Notices
Forced Induction Superchargers | Turbochargers | Intercoolers

Free "boost cut"

 
Old 05-20-2019, 04:15 PM
  #1  
TECH Fanatic
Thread Starter
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,640
Likes: 0
Received 1 Like on 1 Post
Default Free "boost cut"

Well its free if you have Hp tuners or efi live. I know some maybe of you are going to say its not a good idea to do this, but bear with me. Its does work, to and extent...so far...

I had posted a while back about adding a bunch of fuel past the boost that i'm safe with. Got mixed opinions. So I picked 12psi to be my max. I went right past that in my boost enrich table and added a bunch of fuel. And I've hit it a few times. Its feels like the engine loses a bunch of power for a second and I let off, quickly glancing at my wideband, seeing it was flashing 9.xx meaning its pig rich, and it hit like 15 psi. Why tho? Well my china wastegate failed on me and locked shut. Nice. That could have ended real bad. So theres reason 1 for me. Ive since replaced it with a Tial wastegate.
Second reason. I recently upgraded my down pipe to a much better flowing setup. Now I get even more boost by 1-1.5psi at peak. Well I hit it then too. I felt it and let off, saw 13.5psi. Ive passed my max boost a couple times while dialing in my boost controller, so I feel like its saved me. I guess if The boost were to go really really high and the fuel didnt drown it but actually matched the boost, well i'd notice a huge power increase and let off. I never try to be a hero....any little thing out the norm, I let off. What say you?
Kfxguy is offline  
Old 05-20-2019, 05:12 PM
  #2  
TECH Veteran
iTrader: (22)
 
truckdoug's Avatar
 
Join Date: Nov 2013
Location: Portlandia
Posts: 4,864
Received 1 Like on 1 Post
Default

you can pull timing too via a NC hobbs switch put in line with the ground side of the IAT

above a certain psi, the opens and the IAT reads -38* F

go into that cell in the IAT timing table and pull whatever timing you want

I found that was a little safer than dumping unburnt fuel on a hot turbine wheel (although doesn't make as many cools sounds)
truckdoug is offline  
Old 05-20-2019, 05:36 PM
  #3  
TECH Fanatic
Thread Starter
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,640
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by truckdoug View Post
you can pull timing too via a NC hobbs switch put in line with the ground side of the IAT

above a certain psi, the opens and the IAT reads -38* F

go into that cell in the IAT timing table and pull whatever timing you want

I found that was a little safer than dumping unburnt fuel on a hot turbine wheel (although doesn't make as many cools sounds)
Not a bad idea!
Kfxguy is offline  
Old 05-20-2019, 07:43 PM
  #4  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,803
Received 26 Likes on 25 Posts
Default

Yep, don't just add fuel. Pull timing, it's actually safer.
ddnspider is offline  
Old 05-21-2019, 02:13 AM
  #5  
TECH Junkie
iTrader: (1)
 
Join Date: Sep 2004
Location: Stockbridge GA
Posts: 3,099
Likes: 0
Received 0 Likes on 0 Posts
Default

If you are not using meth injection, cutting fuel is a better option. Everybody worries about going lean, but beyond a certain point you no longer have enough fuel to do any damage, no matter what your timing is set to. You really do need to have an extremely hard transition for this to work, though. Otherwise you could go lean with enough fuel to damage something.
gametech is offline  
Old 05-21-2019, 05:55 AM
  #6  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,803
Received 26 Likes on 25 Posts
Default

Originally Posted by gametech View Post
If you are not using meth injection, cutting fuel is a better option. Everybody worries about going lean, but beyond a certain point you no longer have enough fuel to do any damage, no matter what your timing is set to. You really do need to have an extremely hard transition for this to work, though. Otherwise you could go lean with enough fuel to damage something.
Or you just pulling timing and there's no chance of detonation regardless of how much or little fuel or oil is in the chamber.
ddnspider is offline  
Old 05-21-2019, 10:22 AM
  #7  
TECH Fanatic
Thread Starter
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,640
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by gametech View Post
if you are not using meth injection, cutting fuel is a better option. Everybody worries about going lean, but beyond a certain point you no longer have enough fuel to do any damage, no matter what your timing is set to. You really do need to have an extremely hard transition for this to work, though. Otherwise you could go lean with enough fuel to damage something.
this is scary. I could set my 210 kpa line to all zero's, but my ***** aint big enough to do that. lol
Kfxguy is offline  
Old 05-22-2019, 02:45 AM
  #8  
TECH Junkie
iTrader: (1)
 
Join Date: Sep 2004
Location: Stockbridge GA
Posts: 3,099
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by ddnspider View Post
Or you just pulling timing and there's no chance of detonation regardless of how much or little fuel or oil is in the chamber.
With enough overboost your timing has no effect on whether or not you have detonation. A good fuel air mix can easily diesel your motor into pieces with no spark at all if the effective compression ratio is too high.
gametech is offline  
Old 05-22-2019, 06:04 AM
  #9  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,803
Received 26 Likes on 25 Posts
Default

Originally Posted by gametech View Post
With enough overboost your timing has no effect on whether or not you have detonation. A good fuel air mix can easily diesel your motor into pieces with no spark at all if the effective compression ratio is too high.
And comparing the odds, I'd much rather deal with dieseling cause the boost level would have to be stupid high with no spark to cause it, compared to trying to pull fuel and hope there was nothing in the chamber.
ddnspider is offline  
Old 05-22-2019, 08:27 AM
  #10  
TECH Fanatic
Thread Starter
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,640
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by ddnspider View Post
And comparing the odds, I'd much rather deal with dieseling cause the boost level would have to be stupid high with no spark to cause it, compared to trying to pull fuel and hope there was nothing in the chamber.
Yea Iím not brave enough to try cutting fuel. Because consider this. Say the mixture was rich right before the fuel pull and thereís some left. Pull fuel, little bit left ignites. Well youíve got problems.

I do have overboost protection in my controller, which is great if I donít have a wastegate malfunction. I mean usually thatís what causes a overboost mostly anyways (besides creep) and if a line pops off the wastegate, then you have no control either. At least if I dump fuel (and when I say dump fuel, I mean add enough to where is just pig rich but not flooded out) then itíll alert me something is wrong.
Kfxguy is offline  
Old 05-22-2019, 09:31 AM
  #11  
10 Second Club
iTrader: (2)
 
BCNUL8R's Avatar
 
Join Date: Jun 2005
Location: Oskaloosa, Iowa
Posts: 633
Received 2 Likes on 2 Posts
Default

A fuel cut will work. Iíve hit my fuel cut rev limiter without damage enough to know that will work. For what you are trying to do I would go with ddnspider on this and tune for the correct afr under all conditions while pulling timing as a safety net.
BCNUL8R is offline  
Old 05-22-2019, 10:15 AM
  #12  
TECH Senior Member
iTrader: (7)
 
Project GatTagO's Avatar
 
Join Date: Mar 2003
Location: The Druid City
Posts: 7,768
Received 15 Likes on 14 Posts
Default

Why not buy a better wastegate?

Andrew
Project GatTagO is offline  
Old 05-22-2019, 04:49 PM
  #13  
TECH Fanatic
Thread Starter
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,640
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by Project GatTagO View Post
Why not buy a better wastegate?

Andrew
I have a Tial MVR. Do I need to get something else? I thought those were good?
Kfxguy is offline  
Old 05-22-2019, 04:53 PM
  #14  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,803
Received 26 Likes on 25 Posts
Default

Originally Posted by Project GatTagO View Post
Why not buy a better wastegate?

Andrew
A cast unobtainium wastegate won't fix an install/hook up error.
ddnspider is offline  
Old 05-22-2019, 05:18 PM
  #15  
TECH Fanatic
Thread Starter
iTrader: (1)
 
Kfxguy's Avatar
 
Join Date: Apr 2017
Posts: 1,640
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by ddnspider View Post
A cast unobtainium wastegate won't fix an install/hook up error.
a better waste gate wont fix a blown off vaccum line to the wastegate.
Kfxguy is offline  
Old 05-23-2019, 03:01 AM
  #16  
TECH Junkie
iTrader: (1)
 
Join Date: Sep 2004
Location: Stockbridge GA
Posts: 3,099
Likes: 0
Received 0 Likes on 0 Posts
Default

I got lucky once when a map sensor blew out of the intake at 10#s of boost, so I had fueling for 0 boost. The car just laid over with no damage. I'm sure if I had not let off as soon as it laid over something would have been damaged.
gametech is offline  
Old 05-23-2019, 07:38 AM
  #17  
TECH Resident
iTrader: (2)
 
408GT's Avatar
 
Join Date: Jan 2008
Location: GA
Posts: 880
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by Kfxguy View Post
a better waste gate wont fix a blown off vaccum line to the wastegate.
Exactly what I was going to say. The size of the wastegate don't mean you'll never have a boost spike. I had a reference line melt shut and if I had not had a safety setup for over boost, things could have been ugly.
408GT is offline  
Old 05-23-2019, 03:08 PM
  #18  
9 Second Club
 
Join Date: Nov 2003
Location: Norn Iron
Posts: 12,403
Received 4 Likes on 3 Posts
Default

Originally Posted by ddnspider View Post
A cast unobtainium wastegate won't fix an install/hook up error.
So don't install or hook it up wrong ?

It's kinda simple really.
stevieturbo is offline  
Old 05-23-2019, 03:29 PM
  #19  
TECH Senior Member
iTrader: (26)
 
ddnspider's Avatar
 
Join Date: Aug 2004
Location: FL
Posts: 8,803
Received 26 Likes on 25 Posts
Default

Originally Posted by stevieturbo View Post
So don't install or hook it up wrong ?

It's kinda simple really.
Did you see the dude on here who literally installed the entire wastegate backwards??? Not everyone is perfect and stuff happens. That's the point of a fail safe.
ddnspider is offline  
Old 05-23-2019, 03:46 PM
  #20  
9 Second Club
 
Join Date: Nov 2003
Location: Norn Iron
Posts: 12,403
Received 4 Likes on 3 Posts
Default

Originally Posted by ddnspider View Post
Did you see the dude on here who literally installed the entire wastegate backwards??? Not everyone is perfect and stuff happens. That's the point of a fail safe.
Let's be fair though...the sort of person to do that...would probably set up any failsafe incorrectly too.
stevieturbo is offline  

Thread Tools
Search this Thread

About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: