortblock for years at 22lbs before it let go. I'm 90% sure his internals were stock EJ22T. I know the con rods were because thats what went when it finally did pop. Put a rod through the top/side of the engine. From what I understand the EJ22T rods are the weakest part of the internals but they will still take some abuse. I've got '22T rods and crankshaft in my EJ25 hybrid engine and I just started running 11lbs (up from 8lbs).
ej22t rods are the same as any set of 1.8, 2.0, & 2.2 rods - nothing great there
As far as how much boost its all relative as a given boost level from a VF11 is not the same as that boost level from a GT35R since the bigger turbos flow more CFM of air @ a given pressure level...
I suggest you take it easy & increase boost slowly to make sure the rest of your set-up can handle the increased boost levels.
94 Legacy SS
96 Impreza OBS
99 Impreza OBS-T
04 Sienna XLE Limited AWD
96 Impreza OBS
99 Impreza OBS-T
04 Sienna XLE Limited AWD
-
- Fifth Gear
- Posts: 3043
- Joined: Tue Jan 25, 2005 9:14 pm
- Location: Twin Cities, MN
Boost really doesn't matter, as was said before. How much air you are getting into the engine and how much cylinder pressure you are creating is what does matter, aka hp or torque. The turbo is going to be the biggest factor, with the stock heads being next in line.
If you have a much larger turbo and the capability to control it, the heads are going to become a major bottleneck. It took 21psi out of GT2871R for me to make 300whp with stock heads and delta cams. I think Phil's old car ended up making 378 whp or something like that on a stock longblock and a 50 trim. That was with a 3:1 ratio of pump gas to 100 octane, iirc.
If your turbo can support a high enough pressure ratio and you can control your fuel and timing, then go for it.
If you have a much larger turbo and the capability to control it, the heads are going to become a major bottleneck. It took 21psi out of GT2871R for me to make 300whp with stock heads and delta cams. I think Phil's old car ended up making 378 whp or something like that on a stock longblock and a 50 trim. That was with a 3:1 ratio of pump gas to 100 octane, iirc.
If your turbo can support a high enough pressure ratio and you can control your fuel and timing, then go for it.
→Dan
piddster34 at h0tma1l d0t c0m
piddster34 at h0tma1l d0t c0m
So really my max boost question is really about, how well of a setup i create. My parts that i have ready to rock are as followed:
Vf39
04Sti injectors
Cobb/Lsp TBE
Parts that i plan to get:
AWIC. All i do is city drive.
Revtronix ecu management stage 3 or X
Fuel pump of some sort
Thats the major parts to my creation i want. So basically i just want this setup to be as effective a humanly possiable. And i dont think ill need to get the boost over 20psi to make this setup hot!
Vf39
04Sti injectors
Cobb/Lsp TBE
Parts that i plan to get:
AWIC. All i do is city drive.
Revtronix ecu management stage 3 or X
Fuel pump of some sort
Thats the major parts to my creation i want. So basically i just want this setup to be as effective a humanly possiable. And i dont think ill need to get the boost over 20psi to make this setup hot!
93 Legacy Turbo AT Sliver Stock, Ultra Rotty Body
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
-
- Fifth Gear
- Posts: 3043
- Joined: Tue Jan 25, 2005 9:14 pm
- Location: Twin Cities, MN
You probably do not want to push a VF39 over 20psi anyways. I can't find a real compressor map for it as IHI seems to not want to give that data out. I did find this, but it is a joke without any efficiency islands or compressor speed lines. http://www.ihi-turbo.com/turbo_RHE-RHF.htm
I seriously suggest you spend the extra couple hundred bux on a wideband. Not knowing what is going on in your engine is like dancing with the devil.
I seriously suggest you spend the extra couple hundred bux on a wideband. Not knowing what is going on in your engine is like dancing with the devil.
→Dan
piddster34 at h0tma1l d0t c0m
piddster34 at h0tma1l d0t c0m
Wooo wooo. Wideband? What be that? A wideband 02 sensor?
93 Legacy Turbo AT Sliver Stock, Ultra Rotty Body
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD
93 Legacy Turbo MT Silver Rob Tune 550cc Lowered GT28 AWIC 4.11 05 Leg GT rims Mint body
95 Chevy Corvette MT ZR-1 Black X Brace Chipped
94 Legacy Turbo AT Blue Stock SOLD
06 Pontiac G6 AT Green Stock SOLD